Yulan Ding

Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States

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Publications (6)15.56 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.
    Journal of glaucoma 02/2009; 18(1):37-43. · 1.74 Impact Factor
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    ABSTRACT: Dependences on addictive substances are substantially-heritable complex disorders whose molecular genetic bases have been partially elucidated by studies that have largely focused on research volunteers, including those recruited in Baltimore. Maryland. Subjects recruited from the Baltimore site of the Epidemiological Catchment Area (ECA) study provide a potentially-useful comparison group for possible confounding features that might arise from selecting research volunteer samples of substance dependent and control individuals. We now report novel SNP (single nucleotide polymorphism) genome wide association (GWA) results for vulnerability to substance dependence in ECA participants, who were initially ascertained as members of a probability sample from Baltimore, and compare the results to those from ethnically-matched Baltimore research volunteers. We identify substantial overlap between the home address zip codes reported by members of these two samples. We find overlapping clusters of SNPs whose allele frequencies differ with nominal significance between substance dependent vs control individuals in both samples. These overlapping clusters of nominally-positive SNPs identify 172 genes in ways that are never found by chance in Monte Carlo simulation studies. Comparison with data from human expressed sequence tags suggests that these genes are expressed in brain, especially in hippocampus and amygdala, to extents that are greater than chance. The convergent results from these probability sample and research volunteer sample datasets support prior genome wide association results. They fail to support the idea that large portions of the molecular genetic results for vulnerability to substance dependence derive from factors that are limited to research volunteers.
    BMC Medical Genetics 01/2009; 9:113. · 2.54 Impact Factor
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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.
    American Journal of Ophthalmology 10/2008; 147(1):39-44.e1. · 4.02 Impact Factor
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    ABSTRACT: We investigated the association between major depressive disorder and type 2 diabetes, whether that association is explained by health behaviors, and whether it is influenced by educational attainment. We used discrete-time Cox proportional hazards models to determine the risk of type 2 diabetes associated with depression in a 23-year population-based cohort study. Major depressive disorder was associated with higher risk of type 2 diabetes (hazard ratio [HR]=1.62) after we controlled for age, gender, race, education, smoking status, alcohol use, social network size, and antidepressant use. This association was more pronounced after we controlled for body mass index, family history, and health behaviors (HR=2.04; 95% confidence interval=1.09, 3.81). In stratified analyses, the risk associated with major depressive disorder was elevated among those with 12 or fewer years of education compared with those with at least some education beyond high school. The risk of type 2 diabetes associated with major depressive disorder persists over the life course and is independent of the effects of health behaviors, body mass index, and family history. Education is an important moderator of this association.
    American Journal of Public Health 09/2008; 98(8):1480-5. · 3.93 Impact Factor
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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.
    Journal of Glaucoma 05/2006; 15(2):152-7. · 1.87 Impact Factor
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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.
    Ophthalmic Surgery Lasers and Imaging 01/2003; 34(1):7-16. · 1.46 Impact Factor

Publication Stats

100 Citations
15.56 Total Impact Points

Institutions

  • 2009
    • Johns Hopkins Bloomberg School of Public Health
      Baltimore, Maryland, United States
    • Johns Hopkins Medicine
      • Wilmer Eye Institute
      Baltimore, MD, United States
  • 2008
    • National Eye Institute
      Maryland, United States
    • University of Michigan
      • Department of Epidemiology
      Ann Arbor, MI, United States
  • 2006–2008
    • Johns Hopkins University
      • Wilmer Eye Institute
      Baltimore, Maryland, United States
  • 2003
    • Wonkwang University School of Medicine and Hospital
      Riri, North Jeolla, South Korea