The influence of the incision length on the early postoperative intraocular pressure following cataract surgery.

In a prospective study we recorded the early postoperative intraocular pressure of 60 eyes following phacoemulsification and posterior chamber lens implantation. In 30 patients each the implantation either of a folded polyHema intraocular lens through a 3.5 mm incision or of a polymethylmetacrylate intraocular lens through a 7 mm incision was performed. Healon was used in all eyes and thoroughly evacuated from the capsular bag behind the implanted lens and the anterior chamber. For intraoperative miosis 0.5 ml acetylcholine chloride was injected into the anterior chamber after wound closure. Intraocular pressure was measured preoperatively as well as six hours, 18 hours, one week and two months postoperatively without the influence of antiglaucomatous medication. We found no statistically significant change of intraocular pressure at any measurement time in the 3.5 mm group (Student's t-test, p > 0.1). In the 7 mm group only the rise of intraocular pressure at 18 hours was statistically significant (p < 0.05, student's t-test). The comparison of the changes of intraocular pressure from preoperative values between both groups revealed a statistically significant difference at 18 hours (p < 0.05, student's t-test) but not at any other time recorded. Intraocular pressure exceeding 22 mmHg was found at 6 hours in 4 (13.3%) patients of both groups and at 18 hours in 3 (10%) eyes of the 3.5 mm group and 5 (16%) eyes of the 7 mm group (p > 0.1, Fisher's Exact Test). From these results we conclude that 1) regardless of the wound size the pressure rising effect of Healon is successfully counteracted by the aspiration technique described, and 2) with small-incision cataract surgery statistically significant less changes of intraocular pressure are observed in the early postoperative period.