Contrast sensitivity in patients with nuclear cataracts
M. A. Drews-Bankiewicz, R. C. Caruso, M. B. Datiles and M. I. Kaiser-Kupfer
Ophthalmic Genetics and Clinical Services Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892.
Spatial contrast sensitivity and lens density were measured in 30 subjects
(18 patients with pure nuclear cataracts and 12 age-matched controls).
Contrast sensitivity was assessed using two techniques: a conventional
monitor method in which gratings were viewed through the cataract (overall
spatial contrast sensitivity) and a laser interferometer method in which
gratings were formed directly on the retina (interferometric spatial
contrast sensitivity), thus reducing the effect of an opaque lens on
grating contrast. The degree of lens nuclear opacity was measured by
assessing the density of Zeiss Scheimpflug slit-lamp video camera images. A
contrast sensitivity loss was found by using both methods; this reduction
reached statistical significance only when monitor stimuli were used. There
was a significant correlation between lens nuclear density and sensitivity
loss at spatial frequencies from 4 to 16 cycles/degree (r = .56 to .79 and
P less than .05 to less than .001). A correlation coefficient of .82 (P
less than .001) characterized the relationship between visual acuity (log
of the minimal angle of resolution) and lens density. Nuclear lens opacity
significantly affects contrast sensitivity; pure nuclear cataracts produce
spatial visual losses at intermediate and high spatial frequencies.
