A double-blind, parallel, randomized study was conducted to compare the efficacy of Healon GV versus Healon in penetrating keratoplasty (PK). Its objective was to investigate whether Healon GV maintains space in the open anterior chamber better than Healon does during removal of the corneal button. Excluding those patients with an anterior chamber lens implant or a known history of glaucoma, 35 patients scheduled for PK entered the study. After penetration of the cornea with the trephine, a specific amount (0.2 ml) of Healon GV or Healon was injected into the anterior chamber. The corneal button was removed and the distance (mm) between iris and cornea (epithelial side) was measured with a digital slide gauge mounted between the permanent and mobile stand of the microscope. A significant difference between the two groups was shown in the measurements of the distance between the iris and the outer side of the cornea. The mean distance for Healon GV was 1.5 +/- 0.6 mm and for Healon it was 1.1 +/- 0.4 mm (p = 0.038). The removal of the corneal button was significantly facilitated when Healon GV was used (p = 0.021). In conclusion, Healon GV was found to be superior in the ability to maintain space in the open anterior chamber.