Incidence of hypotony and sympathetic ophthalmia following trans-scleral cyclophotocoagulation for glaucoma and a report of risk factors

ObjectiveTo report the incidence and risk factors for hypotony and estimate the risk of sympathetic ophthalmia following diode laser trans-scleral cyclophotocoagulation (TSCPC). DesignRetrospective study using data from a private tertiary glaucoma clinic and review of the literature. ParticipantsSeventy eyes of 70 patients with refractory glaucoma who received TSCPC treatment. MethodsReview of the records of consecutive patients who underwent TSCPC by a single ophthalmic surgeon and review of the literature. Main Outcome MeasuresHypotony (including phthisis bulbi), sympathetic ophthalmia. ResultsSeven eyes (10%; CI 5-19%) developed hypotony and included 4 eyes that developed phthisis. Higher total energy delivered during TSCPC treatment was associated with an increased risk of hypotony: eyes that developed hypotony received a mean total energy of 192.573.2 joules, compared to a mean of 152.9 +/- 83.2 joules in hypotony-free cases. The risk of sympathetic ophthalmia estimated from a review of the published literature and current series was one in 1512, or 0.07% (CI 0.03%-0.17%). ConclusionsTotal laser energy is one of several risk factors that act in a sufficient component cause-model to produce hypotony in an individual patient. The small sample size precluded inference for other individual putative risk factors but titrating laser energy may help decrease the occurrence of hypotony. The risk of sympathetic ophthalmia calculated from the literature is likely an overestimate caused by publication bias.