Contrast sensitivity after implantation of diffractive bifocal and monofocal intraocular lenses.

PURPOSE: To compare contrast sensitivity (CS) after implantation of a diffractive bifocal intraocular lens (IOL) and a monofocal IOL of similar design. SETTING: Seven European centers. METHODS: In this randomized, prospective study, CS was tested 5 months after cataract and IOL implantation surgery in 115 patients with a diffractive bifocal IOL and 106 patients with a monofocal IOL. It was also tested in a subgroup of 38 patients who had bilateral implantation of a diffractive bifocal IOL. Contrast sensitivity was tested using the Vision Contrast Test System (VCTS). RESULTS: In patients with a best corrected visual acuity (BCVA) of 1.0 or better, the CS at all spatial frequencies (1.5 to 18 cycles/degree), both at distance and near, was slightly lower in the bifocal IOL group than in the monofocal group. Mean values were within the normal range. In patients with a BCVA of less than 1.0, the CS was lower and the difference between the bifocal and monofocal groups was less. In patients with bilateral bifocal IOLs, CS was better when tested bilaterally than when testing the better eye alone. Pupil size affected the results to a small degree. Contrast sensitivity appeared to improve over time after implantation of a diffractive bifocal IOL. CONCLUSIONS: In patients with cataract and no other eye pathology, the diffractive bifocal IOL with slightly reduce the CS at all spatial frequencies. In those with reduced visual acuity after cataract surgery, CS will be reduced accordingly. In this situation, the reduction from the diffractive bifocal optic would be minor.

Comparison of a diffractive bifocal and a monofocal intraocular lens.

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.

Regional anesthesia for cataract surgery: comparison of retrobulbar and peribulbar techniques.

METHODS. The features of retrobulbar and peribulbar blocks were compared prospectively in 300 patients undergoing elective, ambulatory cataract surgery. Both techniques were clinically applicable, but to achieve total akinesia of the eye muscles, an additional injection was needed in 13% of the patients with retrobulbar block and in 35% with periocular block. RESULTS. In younger patients (less than 65 years), the number of injections and the volume of the local anesthetic needed to produce a total akinesia of the eye were significantly higher when compared with the elderly.