The aim of the study was to compare the best corrected visual acuity (BCVA) before and at the 1st day after the cataract surgery for mature or the hard nuclear cataract. The phacoprobe NeoSoniX equipment Legacy (Alcon Laboratories) was used for the cataract surgery. Trypan blue for vital staining of the anterior capsule was used in case of the white cataract. The prevalence and the effect of the complication on BCVA were evaluated. 561 eyes were operated for the cataract. 57 (10.16%) had cataract grade NO4-NC6 and NC4-NC6 (LOCS III). Postoperative complications were: the transient edema of cornea in 8 eyes (14%), one case of (1.75%) erosio cornea caused by patient and in one case (1.75%) the intraocular pressure was elevated for a short time. The results of this study confirm that phacoemulsification is an appropriate method for the resolution of cataracts at advanced stages (Tab. 2, Fig. 3, Ref. 24). Full Text (Free, PDF) www.bmj.sk.