A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy

• Published in: Diabetic medicine 2003-07, Vol.20 (7), p.528-534
• Main Authors: Olson, J. A., Strachan, F. M., Hipwell, J. H., Goatman, K. A., McHardy, K. C., Forrester, J. V., Sharp, P. F.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Associated diseases and complications; automated; Biological and medical sciences; colour slide; Diabetes. Impaired glucose tolerance; diabetic retinopathy; Diabetic Retinopathy - diagnosis; Diagnostic Techniques, Ophthalmological; digital; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Female; Humans; Male; Mass Screening - methods; Medical sciences; Middle Aged; optometrist; Optometry - methods; Photography - methods; screening; Sensitivity and Specificity
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1046/j.1464-5491.2003.00969.x

Aims To compare the respective performances of digital retinal imaging, fundus photography and slit‐lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme. Methods A group of 586 patients recruited from a diabetic clinic underwent three or four mydriatic screening methods for retinal examination. The respective performances of digital imaging (n = 586; graded manually), colour slides (n = 586; graded manually), and slit‐lamp examination by specially trained optometrists (n = 485), were evaluated against a reference standard of slit‐lamp biomicroscopy by ophthalmologists with a special interest in medical retina. The performance of automated grading of the digital images by computer was also assessed. Results Slit‐lamp examination by optometrists for referable diabetic retinopathy achieved a sensitivity of 73% (52–88) and a specificity of 90% (87–93). Using two‐field imaging, manual grading of red‐free digital images achieved a sensitivity of 93% (82–98) and a specificity of 87% (84–90), and for colour slides, a sensitivity of 96% (87–100) and a specificity of 89% (86–91). Almost identical results were achieved for both methods with single macular field imaging. Digital imaging had a lower technical failure rate (4.4% of patients) than colour slide photography (11.9%). Applying an automated grading protocol to the digital images detected any retinopathy, with a sensitivity of 83% (77–89) and a specificity of 71% (66–75) and diabetic macular oedema with a sensitivity of 76% (53–92) and a specificity of 85% (82–88). Conclusions Both manual grading methods produced similar results whether using a one‐ or two‐field protocol. Technical failures rates, and hence need for recall, were lower with digital imaging. One‐field grading of fundus photographs appeared to be as effective as two‐field. The optometrists achieved the lowest sensitivities but reported no technical failures. Automated grading of retinal images can improve efficiency of resource utilization in diabetic retinopathy screening. Diabet. Med. 20, 528–534 (2003)