Five-Year Changes of Anterior Corneal Indices in Diabetics versus Non-Diabetics: The Shahroud Eye Cohort Study

ABSTRACT

Purpose: To compare 5-year changes of central and peripheral corneal thickness, corneal volume, and keratometry between diabetic and non-diabetic individuals (>40 years) in a population-based study.

Materials and Methods: Right eye corneal indices of the 333 diabetic persons were compared with 2865 non-diabetics. Studied indices included the apical corneal thickness (ACT), minimal corneal thickness (MCT), thickness values on corneal rings of 4 mm, 6 mm, and 8 mm in diameter, the volume of the 10 mm of the corneal diameter, and the central 3 mm keratometry in two steep (Kmax) and flat (Kmin) axes as measured with Pentacam (Oculus, Inc, Lynnwood, WA).

Results: In the diabetic and non-diabetic groups, respectively, the 5-year change was +0.1 ± 11.9 and −1.2 ± 11.9 μm (p = 0.035) for ACT, −1.1 ± 12.1 and −2.4 ± 11.9 μm (p = 0.056) for MCT, −3.9 ± 12.6 and −5.1 ± 12.3 μm (p = 0.007) for the 4 mm ring, −5.0 ± 15.3 and −7.5 ± 14.5 μm (p = 0.006) for the 6 mm ring, and −7.0 ± 20.1 and −10.8 ± 19.2 μm (p = 0.011) for the 8 mm ring. The diabetic group showed less reduction in corneal volume (−0.5 ± 1.8 mm³) compared to non-diabetics (−0.8 ± 1.6 mm³) (p = 0.030). Kmax (+0.3 ± 0.5D vs. +0.4 ± 0.5, p = 0.028) and Kmin (+0.4 ± 0.5D vs. +0.5 ± 0.5, p = 0.005) showed less change in diabetics compared to non-diabetics.

Conclusions: The overall patterns of change in corneal thickness and shape in over 40-year old diabetics are similar to non-diabetics, such that with aging, reduced thickness and increased keratometry take the cornea towards a prolate shape. However, the age-related changes in central and peripheral corneal thickness, volume and corneal shape are less pronounced in diabetic subjects.

KEYWORDS:

• Diabetes
• corneal thickness
• corneal volume
• keratometry
• longitudinal study

Acknowledgments

The authors have no proprietary interest in any of the materials mentioned in this article.

Disclosure Statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

None.