Epithelial morphological response to soft hydrogel contact lenses

Area of Science:

• Ophthalmology
• Corneal Physiology
• Biomaterials Science

Background:

• Hydrogel (HEMA) contact lenses are widely used for vision correction.
• Understanding the corneal response to contact lens wear is crucial for eye health.
• Increased lens thickness may alter corneal physiology due to reduced oxygen transmission.

Purpose of the Study:

• To investigate the ultrastructural changes in the corneal epithelium of owl monkeys wearing hydrogel contact lenses of varying thicknesses.
• To assess the effects of open and closed eye conditions on the corneal response.
• To identify factors contributing to epithelial changes and their implications for contact lens wear.

Main Methods:

• Owl monkeys (Aotus tivergatus) wore hydrogel (HEMA) contact lenses of 0.07 mm and 0.4 mm thickness.
• Corneal tissues were examined ultrastructurally under both open and closed eye conditions.
• Epithelial thickness, cell morphology, basement membrane integrity, and innervation were analyzed.

Main Results:

• The 0.07 mm thick lens induced epithelial thinning without edema, attributed to cell loss and flattening.
• The 0.4 mm thick lens in closed eyes led to significant epithelial stripping, edema, and cell degeneration.
• The corneal basement membrane remained intact, and epithelial innervation was preserved except in closed-eye conditions.

Conclusions:

• Contact lens thickness significantly impacts corneal epithelial health, with thicker lenses posing greater risks.
• Anoxia, trauma, lid pressure, and lens weight are potential factors in hydrogel lens-induced epithelial changes.
• Preserved basement membrane and innervation suggest that corneal integrity can be maintained with appropriate lens selection and wear protocols.