Differences between micropulse versus continuous wave transscleral cyclophotocoagulation on patient experience and post-operative inflammation

The theorized benefit of micropulse cyclophotocoagulation (CPC) is that it is gentler on the targeted ciliary body with less off-site impacts based on its mechanism. The goal of the article from Keidel et al., “Inflammation and patient satisfaction in micropulse versus continuous wave transscleral cyclophotocoagulation”, was to compare post-intervention inflammation and to gauge tolerance of micropulse transscleral cyclophotocoagulation (MPCPC) versus continuous wave cyclophotocoagulation (CWCPC) (1). The structure of study was a prospective, randomized controlled trial at one academic medical center. The outcomes included post-operative inflammation, measured in anterior chamber flare and central macular thickness, and patient experience, evaluated using two validated surveys, the Visual Analogue Scale (VAS) and the Glaucoma Activity Limitation 9 (GAL9) questionnaire. Results included larger amounts of short-term anterior inflammation in CWCPC that equalized at week 6 while there were not significant differences in patient experience, as judged by VAS and GAL9 scores. Thus, it was concluded that MPCPC was associated with less immediate postoperative inflammation post-operatively but was similarly (interestingly, not better) tolerated.

This study sought to provide evidence for theoretical benefits of MPCPC versus CWCPC, an area of understanding that it is noticeably lacking and would be helpful for clinical decision-making. The study was thoughtfully designed to be as standardized as possible (one physician performing procedure, same amount of total energy delivered, same post-operative regimen) to minimize the impact of confounders. Additionally, it provided novel findings on the possible difference, although not statistically significant, in posterior inflammation (via cystoid macular edema, CME) in these procedures, a finding that could change practice patterns. Importantly, the authors attempted to report patient experiences, which is underrepresented in scientific investigation.

While these outcomes are important proxies for inflammation that may be visually significant, it is critical to highlight that study did not include information on glaucomatous progression, including visual field loss or retinal nerve fiber layer thinning on optical coherence tomography, which would arguably be the most influential in selecting a cyclodestructive procedure. Similarly, while the study reported interesting findings on the correlation between treatment success and inflammation, it did not provide comparative rates of success as defined in the study methods or amounts of intraocular pressure (IOP) reduction between the two methods of laser. Without this information, the clinical utility of this study is profoundly limited, as there has not been an established consensus on the equivalence of efficacy of these two procedures in the scientific literature. While MPCPC has been demonstrated to be similarly efficacious in some studies (2), other reports demonstrate the IOP reduction may be inferior to CWCPC (3,4). Additionally, more timepoints would be helpful to determine correlation with long term IOP reduction (past 6 months), as after both CWCPC and MPCPC, the effect may not be sustained (3). Further, although the laser power delivered was equivalent between diode types, the actual energy experienced by the tissue may not be the same due to the difference in mechanisms of action of the lasers. It is possible methodologic adjustment may be needed to make the energy delivered truly equivalent.

The second goal of this investigation was to determine whether MPCPC was better tolerated than CWCPC, for which VAS and GAL9 were used. While it is helpful that the VAS is standardized, it lacks important nuance that could miss relevant themes in patient experience, such as other bothersome symptoms, including foreign body sensation or excessive tearing, that negatively impact patient experience but are not “pain”. Similarly unaddressed is characterization of changes in quality of life (QoL) after both types of CPC—it would be helpful to know what changes in the GAL9 were observed pre- and post-operatively, even if these did not differ between the two interventions. That being said, it is somewhat surprising that there is no difference in reported pain or GAL9 between CWCPC and MPCPC, considering the difference in objective measures of post-operative inflammation, although this has been supported in other studies (5).

In theory, MPCPC should provide respite for the ciliary body in between laser applications and is thought to have more localized impact with less off-target tissue involvement, and for that reason was conventionally hypothesized to be less painful and more easily tolerated for patients (1). This line of thinking is supported by lower levels of anterior inflammation immediately post-operatively as demonstrated by the current study. However, this equalized six weeks after the procedure. While it is notable that there was more CME associated with CWCPC, this difference was not significant and the impact of this was not clear, as visual acuity was not reported. Therefore, one must interpret these findings with substantial caution. Finally, there was no difference in reported post-operative pain or QoL. In conclusion, this study provides interesting information that will build on our foundation of knowledge but does not convincingly support one side of the MPCPC versus CWCPC debate.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Annals of Eye Science. The article has undergone external peer review.

Peer Review File: Available at https://aes.amegroups.com/article/view/10.21037/aes-2026-0021/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://aes.amegroups.com/article/view/10.21037/aes-2026-0021/coif). S.C.M. received grants from Wilmer Resident Research Grant. C.L.K. received grants from Knights Templar Eye Foundation. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

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References

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