[2 years results of implantation of diffractive multifocal intraocular lenses]

In an ongoing prospective study, we investigated 52 eyes of 40 patients 2 years (range: 22-26 months) after implantation of a diffractive multifocal intraocular lens (3M, type 815LE). The distance visual acuity averaged 0.48 without correction and 0.83 with best correction. The mean refraction (spherical equivalent) amounted to -1.2 D (compared to only -0.32 D 3 months postoperatively). The corrected distance acuity was > or = 1.0 in 40% and > or = 0.5 in 100% of the eyes. A near visual acuity of Nieden 1-3 was achieved in 70.3% without correction, in 75% with distance correction only, and in 100% with additional near addition. Compared to our results 3 months after multifocal lens implantation, the uncorrected distance acuity decreased and the uncorrected near acuity increased 2 years postoperatively both phenomena being attributable to the postoperative minus-shift in refraction. The other acuity values were unchanged in comparison with the 3-month results. Measured with the Ginsburg test, contrast sensitivity at low and medium spatial frequencies improved significantly compared to the 3-month results. An improvement in contrast sensitivity since the early postoperative phase was also found using the Pelli Robson contrast sensitivity chart and--in tendency--using the Regan contrast charts. Hypothetically, these findings may be traced back to a retinal or central nervous cybernetic adaptation mechanism to the implanted multifocal optic.