The Wisconsin age-related maculopathy grading system.

A new system for grading age-related maculopathy is described and measures of reliability are reported. A number of characteristics of age-related maculopathy are graded in a semiquantitative fashion from stereoscopic 30 degrees color fundus photographs, using a grid to define subfields, standard circles printed on plastic to assess size and area, and a specially designed lightbox to allow better discrimination of subtle drusen. The degree of exact agreement achieved between two trained graders across a variety of lesions ranged from 67.1% for drusen size to 99.6% for geographic atrophy. Kappa scores ranged from 0.55 (for drusen confluence) to 0.95 for geographic atrophy. This system will be useful in epidemiologic studies and clinical trials.

Assessment of cataracts from photographs in the Beaver Dam Eye Study.

Presence and severity of age-related cataract was determined in adults 43 to 84 years of age in Beaver Dam, Wisconsin. Duplicate photograph gradings for nuclear sclerosis (n = 1160), cortical opacities (n = 1159), and posterior subcapsular cataract (n = 1137) were performed. There are five levels of nuclear sclerosis. Exact agreement occurred in 64.7% of the cases; agreement within one category in 99.8%. For cortical opacities, graders estimate involved area in nine segments of the lens. When the continuous scale is divided into 12 categories of severity, exact agreement varied between 73.5 and 82.4%; for agreement within one category, rates varied between 84.6 and 89.9%. For posterior subcapsular cataracts, exact agreement for involvement of the central circle occurred in 95.0% and agreement within one category occurred in 97.7%. Intraobserver comparisons disclosed similar concordance. These grading schemes are semiquantitative, reproducible, and can be performed for the large numbers of photographs from population-based studies.

Neuroretinal rim area in diabetes mellitus.

Neuroretinal rim area (NRA) may indicate the amount of viable optic nerve tissue. Changes in the NRA have been found to occur in people with glaucoma. We sought to determine whether there were effects of retinopathy and intraocular pressure (IOP) on NRA in eyes of people with diabetes. Measurements of optic discs and cups were taken from 35-mm stereoscopic slides taken with a Zeiss fundus camera. The photographs were taken during a population-based study. The difference between disc and cup area was taken to be the NRA. Median photographic NRA from 2085 right eyes was 10.5 mm2. In younger- and older-onset persons, NRA showed a tendency to increase with age and, inconsistently, with the severity of diabetic retinopathy; it decreased with increasing IOP in older-onset persons not taking insulin. The cohort was reevaluated 4 yr later. NRA increased in all groups. Measurements from photographs taken of a nondiabetic comparison group showed no change over the same interval. These data suggest that NRA may be affected by diabetes. This could be due to nerve swelling.

Optic disc cupping: prevalence findings from the WESDR.

Increased cupping of the optic disc is considered to be an indication of pressure-related damage of the optic nerve. This paper explores the relationship of intraocular pressure and cupping in persons with diabetes mellitus, a group of people whose optic nerves may be more susceptible to the effects of intraocular pressure. Stereoscopic fundus photographs of the seven standard fields were obtained in all persons participating in the Wisconsin Epidemiologic Study of Diabetic Retinopathy at the time of the initial prevalence survey. Measurements of disc and cup diameters in the vertical and horizontal meridia were made by two trained graders. Cup-to-disc ratios were computed for both diameters of each eye and the mean of the two gradings was used. A history of glaucoma was significantly associated with larger cup-to-disc ratios at the prevalence examination. Cup-to-disc ratios were not larger in those with high IOP, nor in those who had panretinal photocoagulation.

Optic disc cupping: four year follow-up from the WESDR.

Change in optic disc cupping was evaluated in a 4-year follow-up of a well defined cohort of people with diabetes mellitus. Cup-to-disc ratios were computed for both vertical and horizontal diameters of each eye at the baseline and 4-year follow-up examinations. Graders were masked as to the identity of participants and to the dates of the photographs. Increases of at least 0.1 between baseline and follow-up were used as clinically significant change in the ratios. None of the following factors at baseline were consistent predictors of such a change: intraocular pressure, age, duration of diabetes, hypertension or severity of diabetic retinopathy. People who developed proliferative retinopathy by the follow-up examination were not more likely to have such an increase in ratio at the follow-up. We conclude that clinically significant increases in cup-to-disc ratio cannot be consistently predicted in people with diabetes from the risk factors evaluated with the grading system used in this study.

Optic disc cupping as clinically estimated from photographs.

Cup-to-disc ratios of 204 right eyes were evaluated by two clinicians and by a trained grader using a standardized grading scheme. Mean measurements by the grader were greater than estimates made by either clinician. The measurement scheme used by the trained grader has a high degree of reliability and validity. The standard protocol provides an objective assessment of optic disc cupping and could be easily adapted for office use.

