Screening for diabetic retinopathy using Polaroid retinal photography through undilated pupils

Abstract

Abstract Though blindness can be prevented by photocoagulation, serious diabetic retinopathy (DR) goes undetected in many diabetic patients. The Canon non‐mydriatic Polaroid retinal cameras (CR2‐45NM and CR3‐45NM) provide an instant photograph of a 45° field (including macula and disc) through undilated pupils. In a series of studies involving 400 eye photographs, we have assessed their potential in the screening for DR in busy diabetic clinics. In patients randomly selected during these clinics, the cameras were compared with ophthalmoscopy by one of 15 diabetic clinic physicians (OP), through undilated (OPu) and dilated (OPd) pupils. Twenty per cent of the photographs showed DR. This was missed by OPu in 76% and OPd in 56%. The detection rate was higher for the CR3 (23%) than the CR2 (18%). Furthermore, the photographic failure rate was considerably reduced for the CR3 (6%) compared to the CR2 (22%), which requires a larger pupil. When the CR3 was compared with OP for the detection of individual lesions, those missed by OPd (OPu in brackets) were: microaneurysms 50% (50%); haemorrhages 50% (75%); hard exudates 50% (90%); soft exudates 66% (66%); circinate rings 100% (100%). After 10 minutes' instruction, medical, nursing, technical and lay persons all produced top‐grade photographs. The maximum photography rate during clinics was 12 patients/hour. More extensive fundal mapping was possible but resulted in a loss of quality unless the pupils were dilated. Though important lesions were sometimes present outside the standard field, in all such cases background retinopathy, which was at least moderate in degree, was present on the standard photograph. The CR3‐45NM is relatively cheap and could revolutionise the screening of the diabetic population for DR ( Abstract of presentation to the XIIth Congress of the International Diabetes Federation, Madrid, Spain, September 23 – 28, 1985 ).