Digital Fundus Photography Research Articles

Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN--DREAMS III): Study design and research methodology

BackgroundTo describe the methodology of the Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III, an ongoing epidemiological study to estimate the prevalence of Diabetes and Diabetic Retinopathy in rural population of Kanchipuram and Thiravallur districts of Tamil Nadu, India and to elucidate the clinical, anthropometric, biochemical and genetic risk factors associated with diabetic retinopathy in this rural population.MethodsSankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III will be a mobile van based epidemiological study; 11,760 participants aged ≥ 40 years will be recruited from the study areas. Eligible subjects will undergo blood sugar estimation to diagnose Diabetes. Oral Glucose Tolerance Test will be done to conform diabetes. All subjects with diabetes will undergo complete information of knowledge, aptitude and practice of diabetes and diabetic retinopathy, Diet questionnaire, demographic data, socioeconomic status, physical activity, anthropometric measurements, and risk of sleep apnoea. A detailed medical and ocular history, a comprehensive eye examination including refraction, slit lamp biomicroscopy examination, indirect ophthalmoscopy, slit lamp biomicroscopy, digital stereo fundus photography and ultrasound of eye will be done in the mobile van. Blood will be collected for biochemical investigations including blood hemoglobin, glycosylated hemoglobin, lipid profile, urea and creatinine, genetic study. Urine will be collected for microalbuminuria. All fundus photographs will be graded at base hospital. Participants who need treatment will be sent to the base hospital. A computerized database is created for the records.ConclusionThe study is expected to provide an estimate of the prevalence of Diabetes and Diabetic Retinopathy and also a better understanding of the genetic, anthropometric and socio-economic risk factors associated with Diabetic Retinopathy in a Rural South Indian population.

Retinal arteriolar caliber and urine albumin excretion: the Multi-Ethnic Study of Atherosclerosis

Changes in retinal microvascular caliber, which occur prior to onset of retinopathy, may indicate presence of kidney damage. This study examined the association between retinal arteriolar [central retinal artery equivalent (CRAE)] and venular caliber [central retinal venule equivalent (CRVE)] and presence of albuminuria (micro- or macroalbuminuria) among participants of the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort of adults aged 45-84 years without baseline clinical cardiovascular disease. During the second MESA exam, digital fundus photography was completed in 5897 participants who provided spot urine specimens. Albuminuria was defined by spot urine albumin/creatinine ratios ≥ 30 mg/g. Multivariable adjusted odds of albuminuria by quintiles of CRAE and CRVE were determined using logistic regression. Analyses were repeated after stratifying by presence of type 2 diabetes. Albuminuria was noted in 11.5% (n = 675) and included 584 subjects with microalbuminuria and 91 with macroalbuminuria. A significant U-shaped pattern was seen with higher prevalence of albuminuria across quintile extremes in CRAE (15.7, 8.8 and 10.6% in CRAE Quintiles 1, 3 and 5, respectively; P <0.0001). After adjustment for covariates, both narrower CRAE [odds ratios (OR) 1.55; 95% confidence interval (CI) 1.17-2.04, Quintile 1 versus 3) and wider CRAE (OR 1.44; 95% CI 1.07-1.93, Quintile 5 versus 3) were significantly associated with albuminuria. Associations appeared substantially stronger in adults with than without type 2 diabetes but the interaction term for diabetes and CRAE on presence of albuminuria did not meet statistical significance (P = 0.3). No association was noted between CRVE quintiles and albuminuria. Albuminuria is associated with narrower and wider arteriolar caliber. Future studies should determine whether variation in arteriolar caliber predicts incident albuminuria and whether associations are mediated by hypertension and diabetes. Such information could further clarify early microvascular processes in the pathogenesis of kidney disease.

