| 1. |
- 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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| 2. |
- Alhamami, Mastour, et al.
(författare)
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Comparison of Cysts in Red and Green Images for Diabetic Macular Edema
- 2017
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Ingår i: Optometry and Vision Science. - 1040-5488 .- 1538-9235. ; 94:2, s. 137-149
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate whether cysts in diabetic macular edema are better visualized in the red channel of color fundus camera images, as compared with the green channel, because color fundus camera screening methods that emphasize short-wavelength light may miss cysts in patients with dark fundi or changes to outer blood retinal barrier.Methods: Fundus images for diabetic retinopathy photoscreening were acquired for a study with Aeon Imaging, EyePACS, University of California Berkeley, and Indiana University. There were 2047 underserved, adult diabetic patients, of whom over 90% self-identified as a racial/ethnic identify other than non-Hispanic white. Color fundus images at nominally 45 degrees were acquired with a Canon Cr-DGi non-mydriatic camera (Tokyo, Japan) then graded by an EyePACS certified grader. From the 148 patients graded to have clinically significant macular edema by the presence of hard exudates in the central 1500 [mu]m of the fovea, we evaluated macular cysts in 13 patients with cystoid macular edema. Age ranged from 33 to 68 years. Color fundus images were split into red, green, and blue channels with custom Matlab software (Mathworks, Natick, MA). The diameter of a cyst or confluent cysts was quantified in the red-channel and green-channel images separately.Results: Cyst identification gave complete agreement between red-channel images and the standard full-color images. This was not the case for green-channel images, which did not expose cysts visible with standard full-color images in five cases, who had dark fundi. Cysts appeared more numerous and covered a larger area in the red channel (733 +/- 604 [mu]m) than in the green channel (349 +/- 433 [mu]m, p < 0.006).Conclusions: Cysts may be underdetected with the present fundus camera methods, particularly when short-wavelength light is emphasized or in patients with dark fundi. Longer wavelength techniques may improve the detection of cysts and provide more information concerning the early stages of diabetic macular edema or the outer blood retinal barrier.
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| 3. |
- 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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| 4. |
- 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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| 5. |
- Baskaran, Karthikeyan, et al.
(författare)
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Stability of fixation in diabetes patients with and without clinically significant macular edema
- 2014
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Konferensbidrag (refereegranskat)abstract
- Purpose - Eye diseases affecting central vision impair fixation and interfere with day-to-day tasks such as reading. Diabetic retinopathy and clinically significant macular edema (CSME) are leading causes of visual impairment in diabetes patients. The aim of this study is to find whether diabetic patients with CSME have poorer fixation stability compared to patients without CSME, by analyzing the fundus images obtained from the Laser Scanning Digital Camera (LSDC).Methods - Two hundred underserved, diabetic patients were screened for diabetic retinopathy at the Eastmont Wellness Center within the EyePACS telemedicine network, using LSDC. One eye of each patient who had diabetic retinopathy was included in this study. Non-mydriatic color fundus photos were classified for presence of CSME by two independent, certified EyePACS graders. The first 50 patients (25 males & 25 females) with CSME were selected and 50 (27 males & 23 females) diabetic patients without CSME were selected as controls. Mean age was 59 (±9) years for patients with CSME and was 55 (±10) years for patients without CSME. The subjects included 53% Hispanics, 26% African Americans and 21% other. A series of 20 images (36 deg field, 1024 X 1024 pixels, and 850 nm) were acquired at 11 fps. Eye positions were obtained by selecting a region of interest in the first image of each series and aligning the remaining images to that region by cross-correlation. The bi-contour ellipse area (BCEA) and the standard deviation of the Euclidean distance (SDED) were used to quantify fixation stability.Results - The fixation stability for patients with CSME was significantly worse than for those without CSME (t test: p < 0.001, 0.007 for BCEA and SDED, respectively). The mean fixation stability obtained by the BCEA metric was 2.74 (±0.40) log(minArc2) and 2.34 (±0.42) log(minArc2) for patients with and without CSME, respectively. For SDED the mean was 48.4 (±28.8) microns and 34.6 (±20.4) microns for patients with and without CSME, respectively. The correlation with age was not significant for either group (R2 = 0.052, 0.011).Conclusions - Diabetic patients with CSME had poorer fixation stability than patients without CSME for both metrics. Fixation stability is a potential tool for assessing macular function and could be used for tracking the treatment and progression of macular edema.The LSDC images provide one method to quantify fixation stability rapidly.
