This retrospective study assessed the treatment parameters used by 5 physicians performing transscleral diode cyclophotocoagulation (TCP) and compared resulting patient outcomes.
Study design
Researchers retrospectively identified 236 glaucomatous individuals who underwent TCP over a 10-year period. Procedures were all performed by 1 of 5 physicians. Patient diagnoses included a variety of glaucoma types, with the largest group consisting of patients with primary open-angle glaucoma. Patients received 1 (n=180), 2 (n=42), 3 (n=11) or 4 (n=3) TCPs.
Successful TCP was defined as a 20% reduction in IOP, with pressure equal to or greater than 21 mm Hg without additional IOP-lowering procedures, with or without glaucoma medication. Each of the 5 practitioners completed a questionnaire pertaining to their usual treatment habits.
Outcomes
Nearly 70% of eyes that received 1 or more cyclophotocoagulation treatments were considered a success by the last follow-up. In eyes that underwent only 1 TCP, higher rates of success were associated with more power delivered per laser application compared with failed eyes (135 J vs. 98 J; P=0.0009). However, neither the total number of deliveries nor extent of eye circumference treated had a significant association. Three physicians report using audible cues to increase and adjust laser power.
While most of the patients who reported glaucoma-related preoperative pain were pain free at final follow-up, 29% of those without preoperative pain reported low-level pain within the first week after TCP. Seven eyes had phthisis, 5 of which had severe secondary disease. Visual acuity was worse than baseline in 54% of eyes, unchanged in 30%, improved by 1 category in 12% and undetermined in 4%.
Limitations
The study predominantly included eyes with relatively poor visual acuity (<20/200). As cyclophotocoagulation techniques move earlier in the glaucoma treatment paradigm, it would be interesting and useful to see results in patients with better baseline levels of visual acuity. In addition, as none of the treating physicians routinely used transillumination to identify the position of the ciliary body; the effect of this practice on success rates could not be determined.
Clinical significance
This study is relevant to clinical practice. It suggests practitioners adopt relatively longer durations to deliver higher energy levels per application. Audible cues could also be used to adjust treatment parameters to improve TCP success rates.