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- Allen, Peter M., et al.
(författare)
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Aberration control and vision training as an effective means of improving accommodation in individuals with myopia.
- 2009
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 50:11, s. 5120-5129
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To test the efficacy of a novel dual treatment for improving accommodative accuracy and dynamics in young persons with myopia.METHODS: Ninety-three young persons with myopia (mean spherical equivalent, -3.0 +/- 1.8 D; age 16.8 +/- 2.1 years; spherical aberration +0.06 +/- 0.04 microm) participated in the study. Custom-designed soft contact lenses were used to alter ocular SA to -0.10 microm to improve accommodative accuracy and reduce any lag of accommodation. A vision training regimen was performed for 18 minutes per day for up to 6 weeks to improve speed of dynamic accommodation. Control groups had contact lenses with no added SA and/or no exercises. To avoid any effects of natural levels of negative aberration on the results of the study, all participants who had negative SA were excluded.RESULTS: The treatment contact lenses produced a significant reduction in lag of accommodation (P < 0.05) at all proximal viewing distances measured. The vision training measurement and treatment resulted in a significant increase in distance facility rate for all groups compared with their own baselines (P < 0.05). Near facility rate improved in the vision training treatment group only compared with its baseline (P < 0.05). Both positive and negative response times for distant viewing were significantly shorter in all groups after training compared with their baseline values (P < 0.05). At near, the positive response times were decreased significantly (P < 0.05) in both groups, whereas the negative response times decreased significantly only in the vision training treatment group.CONCLUSIONS: After 3 months, the dual treatments (altering SA and vision training) used in the study were effective in modifying accommodation. The static accommodative response to targets at proximal distances was increased by the altered SA contact lenses and rates of dynamic accommodation improved with vision training.
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| 2. |
- Baptista, Antonio M. G., et al.
(författare)
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Causes of Vision Impairment in Portugal : A hospital based study
- 2015
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 56:7
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Causes of vision impairment (VI) are influenced by factors such as race or socio-economic circumstances. Because of this collecting national information is important for planning reduction of vision loss. The aim of this study was to determine causes of vision impairment in a population visiting ophthalmology departments in public hospitals in Portugal.Methods This study was designed according with the guidelines of the Vancouver Economic Burden of Vision Loss Group (IOVS, 2010, V51/4/1801). Recommendations are to collect hospital data during 1 year to determine causes of VI. We selected four public hospitals that are expected to have over 120-140K appointments per year. Files are analysed weekly to detect patients with vision impairment. Inclusion criteria are: visual acuity with the current refractive correction equal or less than 0.5 (20/40) in the better-seeing eye and/or a visual field of less than 20 degrees. Patients were selected by trained hospital staff (medics and orthoptists) and inserted in a database. Diagnoses were classified according the ICD9. Data collected included fundamental demographic information, main diagnosis, secondary diagnosis and comorbidities.Results We have now 2462 patients selected that correspond to 4 to 33 weeks of data collection. The number of weeks is variable because we did not start all hospitals simultaneously. From the current number of cases detected, 58% are female, 1.9% are under 20, 8.2% are between 20 and 50 and 89.9% are 50 years or older. The leading causes of vision impairment among these patients are diabetic retinopathy (DR), cataract (C), glaucoma (GC) and age-related macular degeneration (AMD). Using the North American definition of VI the proportions are 26.8% for DR, 25.5% for C, 10.4% for GC and 8.2% for AMD. The remaining causes of VI have percentages below 5% and in total they correspond to approximately 29% of the cases detected.Conclusions Our results show that the most common causes of vision impairment are eye diseases related with systemic conditions and aging of the population. Vision impairment was relatively low under the age of 20 and the causes were mostly inherited diseases. Numbers reported now will be more accurate at the end of the study but they already highlight the importance of targeting conditions such as diabetes.
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| 3. |
- Baskaran, Karthikeyan, et al.