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| 6. |
- 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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| 7. |
- Ingling, Allen W, et al.
(författare)
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Fixation stability readily obtained from confocal color fundus imaging
- 2015
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Ingår i: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 56:7, s. 515-515
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Tidskriftsartikel (refereegranskat)abstract
- PurposeStabile fixation underpins most visual tasks such as reading, and is important for accurate assessment of visual function and treatment. Retinal imaging instruments average images over time to improve the signal to noise ratio, discarding useful eye movement data. We determined whether the frame-to-frame motion of the retina during non-mydriatic color fundus imaging could provide fixation stability measures, e.g. Bivariate Contour Ellipse Area (BCEA). MethodsNon-mydriatic color fundus images were acquired using the Digital Light Ophthalmoscope (DLO). Twenty subjects with varied fundus pigmentation were tested without mydriasis. The DLO uses a digital light projector with LED light sources to provide the illumination for both confocal imaging and fixation stimuli. The DLO projects a series of lines across the fundus that is synchronized to the 2D CMOS sensor, providing high contrast confocal imaging. Monochromatic 40 deg images were acquired with alternating red and green LED illumination at 14.3 Hz and overlayed to present a pseudo-color image to the operator in real time. To reduce pupil constriction and patient discomfort, the green LED was long-pass filtered with a 570 nm filter. A 1.5mm entrance pupil and time-averaged power of <30 uW were used. Images were aligned automatically with custom software (MATLAB) using cross-correlation and 2D translation. A canvas of twice the image size was used to allow image alignment despite moderate eye movements. Blinks and large saccades were discarded and BCEA was computed. ResultsThe image alignment algorithm successfully aligned nearly all the frames, rejecting 3.7%, and allowing fixation stability to be computed from color fundus image data. The BCEA for 1 standard deviation was 2.97 log minarc2 for all subjects and both the red and yellow-orange illumination. There was no difference between the BCEA for red or yellow-orange illumination (t = .86). ConclusionsThe color DLO records sufficiently high quality images to reliably calculate measures of fixation stability. Despite recruiting an especially challenging population that included dark fundi, small pupils, high refractive errors, and media issues, we achieved success in all subjects tested to date.
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| 8. |
- Lieder, RM, et al.
(författare)
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Development of gamma-ray tracking detectors
- 2001
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Ingår i: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254. ; 32:9, s. 2395-2401
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy AGATA will consist of gamma -ray tracking detectors. They represent high-fold segmented Ge detectors and a front-end electronics, based on digital signal processing techniques,
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| 9. |
- Lieder, RM, et al.
(författare)
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Gamma-ray tracking arrays
- 2001
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Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS. - : ELSEVIER SCIENCE BV. - 0146-6410. ; 46, s. 399-407
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamm
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| 10. |
- Lieder, R M, et al.
(författare)
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Gamma-ray tracking arrays
- 2001
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Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 46. ; , s. 399-407
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Konferensbidrag (refereegranskat)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.
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| 11. |
- Lieder, RM, et al.
(författare)
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The TMR network project "Development of gamma-ray tracking detectors"
- 2001
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Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 682, s. 279C-285C
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve gamma -ray tracking detectors. They consist of high-fold segmented Ge detectors and a front-end electronics, based on new digital signal processing techniques, whic
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| 12. |
- Muller, Matthew S, et al.
