Contact lens characteristics and contrast sensitivity of patients with keratoconus

The aim was to describe the contact lens characteristics and contrast sensitivity of patients with keratoconus managed conservatively with contacts lenses at a tertiary eye center in Singapore.

A prospective cross-sectional study of 116 patients with clinically evident or suspected keratoconus (on videokeratography) recruited over 11 months. Demographic and medical details, visual acuity (VA) and refraction, corneal topography and contact lens characteristics were documented. Contrast sensitivity with contact lenses was performed with the Vision Contrast Test System 6500 under standardized conditions.

Overall, 67% of the study patients were wearing contact lenses. Of the 129 eligible eyes analyzed, there were 108 eyes with keratoconus and 21 eyes with keratoconus suspect, and 94% were fitted with rigid gas permeable (RGP) lenses. Proprietary keratoconus design lenses were fitted in 74.9% of keratoconus eyes and 30.0% of suspect eyes. With contact lens wear, 83.3% of keratoconus eyes and 100% of suspect eyes achieved 0.3 vision. Mean contrast sensitivity curves of eyes with keratoconus and keratoconus suspect were found to be within normal, although contrast sensitivity in the keratoconus group was consistently lower.

Most of our patients were managed conservatively with contact lenses, and keratoconus design RGP lenses were the most common type fitted. Good VA can be achieved, but patients with keratoconus may still experience a reduction in contrast sensitivity.