Prevalence and risks factors of age-related macular degeneration in Oklahoma Indians: the Vision Keepers Study.

OBJECTIVE: To determine the prevalence of age-related macular degeneration (AMD) and to identify its risk factors in an Oklahoma Indian population. DESIGN: Cross-sectional study design. PARTICIPANTS: Included 1019 Oklahoma Indians who participated in baseline and second examinations of the Strong Heart Study. METHODS: Retinal photographs of at least 1 eye were obtained and graded for AMD by the University of Wisconsin Ocular Epidemiology Reading Center. Retinal photographs of 986 participants were considered gradable and were included in the study. MAIN OUTCOME MEASURES: Age-related macular degeneration (early and late). RESULTS: The overall prevalence of AMD in the study was 35.2%, including a prevalence of 0.81% for late AMD. The prevalence of early AMD increased from 30.6% in those aged 48 to 59 years to 46.1% in those 70 to 82 years of age. When potential risk factors were analyzed individually (univariate analyses), men with hypertension had a significantly higher prevalence of AMD (P = 0.02) than those without hypertension. In women, high-density lipoprotein cholesterol and sun exposure were associated positively with the prevalence of AMD (P = 0.01), whereas a history of using multivitamins was associated with lower AMD prevalence (P = 0.005). When multiple risk factors were analyzed simultaneously using logistic regression, only age showed significant association with AMD in both men (P = 0.02) and women (P<0.0001) and was the only significant risk factor in men. In women, multivitamin use and total cholesterol had a significant inverse association with AMD, whereas sun exposure and high-density lipoprotein cholesterol had a positive association. When men and women were combined, age and high-density lipoprotein cholesterol had significant positive associations, whereas total cholesterol, multivitamin use, and current alcohol use showed a significant inverse association with AMD. CONCLUSIONS: This study was the first to report a detailed prevalence of AMD in Oklahoma Indians and its risk factors. The prevalence seemed to be relatively high compared with that in other ethnic groups. Some of the modifiable risk factors identified confirmed previous findings and can be used to design preventive programs to reduce the burden of AMD, although longitudinal data are still needed.

Visual impairment and eye abnormalities in Oklahoma Indians.

OBJECTIVE: To determine the prevalence of visual impairment and eye abnormalities in Oklahoma Indians. METHODS: The cross-sectional study included 1019 Oklahoma Indians, aged 48 to 82 years; 60.2% were women. All participants gave a personal interview, and all underwent an eye examination, including the determination of best-corrected visual acuity and an ophthalmoscopic examination. In addition, two 45 degrees fundus photographs were taken of each eye, and these photographs were graded by the Fundus Photography Reading Center at the University of Wisconsin, Madison. RESULTS: Among the 1019 participants, 77.4% had a visual acuity of 20/20 or better, 19.5% and 2.5% had visual acuities of between 20/25 and 20/40 and between 20/50 and 20/190, respectively; and 0.6% were legally blind, all in the better eye. Cataract was the most frequent contributing cause and age-related macular degeneration the second most frequent contributing cause of visual impairment. The overall prevalence proportions of age-related macular degeneration, cataract, diabetic retinopathy, and definite glaucoma were 33.6%, 39.6%, 20.1%, and 5.6%, respectively. Most of the other eye abnormalities were rare in the study participants, except for pinguecula (42.4%) and dermatochalasis (30.1%). CONCLUSIONS: Oklahoma Indians have a higher prevalence of visual impairment, age-related macular degeneration, and diabetic retinopathy than other ethnic groups. The implementation of adequate treatment and prevention programs for eye diseases is indicated.

Computer classification of nonproliferative diabetic retinopathy.

OBJECTIVE: To propose methods for computer grading of the severity of 3 early lesions, namely, hemorrhages and microaneurysms, hard exudates, and cotton-wool spots, and classification of nonproliferative diabetic retinopathy (NPDR) based on these 3 types of lesions. METHODS: Using a computer diagnostic system developed earlier, the number of each of the 3 early lesions and the size of each lesion in the standard photographs were determined. Computer classification criteria were developed for the levels of individual lesions and for NPDR. Evaluation of the criteria was performed using 430 fundus images with normal retinas or any degree of retinopathy and 361 fundus images with no retinopathy or the 3 early lesions only. The results were compared with those of the graders at the University of Wisconsin Ocular Epidemiology Reading Center and an ophthalmologist. MAIN OUTCOME MEASURES: Agreement rates in the classification of NPDR between the computer system and human experts. RESULTS: In determining the severity levels of individual lesions, the agreement rates between the computer system and the reading center were 82.6%, 82.6%, and 88.3% using the 430 images and 85.3%, 87.5%, and 93.1% using the 361 images, respectively, for hemorrhages and microaneurysms, hard exudates, and cotton-wool spots. When the "questionable" category was excluded, the corresponding agreement rates were 86.5%, 92.3%, and 91.0% using the 430 images and 89.7%, 96.3%, and 97.4% using the 361 images. In classifying NPDR, the agreement rates between the computer system and the ophthalmologist were 81.7% using the 430 images and 83.5% using the 361 images. CONCLUSIONS: The proposed criteria for computer classification produced results that are comparable with those provided by human experts. With additional research, this computer system could become a useful clinical aid to physicians and a tool for screening, diagnosing, and classifying NPDR.