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Corneal arcus may be associated with elevated IOP, thinner CCT
Arch Ophthalmol. 2010;128(11):1455-1461.
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Corneal arcus may be associated with higher IOP and lower central corneal thickness, according to a study.
In the population-based, cross-sectional Singapore Malay Eye Study, of the 3,015 participants between the ages of 40 and 80 years, 1,747 (57.9%) had corneal arcus in their right eyes. Corneal arcus was evaluated using a slit lamp and defined as "gray-white or yellow opacity located near the periphery of the cornea but separated from the limbus by a clear zone," the study authors said.
After adjusting for age, sex and systemic factors, IOP was higher, 15.87 mm Hg vs. 14.86 mm Hg (P < .001), and central corneal thickness (CCT) was thinner, 540.6 µm vs. 543.4 µm (P = .03), in eyes with corneal arcus compared with eyes without the ring.
"There is no known explanation for the association of corneal arcus with higher IOP. There may be changes in biomechanical properties of the cornea in eyes with corneal arcus, as such mechanisms are emerging as important clinical variables that may affect IOP measurements," the authors said.
Linear regression analysis IOP was an average of 1.14 mm Hg higher in eyes with corneal arcus than in eyes without corneal arcus. The linear correlations of CCT and IOP and of corneal curvature radius and IOP were altered in the presence of corneal arcus.
In addition, the prevalence of ocular hypertension, but not primary open-angle glaucoma, was significantly higher among participants with corneal arcus than among participants without it, the study said.
According to the authors, further research is needed to confirm the results, as well as the clinical importance of CCT and IOP differences between subjects with and without corneal arcus.