| 1. |
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| 2. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Reading performance in Portuguese children from second to tenth grade with the MNREAD reading acuity test
- 2023
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Ingår i: Journal of Optometry. - : Elsevier. - 1888-4296. ; 16:4, s. 261-267
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo assess reading performance and report normative values for normal sighted Portuguese schoolchildren using the Portuguese version of the MNREAD reading acuity chart.MethodsChildren in the 2nd, 4th, 6th, 8th, and 10th grade in Portugal were recruited for this study. One hundred and sixty-seven children from 7 to 16 years of age participated. The Portuguese version of the printed MNREAD reading acuity chart was used to measure reading performance in these children. The non-linear mixed effects model with negative exponential decay function was used to compute maximum reading speed (MRS) and critical print size (CPS) automatically. Reading acuity (RA) and reading accessibility index (ACC) were computed manually.ResultsThe mean MRS in words-per-minute (wpm) for the 2nd grade was 55 wpm (SD = 11.2 wpm), 104 wpm (SD = 27.9) for the 4th grade, 149 wpm (SD = 22.5) for 6th grade, 172 wpm (SD = 24.6) for 8th grade and 180 wpm for the 10th grade (SD = 16.8). There was a significant difference in MRS between school grades (p < 0.001). Participants’ reading speed increased by 14.5 wpm (95% CL: 13.1–15.9) with each year of increase in age. We found a significant difference between RA and school grades, but not for CPS.ConclusionsThis study provides normative reading performance values for the Portuguese version of the MNREAD chart. The MRS increased with increasing age and school grade, while RA shows initial improvement from early school years and gradually stabilizes in the more mature children. Normative values for the MNREAD test can now be used to determine reading difficulties or slow reading speed in, for example, children with impaired vision.
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| 3. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Scoring reading parameters : An inter-rater reliability study using the MNREAD chart
- 2019
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 14:6, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Purpose First, to evaluate inter-rater reliability when human raters estimate the reading performance of visually impaired individuals using the MNREAD acuity chart. Second, to evaluate the agreement between computer-based scoring algorithms and compare them with human rating. Methods Reading performance was measured for 101 individuals with low vision, using the Portuguese version of the MNREAD test. Seven raters estimated the maximum reading speed (MRS) and critical print size (CPS) of each individual MNREAD curve. MRS and CPS were also calculated automatically for each curve using two different algorithms: the original standard deviation method (SDev) and a non-linear mixed effects (NLME) modeling. Intra-class correlation coefficients (ICC) were used to estimate absolute agreement between raters and/or algorithms. Results Absolute agreement between raters was ‘excellent’ for MRS (ICC = 0.97; 95%CI [0.96, 0.98]) and ‘moderate’ to ‘good’ for CPS (ICC = 0.77; 95%CI [0.69, 0.83]). For CPS, inter-rater reliability was poorer among less experienced raters (ICC = 0.70; 95%CI [0.57, 0.80]) when compared to experienced ones (ICC = 0.82; 95%CI [0.76, 0.88]). Absolute agreement between the two algorithms was ‘excellent’ for MRS (ICC = 0.96; 95%CI [0.91, 0.98]). For CPS, the best possible agreement was found for CPS defined as the print size sustaining 80% of MRS (ICC = 0.77; 95%CI [0.68, 0.84]). Absolute agreement between raters and automated methods was ‘excellent’ for MRS (ICC = 0.96; 95% CI [0.88, 0.98] for SDev; ICC = 0.97; 95% CI [0.95, 0.98] for NLME). For CPS, absolute agreement between raters and SDev ranged from ‘poor’ to ‘good’ (ICC = 0.66; 95% CI [0.3, 0.80]), while agreement between raters and NLME was ‘good’ (ICC = 0.83; 95% CI [0.76, 0.88]). Conclusion For MRS, inter-rater reliability is excellent, even considering the possibility of noisy and/or incomplete data collected in low-vision individuals. For CPS, inter-rater reliability is lower. This may be problematic, for instance in the context of multisite investigations or follow-up examinations. The NLME method showed better agreement with the raters than the SDev method for both reading parameters. Setting up consensual guidelines to deal with ambiguous curves may help improve reliability. While the exact definition of CPS should be chosen on a case-by-case basis depending on the clinician or researcher’s motivations, evidence suggests that estimating CPS as the smallest print size sustaining about 80% of MRS would increase inter-rater reliability.
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| 4. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Scoring reading parameters: an inter-rater reliability study using the MNREAD test
- 2017
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Konferensbidrag (refereegranskat)abstract
- Aim: Estimating MNREAD parameters such as Critical Print Size (CPS) and Maximum Reading Speed (MRS) - using the time taken to read blocks of text - often requires subjective analysis of the reading profile. Depending on the rater, parameters may be over- or under-estimated, resulting in difficult or even impossible between-study comparisons. The aim of this project was to evaluate the inter-rater reliability of MNREAD parameters in subjects with visual impairment. Methods: Reading times for the Portuguese version of the MNREAD chart from 32 subjects, reading binocularly were analyzed. Reading speed was computed by a single experimenter (AFM) using reading time and number of errors. Based on reading speeds, three experimented raters (AFM, AC and KB) computed MRS and CPS using the following method. CPS was defined as the print size at which subsequent smaller print sizes were read at 1.96 x standard deviation slower than the mean of the preceding print sizes; MRS was estimated as the mean reading speed for sentences in print larger than the CPS. Inter-rater reliability was assessed using intra-class correlation (ICC) coefficient for both MRS and CPS for all three raters. Results: Near acuity range was 0.14-1.9 logMAR. The average measure ICC for CPS was 0.896 with a 95% CI from 0.814 to 0.946 (p< 0.001). The average measure ICC for MRS was 0.984 with a 95% CI from 0.970 to 0.992 (p< 0.001). Conclusion: A high degree of reliability was found between the three raters for both CPS and MRS. Even though some small variability exists this may be due to raters’ high-level experience with MNREAD data. Future directions will involve: 1) including more raters with various level of experience in MNREAD rating; 2) investigating the degree of inter-rater reliability for raters using different estimation methods.
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| 5. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Swedish version of the Massof activity inventory to measure vision-related activity difficulties among patients with nAMD
- 2024
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Ingår i: Acta Ophthalmol, vol 102, issue S279: Special Issue:Abstracts from the 2023 European Association for Vision and Eye Research Festival, 26‐28 October 2023, Valencia. - : John Wiley & Sons.
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Konferensbidrag (refereegranskat)abstract
- Aims/Purpose: The aim of this study was to assess vision-related activity difficulties among patients with neovascular AMD using a Swedish version of the mass of activity inventory (MAI). Methods: Participants were patients diagnosed with neovascular AMD receiving treatment for the disease in a hospital in southeast Sweden. Participants completed the Swedish version of the MAI questionnaire. MAI can be used to measure the overall visual ability and visual ability in 4 functional domains: reading, mobility, visual motor function and visual information processing. Best corrected distance and near visual acuity (VA) were also measured. Results: Among the 196 participants (mean age=78.5 years, SD=7.67, 66% female) the median VA in the better seeing eye was 0.18 logMAR (IQR=?0.34), and in the worse eye was 0.54 logMAR (IQR=0.98). The median visual ability for all participants was 1.92 logits (IQR=2.69). There was a significant negative correlation between distance VA in the better eye and visual ability (rho=0.4025, p<0.01). Using ROC curves, we tested the capacity of the MAI to detect cases of any vision impairment (VA worse than 0.3 logMAR in the better seeing eye), the area under the curve (AUC) was 0.717 (95% CI=0.643 - 0.791 p<0.001). When we tested for detection of moderate vision impairment (VA worse than 0.5 logMAR in the better seeing eye) the AUC was 0.738 (95% CI=0.648 - 0.829 p?<0.001). Conclusions: The results indicate that the Swedish version of the MAI produce measures of visual ability that are consistent with clinical measures among patients with nAMD. The Swedish version of the MAI can be used as outcome measure in interventions for people with nAMD.References1. Macedo, A.F. et al. Predictors of problems reported on the EQ-5D-3L dimensions among people with impaired vision in northern Portugal. Health Qual Life Outcomes 2022; 20: 132.
