Many surgeons have noted that when the visual field is markedly constricted, immediate and permanent loss of central vision may follow otherwise successful glaucoma surgery. The present study was undertaken to assess the relative risk of surgical therapy in the loss of central vision in patients with advanced glaucoma. We reviewed the records of 44 eyes (including 8 macular split eyes) of 36 patients who had undergone trabeculectomy for intraocular pressure (IOP) control. The patients were followed for a minimum of 4 months with an average follow-up of 4.1 years. None of the patient suddenly lost visual field following surgery when central vision was spared at the time of operation. There was good preservation of preoperative visual acuity except in 3 eyes which developed lens opacity. There was no progression of visual field loss when the IOP was controlled below 21 mmHg. There was good control of IOP of 43 eyes in 44 eyes operated. However, in one of the 2 reoperated eyes, we could not control the IOP below 21 mmHg.