Occurrence and pattern of ocular disease in children with cholestatic disorders

To describe visual function and ocular manifestations in patients with onset of cholestasis during the neonatal period. Patients with neonatal cholestasis, either transitory or chronic, who came for assessment to our tertiary referral centre were included in a cross-sectional study and underwent ophthalmological examinations including fundus photography. A total of 57 patients (24 girls and 33 boys), aged 0.4-18.0 years, were included. Of these, 28 patients had biliary atresia, 11 had Alagille's syndrome, five had progressive familiar intrahepatic cholestasis and nine had different disorders such as pituitary insufficiency, alpha-1-antitrypsin deficiency, mitochondriopathy, congenital infections or cholestasis caused by unknown reasons. Visual dysfunction and/or one or several ocular manifestations occurred in 39 out of 57 patients. Major ocular malformations occurred in five patients. Out of three patients with biliary atresia, one patient had severe visual impairment caused by microphthalmia and chorioretinal coloboma, one patient with Cat Eye syndrome had bilateral uveochorioretinal coloboma and one patient had Rieger's anomaly. Two patients, both with pituitary deficiency and transient cholestasis, had severe unilateral visual impairment caused by optic nerve hypoplasia. The majority (68%) of the patients with cholestasis had ocular manifestations. Although the severity of ocular complications varied with diagnosis, and was most apparent among patients with biliary atresia or pituitary deficiency, no conclusion can be drawn regarding the connections between these conditions from the present study. Nevertheless, ocular assessment is important for diagnostic purposes and for early intervention in patients with cholestasis.

Heritability of optic disc diameters: a twin study

To assess the relative influence of genetic and environmental factors on optic disc size and cup/disc ratio in healthy eyes. A sample of 55 monozygotic and 50 dizygotic healthy twin pairs aged 20-46, all having the same sex within pairs (47 pairs were male) had optic discs measured from colour fundus photographs according to the Wisconsin Protocol. Structural equation modelling was used to estimate the relative contribution of genetic and environmental factors to the phenotype. Disc dimensions did not vary significantly by age or sex. After adjusting for age and sex, additive genetic factors (i.e. heritability) explained 77% (95% CI: 65-85%) of variation of vertical disc diameters, whereas estimated unshared environmental effect was 23% (95% CI: 15-35%). For vertical cup diameters, heritability accounted for 70% (95% CI: 55-80%) and environmental factors 30% (95% CI: 20-45%). For cup/disc ratio, additive genetic and unshared environmental factors explained 66% (95% CI: 48-77%) and 34% (95% CI: 23-52%) of the variations, respectively. In this healthy twin sample, we found that three quarters of the variations in vertical optic disc and optic cup diameters were attributable to genetic influence.

Delayed Appearance of High Altitude Retinal Hemorrhages

BackgroundRetinal hemorrhages have been described as a component of high altitude retinopathy (HAR) in association with altitude illness. In this prospective high altitude study, we aimed to gain new insights into the pathophysiology of HAR and explored whether HAR could be a valid early indicator of altitude illness.Methodology/Principal Findings28 mountaineers were randomly assigned to two ascent profiles during a research expedition to Mt. Muztagh Ata (7546 m/24,751 ft). Digital fundus photographs were taken prior to expedition at 490 m (1,607 ft), during expedition at 4497 m (14,750 ft = base camp), 5533 m (18,148 ft), 6265 m (20,549 ft), 6865 m (22,517 ft) and 4.5 months thereafter at 490 m. Number, size and time of occurrence of hemorrhages were recorded. Oxygen saturation (SpO2) and hematocrit were also assessed. 79% of all climbers exhibited retinal hemorrhages during the expedition. Number and area of retinal bleeding increased moderately to medium altitudes (6265 m). Most retinal hemorrhages were detected after return to base camp from a high altitude. No post-expeditional ophthalmic sequelae were detected. Significant negative (SpO2 Beta: −0.4, p<0.001) and positive (hematocrit Beta: 0.2, p = 0.002, time at altitude Beta: 0.33, p = 0.003) correlations with hemorrhages were found.Conclusions/SignificanceWhen closely examined, a very large amount of climbers exhibit retinal hemorrhages during exposure to high altitudes. The incidence of retinal hemorrhages may be greater than previously appreciated as a definite time lag was observed between highest altitude reached and development of retinal bleeding. Retinal hemorrhages should not be considered warning signs of impending severe altitude illness due to their delayed appearance.

