Corneal densitometry (CD), or corneal backscattering, is a surrogate measure of corneal clarity. According to the results of this study, type 1 diabetes mellitus (T1DM) appears to be linked with higher CD values, an indication of poorer corneal clarity, with longer T1DM duration and greater hemoglobin A1c values correlating with greater CD, especially in certain anterior and central zones of the cornea.
Study design
This was a prospective, cross-sectional study conducted in Turkey that evaluated CD findings in 60 patients (60 eyes) with T1DM and 101 age- and gender-matched healthy controls (101 eyes). Scheimpflug tomography was conducted to document CD. The authors also obtained data on glycosylated hemoglobin (HbA1c) and mean duration with diabetes.
Outcomes
The average age of patients with T1DM was 29.9 years vs 27.3 years in the control group. In the T1DM group, average HbA1c was 8.4 and T1DM duration was 14.1 years. Significantly higher CD was seen in the T1DM group in the 0–2 mm corneal zone at all depths as well as in the anterior and central 6–10 mm zones. The authors also found a positive correlation between longer diabetes duration and greater CD values in the anterior 0–2 mm, central 6–10 mm, posterior 6–10 mm, and posterior 10–12 mm zones. Crystalline lens densitometry was not significantly different between the T1DM and control groups.
Limitations
Limitations of this study include its small sample size and exclusion of patients with type 2 diabetes mellitus and retinopathy, limiting broader generalizability.
Clinical significance
Given the association of T1DM with decreased corneal sensitivity, poor wound-healing, and non-healing epithelial defects, CD may be used to help identify early changes in the cornea in patients with T1DM. Such findings could prompt closer follow-up of at-risk patients in order to monitor structural and functional changes in the cornea, allowing for earlier treatment for diabetic keratopathy.
Financial Disclosures: Dr. Zeba A. Syed discloses financial relationships with Bio-Tissue, Recordati (Lecture Fees/Speakers Bureau); Dompé, Glaukos (Grant Support).