Evaluation of quality of non-mydriatic fundus images obtained with non-contact TrueColor, confocal scanner during third phase of nationwide lockdown

Abstract

Aims: This study aims to evaluate the non-mydriatic fundus image quality obtained with a confocal fundus device. Also, to evaluate the influence of non-mydriatic pupil size on image quality. Settings and Design: A cross-sectional study was conducted in the outpatient department of a high-volume tertiary eye care centre in South India during the third phase of the COVID-19 lockdown. Subjects and Methods: 831 consenting, consecutive patients (1539 eyes) were photographed from May 5 to May 17, 2020, and were graded excellent, fair, adequate, or inadequate; based on white noise, black noise, and image acquisition signals. Pupil diameters were obtained with light-emitting diode flash technology. Statistical Analysis: The collected data were analyzed using SPSS software. Descriptive statistics in the form of frequencies and percentages were calculated. Simple (univariate) linear regression analysis and adjusted regression analysis were used to establish the relationship between pupil size and fundus photo quality. Results: The quality of the fundus photo was excellent in 70.12% (n = 1079), fair in 15.72% (n = 242), adequate in 5.78% (n = 89), and inadequate in 8.38% (n = 129). Of the 1410 obtained images (subtracting the inadequate quality images), 87.66% (n = 1236) were normal and 12.34% (n = 174) were pathological. There was a positive linear relationship between pupil size and quality of retinal photograph; OS (R2 = 0.935) had a slightly better association than OD (R2 = 0.901). Conclusions: The majority of the confocal images were excellent in quality. Our four-point grading system serves as a reliable measure of non-mydriatic photograph quality. Pupil size is a significant predictor of image quality for non-mydriatic photographs in surveillance programs.

Keywords

• confocal fundus scanning
• fundus imaging quality
• non-mydriatic images
• pupil size