Prevalence of Age-Related Macular Degeneration in Thailand

Purpose: To determine the prevalence of age-related macular degeneration (AMD) in Thailand.Methods: In this population-based study, data of participants in the Thailand National Survey of Visual Impairment in 2006–2007 were analyzed. Participants selected for this study were more than 50 years old, and were recruited from 42 districts of 21 provinces. They were interviewed, tested for visual acuity, examined for eye screening, and measured for intraocular pressure. They had digital fundus photographs taken using a nonmydriatic fundus camera through dilated pupils. The diagnosis of AMD, according to the standard international grading system, was made from the interpretation of the digital images by at least 2 retinal specialists. The observed data were used for predicting estimates of the prevalence of AMD in Thailand.Results: Data from 10,788 participants were analyzed. There were 321/10,788 (3%, 95% CI: 2.7–3.3%) participants diagnosed as having AMD. The mean age was 62.1 (range 50–98, SD 8.8) years old. There were 294 (2.7%) and 27 (0.3%) participants with early AMD (38.4% male) and late AMD (74.1% male) respectively. Of the late AMD, 20 (74.1%) were wet AMD and 7 (25.9%) were geographic atrophy. Based on the population census of Thailand, this could be translated into 351,000 and 39,000 patients with early and late AMD respectively.Conclusions: Based on these data, it is projected that Thailand will have a large number of late AMD sufferers. This makes it imperative to develop new strategies for the national public health system, aiming to incorporate already available late AMD treatment.

Diabetic retinopathy screening using single-field digital fundus photography at a district level in Costa Rica: a pilot study

To report on our initial experience screening for diabetic retinopathy (DR) using digital fundus photography and standarized criteria. Cross-sectional prospective study of all 1327 diabetic patients referred to the Ophthalmology Department of the Clorito Picado Clinic in San José, Costa Rica between April 2008 and March 2009. Patients were screened with a single-field 45-degree digital color retinal image centered on the fovea. The main outcome measures were prevalence of DR, waiting time for a fundus photograph appointment and the number of patients that needed to be evaluated by an ophthalmologist. In this population of 1327 patients, 85% did not have any retinopathy. The prevalence of DR was 15%. Mild non-proliferative DR (NPDR) was seen in 5.8% (70/1215), moderate NPDR in 3.9% (47/1215), severe NPDR in 4.7% (57/1215) and proliferative DR in 0.6% (8/1215). Macular edema was present in 2.6% (32) patients. 13.8% of patients required pupillary dilation for an adequate image to be taken and 8.8% of the images were unreadable. The average waiting time for a fundus photograph appointment was 49.1 days. A total of 13.8% (183/1327) patients were referred to the ophthalmologist. Of these referrals, 61.2% (112/183) were because of unreadable images and 38.8% (71/183) were referred for further ophthalmic treatment. Digital fundus photographic screening for DR appears to be a viable option for the improvement of screening for DR in Costa Rica.

Clinical Evaluation and Treatment Accuracy in Diabetic Macular Edema Using Navigated Laser Photocoagulator NAVILAS

To evaluate the clinical use and accuracy of a new retinal navigating laser technology that integrates a scanning slit fundus camera system with fluorescein angiography (FA), color, red-free, and infrared imaging capabilities with a computer steerable therapeutic 532-nm laser. Interventional case series. Eighty-six eyes of 61 patients with diabetic retinopathy and macular edema treated by NAVILAS. The imaging included digital color fundus photographs and FA. The planning included graphically marking future treatment sites (microaneurysms for single-spot focal treatment and areas of diffuse leakage for grid pattern photocoagulation) on the acquired images. The preplanned treatment was visible and overlaid on the live fundus image during the actual photocoagulation. The NAVILAS automatically advances the aiming beam location from one planned treatment site to the next after each photocoagulation spot until all sites are treated. Aiming beam stabilization compensated for patient's eye movements. The pretreatment FA with the treatment plan was overlaid on top of the posttreatment color fundus images with the actual laser burns. This allowed treatment accuracy to be calculated. Independent observers evaluated the images to determine if the retinal opacification after treatment overlapped the targeted microaneurysm. Safety and accuracy of laser photocoagulation. The images were of very good quality compared with standard fundus cameras, allowing careful delineation of target areas on FA. Toggling from infrared, to monochromatic, to color view allowed evaluation and adjustment of burn intensity during treatment. There were no complications during or after photocoagulation treatment. An analysis of accuracy of 400 random focal targeted spots found that the NAVILAS achieved a microaneurysm hit rate of 92% when the placement of the treatment circle was centered by the operating surgeon on the microaneurysm. The accuracy for the control group analyzing 100 focal spots was significantly lower at 72% (P<0.01). Laser photocoagulation using the NAVILAS system is safe and achieves a higher rate of accuracy in photocoagulation treatments of diabetic retinopathy lesions than standard manual-technique laser treatment. Precise manual preplanning and positioning of the treatment sites by the surgeon is possible, allowing accurate and predictable photocoagulation of these lesions. Proprietary or commercial disclosure may be found after the references.

