Investigators in Singapore evaluated factors that determine postsurgical outcomes of micropulse transscleral cyclophototherapy (MPTCP) in patients with primary open-angle glaucoma (POAG).
Study design
This was an interventional exploratory case series of all patients with POAG who underwent MPTCP from January 2013 to April 2019 at a single institution (N = 55 eyes). Typical laser settings were 2 W over 100 seconds of treatment time, delivering 62.6 J in total. Twelve months of post-MPTCP data were collected, including visual acuity (VA), IOP, visual field mean deviation (MD), postoperative complications, duration of postoperative steroid use, and the need for any additional surgical interventions for IOP control.
Outcomes
Mean pretreatment IOP was 24.8 ± 1.0 mm Hg, decreasing to 21.8 ± 1.1 mm Hg by postoperative month 12. There were no significant changes in VA or visual field MD in the 12 months post-MPTCP, and there was no statistically significant change in the number of classes of IOP-lowering medications needed; however, IOP remained lower than pretreatment levels at all measured timepoints. Factors associated with a higher maximum IOP decrease included greater preoperative IOP, higher laser power, and better VA. Seventeen eyes required further surgical treatment: Seven underwent repeat MPTCP and 10 underwent glaucoma drainage device implantation. No complications were noted.
Limitations
During the 12 months of follow-up, mean IOP slowly continued to rise. A longer follow-up time would have helped define the longevity of this procedure's effectiveness. Patients in this study were primary of Chinese descent (81.3%), which may limit this study's applicability to patients of other demographic and ethnic backgrounds. Average postsurgical IOPs were quite high, and given these IOP levels many glaucoma surgeons would have elected for further surgical treatment, which may be overestimating the success of this procedure.
Clinical significance
The MPTCP procedure was effective in achieving modest IOP reduction for 12 months and had a good safety profile, although IOP did rise over time. However, on average the IOP reduction was not significant enough to decrease medication burden. The use of MPTCP may be a good option as a temporary measure until definitive surgery can be performed, or in elderly patients who are unlikely to outlive their need for vision correction and may wish for more a more conservative treatment approach. Results from this study can aid in setting appropriate expectations for patients undergoing this procedure.