Central corneal thickness (CCT), corneal epithelial thickness (CET), and corneal stromal thickness (CST) are significantly thicker in patients with diabetes mellitus, according to research published in Photodiagnosis and Photodynamic Therapy. These measurements may serve as a biomarker for the early diagnosis of diabetic retinopathy (DR). 

Researchers compared 60 eyes of 30 patients with diabetes mellitus and no signs of DR (mean age, 55±4 years; 16 women) with 60 eyes of 30 age- and sex-matched healthy control individuals (mean age, 54±5 years; 15 women). Participants underwent comprehensive examinations including slit lamp evaluation and tear breakup time (TBUT), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) measurement. CCT, CET, and CST measurements were obtained, and patients with ocular or systemic disorders that could affect the cornea or systemic vascular diseases were excluded from the analysis.

Patients with diabetes had a BCVA of 0.15±0.2 logMAR and IOP of 12.24±1.5 mmHg. There were no significant differences in BCVA, IOP, TBUT, or Schirmer I measurements between participants with diabetes and control group participants. 


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CCT was thicker in patients with diabetes compared with control individuals (606.26±47.22 μm vs 571.15±42.25 μm; P <.001). Patients with diabetes also had increased corneal thickness in paracentral and mid peripheral sectors compared with control individuals.

CET and CST were also thicker among patients with diabetes compared with controls (epithelial thickness of central sector: 55.48±3.67 μm vs 51.80±4.67 μm, P =.030; stromal thickness of central sector: 552.31±45.10 μm vs 521.93±46.34 μm, P <.001).

Investigators stress the role these measurements play in clinical practice. “[T]hese results highlight the possible role of corneal layer measurement as a biomarker of early diabetic damage in patients without retinal involvement,” according to the researchers.

Study limitations include a small sample size and single center design.

Reference

D’Andrea L, Montorio D, Concilio M, Giordano M, Cennamo G, Costagliola C. Anterior segment-optical coherence tomography and diabetic retinopathy: could it be an early biomarker? Photodiagnosis Photodyn Ther. Published online July 3, 2022. doi:10.1016/j.pdpdt.2022.102995