(författare)
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Ocular Aberrations in the Peripheral Visual Field With a Commercial Open-View Aberrometer
- 2010
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 51:5
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe interest in off-axis aberrations has increased with the discovery of a possible link between myopia development and peripheral optics. The most common technology to measure the off-axis aberrations is a Shack-Hartmann wavefront aberrometer. This is the first study to report peripheral aberrations in a large sample of emmetropic population with a commercial open-view Shack-Hartmann aberrometer. MethodsThe commercial open-view Shack-Hartmann aberrometer COAS-HD VR was used to measure the aberrations in the peripheral vision. Aberrations of the right eye of 30 emmetropes (24 {+/-} 4 years) were studied. Off-axis aberrations were measured in steps of 10{degrees} out to {+/-} 30{degrees} in the horizontal visual field. The subjects turned their eye to view the off-axis fixation target (light emitting diode placed at 3 meters) during the measurement. The resulting wavefront aberrations were parameterized with Zernike coefficients for a 5 mm diameter pupil. All analyzes are reported according to optical society of America (OSA) recommended standards. ResultsAberrations from the 2nd to 6th order and the total higher-order root-mean-square (HO RMS) were analyzed using one-way ANOVA. The defocus C02 was significantly myopic in the nasal visual field (+20{degrees}, +30{degrees}) whereas there was no significant difference in the temporal visual field. Astigmatism C22 increased quadratically from {+/-}10{degrees} in the periphery and coma C13 showed a linear increase across the horizontal visual field (p < 0.05). The spherical aberration C04 and the total HO RMS showed a significant change at {+/-}30o. ConclusionsOur results showed that in young emmetropes there was a significant increase of HO RMS at {+/-}30{degrees}, which is expected. Astigmatism, horizontal coma, and spherical aberration vary systematically across the horizontal visual field in agreement with Seidel theory. The findings of our study with a large sample of emmetropic population agree with the previous studies done with laboratory built aberrometers.
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| 4. |
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| 5. |
- Carneiro de Freitas, Rui, et al.
(författare)
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Prevalence of Visual Impairment in Portugal : study design and initial results
- 2015
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 56:7
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Information about the prevalence of visual impairment is fundamental to define policies that deal with vision loss. The aim of this study is to determine the prevalence of visual impairment (VI) in the population looking for eye care in public hospitals in Portugal.Methods We designed an observation, cross-sectional prospective study (Prevalence and Costs of Visual Impairment in Portugal: PC-VIP study) to investigate the prevalence of VI in patients attending outpatient appointments in four public hospitals in Portugal. Hospital selected provide from general eye care (3-6 ophthalmologists) to high-specialized eye care (40+ ophthalmologists) that in total have between 120-140K hospital appointments per year. Files of patients are analysed weekly to detect patients with VI. Inclusion criteria were: visual acuity equal or worse than 0.5 (USA definition 20/40) in the better eye and/or a visual field of less than 20deg. Cases are selected by trained hospital staff and inserted in a database. Data collected included demographic information, acuity from both eyes, qualitative information about visual field (good, reduced, requires investigation), main diagnosis, secondary diagnosis and comorbidities. Diagnoses were classified according with ICD9.Results We have now detected 2462 cases of VI that correspond to 4 to 33 weeks of data collection. The number of weeks is variable because collection did not start simultaneously in all sites. From the number of cases detected, 58% were female, 1.9% were under 20y, 8.2% were between 20y and 50y and 89.9% were ≥50y. The mean prevalence of visual impairment was 13.6% (SD=5.6) using the USA definition and it was 7.0%(SD=4.1) using the WHO definition (acuity equal or worse than 0.3 or ~20/63). With a methodology that controls for demographics the lowest and highest estimates were calculated. Considering the USA definition, the prevalence in the general population would be in the range 0.4 -0.4% (age<40y) and 0.8-2.4% (age>=40y). Considering WHO definition, it would be 0.2-0.5% (age<40y) and 0.4-1.0% (age>=40y).Conclusions A hospital-based study can provide effective estimates of the prevalence of visual impairment in a population. Estimates for the country are in agreement with the expected results that can be deducted from neighbour countries and self-reported visual impairment in census 2001.
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| 9. |
- Henrysson, Ida, et al.
