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Objectives-To compare the effectiveness of a mobile screening unit with a non-mydriatic polaroid camera in detecting diabetic retinopathy in rural and urban areas. To estimate the cost ofthe service.Design-Prospective data collection over two years of screening for diabetic retinopathy throughout Tayside.Setting-Tayside region, population 390000, area 7770 km2.

Aims: To evaluate the sensitivity and specificity of wide-field scanning laser ophthalmoscopy (WSLO) in the detection of referable diabetic eye disease, and to compare its performance with digital retinal photography. Methods: Patients enrolled into the study underwent non-mydriatic WSLO imaging, then single- and dual-field mydriatic digital retinal photography, and examination with slit lamp biomicroscopy, the reference standard. Grading of retinopathy was performed in a masked fashion. Results: A total of 380 patients (759 eyes) were recruited to the study. Technical failure rates for dilated single-field retinal photography, dual-field retinal photography and undilated WSLO were 6.3, 5.8 and 10.8%, respectively (0.005 < p < 0.02 for photography vs. WSLO). The respective indices for screening sensitivity were 82.9, 82.9 and 83.6% (p > 0.2). Specificity was 92.1, 91.1 and 89.5%, respectively (p > 0.2). Conclusions: Sensitivity and specificity for WSLO were similar to retinal photography. The technical failure rate was greater for the WSLO used in this study.

Introduction of a systematic retinal screening programme can reduce the proportion of patients referred to the ophthalmology clinic, and use ophthalmology services more efficiently.

Fundus photography has been shown to be a useful screening tool for the detection of diabetic retinopathy. In this paper the authors assess the incidence of blind and partially sighted registration due to diabetic eye disease in patients screened by a mobile fundus photography unit and identify the factors that contributed to loss of vision in the registered group.Methods A retrospective review of blind and partially sighted registrations between 1990 and 1995 was performed in a diabetic population screened by a mobile fundus photography unit in a region with a population of 390 000. The incidence of blind and partially sighted registration in the screened diabetic population was calculated.In the registered group, cause of visual loss, accuracy of photograph reporting, delay in laser treatment, adequacy of laser treatment and non-attendance rates at ophthalmic clinics were assessed.Results Of the 5390 patients screened by the mobile unit over 6 years, 68 (210 per 10 5 patient-years) were registered blind or partially sighted, but in only 17 patients (53 per 10 5 patient-years) was this as a result of diabetes. The factors contributing to loss of vision were found to be failure of laser treatment, rapidly progressive disease and poor patient attendance.Conclusions As the majority of visual impairment in patients with diabetes is not due to diabetic retinopathy, this has important implications for screening programmes and may make the St Vincent Declaration targets difficult to achieve. The rate of new blind and partially sighted registration due to diabetes in the screened population was low at 53 per 10 5 patient-years (95% confidence interval, 29-76).