# The effect of cumulative energy in repeated subliminal transscleral cyclophotocoagulation: a retrospective study

## TL;DR

Repeated subliminal laser treatments safely lower eye pressure in glaucoma patients over a year.

## Contribution

Demonstrates the safety and efficacy of repeated subliminal transscleral cyclophotocoagulation with cumulative energy scaling.

## Key findings

- IOP decreased significantly at all postoperative timepoints, with the highest reduction in the high cumulative energy group.
- Three-quarters of patients discontinued oral carbonic anhydrase use after 12 months.
- Eyes with silicone oil showed a greater response to treatment.

## Abstract

The long-term safety and efficacy of repeated applications of subliminal transscleral cyclophotocoagulation (SL-TSCPC) with a focus on cumulative energy was evaluated in glaucoma patients.

In this retrospective, multicentric study the data of a total of 82 eyes with various causes of glaucoma that were treated with a single or multiple applications of SL-TSCPC were collected. Treatments were performed under general or local anesthesia with an 810 nm diode laser. Power was 2000 mW; duty cycle, 31.3%; total treatment duration, 80–320 s; equaling a total energy of 50–200 J per treatment session. Fifty-five eyes (55 patients) presented for all follow-ups, and these eyes were selected for further statistical analysis. The mean age was 60.0 ± 17.1 years, and 22 (40%) of the patients were female. Intraocular pressure (IOP) and dependence on further glaucoma medication were evaluated at 12 months following the initial treatment.

Eyes underwent 1 or 2 consecutive SL-TSCPC treatments. Median (min–max) baseline IOP of 34 (13–69) decreased to 21.5 (7–61), 22 (8–68), 20 (9–68), and 19.5 (3–60) mmHg at the 1, 3, 6, and 12-month postoperative timepoints respectively. The mean (± SD) IOP decrease at 12 months was 26 ± 27%, 39 ± 32%, and 49 ± 33% in the low (below 120 J, n = 18), medium (120–200 J, n = 24), and high (above 200 J, n = 13) cumulative energy groups respectively. At the 12-month timepoint, oral carbonic anhydrase use was discontinued in ¾ of the cases.

It was found that the repeated application of SL-TSCPC safely and efficiently decreases IOP in a Caucasian population with heterogenous causes of glaucoma, eyes with silicone oil responded to a greater extent. Inclusion of cumulative energy scales may contribute to better addressing repeated procedures in a standardized fashion.