Spatial resolution threshold in pseudophakic patients with monofocal and multifocal intraocular lenses

To compare the spatial resolution threshold in the central visual field of pseudophakic patients with monofocal and multifocal intraocular lenses (IOLs).

Eye Clinic, University of Trieste, Italy.

Twenty phakic normal subjects and four groups of 20 pseudophakic patients each, implanted with refractive and diffractive multifocal IOLs (Domilens Progress 1, AMO Array MPC25NB, or Pharmacia 811X) or with monofocal IOLs (Allergan PC43NB), were studied. The spatial resolution threshold in the central visual field was assessed using high-pass resolution perimetry. Measurements were performed adding spherical correction to test the different foci of the IOL.

No significant differences between phakic subjects and pseudophakic patients with monofocal IOLs were found. In distance vision, no significant differences between patients with refractive multifocal IOLs and those with monofocal IOLs were found. The group with the diffractive multifocal IOL showed a significantly higher spatial resolution threshold (P = .003). In intermediate vision, the AMO Array group showed a significantly lower spatial resolution threshold than the other groups (P < .01). The best performance at near distance was in the diffractive group, which was statistically significantly different from the other groups (P < .001).

In the diffractive group, the high spatial resolution threshold in distance vision could be explained by the lower brightness of the principal focus, related to a different light energy division between the foci. In the Domilens group, the high spatial resolution threshold in near vision could be related to the light energy scattered in a large number of foci.