[Resistance to blindness and frequency-contrast characteristics of the eye with artificial lens]

Contrast sensitivity of vision was examined by the frequency-contrast characteristics method (FCC) and vision resistance to glare studies with Niktoskop equipment in 48 patients with artiphakia. FCC was estimated from the curve shape as well as from the mean threshold contrast in all space frequencies. Blindness resistance was assessed from the period of mesopic vision acuity recovery (MVAR) up to 0.3 diopters after the glare flash. The group included 28 patients with iris clips lenses and 20 with posterior-chamber lenses. Patients with vision acuity of 0.8-1.0 diopters were referred to the first and those with vision acuity of 0.5-0.7 diopters to the second category. The mean threshold contrast, whose normal value is 8.0 +/- 0.7 percent, was drastically elevated 3 months after surgery in all the patients and only in a year normalized in the first-category patients with iris clips lenses or posterior-chamber lenses after posterior chamber dissection. Blindness resistance of patients with intraocular lenses was on the whole worse than in normal eyes: MVAR was by 26.2 +/- 0.7 percent higher than the normal value and normalized to reach 29.0 +/- 0.6 sec only in a year in the first-category patients with posterior-chamber lenses whose posterior capsule was not dissected. Therefore, FCC and MVAR values depend on the end vision acuity and type of intraocular lens and are on an average better after implantation of posterior-chamber lenses and not of iris clips lenses.