M.Med. Faculty of Health Sciences, University of the Witwatersrand, 2009 / Purpose To compare the outcomes of primary viscocanalostomy with trabeculectomy augmented with mitomycin C (MMC) in black South African patients with primary open-angle glaucoma (POAG). Method A prospective, randomized study was conducted over a four year period. Fifteen black South African patients with bilateral open-angle glaucoma requiring surgery that met the inclusion criteria and gave informed consent to participate in the trial were randomized to receive either a viscocanalostomy or a trabeculectomy with MMC in the first eye requiring surgery. The fellow eye then received the alternate procedure. Patients were followed up for two years postoperatively. Results There were no significant differences between the two surgical groups preoperatively. Twelve eyes in each group were followed for twenty-four months. In both groups the intraocular pressure (IOP) was significantly reduced post-operatively (p < 0.01) and the average number of medications used per eye was significantly reduced (p < 0.02). At twenty-four months, complete success (IOP less than or equal to 18mmHg without glaucoma medication and with no evidence of glaucoma progression) was seen in 75% of eyes undergoing trabeculectomy with MMC that completed the follow up, but in only 33% of eyes undergoing viscocanalostomy (p = 0.0498). Survival curves for both success and qualified success (IOP less than or equal to 18mmHg with glaucoma medications) in the two surgical procedures confirmed the superiority of trabeculectomy with MMC over viscocanalostomy. Conclusion Viscocanalostomy may offer some advantages because it is less invasive, but intraocular pressure control appears to be superior with trabeculectomy with MMC and this continues to be the filtering procedure of choice for the management of glaucoma in black South African patients.