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Low contrast visual acuity in pseudophakic patients implanted with an anterior surface modified prolate intraocular lens.

PURPOSE
To determine whether implantation of a new intraocular lens (IOL) with a modified prolate anterior surface, designed to reduce the positive spherical aberration of the pseudophakic eyes, results in improved contrast sensitivity assessed in terms of low contrast visual acuity (VA).


METHODS
We carried out an intraindividual study of 12 patients with bilateral cataracts, randomized to receive a prolate anterior surface IOL (Tecnis Z9000, Pharmacia) in one eye and a biconvex spherical surface IOL (CeeOn 911 A, Pharmacia) in the other. High and low contrast VA was assessed under photopic conditions, before and after pupil dilation.


RESULTS
After mydriasis, the Technis Z9000 provided significantly better low contrast VA at contrast levels < or = 25%. No significant difference was found under normal pupil conditions.


CONCLUSION
Our results confirm the hypothesis that the spherical aberration of the eye after cataract surgery can be reduced by an anterior prolate surface IOL.