Yulan Ding

Johns Hopkins University, Baltimore, Maryland, United States

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Publications (4)9.4 Total impact

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    ABSTRACT: Retinal thickness (RT) is a useful measurement for describing diseases that affect the thickness of the retina, such as glaucoma. Existing normative data are derived from relatively young individuals; however, glaucoma is most prevalent in older individuals. We therefore studied the RT in older normal individuals. Participants of the Baltimore Eye Study, persons accompanying patients, and staff were recruited and underwent visual field testing and a comprehensive eye examination by a glaucoma specialist. RT was measured with the retinal thickness analyzer (RTA, Talia Technology) and RT values in specific regions were derived using a custom-designed MatLab program. One hundred and three eyes of sixty-two individuals were studied. Mean age was 61 years. Sixty-six percent were female and 82% were of European descent. The average mean deviation on visual field testing was 0.03 dB and the average pattern SD was 1.51 dB. The mean RT of the entire macula was 159+/-16 microm, and was lowest in the foveal pit and highest in the parafoveal annulus. The average distance from the foveal pit to the thickest point in the parafoveal annulus was 1240+/-138 microm. The mean RT of the entire macula was slightly less in older individuals (slope=-5.7 microm/10 y, P=0.02) but the height of the parafoveal annulus relative to the foveal pit, which is determined by the combined thickness of the parafoveal nerve fibers, ganglion cells, inner plexiform layer, and inner nuclear layer, did not vary with age (P=0.62). Although the average RT of the entire macula was slightly thinner with increasing age, the height of the parafoveal annulus relative to the foveal pit did not change with age and would therefore seem to be a better marker of neuronal tissue health than the average RT of the entire macula.
    No preview · Article · Feb 2009 · Journal of glaucoma
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    ABSTRACT: To determine the agreement among glaucoma specialists in assessing progressive disc changes from photographs in a cohort of patients with glaucomatous visual field loss. Retrospective cohort study. Three glaucoma specialists, masked to chronological sequence, examined pairs of optic disc stereophotographs to determine whether the appearance of the optic disc had changed. Eyes for which the observers disagreed were adjudicated to reach a consensus about which discs had changed over time. Sequential stereophotographs, separated in time by a median of 26 months (range, five to 50), from 164 eyes of 111 patients were analyzed. Among the three observers, the number of interpretable discs judged to have changed was 11 of 155 (7%) for Observer 1, 17 of 155 (11%) for Observer 2, and 44 of 155 (28%) for Observer 3 (kappa = 0.20). Sixty-six eyes (43%) required adjudication. After adjudication, the consensus was that 10 discs had changed, six eyes in which the disc was worse in the later photograph and four eyes in which the disc was judged to appear more glaucomatous in the earlier photograph. Interobserver agreement among glaucoma specialists in judging progressive optic disc change from stereophotographs was slight to fair. After masked adjudication, in 40% of the cases in which the optic disc appeared to have progressed in glaucoma severity, the photograph of the "worse" optic disc was in fact taken at the start of the study. Caution must be exercised when using disc change on photographs as the "gold standard" for diagnosing open-angle glaucoma or determining its progression.
    Full-text · Article · Oct 2008 · American Journal of Ophthalmology
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    ABSTRACT: To determine the test-retest variability in perimetric, optic disc, and macular thickness parameters in a cohort of treated patients with established glaucoma. In this cohort study, the authors analyzed the imaging studies and visual field tests at the baseline and 6-month visits of 162 eyes of 162 participant in the Glaucoma Imaging Longitudinal Study (GILS). They assessed the difference, expressed as the standard error of measurement, of Humphrey field analyzer II (HFA) Swedish Interactive Threshold Algorithm fast, Heidelberg retinal tomograph (HRT) II, and retinal thickness analyzer (RTA) parameters between the two visits and assumed that this difference was due to measurement variability, not pathologic change. A statistically significant change was defined as twice the standard error of measurement. In this cohort of treated glaucoma patients, it was found that statistically significant changes were 3.2 dB for mean deviation (MD), 2.2 for pattern standard deviation (PSD), 0.12 for cup shape measure, 0.26 mm for rim area, and 32.8 microm and 31.8 microm for superior and inferior macular thickness, respectively. On the basis of these values, it was estimated that the number of potential progression events detectable in this cohort by the parameters of MD, PSD, cup shape measure, rim area, superior macular thickness, and inferior macular thickness was 7.5, 6.0, 2.3, 5.7, 3.1, and 3.4, respectively. The variability of the measurements of MD, PSD, and rim area, relative to the range of possible values, is less than the variability of cup shape measure or macular thickness measurements. Therefore, the former measurements may be more useful global measurements for assessing progressive glaucoma damage.
    No preview · Article · May 2006 · Journal of Glaucoma
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    ABSTRACT: To evaluate the ability of a retina specialist's grading of 30 degrees color stereoscopic fundus photographs to identify areas of significant retinal thickening as assessed by the Retinal Thickness Analyzer (RTA) and to determine whether this ability was affected by the presence of retinal pathology. Thirty-two eyes in 29 patients clinically diagnosed as having diabetic macular edema underwent RTA scanning and nonsimultaneous 30 degrees color stereoscopic fundus photography. Retinal thickness maps of the macular area were generated, and regions with significant retinal thickening (> or = 2 SD above normal values) were identified. A retina specialist reader, masked to the RTA measurements, identified areas with macular edema on the stereoscopic fundus photographs, which subsequently were overlaid on the retinal thickness maps. The sensitivity (percent of significant retinal thickening areas identified by the retina specialist grading the stereoscopic fundus photographs) was calculated separately for areas with and without retinal pathology. Specificity of the stereoscopic fundus photograph grading was assessed similarly. The retina specialist's stereoscopic fundus photography grading identified 78.8% of areas with significant retinal thickening (range over eyes: 20.4%-100%) and was slightly more likely to identify significant retinal thickening when pathology was present (89.6%) than when pathology was not present (78.4%; pooled risk ratio, 1.14 [95% CI = 0.54, 2.42]). Specificity of stereoscopic fundus photography grading was 58%, ie, 42% of areas without significant retinal thickening were (incorrectly) identified as edematous by the stereoscopic fundus photograph grading. This misidentification was more likely if pathology was present (76.9%) than if pathology was not present (41.1%; pooled risk ratio, 1.87 [95% CI = 1.28, 2.73]). This study shows the determination of macular edema by a retina specialist reading color stereoscopic fundus photographs is sensitive but not specific with reference to edema identified by the RTA. Furthermore, the presence of retinopathy tends to cause false-positive readings with reference to edema identified by the RTA. These findings indicate the need to use objective, quantitative methods in clinical studies to detect and monitor macular edema.
    No preview · Article · Jan 2003 · Ophthalmic Surgery Lasers and Imaging