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| 6. |
- Demir, Pelsin, 1994-, et al.
(författare)
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All retinas are not created equal : Fovea‐to‐macula thickness ratio and foveal microvasculature in healthy young children
- 2022
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Ingår i: Ophthalmic & physiological optics. - : John Wiley & Sons. - 0275-5408 .- 1475-1313. ; 42:3, s. 644-652
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Markers for the relationships between structural and microvasculature measures given by optical coherence tomography angiography are necessary to increase the diagnostic and prognostic value of this technique. The aim of this study was to investigate relationships between structural and microvasculature measures around the fovea in healthy eyes of healthy children.Methods: Observational cross-sectional study involving children aged 8–17 years, born at full-term, with no eye disease. The better of two 3 × 3 mm macular scans obtained with a Cirrus 5000HD-OCT was analysed. Images were corrected for lateral magnification errors. Vessel density and perfusion were measured with ImageJ/Fiji software for the superficial capillary plexus. Structural measures including foveal and macular thicknesses were performed manually.Results: The sample included 86 participants, 51 (59%) females. Mean age was 12.4 years (SD = 2.5); mean best-corrected acuity was −0.10 logMAR (SD = 0.09); mean refractive error was +0.59 D (SD = 1.3) and mean axial length was 23.1 mm (SD = 0.86). Mean area of the foveal avascular zone (AFAZ) was 0.20 mm2 (SD = 0.88); median fovea-to-macula thickness ratio (FMTR) was 0.63 (IQR = 0.08); mean central vessel density was 12.42 mm−1 (SD = 2.78) and mean central perfusion was 38.66% (SD = 3.83). AFAZ was correlated with central vessel density (p < 0.001), perfusion (p < 0.001), foveal thickness (p < 0.001) and FMTR (p < 0.001). Central vessel density was correlated with foveal thickness (p < 0.001) and FMTR, (p = 0.01). Central perfusion was correlated with foveal thickness (p < 0.001) and FMTR, (p = 0.003).Conclusion: In this study, foveal thickness, FMTR and foveal microvasculature measurements were correlated. Clinicians need to be aware that shallow foveal pits and persistent foveal microvasculature are likely to occur in optical coherence tomography angiography images. In healthy eyes from healthy children, an atypical high FMTR and a small AFAZ may be associated with incomplete foveal development. The mechanism and functional implications of this remain unknown.
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| 7. |
- Demir, Pelsin, 1994-, et al.
(författare)
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Comparison of an open view autorefractor with an open view aberrometer in determining peripheral refraction in children
- 2023
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Ingår i: Journal of Optometry. - : Elsevier. - 1888-4296. ; 16:1, s. 20-29
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe aim of this study was to compare central and peripheral refraction using an open view Shin-Nippon NVision-K 5001 autorefractor and an open view COAS-HD VR aberrometer in young children.MethodsCycloplegic central and peripheral autorefraction was measured in the right eye of 123 children aged 8 to 16 years. Three measurements each were obtained with both Shin-Nippon NVision-K 5001 autorefractor and COAS-HD VR aberrometer along the horizontal visual field up to 30° (nasal and temporal) in 10° steps. The refraction from the autorefractor was compared with aberrometer refraction for pupil analysis diameters of 2.5-mm and 5.0-mm.ResultsThe Shin-Nippon was 0.30 D more hyperopic than COAS-HD VR at 2.5-mm pupil and 0.50 D more hyperopic than COAS-HD VR at 5-mm pupil for central refraction. For both pupil sizes, the 95% limits of agreement were approximately 0.50 D for central refraction, and limits were wider in the nasal visual field compared to the temporal visual field. The mean difference for both J0 and J45 were within 0.15 D and the 95% limits of agreement within 0.90 D across the horizontal visual field.ConclusionDefocus components were similar between the Shin-Nippon autorefractor and the COAS-HD VR aberrometer with a 2.5-mm pupil for most visual field angles. However, there was a significant difference in defocus component between the Shin-Nippon autorefractor and the COAS-HD VR aberrometer with a 5.0-mm pupil, wherein the autorefractor measured more hyperopia. The astigmatic components J0 and J45 were similar between instruments for both central and peripheral refraction.
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| 8. |
- Demir, Pelsin, 1994-, et al.
(författare)
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Incidence of myopia in Swedish schoolchildren : A longitudinal study.
- 2024
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Ingår i: Ophthalmic & physiological optics. - : John Wiley & Sons. - 0275-5408 .- 1475-1313. ; 44:6, s. 1301-1308
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The prevalence of myopia in Scandinavia tends to be lower than in other parts of the world. This study aimed to investigate the incidence of myopia and its predictors in Swedish children to characterise this trend.METHODS: A 2-year longitudinal study was conducted following a cohort of schoolchildren aged 8-16 years. Myopia was defined as a spherical equivalent refraction (SER) ≤ -0.50 D. The study enrolled 128 participants, 70 (55%) females with a mean age of 12.0 years (SD = 2.4).RESULTS: The cumulative incidence of myopia during the follow-up period was 5.5%, and the incidence rate of myopia was 3.2 cases per 100 person-years. Participants with myopia at baseline exhibited a faster increase in refractive error during the follow-up period. Likewise, participants with two myopic parents exhibited a more marked change towards myopia, regardless of their initial refractive error.CONCLUSION: In the current study, similar to prevalence, the incidence of myopia was low when compared with other parts of the world. These results lead us to formulate a new hypothesis that the normal emmetropisation process may be protected by low educational pressure practised in Sweden during early childhood. Further research is necessary to test this new hypothesis.
