Among patients with type 2 diabetes, those who develop incident diabetic retinopathy (IDR) experience faster ganglion cell-inner plexiform layer (GC-IPL) and choroidal thickness (CT) thinning than those without diabetic retinopathy, according to a study published in the American Journal of Ophthalmology.
The analysis included 924 patients (average age, 63.7±7.7years; 61% women; average diabetes duration, 8.6±6.7 years) with type 2 diabetes. All patients underwent ophthalmic examinations including swept-source optical coherence tomography (SS-OCT) which provided CT, retinal thickness (RT), and GC-IPL thickness measurements. At 3-year follow-up, researchers compared the changes in GC-IPL, CT and RT between patients who developed IDR and those who did not have DR (NDR).
A total of 159 (17.2%) patients experienced IDR onset within the 3-year study duration. Researchers observed a reduction of GC-IPL, RT, and CT in patients with NDR and IDR, but CT thinning in patients with IDR was significantly accelerated. Patients with IDR experienced an average CT reduction of -6.98 micrometers (μm)/year (95% CI, -8.26 to -5.71) compared with -3.98 μm/year (95% CI, -4.60 to -3.36) in participants with NDR (P =.001). Average GC-IPL thickness decreased in both groups over 3 years (IDR: -0.97 μm/year; 95%CI, -1.24 to -0.70; NDR: -0.76 μm/year; 95% CI, -0.82 to -0.70; P =.025). RT increased in individuals with IDR and decreased in participants with NDR, with an adjusted difference of 2.09 μm/year (95% CI, 1.01-3.16; P <.001) for central field RT.
“These findings suggest CT and GC-IPL changes may be helpful clinical parameters for predicting DR,” according to the researchers. “The current study found significant rates of RT thickening and thinning of the CT and GCIPL in IDR patients after adjustment for confounding factors, which are novel findings not reciprocated by previous studies.”
Study limitations include a relatively short follow-up time, the potential for geographical bias, and failure to perform visual field examinations.
Huang Y, Zhang N, Bulloch G, et al. Rates of choroidal and neurodegenerative changes over time in diabetic patients without retinopathy: a 3-year prospective study. Am J Ophthalmol. Published online July 20, 2022. doi:10.1016/j.ajo.2022.07.011