(författare)
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Binocular Vision, Reading Ability and Associated Symptoms in School Children
- 2015
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 56:7, s. 530-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: The purpose of this study was to investigate relationship between binocular vision, reading ability and any associated symptoms in School Children.Methods: The study was conducted in a School in western Sweden. A sample of 54 Children aged between 10 and 12 years were invited to participate in this study. A consent form and a letter with information was sent to their parents. Children with at least 20/25 and N6 visual acuity and good Stereopsis were included. After receiving consent forms, 27 Children participated in all the measurements. Amplitude of accommodation was measured using push-up method both monocularly and binocularly. Accommodative facility was measured using ± 2.00 D flippers at 40 cm both monocularly and binocularly. Near point of convergence was measured using a Royal Air Force (RAF) ruler and both break and recovery points were documented. All the Children performed a group of reading ability tests to detect whether they have any reading difficulties. A questionnaire called "The College of Optometrists in Vision Development Quality of Life (COVD-QOL)" was filled by their parents together with their Children. A score of 20 or more is considered as symptomatic.Results: Mean amplitude of accommodation was OD 10.8 ± 4.0 D, OS 11.8 ± 4.1 D and OU 14.2 ± 3.7 D. Amplitude of accommodation was low in terms of Hofstetter's formula. Based on age, 59% of the Children were below expected value. The accommodative facility was lower than expected, with mean values of OD 5.5 ± 4.0 cpm, OS 5.5 ± 4.0 cpm and OU 5.0 ± 3.5 cpm. Mean near point of convergence was 6.0 ± 5.4 cm for break and 6.6 ± 5.9 cm for recovery. In the reading ability tests all the Children had normal values. Three Children received ≥ 20 points on the symptom questionnaire COVD-QOL, which is considered to be high. All of these three Children had values below normal limits for the amplitude of accommodation and/or the accommodative facility. Regression analysis showed no significant correlation between binocular vision tests, reading ability and symptom score (r < 0.6; p > 0.05).Conclusions: Amplitude of accommodation and accommodative facility was lower than expected values for their age. Near point of convergence values reached the expected normal level. There was no significant correlation between binocular vision tests, reading ability and associated symptoms in this sample of Swedish Children.
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| 10. |
- Hernández-Moreno, Laura, et al.
(författare)
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The Portuguese version of the activity inventory
- 2015
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 56:7
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To characterize interventions needed by the population with visual impairment or to assess interventions in vision rehabilitation validated and standardized instruments used in different cultural contexts are necessary. The aim of this work was to characterize the functional status of a sample of people with visual impairment with the Portuguese version of the activity inventory (AI)Methods: A group of participants in the study Prevalence and Costs of Visual Impairment in Portugal (PC-VIP) was recruit to face-to-face interviews and the activity inventory was administered. The AI examines 50 goals split between three objectives: social functioning, recreation and daily living. Goals rated ‘not important’ were skipped, but for all other goals the participant was asked to rate its difficulty on a five point scale ranging from ‘not difficult’ to ‘impossible without help’. The difficulty responses were Rasch analysed (Winsteps v3.81.0) to produce a continuous measure of visual ability (AI score). Additional information about distance and near visual acuity (ETDRS scale), contrast sensitivity (MARS test) and critical print size (MNREAD test) was collected.Results: A total of 94 persons participated in this study. Some participants were not able to read or recognize letters due to their poor vision or poor literacy and were excluded from further analysis. Data reported here are from 62 participants, median age 63y (range=12-85) and the most common cause of visual impairment were retinal diseases. Mean presenting acuity in the better eye was 0.93logMAR (SD=0.5). The mean difficulty (item measure) in the AI was -0.33 logits (SD=0.96). The most difficult items were "sew or do needlework", "read the newspaper", "drive" and the easiest items were "provide care for a pet", "eat your meals", "use the restroom in a public place". The mean ability score (person measures) was 1.11 logits (SD=2.04). The ability measures in the AI were correlated with distance visual acuity (r=-0.57, p<.001), near visual acuity (r=-0.66, p<0.001), contrast sensitivity (r=0.62, p<.001) and critical print size (r=-0.60, p<.001).Conclusions: Our results indicate that the AI scores in a sample of people Portuguese people with visual impairment were in line with what has been found in other cultural contexts. The visual ability measured by the AI was correlated with visual function assessed by different visual tests, which shows that this instrument can be used with confidence.
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