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| 9. |
- Demir, Pelsin, 1994-
(författare)
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Prevalence of refractive errors and incidence of myopia in Swedish schoolchildren
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- PurposeThe aim of this thesis was to investigate the prevalence, incidence, and risk factors for myopia development in a cohort of Swedish schoolchildren. The specific goals were: - to recruit a cohort of children aged 8 to 16 years and to follow the cohort over a period of 24 months with regular study visits; - to investigate the predictive value of relative peripheral error and other optical parameters for the prevalence and incidence of myopia; - to determine and investigate the predictive value of genetic and environmental factors, and structural characteristics of the eye to the incidence of myopia.MethodsThis was a longitudinal study with a follow-up period of 2-years conducted at Linnaeus University in Kalmar. All participants underwent eye examinations and completed questionnaires at regular intervals during the follow-up period. Data analysis was performed assuming hypotheses such as: - myopia development is associated with genetic factors and environmental factors (Papers I and IV); - changes in refractive error over time are explained by multiple genetic and environmental factors (Paper IV) - instruments with different measurement principles can lead to different refraction results (Paper II); - there is a relationship between refractive error and the characteristics of the choroid (Exploratory study, not published) and the characteristics of the microvasculature of the retina (Paper III).ResultsA total of 128 children (70 females and 58 males) participated in this study with mean age of 12.0 years (SD=2.4). Paper I: based on cycloplegic SER of the right eye, the distribution of refractive errors was: hyperopia 48.0% (CI95=38.8-56.7), emmetropia 42.0% (CI95=33.5-51.2) and myopia 10.0%. (CI95=4.4-14.9). Participants with two myopic parents had higher myopia and increased axial length than those with one or no myopic parents. Paper II: The Shin-Nippon was 0.30 D more hyperopic than COAS-HD VR at 2.5-mm pupil and 0.50 D more hyperopic than COAS-HD VR at 5-mm pupil for central refraction. Paper III: The sample included 86 out of the 128 participants, 51 (59%) females. The area of the foveal avascular zone (AFAZ) was correlated with central vessel density, perfusion, foveal thickness and with fovea-to-macula thickness ratio. Paper IV: The cumulative incidence of myopia during the two-years was 5.5%, incidence rate of myopia was 3.2 cases per 100 person-years. Cox regression revealed that the probability of myopic shift reduced with “age” and increased with “axial length/corneal-curvature ratio”. Myopic children at the baseline and children with two myopic parents showed a significant faster-paced SER change over time.ConclusionThe prevalence and incidence of myopia in Sweden was lower than expected when compared with countries in East Asia. Genetic factors such as parental myopia remains a critical factor to consider when predicting myopia onset and progression. Children born full-term and visual acuity within the normal range can have very different retinal microvasculature at the centre of the macula that may influence refractive error development. Future studies are necessary to find out possible relationships between vasculature, structural changes and refractive error development. In addition, more studies involving children from different ethnicities and incorporating longer follow-up period are necessary to increase our understanding of the incidence of myopia in Swedish schoolchildren.
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| 10. |
- Demir, Pelsin, 1994-, et al.
(författare)
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Refractive error, axial length, environmental and hereditary factors associated with myopia in Swedish children
- 2021
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Ingår i: Clinical and experimental optometry. - : Taylor & Francis Group. - 0816-4622 .- 1444-0938. ; 104:5, s. 595-601
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Tidskriftsartikel (refereegranskat)abstract
- Clinical relevance: Investigation of refractive errors amongst Swedish schoolchildren will help identify risk factors associated with myopia development.Background: Genetic and hereditary aspects have been linked with the development of myopia. Nevertheless, in the case of ‘school myopia’ some authors suggest that environmental factors may affect gene expression, causing school myopia to soar. Additional understanding about which environmental factors play a relevant role can be gained by studying refractive errors in countries like Sweden, where prevalence of myopia is expected to be low.Methods: Swedish schoolchildren aged 8-16 years were invited to participate. Participants underwent an eye examination, including cycloplegic refraction and axial length (AL) measurements. Predictors such as time spent in near work, outdoor activities and parental myopia were obtained using a questionnaire. Myopia was defined as spherical equivalent refraction (SER) ≤ −0.50D and hyperopia as SER ≥ +0.75D.Results: A total of 128 children (70 females and 58 males) participated in this study with mean age of 12.0 years (SD = 2.4). Based on cycloplegic SER of the right eye, the distribution of refractive errors was: hyperopia 48.0% (CI95 = 38.8-56.7), emmetropia 42.0% (CI95 = 33.5-51.2) and myopia 10.0%. (CI95 = 4.4-14.9). The mean AL was 23.1 mm (SD = 0.86), there was a correlation between SER and AL, r = −0.65 (p < 0.001). Participants with two myopic parents had higher myopia and increased axial length than those with one or no myopic parents. The mean time spent in near work, outside of school, was 5.3 hours-per-day (SD = 3.1), and mean outdoor time reported was 2.6 hours-per-day (SD = 2.2) for all the participants. The time spent in near work and outdoor time were different for different refractive error categories.Conclusion: The prevalence of myopia amongst Swedish schoolchildren is low. Hereditary and environmental factors are associated with refractive error categories. Further studies with this sample are warranted to investigate how refractive errors and environmental factors interact over time.
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| 11. |
- Hernandez-Moreno, Laura, et al.
(författare)
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Absent Foveal Pit, Also Known as Fovea Plana, in a Child without Associated Ocular or Systemic Findings
- 2018
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Ingår i: Case Reports in Ophthalmological Medicine. - : Hindawi Publishing Corporation. - 2090-6722 .- 2090-6730. ; , s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this report is to describe a case of bilateral foveal hypoplasia in the absence of other ophthalmological or systemic manifestations. We characterize the case of a 9-year-old Caucasian male who underwent full ophthalmologic examination, including functional measures of vision and structural measurements of the eye. Best corrected visual acuity was 0.50 logMAR in the right eye and 0.40 logMAR in the left eye. Ophthalmoscopy revealed a lack of foveal reflex that was further investigated. Optical coherence tomography (OCT) confirmed the absence of foveal depression (pit). OCT images demonstrated the abnormal structure of retina in a region in which we expected a fovea; these findings were decisive to determine the cause of reduced acuity in the child.
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| 12. |
- Miranda, Antonio Miguel, et al.
(författare)
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Eye movements, convergence distance and pupil-size when reading from smartphone, computer, print and tablet
- 2018
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Ingår i: Scandinavian Journal of Optometry and Visual Science. - : The Norwegian Association of Optometry. - 1891-0882 .- 1891-0890. ; 11:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the use of eye-tracking glasses to monitor visual behaviour when reading from electronic devices and paper in free-viewing conditions. The Tobii-Pro-Glasses were used to monitor 20 subjects with normal vision during reading tasks. Reading was performed in a smartphone, computer, paper and tablet. Texts from the IReST-test were read in devices in a random order. Participants read one text in each device and then repeated the same task 1 hour later; in total each participant read eight different texts. The sequence for the devices was randomized. We found differences between devices for saccade amplitude, fixation duration, convergence distance and pupil size. Reading speed between computer and tablet was slightly different (8 words-per-minute) and pupil size reduced up to 20% in electronic devices compared to print. Behavioural changes observed whilst reading from different devices may reflect an attempt from readers to optimize performance. The need to maintain visual performance under different visual condition may lead to increased visual symptoms. Eye-tracking glasses could be a valuable tool to investigate visual aspects of digital strain.
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| 13. |
- Rodrigues, Clarinda, et al.
(författare)
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An eye tracking study of the effect of sensory and price in-store displays
- 2020
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Ingår i: Emotional, sensory, and social dimensions of consumer buying behavior. - Hershey, PA, USA : IGI Global. - 9781799822202 - 9781799822226 - 1799822206 - 9781799822219 ; , s. 23-49
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Using eye tracking, this chapter investigates if the visual attention varies according to the in-store displays message content (price, sensory, and price-sensory). Results show that participants are more responsive to cognitive content messages (price) than affective messages (sensory) alone. Nevertheless, it is demonstrated that participants are prone to devote more time processing in-store displays messages if prices (cognitive stimuli) are combined with sensory messages (affective stimuli), which increases the likelihood of choosing low involvement products. Finally, it was demonstrated that total fixation duration is predictive of low involvement product choice for all home décor products. This study suggests that shoppers might spend more time and effort searching for low involvement products if in-store displays captivate their visual attention and elicit their sensory imagery. Sensory messages can be used by retailers to highlight product intrinsic characteristics. At the same time, they are inducing positive feelings towards low-involvement products.
