HbA_1c – dependent changes in the anterior segment of the eye in patients with type 2 diabetes

Introduction
The United Kingdom Prospective Diabetes Study and Diabetes Control and Complications Trial showed a linear relationship between the HbA1c and the incidence of chronic complications of diabetes. They affect many organs, including the structures of the anterior part of the eye. The aim of this study was to evaluate HbA1c– dependent changes in the anterior segment of the eye in patients with type 2 diabetes.

Material and methods
87 patients (170 eyes) with type 2 diabetes (DM2) seen at the diabetes clinic were enrolled. They were divided into three groups depending on HbA1clevels. Group A consisted of patients with HbA1c below 6.5%, group B consisted of patients with HbA1c levels ranging between 6.5% and 7.5%, whereas group C consisted of patients with HbA1c above 7.5%. The anterior segment assessment performed in each patient included biomicroscopy, Schirmer test I, gonioscopy, lens opacity rating, the assessment of lid-parallel conjunctival folds, tear break-up time (TBUT), central corneal thickness (CCT), endothelial cell density (ECD), lens thickness evaluation, anterior chamber depth, axial length of the eye and indirect ophthalmoscopy. Serum HbA1c levels were determined by the Central Laboratory of No. 2 University Hospital in Szczecin.

Results
Diabetic patients with higher HbA1c (> 7.5%) levels presented with more advanced features of dry eye syndrome, higher degrees of lens opacity, greater central corneal thickness, decreased endothelial cell density, and blood vessels within the anterior chamber angle. The lens was the thickest in the group with HbA1clevels ranging between 6.5% and 7.5%.

Conclusions
The current results support the elevated risk of ocular complications affecting the anterior segment of the eye in patients with type 2 diabetes mellitus. The majority of these complications are associated with higher HbA1c levels, which should be taken into account in daily practice.