Aim: Fundus photographs using a nonmydriatic digital camera are the reference method for diabetic retinopathy screening today. The aim of this study was to validate a simplified diabetic retinopathy classification, adapted for diabetic retinopathy screening, including all diabetic retinopathy severity scales.
Patients and methods: One hundred and twenty-one diabetic patients had three digital color fundus photographs taken, which were graded by four independent ophthalmologists according to the proposed screening classification, and a reference examination (nine field fundus photographs and optical coherence tomography examination of the macula).
Results: The proposed diabetic retinopathy screening classification was easy to use, as it was based on a visual comparison between the three digital color fundus photographs and standard retinal photographs. This classification provided the diagnosis of severe levels of diabetic retinopathy with high sensitivity and accurate specificity (100% and 50%-58%,respectively, for a moderate nonproliferative diabetic retinopathy level or higher on the screening examination) and the diagnosis of macular edema with a high sensitivity and specificity (96%-97% and 89%-91%, respectively). The results of the screening examination using this classification were highly reproducible (weighted k for interobserver agreement: 0.78-0.93).
Conclusion: These results suggest that this new simplified classification is accurate. The screening method should not be used above the threshold level of mild nonproliferative diabetic retinopathy. Thus, from the moderate nonproliferative level (inclusive), a complete fundus examination should be undertaken. Severe levels of diabetic retinopathy will be referred to an ophthalmologist without delay for laser treatment.