Contrast sensitivity and reading through multifocal intraocular lenses
H. Akutsu, G. E. Legge, M. Showalter, R. L. Lindstrom, R. W. Zabel and V. M. Kirby
Department of Psychology, University of Minnesota, Minneapolis 55455-0344.
Multifocal intraocular lenses are intended to increase depth of focus for
patients with cataracts, but optical considerations predict reduced
retinal-image contrast. We evaluated visual performance through multifocal
intraocular lenses by measuring contrast sensitivity functions and reading
speed for age-matched groups with multifocal and monofocal intraocular
lenses and two normal control groups. Contrast sensitivity functions of the
patients with multifocal lenses did not differ significantly for optical
distances differing by 2.5 diopters, indicating substantial depth of focus.
Normal and monofocal contrast sensitivity functions were nearly identical,
and both were about a factor of two higher than multifocal contrast
sensitivity functions. Patients with multifocal lenses showed deficits in
reading speed only for low-contrast text (less than 30%) and small letters
(0.2 degree and 1.0 degree).