Visual performance in soft contact lens wear. Is there a compromise?

Abstract

Purpose: A six‐month study was performed comparing a group of contact lens wearers against a group of age and refraction matched non‐contact lens wearers.Methods: Visual performance was measured by log MAR visual acuity (VA) and Pelli‐Robson contrast sensitivity (CS). Contact lens wearers were all established wearers of at least six months. Patients were refitted with Hydron Omniflex lenses. The care regimen was Alcon Opti‐free. Visual performance was measured every eight weeks with lenses in situ and any necessary over‐refraction, lenses were removed and visual performance was re‐measured with a full spectable refraction. The order of testing was randomised. In addition, the non‐lens wearers were also assessed every eight weeks.Results: Results suggest that for VA there is no significant change in visual performance with time in the contact lens wearers (F2.40 = 2.031,P > 0.1) or the non‐lens wearers (F2.18 = 0.863, P > 0.1). In addition, there is no significant difference in VA when comparing spectacle VA in the contact lens group against contact lens VA (F1.20 = 0.79, P > 0.1). There is also no significant difference between VA in the non‐lens wearing group and either spectacle VA (F1.29 = 0.877, P > 0.1) or CL VA in the lens wearing group (F1.29 = 1.646, P > 0.1). When CS is measured there is again no significant change with time for lens wearers (F2.40 = 1.771, P > 0.1) or non‐lens wearers (F2.18 = 0.053, P > 0.1). There is, however, a significant drop in visual performance when comparing spectacle CS in the contact lens group against contact lens CS (F1.20 = 18.835, P = 0.0003) and non‐wearers against contact lens CS (F1.29 = 7.719, P = 0.009). There is no significant difference between CS in non‐lens wearers and spectacle CS in lens wearers (F1.29 = 0.982,P > 0.1).Conclusion: These results suggest that even though visual performance measured by VA or CS in contact lens wearers does not deteriorate with lens age. CS is significantly worse when wearing lenses. It is also significantly worse than a non‐lens wearing population. As refractive error was accounted for in the protocol this is not the reason for the significant difference. Other causes of the significant reduction in performance may be lens movement, lens surface drying or lens deposition.Acknowledgements: We thank Hydron UK Ltd and Alcon for help in the form of contact lenses and solutions. Financial support was received from the Visual Research Trust.