Date of Award


Degree Type


Degree Name

Master of Science in Vision Science

Committee Chair

Christina M. Schnider


To evaluate differences in the overnight corneal swelling response between hydrogel toric and equivalent powered spherical contact lenses, 16 subjects participated in an overnight in-clinic test session. After 8-9 hours of sleep the mean percent central corneal swelling was 10.984% for the eyes wearing the toric lenses and 10.074% for the eyes wearing the spherical lenses. There was a statistically significant difference in the mean percent corneal swelling induced by the two groups (P < 0.05 one-tailed repeated measures paired t-test). Qualitative evaluations showed 25% more striae and epithelial punctate staining in the toric group as well. These findings suggest that there is a corneal health basis for prescribing equivalent powered spherical hydrogel contact lenses rather than toric lenses to low cylinder astigmatic patients.

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