The 97.5th and 99.5th Percentile of Vertical Cup Disc Ratio in the United States

The International Society of Geographical and Epidemiological Ophthalmology (ISGEO) suggests a case definition for the prevalence studies of glaucoma based on the 97.5th and 99.5th percentile of vertical optic cup distribution among the evaluated population. Although multiple studies evaluating the prevalence of glaucoma have been undertaken in the last 20 years, case definitions have varied, and data on the underlying population distribution are sparse. This study evaluates the population distribution of 97.5th and 99.5th percentile of vertical cup disc ratio (VCDR) and VCDR asymmetry (VCDRA) in the US population and its association with demographic characteristics, self-reported glaucoma, and visual field. The National Health and Nutrition Examination Survey (NHANES) is a nationally representative sample of the US population, which during the years 2005 to 2008 collected frequency doubling technology screening fields and digital fundus photography. Accounting for the complex design of the NHANES population, estimates of the 97.5th and 99.5th percentile of VCDR and VCDRA were calculated, and national estimates of glaucoma prevalence were generated. Associations between disc characteristics, demographic variables, and self-reported glaucoma were explored. Approximately 2.11% (95% confidence interval, 1.55 to 2.67) of the US population older than 40 years has glaucoma based on ISGEO criteria. A much larger 5.13% (95% confidence interval, 4.43 to 5.85) of the US population older than 40 years self-reports having glaucoma. Based on the estimates from NHANES, 6.89% of the population has a VCDR or VCDRA >97.5th percentile in either eye or OU. For the at-risk population with VCDR/VCDRA above the 97.5th percentile, <20% reported having glaucoma, whereas for those at the 99.5th percentile, <50% reported having glaucoma. The prevalence of glaucoma from NHANES based on ISGEO criteria produces similar population estimated to other population-based studies. Self-reported glaucoma is ∼2.4 times more common than what the prevalence estimates suggest.

Efficacy of Single-Field Non-Mydriatic Digital Fundus Photography for Screening Diabetic Retinopathy

Efficacy of Single-Field Non-Mydriatic Digital Fundus Photography for Screening Diabetic Retinopathy

High-Resolution Optical Coherence Tomography Retinal Imaging: A Case Series Illustrating Potential and Limitations

Purpose. To present a series of retinal disease cases that were imaged by spectral domain optical coherence tomography (SD-OCT) in order to illustrate the potential and limitations of this new imaging modality. Methods. The series comprised four selected cases (one case each) of age-related macular degeneration (ARMD), diabetic retinopathy (DR), central retinal artery occlusion (CRAO), and branch retinal vein occlusion (BRVO). Patients were imaged using the Heidelberg Spectralis (Heidelberg Engineering, Germany) in SD-OCT mode. Patients also underwent digital fundus photography and clinical assessment. Results. SD-OCT imaging of a case of age-related macular degeneration revealed a subfoveal choroidal neovascular membrane with detachment of the retinal pigment epithelium (RPE) and neurosensory retina. Using SD-OCT, the cases of DR and BRVO both exhibited macular edema with cystoid spaces visible in the outer retina. Conclusions. The ability of SD-OCT to clearly and objectively elucidate subtle morphological changes within the retinal layers provides information that can be used to formulate diagnoses with greater confidence.

Relationship of Smoking and Cardiovascular Risk Factors with Polypoidal Choroidal Vasculopathy and Age-related Macular Degeneration in Chinese Persons

