Micropulse transscleral cyclophototherapy (MPTCP) at 1 year did not lead to major improvement in patients with primary open-angle glaucoma (POAG), according to a study published in Journal of Glaucoma. “Our study findings suggest that using the parameters described, MPTCP is, at best, briefly effective in patients with advanced disease with no enduring effect, demonstrating an intraocular pressure (IOP) climb back to pretreatment levels over a period of 6 months,” the study says. The research says this reduction is not adequate to decrease the medication burden.
MPTCP, a treatment that began being used for refractory glaucoma in 2010, has been shown to lower IOP in glaucoma patients more consistently than conventional trans-scleral cyclophototherapy (CWTCP). Research has indicated the treatment aids patients with refractory glaucoma, but data on the effects of MPTCP for POAG is limited. Researchers sought to determine which factors impact the success of MPTCP, particularly in patients with POAG.
Unlike CWTCP, MPTCP has on-off cycles. In this study, the laser distributed micropulses in on-off cycles of 0.5 ms and 1.1 ms respectively as it slid over the superior and inferior quadrants, avoiding the horizontal meridians and any previous surgical sites and typically applying 2W per 100 seconds.
The case series included 48 patients (55 eyes mean age 67.3±14.1 years) with POAG who underwent MPTCP at a hospital in Singapore. Seventeen eyes had previously undergone glaucoma surgery. Mean follow-up time was 9.3±4.0 months.
Mean IOP decreased from prior to MPTCP (baseline 24.8±1.0 mm Hg) to all following time points (P <.001 to .006).
After adjusting for prior glaucoma surgery, the researchers found that IOP decreases were linked with increased preoperative IOP mm Hg. The drop increased 0.41 mm Hg per 1 mm Hg increase before MPTCP (P <.001) and mean IOP increased 0.02 mm Hg per 1 mW in power after adjusting for preoperative IOP as well (P =.007). Mean VA did not significantly change after the operation, and mean MD remained stable (before MPTCP -16.8±1.3 dB 12 months after operation -18.2±1.3 dB).
Post-surgery, patients needed steroid eye drops for 16.7±14.1 days. The number of classes of glaucoma did not significantly change pre- and post-surgery. Four eyes initially responded to MPTCP but needed oral acetazolamide at postoperative month 1, when IOP increased. Beginning 3 months after the surgery, some eyes required another surgery to control IOP. One eye did not respond to the surgery, and 17 eyes required surgery 1 year after MPTCP. Seven eyes underwent MPTCP again (3 with prior glaucoma surgery) and 10 underwent glaucoma drainage device implantation.
In eyes that underwent a second MPTCP, VA and MD remained the same. IOP decreased but returned to pretreatment levels by month 6. The study notes no complications.
“While MPTCP is effective in lowering IOP based on the settings used in our study, it is unable to lower IOP adequately to achieve a decrease in medication burden. … Our observations may suggest that while the effect of MPTCP appears to be transient, it might have a role as a temporizing measure for IOP control before definitive glaucoma surgery,” according to the researchers.
They said steroid response could promote IOP after the surgery and recommended ophthalmologists monitor patients carefully.
Limitations included some patients missing follow-up appointments and variations in treatment parameters between patients.
Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Tong W, Shen TYT, Wong HC, et al. One-year outcomes of micropulse cyclophototherapy for primary open-angle glaucoma. J Glaucoma. 2021;30(10):911-920. doi:10.1097/IJG.0000000000001925