Effect of Scleral Lense Vault on Best Potential Visual Acuity, Contrast Sensitivity and Higher Order Aberrations.

Background: There is great variance in what manufacturers recommend for acceptable central vault of scleral lenses. Results from a previous study conducted at the Michigan College of Optometry suggest that increasing central lens vault has a slight detriment on the subject’s perceived visual acuity. This study will look at visual acuity, contrast sensitivity and higher order aberrations in subjects wearing scleral lenses with the same optical zone, but varying amounts of central vault.
Methods: Patients were fit with four pairs of scleral contact lenses according to the manufacturer fitting guide. The fit was then modified in the mid-peripheral portion to provide roughly 0-199, 200-399, 400-599, and 600-799 micrometers (μm) of central clearance after settling. All other lens parameters were held constant. The lenses were allowed to settle for at least 30 minutes, and the power was verified with an over-refraction prior to data collection. We then tested their visual acuity using a Snellen acuity chart, and contrast sensitivity using a Pelli-Robson chart. Aberrations were measured using the Nidek OPD-Scan III refractive power analyzer. Subjects were asked to fill out a short survey after completing data collection for each lens, as well as a final survey upon completion of all lenses in which they indicated lens preference.
Results and Conclusions: The data collected showed trends and patterns that one would expect clinically. As vault height increased, LogMAR visual acuity decreased. There were no changes in contrast sensitivity and higher order aberrations over time nor between vault categories. Lower order aberrations were shown to have increased between vault categories, and subject lens preference was towards the lower vault categories. As the overall ocular health is optimal with a lower vault clearance, it is fitting that the patients prefer these lenses.