The Investigation of Type 2 Diabetic Retinopathy in Conjunction with Dry Eye Disease: A Pilot Study

Dry Eye Disease (DED) is a prevalent eye condition, with Type 2 Diabetes (T2D) being a risk factor for DED. However, there remains limited up-to-date national research on the association and etiological relationship between Type 2 diabetic retinopathy and dry eye disease (DR-DED). This study aims to compare glycemic biomarkers and ocular surface health in patients with DR-DED and those with DR-only.

This is a pilot exploratory study; we included adult patients (aged ≥ 18) with type 2 diabetes (T2D). This study consists of two groups: DR-DED (n=11) and DR-only (n= 7). Type 1 diabetes mellitus patients, patients with terminal diagnoses such as cancer, and patients who use chemotherapy as a treatment were excluded. All the patients' data were collected from the electronic health system of the Ibsar Specialist Center between January 2023 and December 2023. Statistical analysis was performed with GraphPad Prism. Continuous data were presented as medians with Interquartile Ranges (IQR), and categorical variables were presented as frequencies and percentages. Between-group comparisons were performed using relevant nonparametric statistical tests. Correlations between variables were tested using Spearman’s rank correlation coefficient. A two-sided P value of <0.05 was considered statistically significant.

The DR-DED group showed decreases in both ocular tests (Tear break-up time and Schirmer test) compared to the DR-only group, with statistically significant differences (P < 0.0010 and P < 0.0052, respectively). In addition, the median fasting blood glucose level was lower in the DR-DED group than in the DR-only group, but the difference was not statistically significant. Glycated hemoglobin (HbA1c) was not different across groups. The DR-DED group presented a higher prevalence of systemic comorbidities. The DR-only group was more frequently treated with oral antidiabetic medications instead of insulin. There was a negative correlation, with no statistically significant difference, between HbA1c levels and Schirmer test scores in the DR-DED group, whereas the opposite was observed in the DR-only group.

This pilot study reports that DR-DED patients have blood glycemic biomarkers similar to those in patients with DR-only but differ in ocular surface health. Additionally, DR-only patients taking insulin injections showed improvements in ocular surface health compared to DR-DED patients. Consequently, it is recommended to perform ocular surface screenings as routine alongside routine retinopathy checks to manage early diagnosis of DED in DR populations.

This study shows that patients with DR-DED had a significantly greater ocular tear health burden than those with DR alone, even though their blood sugar levels were controlled to the same extent. These data indicate that factors beyond glycemic management may contribute to ocular surface deterioration in patients with diabetic retinopathy. Further investigation of hypothesized pathways and the influence of systemic treatment on ocular outcomes would require larger prospective studies.