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Comparison of a diffractive bifocal and a monofocal intraocular lens
E D Allen1, R L Burton, S K Webber
1Sunderland Eye Infirmary, England.
Purpose:
To compare a Pharmacia diffractive bifocal intraocular lens (IOL) with a monofocal lens of the same design without the diffractive grating.
Setting:
Multicenter study.
Methods:
This randomized, prospective study comprised 70 patients with a monofocal IOL and 79 with a diffractive bifocal IOL. Follow-up was 5 to 6 months. Near and distance visual acuities, contract sensitivity, patient satisfaction, and spectacle use were evaluated.
Results:
All patients achieved a best corrected visual acuity of 0.5 or better; 80% in the monofocal and 71% in the bifocal group had a best corrected visual acuity of 1.0 or better. Without correction, 93% of the bifocal and 9% of the monofocal group could read J3 or better. With distance correction, 99% and 4%, respectively, could read J3 or better. Contrast sensitivity was slightly lower in the bifocal group at distance and near for all spatial frequencies. In the bifocal group, 46% never used spectacles for near tasks. Overall satisfaction was rated good by 86% of the monofocal and 85% of the bifocal group.
Conclusions:
The diffractive bifocal IOL performed well at distance and near. Patients who no longer require spectacles will benefit significantly from a bifocal IOL, but many with a bifocal IOL in one eye will require spectacles for the fellow eye.