The Influence of Age, Duration of Diabetes, Cataract, and Pupil Size on Image Quality in Digital Photographic Retinal Screening

The Influence of Age, Duration of Diabetes, Cataract, and Pupil Size on Image Quality in Digital Photographic Retinal Screening Peter Henry Scanlon , MRCP 1 , Chris Foy , MSC 2 , Raman Malhotra , FRCO, PHTH 3 and Stephen J. Aldington , DMS 4 1 Department of Ophthalmology, Cheltenham General Hospital, Cheltenham, U.K. 2 R&D Support Unit, Gloucester Hospitals National Health Service Trust, Gloucester, U.K. 3 Oxford Eye Hospital, Oxford, U.K. 4 Retinopathy Grading Centre, Imperial College, London, U.K. Address correspondence and reprint requests to Dr. Peter Scanlon, Gloucestershire Eye Unit, Cheltenham General Hospital, Sandford Road, Cheltenham, GL53 7AN, U.K. E-mail: peter.scanlon{at}glos.nhs.uk Abstract OBJECTIVE —To evaluate the effect of age, duration of diabetes, cataract, and pupil size on the image quality in digital photographic screening. RESEARCH DESIGN AND METHODS —Randomized groups of 3,650 patients had one-field, nonmydriatic, 45° digital retinal imaging photography before mydriatic two-field photography. A total of 1,549 patients were then examined by an experienced ophthalmologist. Outcome measures were ungradable image rates, age, duration of diabetes, detection of referable diabetic retinopathy, presence of early or obvious central cataract, pupil diameter, and iris color. RESULTS —The ungradable image rate for nonmydriatic photography was 19.7% (95% CI 18.4–21.0) and for mydriatic photography was 3.7% (3.1–4.3). The odds of having one eye ungradable increased by 2.6% (1.6–3.7) for each extra year since diagnosis for nonmydriatic, by 4.1% (2.7–5.7) for mydriatic photography irrespective of age, by 5.8% (5.0–6.7) for nonmydriatic, and by 8.4% (6.5–10.4) for mydriatic photography for every extra year of age, irrespective of years since diagnosis. Obvious central cataract was present in 57% of ungradable mydriatic photographs, early cataract in 21%, no cataract in 9%, and 13% had other pathologies. The pupil diameter in the ungradable eyes showed a significant trend ( P < 0.001) in the three groups (obvious cataract 4.434, early cataract 3.379, and no cataract 2.750). CONCLUSIONS —The strongest predictor of ungradable image rates, both for nonmydriatic and mydriatic digital photography, is the age of the person with diabetes. The most common cause of ungradable images was obvious central cataract. Footnotes A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Accept