The ocular response of wearers of daily disposable and extended wear soft contact lenses compared to spectacle wearers

Purpose: To determine the physiological response of the eye to daily disposable and extended wear of contact lenses in comparison to spectacles. Methods: This study was a case-controlled masked assessment of 20 subjects in each group. All participants were recruited from contact lens and spectacle wearing trials at the L.V. Prasad Eye Institute, Hyderabad, India. Contact lens wearers wore etafilcon A lenses on a six-night extended wear and weekly replacement schedule or on a daily disposable schedule. The following ocular parameters were assessed by siltlamp biomicroscopy: tear film characteristics, limbal and bulbar redness, vascularization, the number of epithelial microcysts and vacuoles, the degree of endothelial polymegethism, upper palpebral redness and roughness, and corneal and conjunctival staining. Results: Extended lens wearers had significantly more limbal redness over all quadrants of the eye, and more bulbar redness in the superior quadrant (P<0.05) than daily disposable lens and spectacle wearers. Mean palpebral roughness was significantly greater in the extended lens wearing group in comparison to daily disposable lens wearers. Extended lens wearers had over two-fold more microcysts and vacuoles and a significantly greater amount of endothelial polymegethism than daily disposable or spectacle wearers. All contact lens wearers had a significantly greater degree of conjunctival staining than spectacle wearers (P<0.05). Apart from conjunctival staining, there were no significant differences between the daily disposable lens wearers in comparison to spectacle wearers. Conclusions: The ocular physiological differences between daily disposable and spectacles wearers were negligible. Extended lens wearers had increased signs of hypoxia-induced physiological changes to the anterior segment.