Quality assessment of non-mydriatic fundus photographs for glaucoma screening in primary healthcare centres: a real-world study

Background This study assessed the quality distribution of non-mydriatic fundus photographs (NMFPs) in real-world glaucoma screening and analysed its influencing factors. Methods This cross-sectional study was conducted in primary healthcare centres in the Yinzhou District, China, from 17 March to 3 December 2021. The quality distribution of bilateral NMFPs was assessed by the Digital Reading Department of the Eye Hospital of Wenzhou Medical University. Generalised estimating equations and logistic regression models identified factors affecting image quality. Results A total of 17 232 photographs of 8616 subjects were assessed. Of these, 11.9% of images were reliable for the right eyes, while only 4.6% were reliable for the left eyes; 93.6% of images were readable in the right eyes, while 90.3% were readable in the left eyes. In adjusted models, older age was associated with decreased odds of image readability (adjusted OR (aOR)=1.07, 95% CI 1.06 similar to 1.08, p<0.001). A larger absolute value of spherical equivalent significantly decreased the odds of image readability (all p<0.001). Media opacity and worse visual acuity had a significantly lower likelihood of achieving readable NMFPs (aOR=1.52, 95% CI 1.31 similar to 1.75; aOR=1.70, 95% CI 1.42 similar to 2.02, respectively, all p<0.001). Astigmatism axes within 31(degrees)similar to 60(degrees) and 121(degrees)similar to 150(degrees) had lower odds of image readability (aOR=1.35, 95% CI 1.11 similar to 1.63, p<0.01) than astigmatism axes within 180(degrees)+/- 30(degrees). Conclusions The image readability of NMFPs in large-scale glaucoma screening for individuals 50 years and older is comparable with relevant studies, but image reliability is unsatisfactory. Addressing the associated factors may be vital when implementing ophthalmological telemedicine in underserviced areas.