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| 14. |
- Akram, Muhammad Nadeem, et al.
(författare)
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Improved wide-field emmetropic human eye model based on ocular wavefront measurements and geometry-independent gradient index lens
- 2018
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Ingår i: Optical Society of America. Journal A. - : Optical Society of America. - 1084-7529 .- 1520-8532. ; 35:11, s. 1954-1967
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Tidskriftsartikel (refereegranskat)abstract
- There is a need to better understand the peripheral optics of the human eye and their correction. Current eye models have some limitations to accurately predict the wavefront errors for the emmetropic eye over a wide field. The aim here was to develop an anatomically correct optical model of the human eye that closely reproduces the wavefront of an average Caucasian-only emmetropic eye across a wide visual field. Using an optical design program, a schematic eye was constructed based on ocular wavefront measurements of the right eyes of thirty healthy young emmetropic individuals over a wide visual field (from 40° nasal to 40° temporal and up to 20° inferior field). Anatomical parameters, asymmetries, and dispersion properties of the eye’s different optical components were taken into account. A geometry-independent gradient index model was employed to better represent the crystalline lens. The RMS wavefront error, wavefront shapes, dominant Zernike coefficients, nasal-temporal asymmetries, and dispersion properties of the developed schematic eye closely matched the corresponding measured values across the visual field. The developed model can help in the design of wide-field ophthalmic instruments and is useful in the study and simulations of the peripheral optics of the human eye.
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| 15. |
- Alahamami, Mastour A., et al.
(författare)
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Comparison of cysts in red and green images for diabetic macular edema
- 2014
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Konferensbidrag (refereegranskat)abstract
- Purpose: To improve the detection of macular cyst with photoscreening, we tested whether in a population of largely minority patients the red channel image from a color fundus camera visualizes cysts in diabetic macular edema better than the green channel image. In assessing diabetic retinas for clinically significant macular edema, the presence of cysts must be judged with respect to the central macula. Some grading programs use red free images, often derived from green channel images, to enhance visualization of retinal vessel damage or macular pigment, but some red and near infrared instruments have detected cysts better than short wavelength techniques. Methods: We evaluated macular cysts in 13 diabetic patients diagnosed with clinically significant macular edema, age range 33-68 years. Diabetic patients were selected from the screening study of >2000 underserved patients seen at Eastmont Wellness Center, Oakland, CA. Patients underwent photoscreening with a nonmydriatic color fundus camera (Canon Cr-DGi, Tokyo, Japan) and SD-OCT (iVue, Optovue Inc, Fremont, CA). The color fundus images for those patients were transformed into red and green channels to evaluate the appearance of macular cysts in red channel images and green channel images. The region of each cyst was compared SD-OCT scans (Adobe Photoshop CS5.1, San Jose, CA). Only cysts touching the central 1 mm around the fixation from the SD-OCT scans were sampled. Results: The average size of retinal cysts in red channel images, 124.57 µm (±106.96), was significantly greater than in green channel, 59.44 µm (±76.6), (p<0.006). Entire cysts could not be seen in 5 eyes in the green channel images. Conclusions: Our results indicate that the grading of cysts in the central macular might be improved by incorporating red channel images. There are a number of potential factors that could make cysts less visible in the green channel images, including poorer light penetration through to the deeper retina or macular pigment. Anterior segment issues impact more on green channel images. This population includes mostly minority patients who have dark fundi, and darker images.
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| 16. |
- Alahamami, Mastour A., et al.
(författare)
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Investigation of Photoreceptors in Diabetic Macular Edema
- 2014
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Ingår i: IOVS. - Orlando, Florida, USA.
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Konferensbidrag (refereegranskat)abstract
- Abstract Purpose: To evaluate the photoreceptor integrity in diabetic patients with macular edema using spectral domain optical coherence tomography (SD-OCT) Methods: We compared macular thickness in diabetic patients with and without macular edema to determine the role of damage to the external limiting membrane (ELM) or photoreceptors. Diabetic patients were selected from the screening study of > 2000 minority patients seen at Eastmont Wellness Center, Oakland, CA. Patients underwent photoscreening with a Canon Cr-DGi nonmydriatic camera (Tokyo, Japan) and an iVue OCT (Optovue Inc, Fremont, CA). Retinal scans of 70 diabetic patients, age range 33-68 yr., were selected so that A) 50% of patients had clinical significant macular edema (CSME), as diagnosed by the presence of hard exudates within 1 disc diameter from the fovea in the color photos, B) the full range of central macular thicknesses in our population was included. And C) patients with CSME were the same age as those not diagnosed with CSME. We graded the retinal scans according to the external limiting membrane (ELM) integrity; 6 patients had damaged ELM and the remaining 64 had intact ELM. Similarly, we graded the retinal scans according to the photoreceptor integrity; 14 patients had damaged photoreceptors and the remaining 56 had intact photoreceptors Results: Average retinal thickness was 254 µm (±57.4) and 356 µm (±95.9) in patients with intact and damaged ELM, respectively; and was 240 µm (±30.0), and 363 µm (±90.0) in patients with intact and damaged photoreceptors, respectively. Retinal thickness means were significantly greater for patients with damaged compared with intact ELM ( P=0.031). Similarly, Retinal thickness means in patients with damaged photoreceptors were significantly greater compared to patients with intact photoreceptors ( P = 0.0001). We also observed that all 6 patients who have damaged ELM were diagnosed with CSME, but were not significantly older than the diabetic patients not diagnosed with CSME ( P = 0.393) Conclusions: ELM and photoreceptor layer damage are found more often when retinal thickness exceeds 355 µm. It is not known if this outer retinal damage is the result of the edema or whether there is more edema because the outer retinal blood brain barrier is failing
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| 17. |
- Arthur, Edmund, et al.
(författare)
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Central Macular Thickness in Diabetic Patients : A Sex-based Analysis
- 2019
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Ingår i: Optometry and Vision Science. - : American Academy of Optometry. - 1040-5488 .- 1538-9235. ; 96:4, s. 266-275
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Tidskriftsartikel (refereegranskat)abstract
- SIGNIFICANCE The pathological changes in clinically significant diabetic macular edema lead to greater retinal thickening in men than in women. Therefore, male sex should be considered a potential risk factor for identifying individuals with the most severe pathological changes. Understanding this excessive retinal thickening in men may help preserve vision. PURPOSE The purpose of this study was to investigate the sex differences in retinal thickness in diabetic patients. We tested whether men with clinically significant macular edema had even greater central macular thickness than expected from sex differences without significant pathological changes. This study also aimed to determine which retinal layers contribute to abnormal retinal thickness. METHODS From 2047 underserved adult diabetic patients from Alameda County, CA, 142 patients with clinically significant macular edema were identified by EyePACS-certified graders using color fundus images (Canon CR6-45NM). First, central macular thickness from spectral domain optical coherence tomography (iVue; Optovue Inc.) was compared in 21 men versus 21 women without clinically significant macular edema. Then, a planned comparison contrasted the greater values of central macular thickness in men versus women with clinically significant macular edema as compared with those without. Mean retinal thickness and variability of central macular layers were compared in men versus women. RESULTS Men without clinically significant macular edema had a 12-μm greater central macular thickness than did women (245 ± 21.3 and 233 ± 13.4 μm, respectively; t40 = −2.18, P = .04). Men with clinically significant macular edema had a 67-μm greater central macular thickness than did women (383 ± 48.7 and 316 ± 60.4 μm, P < .001); that is, men had 55 μm or more than five times more (t20 = 2.35, P = .02). In men, the outer-nuclear-layer thickness was more variable, F10,10 = 9.34. CONCLUSIONS Underserved diabetic men had thicker retinas than did women, exacerbated by clinically significant macular edema.
