Sensitivity and specificity of nonmydriatic digital imaging in screening diabetic retinopathy in Indian eyes

Background: Nonmydriatic digital imaging (NMDI) is ideal for screening diabetic retinopathy (DR), but its use in Indian eyes has not been evaluated. Aim: The aim was to evaluate the sensitivity and specificity of NMDI as a screening tool in detecting DR in Indian eyes. Design: A prospective, nonrandomized, noncomparative, noninterventional study. Materials and Methods: A total of 500 diabetic patients visiting the endocrinology clinic (September 2008-June 2010) underwent NMDI (Zeiss Procam), followed by routine dilated fundus photography (FP; Zeiss Visupac 450+) of 345 degrees retinal fields (1) optic disc and macula, (2) superotemporal, and (3) nasal to optic disc. Two-masked retina specialists graded the images for quality and severity of DR, and compared between NMDI and dilated FP. Statistical Analysis: SPSS Windows 17 for version. Results: Mean age was 52.97 +/- 13.46 years (306 males: 194 females). The rate of ungradable images was 30.6% and 31% by the two observers. By observer 1, the sensitivity and specificity of detecting any DR was 58.8% and 69.1%, respectively, (kappa = 0.608) and sight-threatening DR (STDR) was 63.1% and 68.9%, respectively, (kappa = 0.641). By observer 2, the sensitivity and specificity was 57.3% and 68.3%, respectively, for any DR (kappa = 0.593) and 62.8% and 68.3%, respectively, for STDR (kappa = 0.637). The level of agreement between two observers was high (kappa = 0.96). Conclusion: A high rate of poor quality photographs and low sensitivity limited the use of NMDI as a perfect screening system, particularly in dark iris population with diabetes as seen in Indian eyes.