Addressing Technical Failures in a Diabetic Retinopathy Screening Program

Abstract

Purpose

Diabetic retinopathy (DR) is a preventable cause of blindness detectable through screening using retinal digital photography. The Irish National Diabetic Retina Screening (DRS) programme, Diabetic RetinaScreen, provides free screening services to patients with diabetes from aged 12 years and older. A technical failure (TF) occurs when digital retinal imaging is ungradable, resulting in delays in the diagnosis and treatment of sight-threatening disease. Despite their impact, the causes of TFs, and indeed the utility of interventions to prevent them, have not been extensively examined.

Aim

Primary analysis aimed to identify factors associated with TF. Secondary analysis examined a subset of cases, assessing patient data from five time points between 2019 and 2021 to identify photographer/patient factors associated with TF.

Methods

Patient data from the DRS database for one provider were extracted for analysis between 2018 and 2022. Information on patient demographics, screening results, and other factors previously associated with TF were analyzed. Primary analysis involved using mixed-effects logistic regression models with nested patient-eye random effects. Secondary analysis reviewed a subset of cases in detail, checking for causes of TF.

Results

The primary analysis included a total of 366,528 appointments from 104,407 patients over 5 years. Most patients had Type 2 diabetes (89.2%), and the overall TF rate was 4.9%. Diabetes type and duration, dilate pupil status, and the presence of lens artefacts on the camera were significantly associated with TF. The Secondary analysis identified the primary cause of TF was found to be optically dense cataracts, accounting for over half of the TFs.

Conclusion

This study provides insight into the causes of TF within the Irish DRS program, highlighting cataracts as the primary contributing factor. The identification of patient-level factors associated with TF facilitates appropriate interventions that can be put in place to improve patient outcomes and minimize delays in treatment and diagnosis.

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Keywords:

• ungradable image
• cataract
• screen failure
• camera
• retinal photography

Ethics Statement

This study meets the categorization of clinical audit as per the National Office of Clinical Audit (NOCA) GDPR Assessment table Further ethics review was not required by the Reference Research Ethics Committee Midlands Area and Corporate (Regional Health Area B), in accordance with research regulations of Ireland.

Disclosure

Edel McBride, Joanne Harmon, and Shane McMahon are employed by NEC Care, Ireland. Robert Acheson and Louise O’Toole have contractual relationships with NEC Care, Ireland. Louise O’Toole also reports travel grant from and advisory board for Bayer Pharmaceuticals and Novartis Pharmaceuticals, outside the submitted work. Robert Acheson is a founding director of Diabetic Retinopathy-Clinical and Management Services (DR-CMS). Helen Kavanagh and David J Keegan are employed by the National Screening Service, Ireland. The authors report no other conflicts of interest in this work.