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| 18. |
- Arthur, Edmund, et al.
(författare)
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Individual Retinal Layer Thickness in Diabetic Patients with Clinically Significant Macular Edema : A Gender Based Analysis
- 2016
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Konferensbidrag (refereegranskat)abstract
- Purpose: To compare segmented retinal layer thicknesses between male and female diabetics with clinically significant macular edema (CSME). This study expands our earlier analysis of central macular thickness (CMT) measurements in diabetic males vs. females. Methods: Diabetic retinopathy screening of 2080 diabetics from Alameda County, CA, indicated 142 patients with CSME, as judged by EyePACS certified graders using color fundus images (Canon CR6-45NM). Of the 2080 diabetics, 1784 were imaged with SD-OCT (Optovue iVue). From the 142 patients, we selected 11 males with good fixation, CMT > 300 µm, and no other ocular complications, along with 11 females with the greatest values of CMT while controlling for age, HbA1c and diabetes duration. Manual segmentation of retinal layers using custom software (Mathworks Matlab) of the SD-OCT images of these subjects was done. We analyzed thicknesses for regions 1 deg - 2 deg for nasal and temporal retina in a B-scan centered on the fovea. A 2 X 2 ANOVA probed the differences in thickness for gender, meridian, and their interaction. We also analyzed the central 1 mm of the outer retinal layers, and performed t-tests. Results: Males had significantly thicker nerve fiber layer (NFL) (13.30 ± 2.85 µm) than females (10.13 ± 6.13 µm) and ganglion cell layer-inner plexiform layer (GCL-IPL) (62.54 ± 21.18 µm) than females (48.07 ± 25.91 µm), p < 0.05. There was no effect of meridian and no interaction (p > 0.05). All other layers except the retinal pigment epithelium (RPE) were thicker for males than females even though these were not significant (p > 0.05). There were no significant differences for the layers of the outer retina, which were highly variable and distorted by cysts. Conclusion: Outside the fovea, NFL and GCL-IPL thicknesses were significantly higher in males than females.
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| 19. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Closed circuit driving performance in persons with quadrantanopia and hemianopia in Sweden
- 2016
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Ingår i: Scandinavian Journal of Optometry and Visual Science. - 1891-0882 .- 1891-0890. ; 9:2, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, persons with homonymous visual field defects (HVFDs) are not allowed to drive and usually their driving licences are revoked. Although earlier studies (de Haan et al. 2014; Elgin et al. 2010) have shown that HVFDs do not necessarily impair practical fitness to drive, the Swedish transport agency does not allow them any on-road driving testing to prove their practical fitness to drive. The aim of this study was to evaluate driving performance in participants with visual field defects after acquired brain injury in a closed circuit driving track. Eleven former drivers with varying degrees of quadrantanopia and hemianopia after acquired brain damage were recruited for this study from the stroke rehabilitation department at Kalmar County Hospital. The median age of the participants was 55 years and their age ranged from 37 to 73 years. Driving performance was assessed by two experienced driving instructors. They graded the participants on a scale from 1 (major faults) to 5 (excellent) on the following five categories: manoeuvring the vehicle, risk assessment, traffic rules, visual scanning and situation awareness. The subject would pass the driving test only if they had scored 3 or more in each category. The subjects who passed the closed circuit driving track test were evaluated further with a driving simulator. Five (45%) out of 11 participants passed the driving test and were adjudged as fit to drive. The remaining six (55%) participants failed in at least one category. Three failed in visual scanning, two failed in manoeuvring and one failed in both the aforementioned categories as well as risk assessment. Three subjects who passed the closed circuit driving track test were also evaluated in a driving simulator. Out of the three subjects, only one was able to complete and pass the evaluation while the remaining two participants aborted the evaluation due to simulator sickness. Homonymous visual field defects do not necessarily impair fitness to drive. Therefore, an on-road assessment of practical fitness to drive should be allowed in Sweden for this population in the near future. The decision on practical fitness to drive cannot be based solely on the presence of visual field defects. A rehabilitation program aimed at improving safe driving should be put into practice with an on-road driving training and assessment procedure. It should be developed and implemented by experienced traffic inspectors as a complementary part of the decision to either issue or revoke a driving licence for this population.
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| 20. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Driving performance in participants with quadrantanopia and hemianopia in Sweden : a closed circuit driving track study
- 2015
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Konferensbidrag (refereegranskat)abstract
- Background: The ability to drive a car is one of the important aspect of a person’s independent lifestyle. People with visual field defects after stroke or traumatic brain injury (TBI) have more limitations in driving. In Sweden, they are not allowed to drive and their driving licenses are revoked. The Swedish transport agency does not allow any on-road test for them to prove their practical fitness to drive. Therefore, the aim was to evaluate driving performance in participants with visual field defects after TBI in a closed circuit driving track.Methods: Eleven participants with varying degrees of quadrantanopia and hemianopia after TBI were recruited for this study. The mean age of the participants was 58 ±13.7 years (37 - 73 years). All participants underwent 10 weeks of explorative saccadic training at the hospital prior to driving assessment. Driving performance were assessed by two driving instructors and they graded the participants from 1 (fail) to 5 (excellent) on the following five categories: maneuvering the vehicle, safety margin, traffic rules, scanning for potential hazards and reacting to situations. The subject passed the driving test only if they scored 3 or more in each category.Results: Five (45%) out of 11 participants passed the driving test and they were adjudged as fit to drive. Remaining six (55%) participants failed at least in one category. Three of them failed in visual scanning, two failed in maneuvering and one failed in both the aforementioned categories as well as safety margin.Discussion: A rehabilitation program aimed at improving safe driving should be implemented and an on-road assessment of fitness to drive should be allowed in Sweden for this population in future.Conclusion: The decision on practical fitness to drive cannot be based solely on the presence of visual field defect and an on-road assessment is required.
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| 21. |
- Baskaran, Karthikeyan, Senior Lecturer, 1983-, et al.
(författare)
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Effect of accommodation on peripheral refraction in myopes and emmetropes using a COAS-HD VR open field aberrometer.
