Uncomplicated extracapsular cataract extraction (EC) followed by posterior chamber lens implantation (PCL) has been shown to cause long-term lowering of intraocular pressure (IOP) in most patients. Since it has been suggested that Neodymium: YAG (Nd:YAG) laser capsulotomy can provoke persistent glaucoma, we examined the hypothesis that Nd:YAG laser capsulotomy may lead to a permanent elevation of IOP. In a case-control study, we compared two groups of 75 normotensive patients, who were unilaterally pseudophakic after phacoemulsification (PE) + PCL. Patients in group 1 had undergone Nd:YAG capsulotomy at least 2 months prior to this study, while in group 2 the posterior capsule was intact. Both groups were selected at random. Prior to surgery, none of the patients had suffered from glaucoma. Goldmann applanation tonometry was performed in both eyes of each patient and from that the ratio of IOP(pseudophakic)/IOP(phakic) was calculated. The distribution of this ratio for the two groups was compared using the Wilcoxon signed-rank test. There were 52 female and 23 male patients in group 1 versus 56 female and 19 male patients in group 2. Their mean ages were 75 + or -11 (group 1) and 75 + or - 9 years (group 2). The mean interval after PE + PCL was 48 + or - 29 months for patients with Nd:YAG capsulotomy and 16 + or - 17 months for patients with intact posterior capsule. Since the Nd:YAG capsulotomy, 28 + or - 23 months had elapsed on average. The median ratio of IOP (pseudophakic)/IOP(phakic) was higher in the Nd:YAG capsulotomy group than in the group of patients with an intact posterior capsule (1.00 vs. 0.80; p < 0.0001). There was almost no percentile, for which the distribution curve of group 1 intersected the curve of group 2. The median IOP in pseudophakic eyes was 14 mm Hg in group 1 and 12 mm Hg in group 2 (p<0.0001). These results are in accordance with the hypothesis that Nd:YAG capsulotomy will raise IOP permanently in most patients. Therefore Nd:YAG capsulotomy may harbor the risk of glaucomatous optic nerve damage in the long run. Long-term follow-up seems advisable in order to prevent possible glaucoma damage.