A comparison between one- and two-field 60 degrees fundus photography whenscreening for diabetic retinopathy

Purpose: To compare the severity level of diabetic retinopathy obtained whe n assessed from two versus only one 60 degrees photographic field using col our transparencies and red-free, black-and-white photographs. To compare th e areal coverage of these two photographic strategies to that of seven-fiel d 30 degrees photography. Methods: Two ophthalmologists graded photographs of 74 eyes of 74 type I an d II diabetes patients. Inter-method agreement was expressed in percentages and using kappa statistics and scatter-diagrams. The comparison of the app roximate photographic areal coverage was done from diagrams using planimetr y. Results: The severity level of retinopathy when judged from two photographi c fields was more severe in 13.5% (Grader 1) and in 16.2% (Grader 2) from c olour transparencies and in 13.5% (Grader 1) and in 14.9% (Grader 2) from r ed-free black-and-white prints, as compared to assessments from only one fi eld. Kappa values (0.84-0.86) for inter-method agreement for five pooled re tinopathy levels revealed good agreement. Neither grader missed retinopathy requiring clinical assessment or treatment (levels greater than or equal t o 47) when minimal retinopathy (levels 14-20) was detected using only one 6 0 degrees colour slide or red-free photograph. A second optic disc-centred field provided valuable additional information when more severe retinopathy lesions (levels greater than or equal to 30) were detected in the macula-c entred field. One macula-centred 60 degrees photograph covered 60% and two 60 degrees photographs 80% of the area covered by seven-field 30 degrees ph otography. Two-field 60 degrees photography covers areas left outside seven -field 30 degrees photography. Conclusion: We propose the use of one macula-centred 60 degrees photograph when screening for the first lesions of diabetic retinopathy, After they ha ve been found two-field 60 degrees photography is recommended.