Polypoidal choroidal vasculopathy (PCV) has been described as a distinct clinical entity from choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). The present study aimed to determine risk factors for PCV and to compare associations with those for CNV secondary to AMD. Case-control study. Patients of Chinese ethnicity with clinically and angiographically diagnosed PCV (n = 123) or CNV secondary to AMD (n = 128) were recruited from a tertiary eye hospital in Singapore. Controls without signs of PCV, CNV secondary to AMD, or other retinal pathologic features (n = 1489) were selected from a population-based study. Patients underwent an ophthalmologic examination including digital color fundus photography, stereoscopic fluorescein angiography (FA), and indocyanine green angiography (ICGA). Classification into PCV or CNV secondary to AMD was based on FA and ICGA findings. Risk factors were determined from a standardized interview, with blood pressure recorded using a digital automatic blood pressure monitor. Polypoidal choroidal vasculopathy or CNV secondary to AMD. Persons who smoked were more likely to have PCV (39.9% vs. 13.4%) or CNV secondary to AMD (45.0% vs. 12.3%) than those who did not smoke. After controlling for age, gender, diabetes, hypercholesterolemia, and hypertension, persons who smoked were 4 times more likely to have PCV (odds ratio [OR], 4.4; 95% confidence interval [CI], 2.5-7.7; P<0.001) and CNV secondary to AMD (OR, 4.9; 95% CI, 2.7-8.8; P<0.001). A significant, negative association also was found between diastolic blood pressure and CNV secondary to AMD (OR, 0.7; 95% CI, 0.5-0.9; P = 0.017, adjusted for age, gender, smoking, diabetes, and hypercholesterolemia), but diastolic blood pressure was not associated with PCV. Smoking but not other vascular risk factors is significantly associated with both PCV and CNV secondary to AMD in Chinese persons. The similarity of associations suggests that there may be common risk factors and pathological mechanisms.

The change points of HbA1C for detection of retinopathy in Chinese type 2 diabetic patients

AimsTo investigate the change points of HbA1C for detection of retinopathy in Chinese type 2 diabetic patients. MethodsThis cross-sectional investigation included 992 diagnosed type 2 diabetic patients, who received non-mydriatic digital fundus photography examination. Joinpoint regression software was adopted to identify the change points of HbA1C in association with retinopathy prevalence. ResultsThe mean age of all patients was 59.1±8.4 years and the duration of diabetes was 5.5 (95% CI: 5.2–5.9) years. The prevalence of retinopathy was 10.3% in total, and 4.1%, 7.4% and 19.6% in patients with different diabetes duration of ≤5 years, 5–10 years and >10 years, respectively. The change point of HbA1C was 6.5% (95%CI 5.8–7.5%), at which retinopathy prevalence began to rise sharply. Furthermore, in subjects with diabetes duration ≤5 years, 5–10 years and >10 years, the change points of HbA1C were 8.1% (95%CI 7.9–8.3%), 6.1% (95%CI 5.7–6.8%), 5.6% (95%CI 5.1–8.1%) for detection of retinopathy, respectively. ConclusionThe steepest increase in retinopathy prevalence occurred when HbA1C reached 6.5%. However, the duration of diabetes should be taken into concern, when using the change points of HbA1C for detection of retinopathy in diabetic patients.

Fractal analysis of retinal microvasculature and coronary heart disease mortality

Fractal analysis provides a global assessment of vascular network architecture. We examined the relationship of retinal vascular fractal dimension (D(f)) with coronary heart disease (CHD) mortality. We examined the relationship of D(f) with 14-year CHD mortality in a prospective, population-based cohort of 3303 participants aged 49 years or older. D(f) was measured from digitized fundus photographs using computer-automated methods; CHD mortality was documented from Australian National Death Index records. Mean D(f) in this population was 1.441 (standard deviation, 0.024). Over 14 years, there were 468 (14.2%) CHD deaths. Participants with suboptimal D(f) (lowest and highest quartiles) had 50% higher 14-year CHD mortality than those with optimal D(f) (middle quartiles), after adjusting for age, blood pressure, and other risk factors. Among participants aged ≤ 70 years, suboptimal D(f) was associated with a nearly two-fold higher risk of CHD mortality [adjusted hazard ratio (HR) 1.89, 95% confidence interval (CI), 1.25, 2.84 for the lowest quartile and HR 1.87, CI 1.30, 2.69 for the highest quartile, compared with middle quartiles]. D(f) is a novel means of quantifying microvascular branching that independently predicted 14-year CHD mortality. These findings suggest that suboptimal microvascular branching may play a role in development of clinical cardiovascular disease.

Abnormal sleep patterns in subjects with type II diabetes mellitus and its effect on diabetic microangiopathies: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN-DREAMS, report 20)

