Abstract
Purpose: :
Previous studies on the effect of contact lenses on myopia progression have shown equivocal results. Myopia progression is considered to be influenced by several factors including near work and peripheral refraction. The aim of this study is to evaluate the effect of conventional hydrogel and silicone hydrogel contact lenses on peripheral refractive error.
Methods: :
Nine healthy young subjects were fitted with 10 different types of contact lenses. The lenses were made of Vifilcon A, Balafilcon A, Sifilcon A and Lotrafilcon A materials. Sifilcon A and Lotrafilcon A lenses were also manufactured in two different thicknesses (100µm and 200µm) in identical designs to assess the effect of lens modulus and thickness. Refractive error was measured in the central 60 degrees of the horizontal visual field in with a Canon R-1 open-field autorefractor.
Results: :
Baseline peripheral refractive error up to 30 degrees in the temporal and nasal retina was comparable to the previous published results. The conventional hydrogel and silicone hydrogel contact lenses did not alter peripheral spherical equivalent refraction significantly (p>0.05). The effects were, however, much higher in some individuals. The thicker custom made lenses altered the peripheral refraction significantly at 30 degrees eccentricity (p<0.05). The J45 and J180 astigmatic components changed by approximately 0.50D with contact lenses.
Conclusions: :
Our data showed that the conventional hydrogel and silicone hydrogel lenses tested do not significantly alter the spherical equivalent peripheral refractive error while leading to modest changes in the astigmatic components. The changes in some individuals were larger than those seen in others. There changes might be linked to factors such as corneal rigidity and the elastic modulus of the contact lens.
Keywords: myopia • development • contact lens