Influence of special-effect contact lenses (Crazy Lenses) on visual function.

Purpose: Special-effect contact lenses (opaque, tinted soft contact lenses that incorporate decorative images such as cateyes, stars, or hearts to alter eye color and structure) have become increasingly popular. The purpose of this study was to investigate whether such lenses impair visual function. Methods: A clear soft contact lens and a special-effect soft contact lens (Crazy lens,®) were fit in changing sequence in nine healthy subjects. The parameters studied included: visual acuity, contrast sensitivity (with and without glare), visual field, and mesopic vision (with and without glare). Results: The following parameters displayed a statistically significant difference (P < 0.05). Visual acuity was decreased to 0.9 ± 0.23 in the Crazy lens group as compared with 1.2 ± 0.13 in the clear lens group. Goldmann visual field displayed a significant constriction of the isopters: III.4, I/4, and I/3. Mesopic vision without glare was reduced from 1:2.5 to 1:7.4. Contrast sensitivity was significantly reduced in a photopic condition with and without glare and in a scotopic condition without glare. Furthermore, the special-effect lenses were associated with a decrease in lens wearing comfort. Conclusions: Special-effect contact lenses were associated with a reduction of many visual functions, including visual acuity and contrast sensitivity. For some wearers this may interfere with activities where excellent vision is crucial, such as driving a car.