Retinal Thickness and Foveal Function in Adolescents with Type 1 Diabetes

Abstract

Purpose: : To determine whether there are retinal thickness and functional differences between healthy adolescents and adolescents with type I diabetes and no diabetic retinopathy.

Methods: : Retinal thicknesses from 22 healthy adolescents and 73 adolescents with type 1 diabetes were measured using spectral domain Cirrus HD OCT. They were examined in the 9 ETDRS sectors within the central 20 deg. Right eyes were examined in our analyses, and left eyes were examined for confirmation. Mean HbA1c level for the adolescents with diabetes was 9.3 +/- 1.8%, age range was 13-19.2 years, duration of diabetes was 6.1 +/- 3.8 years, and blood glucose level was 232.1 +/- 96.7 mg/dl. Local retinal thicknesses of the patients were considered to be abnormal if they were outside the range of the control group. Multifocal electroretinograms (mfERGs) were recorded to determine whether neural function abnormalities of the retina were related to thickness abnormalities.

Results: : The greatest frequency of abnormality was in the foveal region, with abnormal retinal thinning in 17 out of 73 (23.3%) patients. In the fovea, none of the adolescent patients had abnormally thick retinas. Temporal and inferior perifoveal regions were also abnormally thin in 15.1% and 16.4% of the patients, respectively. The lowest abnormality rate, 1.4%, was found in the peripheral nasal and temporal sectors. The left eyes showed a very similar pattern. Central mfERG implicit time did not differ between patients with abnormally thin foveas and those with normal foveal thicknesses. However, central mfERG amplitude was significantly smaller in patients with abnormally thin foveas compared to those with normal foveal thicknesses (p=0.016).

Conclusions: : The results indicate that there is abnormal thinning of the central retina in significant numbers of adolescents with type 1 diabetes and no retinopathy. This structural abnormality is accompanied by reduced central mfERG amplitude. Spectral domain OCT and the mfERG may be important complementary clinical tools to monitor changes in the retinas of young patients with type 1 diabetes.

Keywords: diabetes • imaging/image analysis: clinical • electroretinography: clinical