[Mesoptic vision in multi- and monofocal pseudophakia and in phakic control eyes]

The mesopic visual acuity (MVA) after intraocular lens (IOL) implantation is reduced compared to phakic patients of the same age. However, previous studies from our clinic have shown no significant MVA difference between multi- and monofocal IOLs. In the present study (with the patients matched exactly for age), this topic was reevaluated.

We investigated three groups, each consisting of 28 persons, 51 to 60 years of age. Group I consisted of healthy phakic volunteers, group II of patients 3 months after cataract extraction and implantation of a monofocal posterior chamber IOL (Pharmacia 720A) and group III of patients 3 months after implantation of a diffractive multifocal posterior chamber IOL with biconvex optic configuration (3M 825X). The MVA was examined using the "Ocutrast," described by Nowak. The Ocutrast, a modification of the Mesoptometer II, provides a field luminance of 1 cd/m2 and a contrast of 1:23 between test optotype and background; the intensity of illumination under glare conditions amounts to 0.35 lx at the level of the pupil.

The MVA without glare amounted to 0.50 +/- 0.12 (group I, healthy phakic eyes), 0.45 +/- 0.15 (group II, monofocal IOLs) and 0.32 +/- 0.11 (group III, multifocal IOLs). The MVA with glare amounted to 0.47 +/- 0.08 (group I), 0.35 +/- 0.12 (group II) and 0.24 +/- 0.10 (group III). Both for the MVA with and without glare there was a significant group difference (P < 0.05; two-factor analysis of covariance with repeated measurements).

After implantation of diffractive multifocal IOLs of the presently used type (3M 825X), the mesopic vision--both with and without glare--is even more reduced than after monofocal IOL implantation. These findings are particularly relevant for aged pseudophakic car drivers, especially for driving at night.