SENSITIVITY AND SPECIFICITY OF PHOTOGRAPHY AND DIRECT OPHTHALMOSCOPY IN SCREENING FOR SIGHT THREATENING EYE DISEASE - THE LIVERPOOL DIABETIC EYE STUDY

Objective-To evaluate different methods for community based screening for sight threatening diabetic eye disease. Design-Prospective study. Setting-Mobile screening unit visiting inner city community clinics; h ospital assessment clinic (tertiary centre). Subjects Subjects-395 dia betic patients registered with four general practices in an inner city location. Interventions-Community based photography with mydriasis an d direct ophthalmoscopy through dilated pupils by an experienced ophth almologist, both compared with reference standard of slit lamp biomicr oscopy by a consultant specialist in medical retinal disease. Main out come measures-Sensitivity and specificity of screening method and prev alence of sight threatening diabetic eye disease (moderate preprolifer ative retinopathy, circinate maculopathy, exudate within 1 disc diamet er of fixation, other diabetes related eye disease). Results-358 subje cts underwent photography, 326 attended hospital clinic for ophthalmos copy, and six were ungradable on photographs and biomicroscopy, leavin g 320 for analysis. Of these 295 (91%) attended clinic within four mon ths of photography. Sensitivity of detection of eye disease by photogr aphy was 89% (95% confidence interval 80% to 98%), significantly bette r than for direct ophthalmoscopy (65% (51% to 79%)). Analysis of patie nts with false negative results indicated possible improvement of phot ographic sensitivity to 93% by addition of stereoscopic macular pair p hotographs. Specificity of detection of sight threatening eye disease was 86% (82% to 90%) for photography and 97% (95% to 99%) for direct o phthalmoscopy. Conclusions-Since high sensitivity is essential for an effective screening programme, a photographic method should be conside red as preferred option in national, community based screening program mes. Even in the hands of an experienced ophthalmologist, direct ophth almoscopy is limited by weaknesses inherent to the instrument.