Does orthokeratology contact lens wear suppress the immune cell response in the human corneal epithelium, while soft contact lens wear enhances it?

Abstract

Background: Orthokeratology (OK) contact lenses are increasingly prescribed for myopia control but their impact on corneal epithelial immune cells (CEIC) is unclear. This study compares CEIC in OK wearers to soft contact lens (SCL) wearers and non-wearers.

Methods: In vivo confocal microscope images at the corneal central and mid-peripheral subbasal level were evaluated in 18 OK wearers, 18 SCL wearers and 18 non-wearers (mean age 27.6±8.0 years; 65% female). Corneal epithelial immune cell density was manually quantified and morphology was graded using a published system. Statistical significances (p<0.05) were examined using generalised estimating equations.

Results: Corneal epithelial immune cell density in OK wearers was lower than in SCL wearers (p=0.03) at the central cornea, but not at the mid-periphery. Compared to SCL wearers, OK wearers had smaller cell bodies, with fewer participants displaying CEIC with dendrites, long and thick dendrites at both corneal locations (p<0.001). Orthokeratology wearers also had smaller CEIC bodies (p=0.01) and fewer participants had CEIC with dendrites (p=0.01) than non-wearers at both locations. Contrarily, SCL wearers had larger CEIC bodies, with a greater proportion of SCL wearers displaying CEIC with dendrites, long and thick dendrites compared to non-wearers (p≤0.04) at both locations. Corneal epithelial immune cell density was higher at the central cornea than at mid-periphery in SCL wearers (p<0.001) and non-wearers (p=0.01), but not in OK wearers (p=0.26).

Conclusions: In long-term OK lens wear, immune cells observed in the corneal epithelium are fewer in number and are less likely to present with dendrites, suggesting a suppressed CEIC response in OK lens wear which should be investigated further.