Comparison of optometry vs digital photography screening for diabetic retinopathy in a single district

To compare (a). the clinical effectiveness and (b). cost effectiveness of the two models in screening for diabetic retinopathy.

(a). Retrospective analysis of referral diagnoses of each screening model in their first respective years of operation and an audit of screen positive patients and a sample of screen negatives referred to the hospital eye service from both screening programmes. (b). Cost effectiveness study.

(1). A total of 1643 patients screened in the community and in digital photography clinics; (2). 109 consecutive patients referred to the Diabetic Eye Clinic through the two existing models of diabetic retinopathy screening; (3). 55 screen negative patients from the optometry model; (4). 68 screen negative patients audited from the digital photography model.

The compliance rate was 45% for optometry (O) vs 50% for the digital imaging system (I). Background retinopathy was recorded at screening in 22% (O) vs 17% (I) (P=0.03) and maculopathy in 3.8% (O) vs 1.7% (I) (P=0.02). Hospital referral rates were 3.8% (O) vs 4.2% (I) Sensitivity (75% for optometry, 80% for digital photography) and specificity (98% for optometry and digital photography) were similar in both models. The cost of screening each patient was pound 23.99 (O) vs pound 29.29 (I). The cost effectiveness was pound 832 (O) vs pound 853(I) in the first year.

The imaging system was not always able to detect early retinopathy and maculopathy; it was equally specific in identifying sight-threatening disease. Cost effectiveness was poor in both models, in their first operational year largely as a result of poor compliance rates in the newly introduced screening programme. Cost effectiveness of the imaging model should further improve with falling costs of imaging systems. Until then, it is essential to continue any existing well-coordinated optometry model.