# Prevalence of Diabetic Retinopathy Among Patients With Diabetes and Its Correlation With Inflammatory Marker Levels in Tear Fluid

## TL;DR

This study found that 38% of asymptomatic diabetic patients had diabetic retinopathy, but tear fluid inflammation markers were not reliably linked to the condition.

## Contribution

The study evaluates tear fluid inflammatory markers as potential non-invasive biomarkers for diabetic retinopathy in asymptomatic diabetic patients.

## Key findings

- Diabetic retinopathy was detected in 38% of asymptomatic diabetic patients.
- Tear fluid inflammatory markers like TNF-α and IL-6 were inconsistently elevated and not significantly correlated with DR.
- Sample dilution and ocular surface conditions likely affected the reliability of biomarker measurements.

## Abstract

Background

Diabetic retinopathy (DR) is a leading microvascular complication of diabetes mellitus (DM) and a primary cause of vision loss worldwide. Markers such as NF-κB, TNF-α, and IL-6 have been proposed as potential early indicators on the basis of Inflammation playing a critical role in DR pathogenesis. This study aimed to determine the prevalence of DR among asymptomatic diabetic patients and evaluate correlations between tear fluid inflammatory markers and DR severity.

Methods

A cross-sectional observational study was conducted over two months at a tertiary care hospital in Kerala, India. Although an initial target of 120 participants was set, logistical and technical challenges in tear sample isolation limited recruitment to 50 asymptomatic diabetic patients. Fundus images were captured using a non-mydriatic handheld fundoscopy device with artificial intelligence (AI)-assisted grading of DR. Tear fluid samples, collected using Schirmer paper, were analysed for nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (NF-α), and interleukin-6 (IL-6) via reverse transcription polymerase chain reaction (RT-PCR). Patient demographics, diabetes duration, comorbidities, and treatment history were documented. Associations between the presence of DR, clinical variables, and tear marker levels were analysed.

Results

DR was detected in 38% of participants, predominantly among patients aged >60 years and with longer diabetes duration. Insulin use and disease duration were significantly associated with DR, while age, gender, and oral antidiabetic use were not. Tear fluid inflammatory markers did not show a significant correlation with DR status. NF-κB was undetectable, and TNF-α and IL-6 levels were inconsistently elevated in DR-positive patients. Methodological factors, including tear sample over-dilution in 2 mL universal transport medium (UTM) and ocular surface conditions, likely contributed to these findings.

Conclusion

DR prevalence among asymptomatic diabetic patients is high, underscoring the importance of routine retinal screening. Non-mydriatic AI-assisted fundus imaging is an effective and practical tool for early detection. Tear fluid inflammatory markers, as measured in this study, were not predictive of DR, likely due to sample collection and amplification limitations. Future studies optimizing tear collection and RNA stabilization may establish reliable non-invasive biomarker-based screening, enabling earlier intervention and reducing vision-related morbidity in high-risk populations.