Alterations in retinal nerve fiber layer thickness in early stages of diabetic retinopathy and potential risk factors

ABSTRACT

Aims: To investigate the loss of retinal nerve fiber layer (RNFL) in type-2 diabetic patients with early-stage diabetic retinopathy (DR) and to identify potential risk factors accounting for these alterations.

Methods: In this cross-sectional study, 158 type-2 diabetic patients were divided into three groups based on their DR status. RNFL thickness and other optic disc parameters were obtained by optical coherence tomography (OCT) and then compared among different groups. We investigated the potential association between RNFL loss and systemic risk factors for DR, including diabetes duration, body mass index (BMI), serum lipids, hemoglobin A1c (HbA1c) and albumin-creatinine ratio (ACR). One-way ANOVA was carried out to compare RNFL thickness among different groups, Pearson correlation and multivariate linear regression analysis were performed to determine potential risk factors related to RNFL thickness in these patients.

Results: There were significant differences in the average (F = 8.872, P = 0.003), superior (F = 8.769, P = 0.004), and inferior (F = 8.857, P = 0.003) RNFL thickness of both eyes among the groups, but no obvious difference in optic disc parameters was found. Diabetic duration, BMI, TG, High density lipoprotein cholesterol (HDL), HbA1c, and ACR were found negatively related to the RNFL thickness in both or single eye according to Pearson correlation analysis. After controlling for age, gender, and axis length (AL) in multivariate linear regression analysis, the diabetic duration was associated significantly with RNFL thickness of superior in both eye (right eye: p = 0.016, left eye: p = 0.024), BMI was related to the nasal quadrant of the right eye (p = 0.034), and TG was related to the inferior of the right eye (p = 0.037), HbA1c (p = 0.026) was associated significantly with the average RNFL thickness of the right eye. In addition, ACR was found negatively related to average (p = 0.042) and inferior quadrant (p = 0.014) of the left eye, respectively.

Conclusions: RNFL loss might be the earliest structural change of retina in diabetic patients, and associated with diabetic duration, BMI, TG, HbA1c, and ACR. The conclusions of this study need to be proved by other well-matched and large-scale prospective clinical trials in the future, because the correlations discovered in our study were weak.

KEYWORDS:

• Diabetic retinopathy
• RNFL thickness
• neurodegeneration
• risk factors
• ACR

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

This work was supported by grants from the National Natural Science Foundation of China (No. 81500726) to Rong Li and Science & Technology project for Social development of Shaanxi Province in China (No. 2017SF-249) to Rui Shi. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript; the National Natural Science Foundation of China [81500726];

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China (No. 81500726) to Rong Li and Science & Technology project for Social development of Shaanxi Province in China (No. 2017SF-249) to Rui Shi. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript; the National Natural Science Foundation of China [81500726];

Notes on contributors

Rong Lin

Rui S, Lei Z and Rong Lin designed the study; Zhonglan Guo operated OCT, Rong Li and Rui S collected data and performed the analyses; Rui S, Lei Z and Feng W drafted the manuscript; Lei Z and Rui S contributed to the discussion and revised the manuscript.