To study the prevalence of Abnormal Sleep Patterns (ASPs), gender-wise, in subjects with type II diabetes mellitus and its influence on diabetic microangiopathies. A population-based cross-sectional survey was conducted among 1,414 patients having type II diabetes mellitus. Diabetic retinopathy was graded using stereoscopic digital fundus photography. Neuropathy was assessed by measuring vibration perception threshold using a sensitometer. Nephropathy was diagnosed by the presence of microalbuminuria in the first morning urine sample. ASPs were defined as either short (less than 5 h) or long (more than 9 h) duration of sleep with excessive daytime sleepiness. The Epworth Sleepiness Scale (ESS) score was assessed to note excessive daytime sleepiness; a score of more than 10 was considered as abnormal. The prevalence of ASPs was more in subjects with diabetes than with those without diabetes (14.8 vs. 6.6%) (P = 0.009), especially in women (15.7 vs. 5.6%) (P = 0.021). Likewise, the prevalence of short duration of sleep was higher in subjects with diabetes compared to those without diabetes (6.6 vs. 2.2%) (P = 0.040). The mean age of women subjects with diabetes, having ASPs, was higher than those without diabetes (56.4 ± 8.9 years vs. 47.2 ± 5.9 years, P = 0.033). Women subjects with ASPs had a higher risk of diabetic neuropathy on both univariate and multivariate analysis. ASPs are not only related to diabetes but can also influence the microvascular complications arising due to diabetes, particularly diabetic neuropathy. Diabetology and sleep medicine specialists need to work together to prevent the negative interactions between these two groups.

Prevalence of Metabolic Syndrome and its influence on microvascular complications in the Indian population with Type 2 Diabetes Mellitus. Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular Genetic Study (SN-DREAMS, report 14)

BackgroundThe Metabolic syndrome (MS) consists of central obesity, glucose intolerance, hyperinsulinemia, low high density lipoproteins, high triglycerides and hypertension. Different studies have observed that MS causes microvascular complications in patients with type 2 diabetes. The aim of the study was to find out the prevalence of MS in the Indian population with type 2 diabetes mellitus in relation to gender, duration of diabetes, and to evaluate the influence of MS and its individual components on microvascular complications such as diabetic retinopathy, diabetic nephropathy and diabetic neuropathy.MethodsA population-based cross sectional survey was conducted with 1414 patients having type 2 diabetes mellitus. The International Diabetes Federation (IDF) criteria were used to identify the metabolic syndrome. Diabetic retinopathy was graded using the stereoscopic digital fundus photography. Neuropathy was assessed by measuring the vibration perception threshold through a sensitometer. Nephropathy was diagnosed by the presence of microalbuminuria in the first morning urine sample.ResultsThe age and gender adjusted prevalence of MS, using the IDF criteria, in the South Indian population was 73.3%. The prevalence was higher in women (83.3%), compared to men (65.3%). In subjects with diabetes mellitus, without and with MS, the prevalence of retinopathy was 21.3% and 16.9% (p = 0.057); prevalence of nephropathy was 20.5% and 18.0% (p = 0.296), and prevalence of neuropathy was17.2% and 19.4% (p = 0.353) respectively. Overall and in women, the clustering of MS components led to an increase in the prevalence of diabetic nephropathy. The prevalence of retinopathy and neuropathy in MS subjects, who had diabetes for < 10 years, was more in both men and women; it was more in women but not in men when the duration of diabetes varied from 11-20 years.ConclusionsThe association of MS with microangiopathies decreased with an increase in the duration of diabetes. MS behaved differently in men and women. It may need to be managed differently in the two groups.

Digital versus Film Fundus Photography for Research Grading of Diabetic Retinopathy Severity

To assess agreement between digital and film photography for research classification of diabetic retinopathy severity. Digital and film photographs from a 152-eye cohort with a full spectrum of Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels were assessed for repeatability of grading within each image medium and for agreement on ETDRS discrete severity levels, ascending severity thresholds, and presence or absence of diabetic retinopathy index lesions, between digital and 35-mm slides (film). Digital photographs were color balanced to match film. There was substantial agreement (κ = 0.61, κ(w) [linear weighted] = 0.87) in classification of ETDRS diabetic retinopathy severity levels between digital images and film. Marginal homogeneity analyses found no significant difference in frequency distributions on the severity scale (P = 0.21, Bhapkar test). The κ results ranged from 0.72 to 0.95 for presence or absence of eight ascending diabetic retinopathy severity thresholds. Repeatability of grading between readers viewing digital images was equal to or better than that obtained with film (pair-wise interreader κ for digital images ranged from 0.47 to 0.57 and for film from 0.43 to 0.57. The κ results for identifying diabetic retinopathy lesions ranged from moderate to almost perfect. Moderate agreement of intraretinal microvascular abnormalities and venous beading between digital images and film accounted for slightly lower concordance for severity thresholds ≥47 and for slightly lower interreader agreement within digital and film images at severity thresholds ≥43 and ≥47. Under controlled circumstances, digital photography can equal the reliability of 35-mm slides for research classification of ETDRS severity level.

