Retinal image contrast and functional visual performance with aspheric, silicone, and acrylic intraocular lenses. Prospective evaluation.

PURPOSE

To compare the effects of an aspheric intraocular lens (IOL) (Tecnis Z-9000, Pharmacia Corp.) with those of conventional silicone (AA4207VF, Staar Surgical) and acrylic (AcrySof SA60AT, Alcon Surgical) lenses on retinal imaging and functional visual performance.

SETTING

Eye Laser Center, Tucson, Arizona, USA.

METHODS

In this prospective study, 221 eyes of 156 patients were randomly assigned to receive 1 of 3 IOLs. Visual acuity was measured preoperatively and 1 day, 1 and 3 weeks, and 1, 3, and 6 months postoperatively. Fundus photography and photopic and mesopic functional acuity contrast testing were performed preoperatively and 3 months postoperatively.

RESULTS

The differences in the preoperative and postoperative spherical and astigmatic refractive errors and best corrected visual acuity among groups were not statistically significant. The postoperative uncorrected visual acuity was best in the aspheric group in the first month. Functional acuity contrast testing showed the aspheric IOL group had a 38% to 47% increase in photopic vision, 38% in photopic with glare, 43% to 100% in mesopic, and 9% to 100% in mesopic with glare. There was no increase in photopic vision in the acrylic group but increases of 38% in photopic with glare, 25% to 50% in mesopic, and 36% to 50% in mesopic with glare. The spherical silicone IOL group had no increase in contrast testing from preoperatively. Digital analysis of retinal imaging showed increased threshold luminance levels in the aspheric group (range 116 to 208 cd/m2) and a 4-fold increase in image contrast.

CONCLUSIONS

All 3 IOLs led to improved visual acuity after cataract surgery. The aspheric IOL provided a significant improvement in retinal image contrast and visual performance measured by visual acuity and functional acuity contrast testing. This improvement was greatest in night vision and night vision with glare compared to the performance of conventional spherical silicone and acrylic IOLs.