The influence of smoking on retinal ganglion cell-inner plexiform layer complex in male diabetes

This study aims to evaluate the influence of smoking on ganglion cell-inner plexiform layer complex (GC-IPL) thickness and central macular thickness (CMT) measured by spectral domain optical coherence tomography (OCT) in male diabetes.

90 smoking and 90 never-smoking male subjects were included in this study. They were divided into six groups based on the diagnostic criteria for diabetes and the Early Treatment Diabetic Retinopathy Study (ETDRS) classification: smoking healthy subjects (SH, n = 20), non-smoking healthy subjects (NSH, n = 20), smoking diabetic patients without diabetic retinopathy (SNDR, n = 40), non-smoking diabetic patients without diabetic retinopathy (NSNDR, n = 40), smoking diabetic patients with diabetic retinopathy (SDR, n = 30), and non-smoking diabetic patients with diabetic retinopathy (NSDR, n = 30). After a full ophthalmologic examination, GC-IPL thickness and central macular thickness (CMT) were measured by OCT. Statistical analysis was performed to compare GC-IPL thickness and CMT between groups. Multiple linear regression equations were constructed to explore the potential risk factors of mean GC-IPL thickness.

There were no significant differences in GC-IPL thickness and CMT between SH and NSH (all p > 0.05). Mean, superonasal, superior, superotemporal, inferonasal, inferior GC-IPL (p＜0.001, p＜0.001, p＜0.001, p = 0.003, p = 0.001, and p = 0.005, respectively) were thinner in the SNDR than NSNDR except for inferotemporal GC-IPL thickness and CMT (p = 0.066, p = 0.605, respectively). Mean, superonasal, superior, and inferonasal GC-IPL were thinner in the SDR than NSDR (p = 0.019, p = 0.045, p = 0.037, and p = 0.049, respectively). Multiple regression analysis demonstrated that age (β [SE], -0.141 [0.060]; p = 0.020) and smoking (β [SE], -4.470 [1.015]; p＜0.001) were the most important determinants for mean GC-IPL thickness.

Smoking is associated with reduced retinal GC-IPL thickness in male diabetes. Smoking behavior and age are important determinants of mean GC-IPL thickness.