Prevalence and Risk Factors for Epiretinal Membranes in a Multi-Ethnic United States Population

To describe the prevalence of and risk factors for epiretinal membrane (ERM) in a multi-ethnic population and to evaluate possible racial or ethnic differences. Cross-sectional study. Participants of the Multi-Ethnic Study of Atherosclerosis (MESA), examined at the second visit of the MESA when retinal photography was performed. Data on 5960 participants aged 45 to 84 years from MESA, including white, black, Hispanic, and Chinese persons from 6 United States communities, were analyzed. Epiretinal membrane was assessed from digital nonstereoscopic fundus photographs and was defined as cellophane macular reflex (CMR) without retinal folds or preretinal macular fibrosis (PMF) with retinal folds. Risk factors were assessed from standardized interviews, clinical examinations, and laboratory investigations. Epiretinal membrane prevalence by ethnic or racial group and risk factors associated with ERM. The prevalence of any ERM was 28.9%, of which 25.1% were CMR cases and 3.8% were PMF cases. The prevalence of ERM was significantly higher in Chinese persons (39.0%), compared with Hispanic (29.3%), white (27.5%), or black (26.2%; P<0.001) persons. In multivariate models, increasing age (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.06-1.34, per year increase in age), diabetes (OR, 1.92; 95% CI, 1.39-2.65), and hypercholesterolemia (OR, 1.33; 95% CI, 1.04-1.69) were significantly associated with CMR. This study showed that ERM was significantly more common in Chinese persons compared with whites, blacks, and Hispanics. Risk factors for ERM were increasing age, presence of diabetes, and hypercholesterolemia.

Window to the brain: Can retinopathy be used to assess cognitive function

Objective: Retinopathy status as a screening method to predict cognitive health is limited. The objective of this study was to examine the association between retinopathy and lowered cognitive performance in a Canadian First Nations population.Methods: Eligible individuals were assessed by the Clock Drawing Test (CDT) and the Trail Making Test Parts A and B, which were combined into an executive function score (TMT-exec). Digital fundus photographs were taken for both eyes to assess retinopathy. Anthropometric, vascular and metabolic risk factors were assessed by interview, clinical examinations and blood tests. Carotid atherosclerosis was assessed by Doppler ultrasonography.Results: Retinopathy was detected in 7.1% of the population. Individuals classified as having a previous history of cardiovascular disease, insulin resistance and diabetes were more likely to have retinopathy. No other cardiovascular risk factors were associated. In unadjusted analysis, there were no associations between retinopathy and lowered cognitive performance (CDT, odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.30–2.53; TMT-exec, OR: 1.79, 95% CI: 0.60–5.33). Multivariable adjusted analysis also showed no associations, although sample size may be limiting.Conclusions: Retinopathy was not associated with lowered cognitive performance. Associations for microvascular risk factors suggest a panel of cognitive tests is needed for future studies.

Scale for Photographic Grading of Vitreous Haze in Uveitis

To validate a scale for grading vitreous haze in uveitis using digitized photographs and standardized scoring. Evaluation of clinical research methodology. Calibrated Bangerter diffusion filters inducing incremental decrements of spatial contrast were placed in front of the camera lens while photographing a normal eye to simulate vitreous haze. The photographs were digitized and an ordinal scale was created from 0 (none) to 8 (highest level of opacification at which fundus details could be seen). The scale steps correspond approximately to decimal Snellen visual acuities of 1.0, 0.8, 0.4, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002, with approximately 0.3 log step between each step. For validation, digitized fundus photographs of uveitis patients were displayed on a computer monitor for comparison with the standard photos. Three observers graded the test set twice under standard conditions. Interobserver and intraobserver variability and κ values for agreement greater than chance were calculated. Variance component analysis determined that 87.7% of the variance in grades was attributable to the test item rather than to grader or session. The intraclass correlation between graders and grading sessions varied from 0.84 to 0.91. Simple agreement within 1 grade between graders and sessions occurred in 90 ± 5.5% of gradings. κ values averaged 0.91, which is considered near perfect. A 9-step photographic scale was designed to standardize the grading of vitreous haze in uveitis patients using fundus photographs. The scale is potentially adaptable to clinical trials in uveitis.