(författare)
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Non-mydriatic color fundus imaging with the Digital Light Ophthalmoscope
- 2015
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Konferensbidrag (refereegranskat)abstract
- Purpose To provide non-mydriatic confocal color fundus imaging of sufficient quality for screening for diabetic retinopathy despite dark fundus pigmentation, small pupil, high refractive error, or other anterior segment issues. MethodsNon-mydriatic color fundus images of 34 volunteers (aged 39.2 ± 13.2 yr) were acquired using the Digital Light Ophthalmoscope (DLO). 10 subjects had dark fundi and/or high refractive errors, as well as other anterior segment issues. Unique to retinal cameras, the Digital Light Ophthalmoscope (DLO) uses a digital light projector with LED light sources to provide the illumination for both confocal imaging and fixation stimuli. The DLO projects a series of lines across the fundus that is synchronized to the electronic rolling shutter read-out on a 2D CMOS sensor, providing high contrast confocal imaging that is highly customizable through software. Monochromatic 40 deg field images were acquired with alternating red and green LED illumination at 14.3 Hz and overlayed to present a pseudo-color image to the operator in real time. To reduce pupil constriction and patient discomfort while maintaining strong blood absorption, the green illumination was long-pass filtered with a 570 nm filter, and a 1.5mm entrance pupil and time-averaged power of <30 uW was used. ResultsThe DLO provided gradable quality non-mydriatic fundus images in all tested subjects, including those with dark fundi or pupils < 2 mm, as judged by an EyePACS certified grader. The use of long pass filters in the green LED permitted high contrast, non-mydriatic images with illumination wavelengths >570 nm and limited pupil constriction. Retinal vessels at the 4th branch or smaller, as well as neovascularization in diabetic retinopathy, could be seen. Hyperpigmentation was clearly seen both peripherally as bear tracks and centrally at the posterior pole. The aperture width and color balance can be adjusted to provide high contrast and yet relatively uniform and natural color across the image. ConclusionsThe DLO provides confocal color fundus images in real time without the use of short (< 570nm) wavelength light. Despite recruiting an especially challenging population that included dark fundi, small pupils, high refractive errors, and media issues, we achieved a 100% success rate in obtaining gradable images for screening.
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| 13. |
- Muller, Matthew S., et al.
(författare)
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Non-mydriatic confocal retinal imaging using a digital light projector
- 2015
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Ingår i: <em>Proceedings of SPIE, vol</em> 9376. - : SPIE - International Society for Optical Engineering. ; , s. 93760E-1-93760E-10
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Konferensbidrag (refereegranskat)abstract
- A digital light projector is implemented as an integrated illumination source and scanning element in a confocal nonmydriatic retinal camera, the Digital Light Ophthalmoscope (DLO). To simulate scanning, a series of illumination lines are rapidly projected on the retina. The backscattered light is imaged onto a 2-dimensional rolling shutter CMOS sensor. By temporally and spatially overlapping the illumination lines with the rolling shutter, confocal imaging is achieved. This approach enables a low cost, flexible, and robust design with a small footprint. The 3rd generation DLO technical design is presented, using a DLP LightCrafter 4500 and USB3.0 CMOS sensor. Specific improvements over previous work include the use of yellow illumination, filtered from the broad green LED spectrum, to obtain strong blood absorption and high contrast images while reducing pupil constriction and patient discomfort.
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| 14. |
- 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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| 15. |
- Young, Stuart B., et al.
(författare)
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Central Macular Thickness in Diabetic Patients : A Gender Based Analysis
- 2014
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Konferensbidrag (refereegranskat)abstract
- PURPOSE: To investigate gender differences in central macular thickness (CMT) in underserved diabetic patients who were judged to have clinically significant macular edema (CSME), using the criterion of hard exudates within 1500 microns of the fovea. METHODS: Using EyePACS certified graders, 142 of 2080 diabetic patients from Alameda County, CA, clinics, had CSME as judged from color fundus images (Canon CR6-45NM). Of the 2080 patients, 1784 were imaged with SD-OCT (iVUE). Graders then analyzed the SD-OCT images for hard exudates and macular edema, excluding subjects with poor fixation or other ocular conditions. From these data, 142 patients with CSME, 11 males had CMT >300 microns. The 11 females from the group with the greatest values of CMT were then compared for CMT, and mean age. A control group, diabetic patients without CSME, showed a 12-micron larger CMT for males, as compared with females. Thus, a one-tailed t-test was used to determine if the CMT for males with CSME also was greater than for females by 12 microns. We compared mean age, self-report of duration of diabetes, and HbA1c values between genders. RESULTS: Males with CSME had an average CMT of 377 microns, statistically greater than the 12 micron difference expected between genders, with females averaging 321 microns (p<0.05). There was no statistical significance in the mean age between genders 59.3 vs. 59.2 yr. (p>0.05) or the population HbA1c levels 9.5 vs. 9.3% for males and females (p>0.05), respectively. While females had slightly longer durations of diabetes, Chi square analysis also showed no significance between genders (p>0.05). In the OCT images, males had cysts that were larger and more numerous. CONCLUSIONS: In patients with CSME, males had greater CMT than females. This difference is not explained by differences in thickness with gender when CSME is not found, nor by age or duration of diabetes. Instead, the cystic changes in the retinas of males were more striking.
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