- 2016
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Konferensbidrag (refereegranskat)abstract
- Purpose To investigate the effect of accommodation on both central and peripheral refractive errors in myopes compared to emmetropes using a COAS-HD VR open field aberrometer. Methods 15 myopic subjects (-1.50 D to -8.25 D) and 14 emmetropic subjects (+0.75 D to -0.25 D) participated in this study. The mean age of the myopic group was 24.3 ± 5.7 years and for the emmetropic group was 23.9 ± 5.7 years. Central and peripheral refraction were measured with a COAS-HD VR open field instrument at seven different eccentricities from 0° to ± 30° in 10° steps for three different accommodative demands 0.33 D, 2.50 D and 4.0 D during monocular viewing. The myopic subjects were corrected with soft contact lenses and the measurements were performed on the right eye for a 3 mm pupil diameter for both groups. Relative peripheral refractive error (RPRE) was calculated for all three accommodative demands for both groups. Results Repeated measures ANOVA showed no significant difference in RPRE across eccentricities or between accommodation demands in the myopes (pÂż0.05). The myopic group had minimal hyperopic shift in the periphery for all three accommodative demands. The largest mean hyperopic shift was 0.37 D at 30° nasal retina for an accommodative demand of 4.0 D. On the other hand, the emmetropic group became relatively myopic at peripheral eccentricities, from 20° onwards for all three accommodative demands. The largest mean myopic shift was 1.01 D at 30° temporal retina for an accommodative demand of 2.50 D. Conclusion In the myopic group, we did not find any significant reduction in hyperopic shift in the periphery with accommodation. The emmetropic group showed myopic shift in the periphery for all three accommodative demands with temporal retina being more myopic than nasal retina.
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| 22. |
- Boström, Johanna, et al.
(författare)
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Meibography: Inter-rater reliability
- 2016
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Ingår i: 8th International Conference on the Tear Film & Ocular Surface: Basic Science and Clinical Relevance. ; , s. 47-
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Konferensbidrag (refereegranskat)abstract
- Purpose. The tear film lipid layer holds an important role in maintaining the integrity and health of the anterior surface of the eye. The meibomian glands found in eyelids are responsible for producing most of the lipids of the tear film. Dysfunction of the meibomian glands leads to increased evaporation of tears, which may lead to dry eye. Meibography is a method used for assessing the drop out of meibomian glands. The aim of this study was to evaluate the reliability between two different examiners when rating meibography images. Methods. The Sirius 3D scheimpflug camera (C.S.O., Florence, Italy) was used to photograph the everted upper and lower eyelids of the right and left eye of 52 subjects. The grade of meibomian gland loss was subjectively graded using the five-grade Meiboscale (Pult, 2012) and the percentage of gland loss was calculated using Phoenix Meibography software (version 3.0.1.021, bon Optic VertriebsGmbH, Lübeck, Germany). Data was analyzed using MedCalc for Windows (version 16.4.3, MedCalc Software, Ostend, Belgium). Results. The inter-rater reliability for the Meiboscale grade of meibomian gland loss was calculated using weighted Cohen’s kappa (linear weights). The result for all 208 images was Kw = 0.542 (95 % CI 0.454 to 0.630), which indicates a moderate agreement. The inter-rater reliability for the percentage of meibomian gland loss was calculated using intraclass correlation coefficient. The result for all 208 images was ICC = 0.794 (95 % CI 0.737 to 0.839), which indicates a substantial agreement. Conclusions. Imaging is an invaluable tool when managing patients in clinical practice. When performing meibography to evaluate meibomian gland loss, using software to calculate the percentage of gland loss gives a better inter-rater agreement than subjective grading of the images.
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| 23. |
- Chakraborty, Ranjay, et al.
(författare)
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The effect of intrinsically photosensitive retinal ganglion cell (ipRGC) stimulation on axial length changes to imposed optical defocus in young adults
- 2023
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Ingår i: Journal of Optometry. - : Elsevier. - 1888-4296. ; 16:1, s. 53-63
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The intrinsically photosensitive retinal ganglion cells (ipRGCs) regulate pupil size and circadian rhythms. Stimulation of the ipRGCs using short-wavelength blue light causes a sustained pupil constriction known as the post-illumination pupil response (PIPR). Here we examined the effects of ipRGC stimulation on axial length changes to imposed optical defocus in young adults.Materials and methods: Nearly emmetropic young participants were given either myopic (+3 D, n = 16) or hyperopic (-3 D, n = 17) defocus in their right eye for 2 h. Before and after defocus, a series of axial length measurements for up to 180 s were performed in the right eye using the IOL Master following exposure to 5 s red (625 nm, 3.74 × 1014 photons/cm2/s) and blue (470 nm, 3.29 × 1014 photons/cm2/s) stimuli. The pupil measurements were collected from the left eye to track the ipRGC activity. The 6 s and 30 s PIPR, early and late area under the curve (AUC), and time to return to baseline were calculated.Results: The PIPR with blue light was significantly stronger after 2 h of hyperopic defocus as indicated by a lower 6 and 30 s PIPR and a larger early and late AUC (all p<0.05). Short-wavelength ipRGC stimulation also significantly exaggerated the ocular response to hyperopic defocus, causing a significantly greater increase in axial length than that resulting from the hyperopic defocus alone (p = 0.017). Neither wavelength had any effect on axial length with myopic defocus.Conclusions: These findings suggest an interaction between myopiagenic hyperopic defocus and ipRGC signaling.
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| 24. |
- Chakraborty, Ranjay, et al.
(författare)
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The intrinsically photosensitive retinal ganglion cell (ipRGC) mediated pupil response in young adult humans with refractive errors
- 2022
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Ingår i: Journal of Optometry. - : Elsevier. - 1888-4296. ; 15:2, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, with axons projected to the midbrain that control pupil size and circadian rhythms. Post-illumination pupil response (PIPR), a sustained pupil constriction after short-wavelength light stimulation, is an indirect measure of ipRGC activity. Here, we measured the PIPR in young adults with various refractive errors using a custom-made optical system. Methods PIPR was measured on myopic (−3.50 ± 1.82 D, n = 20) and non-myopic (+0.28 ± 0.23 D, n = 19) participants (mean age, 23.36 ± 3.06 years). The right eye was dilated and presented with long-wavelength (red, 625 nm, 3.68 × 1014 photons/cm2/s) and short-wavelength (blue, 470 nm, 3.24 × 1014 photons/cm2/s) 1 s and 5 s pulses of light, and the consensual response was measured in the left eye for 60 s following light offset. The 6 s and 30 s PIPR and early and late area under the curve (AUC) for 1 and 5 s stimuli were calculated. Results For most subjects, the 6 s and 30 s PIPR were significantly lower (p < 0.001), and the early and late AUC were significantly larger for 1 s blue light compared to red light (p < 0.001), suggesting a strong ipRGC response. The 5 s blue stimulation induced a slightly stronger melanopsin response, compared to 1 s stimulation with the same wavelength. However, none of the PIPR metrics were different between myopes and non-myopes for either stimulus duration (p > 0.05). Conclusions We confirm previous research that there is no effect of refractive error on the PIPR.
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| 25. |
- Elsner, Ann E., et al.
