Purpose To investigate the effect of diode laser cyclophotocoagulation for glaucoma on central visual function in patients with good visual acuity (VA). Patients and methods Patients with preoperative VA 20/60 or better who had undergone cyclodiode treatment according to a standard protocol were evaluated retrospectively. The primary outcome variable was a recorded loss of two or more Snellen lines of best corrected VA during follow-up. Successful intraocular pressure (IOP) control was defined as being between 6 and 21 mmHg inclusive without oral acetazolamide or other glaucoma surgery. Results 49 eyes of 43 patients with a median pretreatment acuity of 20/30 were included (range 20/16–20/60). After a mean duration of follow-up of 5.0 years, median VA was 20/60 with a line loss of two or more recorded in 15 eyes (30.6%) (mean survival time 7.7 years). 67.3% (33/49) retained VA 20/60 or better, but VA deteriorated by one Snellen line or more in 31 (63.2%), and in 16.3% (8/49), final VA was Conclusions Most of these eyes with difficult to manage glaucoma retained their good VA over long-term follow-up after undergoing diode laser cyclophotocoagulation. The proportion losing two Snellen lines is in line with that reported after trabeculectomy or tube surgery. These results suggest a possible role for the use of transscleral cyclodiode in selected eyes with significant visual potential. Further controlled prospective studies are required to better define this role.