An alternative method of grading diabetic retinopathy.

The purpose of this report is to present a system for grading the severity of diabetic retinopathy that is a rapid, relatively inexpensive, and standardized alternative to the more detailed Early Treatment Diabetic Retinopathy Study (ETDRS) system; present data on its reproducibility; and compare it to the detailed ETDRS grading system. The alternative system was used to grade fundus photographs obtained during a large prevalence study, the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR). The alternative method involved grading seven stereoscopic standard fields as a whole, and assigning a level of severity for the eye according to the greatest degree of retinopathy using a modified Airlie House Classification scheme. Using an eight-level classification system of increasing severity of retinopathy, there was 78.3% exact agreement between the alternative and ETDRS systems. A grader regraded all 503 disagreements, and was in exact agreement 49.3% of the time with the alternative system, 35.7% of the time with the detailed system, and 15.0% with neither the alternative or detailed systems. Interobserver agreement for the alternative system was 78.5%; intraobserver agreement over a 9 month to 1 year period was 90.0% for grader 1 and 84.0% for grader 2. The alternative system of grading, when used by experienced graders, is a reproducible method for objectively determining retinopathy status in epidemiologic studies.

Quantitation of optic disc cupping.

In population-based studies and in clinical practice a reliable, objective measure of optic disc cupping is needed. This measure is of special importance when following patients with diagnosed or suspected glaucoma. We have developed a new system using stereoscopic fundus photographs for quantitating optic disc cupping from these photographs. Measurements of the cup are based on cup contour. For this system, measurements of longest and shortest cup and longest and shortest disc diameters by two observers were highly correlated, with correlation coefficients of 0.88, 0.88, 0.77, and 0.82, respectively. Mean cup to disc ratios for long and short disc diameters were within 0.04 (n = 330) between the two observers. The measurements show a high degree of inter- and intra-observer reliability, and are inexpensive in time and materials to perform. This method is well suited to population-based studies.

Diabetic retinopathy. Assessment of severity and progression.

This study describes a classification of overall retinopathy severity based on the presence and severity of lesions graded in the Airlie House classification of diabetic retinopathy, and demonstrates its use in assessing progression of retinopathy over a 6-year period in a group of insulin-taking patients. One hundred and ninety-one insulin-taking patients with diabetes of at least 5 years' duration were identified from their doctors' records in 1970-1971. Patients were seen again in 1972-1973 and 1976-1977. Stereoscopic color fundus photographs of 7 fields in each eye were taken at each visit. All photos were graded using a modification of the Airlie House classification, which specified 6 levels of retinopathy for a given eye; when both eyes are considered an 11-step grading scheme results. Of all patients seen at the 2-year visit whose retinopathy was at risk of progressing, 41.2% showed progression of one level or more on the scale, 19.2% progression of two or more levels. At the 6-year examination comparable rates were 75.0% and 58.4%. Of patients whose retinopathy was level 4 in each eye (nonproliferative retinopathy of "moderate" severity) at the baseline visit, 13/21 (72%) had progressed to proliferative retinopathy in at least one eye at the 6-year examination. The classification scheme proposed appears useful for characterizing overall retinopathy severity of patients on the basis of gradings of fundus photographs. The data presented may be of help in planning trials of treatment aimed at slowing the development or progression of retinopathy.

Prognosis for life in patients with diabetes: relation to severity of retinopathy.

In a group of 709 individuals with diabetes diagnosed prior to age 50 and followed for five to thirteen years a strong inverse relationship was demonstrated between the severity of the retinopathy at the initial visit and survival. Survival in patients with no retinopathy or with microaneurysms only was little different from that of the general population (five-year rate .99, SE .01). The five-year survival rate for patients with more severe nonproliferative retinopathy, characterized by the presence of hemorrhages and/or exudates, but without new vessels or vitreous hemorrhage (B2), was .81 (SE .04), and that for patients with proliferative retinopathy (PDR) was .56 (SE .03). After adjustment for age at diagnosis of diabetes, duration of diabetes and sex, the differences in survival between these three groups were highly statistically significant. Impairment of visual acuity was also shown to be inversely related to survival. The five-year survival rate for patients with visual acuity of 20/200 or worse in each eye was .42 (SE .05). In patients with B2 retinopathy there was a weak but statistically significant trend towards decreasing survival with increasing duration of diabetes. In patients with PDR survival decreased with increasing duration up to 20 years, but then improved for patients with 20 years or more of diabetes.