(författare)
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Underserved diabetic patients with refractive errors insufficient to lead to seeking eyecare
- 2015
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Konferensbidrag (refereegranskat)abstract
- Purpose: The increase in prevalence of diabetes is anticipated to increase the numbers of patients needing eye examinations. For our Phase II SBIR data, we reported that for > 2000 underserved diabetic patients in Alameda County, California, > 60% of patients reported no eye examination for at least 3 years despite that free photo diabetic retinopathy screenings were offered with follow on examination and eyecare. If eye screening for diabetic patients is not mandated, it becomes the responsibility of the patient or their primary care physician or endocrinologist to understand and act on the need for eye examinations. Methods: From the Alameda Health system of clinics, 197 diabetic patients agreed to be photoscreened for diabetic retinopathy. Our sample was enriched to have an increased probability of eye complications; thus, 26% had no apparent diabetic retinopathy; 38%, 17% and 4% had mild, moderate and severe non-proliferative diabetic retinopathy; and 13% had proliferative diabetic retinopathy. Of the 141 patients with diabetic retinopathy, 29% had bilateral CSME. Of the 132 diabetic patients (67 males and 65 females) returning for full eye exams, 52% were Hispanic, 21% African American, 14% Asian, and 8% NonHispanic Caucasian and Other, with an average age of 58.1 ± 9.4 years. Refractive errors were defined as spherical equivalent (SE) refraction, calculated as the spherical power plus one-half of the cylindrical power. Results: The overall mean spherical equivalent refraction M was −0.16 ± 1.50 D in the right eye (−6.0 D to +3.0 D) and +0.14 ± 1.35 D (−7.0 D to +4.0 D) in the left eye. Out of 132 patients, eight patients (6.1%) had visual acuity worse than 0.3 logMAR in both eyes. The right eyes of four patients and left eyes of eight patients had visual acuity worse than 0.3 logMAR, with fellow eyes having normal visual acuity. Conclusions: In a sample of largely minority, working age adults, there was very little refractive error and relatively good visual acuity when refracted, despite diabetic retinopathy or diabetic macular edema. Thus, working age diabetic patients may not regularly seek eye care for spectacle correction that would lead to the detection of diabetic retinopathy or diabetic macular edema.
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| 26. |
- Green, Jason J. A., et al.
(författare)
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Retina Artery to Vein Intensity Ratio as a Function of Wavelength and Dark-Field Offset With Low Cost Ophthalmoscope
- 2014
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Konferensbidrag (refereegranskat)abstract
- PurposeTo quantify light return from retinal vessels for oxygenation status. To use a low-cost Digital Light Ophthalmoscope (DLO) based on a novel structured light pattern Digital Light Projector for quantitative retinal imaging. MethodsFive normal subjects of ages 27-63 and various eye colors were imaged without mydriasis. The DLO produced a progressively scanning 6 pixel wide stripe, 96 stripe illumination pattern (85 μm stripe width at retina) with LEDs at 635 +/- 25nm (Red) and 535 +/- 70nm (Green) with a constant fixation target location across tests. The illumination was synchronized to a 13.2 Hz rolling shutter CMOS sensor (11 μm resolution at retina). To collect the light return from the retina at varying light multiply scattered levels, aperture offset was varied in position with respect to the illumination centerline: dark-field mode was obtained with large offsets and confocal mode had small offsets, where offset was varied from -517 μm (row start 30) to 1353 μm (row start 200). Multiple images of 12 bit dynamic range were captured in sequence, aligned with translational cross correlation, then time averaged to reduce noise. The artery and vein gray scale intensity level was measured at vessel centers for: 1) both vessels over background retina and 2) artery over the optic disc and vein over background. Mean-to-mean intensity ratios were then compared. ResultsWith an aperture width of 704 μm, intensity varied by 2.60 bits (a factor of 4.5) for each subject per condition: red, green, artery, and vein, 3.39 bits if same subject and condition (2.3% Red A/V ratio CoV σ/μ), and by 5.07 bits over all tests. Yet, the ratio (Red/Green Artery)/(Red/Green Vein) was close to unity across offsets and linear fits had an R^2 regression of, for case 1: 0.72, 0.06, 0.25, 0.18, and 0.49, and case 2: 0.0005, 0.89, 0.75, 0.50, and 0.18. The Artery/Vein ratio trend slopes, intercept points, and inversions varied between subjects, i.e. contrast reversals were observed. ConclusionsThe DLO can be utilized electronically to effectively perform quantitative fundus imaging at both Red and Green wavelengths, which is a step towards performing oximetry. 77 is zero offset
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| 27. |
- Muller, Matthew S., et al.
(författare)
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Real-Time Retinal Imaging with Integrated Visual Function Testing Using the Digital Light Ophthalmoscope
- 2014
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Ingår i: IOVS. - Orlando, Florida, USA.
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Konferensbidrag (refereegranskat)abstract
- Abstract Purpose: To perform low cost fixation stability assessment and kinetic perimetry during live fundus viewing using the Digital Light Ophthalmoscope (DLO). Methods: Kinetic perimetry was performed on 12 undilated normal subjects aged 25 - 63 with real-time confocal retinal imaging using the DLO. Having similar functionality to a Scanning Laser Ophthalmoscope, but at far lower cost, the DLO uses a single digital light projector to provide both the illumination for confocal imaging, and the stimuli for visual function measurements. Confocal retinal imaging is performed at 20 Hz with a 35.1 deg field of view. The imaging illumination is provided by a red 630 nm LED, with 40 µW time-averaged power at the cornea. Stimuli are shown in black over the red imaging illumination and are operator controlled in shape and position in real-time. The black stimuli are easily seen by the subject and are also clearly visible on the live view of the fundus. Subjects were instructed to stare at a fixation target while a Goldman V size (1.72 deg diameter) target was presented near the optic nerve head. The path taken by the stimulus was guided by one of eight meridians that converged at a point on the optic nerve head. The meridians were equally separated by 45 deg, and 7 deg long. Each stimulus moved incrementally outwards, from “not seen” to “seen”, at approximately 2.5 deg per sec. Once the stimulus was seen by the subject, an 8 image frame buffer was saved. Fixation stability was separately measured by acquiring 60 frames over 3 sec while the subject fixated on a cross-hair target with 0.3 deg line thickness. Results: The stimuli were directly visible on the retinal image frames, providing precise visual function testing. The visual function maps, formed by registering and superimposing the fundus images obtained for each stimulus meridian path, agreed well with the boundaries of the optic nerve head. The subjects’ fixation was 0.25±0.13 deg, measured over a 2 sec blink-free interval of the 3 sec acquisition. Conclusions: The DLO with integrated visual function testing is a flexible and cost-effective platform for conducting image-corrected visual function tests, such as kinetic perimetry and fixation stability assessment, and can be readily extended to scotoma mapping and reading tests.
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| 28. |
- Nadeem Akram, Muhammad, et al.
(författare)
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Accurate Wide-field Emmetropic Human Eye Model Based On Ocular Wavefront Measurements
- 2017
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Konferensbidrag (refereegranskat)abstract
- Purpose: To develop accurate wide-field eye model that reproduces the wavefront aberration of emmetropic eye. To demonstrate the ability to develop individual eye models based on the newly developed generic eye model. Methods: A high resolution Shack-Hartmann wavefront sensor is employed to measure the wavefront error from 40 deg Nasal to 40deg Temporal field and up to 20deg Inferior field of view in steps of 10deg of thirty young emmetropic subjects. Zernike polynomials up to 6th order are fitted to the measured wavefront over a circular exit pupil diameter of 4 mm. A mean wavefront is constructed for each field angle from the measured data set. A lens design program is used to reconstruct an model-eye that reproduces same wavefront as the mean wavefront of the measured data set over each field angle. Anatomical parameters range limits as well as dispersion of the eye (cornea, aqueous, lens and vitreous regions) is incorporated during model development to give a realistic eye model. Our model is different from previously published models in that it does not use Gradient index lens (GRIN) as the lens material simplifying optical modeling and ray tracing. In addition, the cornea and lens components are allowed to be tilted, decentered and rotated with respect to the optical axis to provide a much better fit to the measured set of wavefronts. Results: The RMS values, the wavefront shapes, Zernike coefficients and chromatic performance as predicted by the developed model closely match the measured values over the field of view. Our model does re-reproduce the Nasal-Temporal asymmetries found in the eye performance. Personalized eye models developed using the generic eye model also give excellent fit to the measured wavefront over the field of view. Conclusion: We believe our wide-field emmetropic eye model provides better ability to model peripheral vision. It can also be used for the design of advanced ophthalmic instruments, designing lenses for myopia control and low vision optical aids.
