The use of spherical power effect bitoric rigid contact lenses in hospital practice.

In this retrospective study of astigmatic contact lens dispensing in the hospital setting, 680 patients were noted to have been dispensed new contact lens prescriptions over a specific 20-month period. Seventy-five patients (11%) received at least one astigmatic rigid or hydrogel contact lens. Forty-nine patients received at least one rigid astigmatic lens; 43 patients (63 eyes)--or about 87% of all rigid lens fittings--were dispensed spherical power effect (SPE) design rigid contact lenses. We find that we usually prescribe bitoric rigid lenses with the flatter (longer) meridian of the lens base curve about 0.50 diopters steeper than the flattest (longest) corneal meridian. Mean diameter was 9.3 mm, and about 80% of lenses were made from rigid gas permeable materials. The majority of patients were successful from a clinical perspective, with most attaining visual acuity equal to or better than with maximum spectacle correction, and with good comfort and physiological results.