OBJECTIVE To learn the long-term outcome of ciliary ablation with diode laser contact transscleral cyclophotocoagulation (TSCPC) in eyes with recalcitrant, severe glaucoma. METHODS Twenty-seven eyes of 27 patients with medically and surgically uncontrollable glaucoma and no previous ciliary ablation enrolled in this study. After baseline measurements and informed consent, the authors performed contact TSCPC. There were 14 pseudophakic, 7 aphakic, and 6 phakic eyes; 15 of these had primary open angle glaucoma and the remainder had various secondary or open- or closed-angle glaucomas. Median follow-up was 19 months (range, 6 weeks to 27 months). Initially after laser surgery, glaucoma medications were continued, except for a 2-week interruption of miotics; the ophthalmologist later adjusted medications in accordance with the patient's status. The authors define failure of TSCPC in two ways, based on IOP measurements during two consecutive study examinations 6 weeks or more after intervention or at the final examination: (1) less than 20% intraocular pressure (IOP) reduction from baseline, and (2) either less than 20% reduction of IOP from baseline or IOP greater than 22 mmHg. RESULTS For 27 eyes, the baseline IOP (mean +/- standard deviation) was 36.4 +/- 12.4 mmHg (range, 20-70 mmHg). The mean IOP at last examination was 20.3 +/- 8.7 mmHg. With failure definition 1, the cumulative probability of success was 84% at 1 year and 62% at 2 years. With failure definition 2 the cumulative probability of success was 72% at 1 year and 52% at 2 years. At the last examination, 19 eyes (70%) had visual acuity improved within one line of visual acuity at eligibility. One of these eyes, with light perception vision at entry, declined to no light perception. Three eyes (11%) lost two lines of vision and five (19%) lost three or more lines. CONCLUSIONS Contact diode laser TSCPC yields long-term improvement of IOP and preservation of visual acuity in a substantial proportion of eyes with severe, medically uncontrolled glaucoma.