Corneal changes following short-term rigid contact lens wear

The aim of this cross-over study was to investigate the changes in corneal thickness, anterior and posterior corneal topography, corneal refractive power and ocular wavefront aberrations, following the short term use of rigid contact lenses.

Fourteen participants wore 4 different types of contact lenses (RGP lenses of 9.5mm and 10.5mm diameter, and for comparison a PMMA lens of 9.5mm diameter and a soft silicone hydrogel lens) on 4 different days for a period of 8h on each day. Measures were collected before and after contact lens wear and additionally on a baseline day.

Anterior corneal curvature generally showed a flattening with both of the RGP lenses and a steepening with the PMMA lens. A significant negative correlation was found between the change in corneal swelling and central and peripheral posterior corneal curvature (all p ≤ 0.001). RGP contact lenses caused a significant decrease in corneal refractive power (hyperopic shift) of approximately 0.5D. The PMMA contact lenses caused the greatest corneal swelling in both the central (27.92 ± 15.49 μm, p<0.001) and peripheral (17.78 ± 12.11 μm, p=0.001) corneal regions, a significant flattening of the posterior cornea and an increase in ocular aberrations (all p ≤ 0.05).

The corneal swelling associated with RGP lenses was relatively minor, but there was slight central corneal flattening and a clinically significant hyperopic change in corneal refractive power after the first day of lens wear. The PMMA contact lenses resulted in significant corneal swelling and reduced optical performance of the cornea.