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| 29. |
- Ozawa, Glen Y., et al.
(författare)
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Central macular thickness of diabetic eyes with and without exudates within one disc diameter of the foveola
- 2014
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Konferensbidrag (refereegranskat)abstract
- Abstract Purpose: In diabetic retinopathy screenings, exudates within 1 disc diameter (DD) of the foveola are routinely used as a surrogate marker for clinically significant macular edema (CSME). We compared central macular thickness of diabetic eyes, which in photos, had and did not have exudates within 1 DD of the foveola. Methods: Patients were recruited from a diabetic retinopathy screening program serving mainly minorities in Alameda County, CA. One eye from each of 200 diabetic patients with diabetes was selected: 100 cases (50 males and 50 females) had exudates within 1 DD of the foveola, and 100 gender-, age-, and ethnicity-matched control diabetics did not have exudates within 1 DD of the foveola. Central macular thickness was determined using the iVue SD-OCT (Optovue Inc, Fremont, CA). Immediately following the OCT, three overlapping fundus photographs of each eye were taken with a Canon Cr-DGi nonmydriatic camera (Tokyo, Japan). Photos were graded by two EyePACS certified graders in a blind manner. Sensitivity and specificity of retinal photos for CSME were determined using the OCT as a gold standard. A 3-way ANOVA was performed for gender, age group (<55 years vs >55 years), and case versus control. Results: Central macular thickness was significantly greater for eyes with exudates within 1DD of the foveola versus eyes without (261±54 vs 244±23 μm, p=0.002). Notably, central macular thickness was greater in eyes with exudates within 1 DD of the fovea compared to those without in only the males (275±54 vs 249±25 μm, p=0.003). In the females, the two groups did not differ (247±51 vs 237±19 μm, p=0.2). ANOVA analysis also showed that central macular thickness was significantly greater among the entire group of males compared to the females (262±45 vs 243±39 μm, p<0.0001). Regardless of exudates, older patients (>55 years) had significantly greater central macular thickness than younger patients (260±54 vs 245±39 μm, p=0.009). In this study, exudates within 1 DD of the foveola had a sensitivity and specificity of 96% (95% CI=90-99%) and 82% (73-88%) for CSME, respectively. Conclusions: This study suggests that the surrogate marker for CSME, exudates within 1 DD of the foveola, is associated with central macular thickening. This central macular thickening is significantly greater in males, but not in females. Thus, the surrogate marker for CSME may be more important in males than in females.
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| 30. |
- Parimi, Vamsi, et al.
(författare)
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Clinically significant macular edema in an underserved population : Association with demographic factors and hemoglobin A1c
- 2024
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Ingår i: Optometry and Vision Science. - : Lippincott Williams & Wilkins. - 1040-5488 .- 1538-9235. ; 101:1, s. 25-36
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Tidskriftsartikel (refereegranskat)abstract
- SIGNIFICANCE: Suspected clinically significant macular edema (SCSME) from exudates differed among ethnic groups in our underserved population. African American and Asian subjects had higher prevalence than Hispanics and non-Hispanic Caucasians, from the same clinics. Men had higher prevalence than women. Highly elevated blood glucose was frequent and associated with SCSME.PURPOSE: We investigated the association between the presence of SCSME from exudates and hemoglobin A1c (HbA1c), as well as demographic factors such as age, sex, and ethnic group. Our population was underserved diabetic patients from the same geographic locations. Ethnic groups were White Hispanic, non-Hispanic Caucasian, African American, and Asian, with a high proportion of underrepresented minorities.METHODS: In a diabetic retinopathy screening study at four community clinics in Alameda County, California, nonmydriatic 45° color fundus images were collected from underserved diabetic subjects following the EyePACS imaging protocol. Images were analyzed for SCSME from exudates by two certified graders. Logistic regression assessed the association between SCSME from exudates and age, sex, ethnic group, and HbA1c.RESULTS: Of 1997 subjects, 147 (7.36%) had SCSME from exudates. The mean ± standard deviation age was 53.4 ± 10.5 years. The mean ± standard deviation HbA1c level was 8.26 ± 2.04. Logistic regression analysis indicated a significant association between presence of SCSME from exudates and HbA1c levels (p<0.001), sex (p=0.027), and ethnicity (p=0.030). African Americans (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.06 to 2.50; p=0.025) and Asians (OR, 1.63; 95% CI, 1.05 to 2.54; p=0.029) had a higher risk than Hispanics. After adjusting for ethnicity, sex, and age, the odds of developing SCSME from exudates increased by 26.5% with every 1% increase in HbA1c level (OR, 1.26; 95% CI, 1.18 to 1.36; p<0.001).CONCLUSIONS: In our underserved population, many diabetic patients had very high HbA1c values. Ethnic background (African American > Asians > Hispanics), sex (male > female), and HbA1c level were strong indicators for identifying who is at increased risk of developing SCSME from exudates.
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| 31. |
- Sivaramakrishnan, V. C., et al.
(författare)
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Influence of convergence on vertical fusional vergence amplitude
- 2005
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Ingår i: American Journal of Ophthalmology. - 0002-9394 .- 1879-1891. ; 139:3 Suppl., s. S46-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Deficiency in vertical fusional vergence amplitude (VFVA) is known to cause asthenopia and oculomotor imbalances. The measurement of VFVA however is confounded by its increase with convergence (Hara et al., 1998). A quantitative relationship between the two vergences is thus necessary to predict the VFVA at a given convergence angle. Here, we sought to derive such a relationship by measuring the VFVA at a range of convergence angles. Methods: 30 subjects (17–21 yrs) wearing red-green goggles fused a pair of red-green concentric circles projected on a computer monitor at a distance of 50 cms in a dark room. The horizontal and vertical separation between the red-green circles determined the convergence and vertical vergence demand respectively. The VFVA was measured at 8 equally spaced convergence demands ranging from 0.58° to 11.13°. The convergence demands were either systematically increased or randomly varied across different sessions. in each session, the convergence demand was kept constant while the vertical vergence demand was varied in steps of 0.03°. The maximum vertical vergence demand that could be fused determined the VFVA. Results: The subjects’ data was divided into four groups based on the range of convergence demands that could be fused. in all the groups, the VFVA increased linearly with the systematic increase in convergence demand (mean regression equation: y 0.15x 0.49). Randomizing the convergence demands did not show any significant change in this relationship (y0.12x 0.80). Conclusion: The VFVA increases linearly in the range of convergence demands tested. The linear regression equation derived could be used in a clinical setup to predict the VFVA at a given convergence angle
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