Abstract
Purpose :
Cyclophotocoagulation (CPC) treats glaucoma by targeting ciliary body aqueous humor production. Traditionally, it's been reserved for patients with end-stage glaucoma with poor visual acuity (VA); however, micropulse transscleral CPC (MP-TSCPC) has allowed for delivery of energy to the ciliary body with minimal collateral damage allowing preservation of VA. We aim to assess long-term efficacy of MP-TSCPC and compare the original MP3 probe to the newer P3 probe.
Methods :
Patients with glaucoma on drop therapy were treated with MP-TSCPC using Iridex MP3 or P3 probe with a standardized protocol. Baseline characteristics as well as intraocular pressure (IOP), number of IOP lowering medications and VA were obtained from pre and post-operative visits. Failure was defined as IOP > 21 mmHg or reduced < 20% below baseline or IOP < 5 mmHg on 2 consecutive follow-up visits after POM1, reoperation for glaucoma or loss of vision to no light perception. Log-rank test was performed as well as cox regression analysis.
Results :
A total of 113 eyes were enrolled, 44 with the MP3 probe and 69 with the P3 probe. No difference in baseline characteristics found except for a longer duration of follow-up with the MP3 probe (19.5±2.0 vs 14.5±2.0 months, p=0.044). Both probes had significant reduction in IOP compared to preop IOP at all time points; however, the MP3 probe had significantly lower IOPs than the P3 probe at POW1 and POM1 (14.7±0.8 vs 17.4±0.8, p=0.021; 15.9±0.9 vs 19.7±1.2, p=0.002, respectively). The P3 probe had a significant reduction in number of IOP meds at POW1, POM1 and POM3 compared to baseline and compared to the MP3 probe eyes at POW1 and POM1 (3.1±0.2 vs 2.3±0.2, p=0.001; 3.1±0.2 vs 2.6±0.2, p=0.039, respectively). No changes in VA were found. Complication rates were low at 6% with no differences between probes. Survival analysis found failure to be higher in the P3 probe at 75% and time to failure of 4.8±0.7 months versus 65% and 6.1±1.1 months in the MP3 probe (p=0.04). The type of probe used was the only variable associated with rate of failure (Hazard ratio 1.58, p=0.04).
Conclusions :
The new P3 probe was associated with a higher rate of failure in patients treated with MP-TSCPC. Overall patients had significant reduction in IOP with preservation of VA; yet, a large proportion required rescue treatment either with additional drops, incisional surgery or repeat MP-TSCPC.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.