title: Lowering of Intraocular Pressure After Phacoemulsification in Primary Open-Angle and Angle-Closure Glaucoma: A Bayesian Analysis.
abstract: Phacoemulsification as treatment for primary open-angle glaucoma (POAG) remains more controversial than for primary angle-closure glaucoma (PACG). If the objective of glaucoma surgery is an additional greater than or equal to 5 to 6 mm Hg reduction of intraocular pressure (IOP), the role of phacoemulsification should be based on the probability of achieving this. A Bayesian analysis of available data was performed to calculate the change in IOP after phacoemulsification in POAG and PACG. Standard meta-analysis formulation with prephacoemulsification and postphacoemulsification IOP-assumed to have normal distributions, with study-specific means and SDs-was used. Absolute and relative change in IOP was calculated using different priors, and sensitivity analyses were performed. The prior that just included a decrease of greater than or equal to 6 mm Hg in the 95% credible interval was identified. The probability of achieving greater than or equal to 5 to 6 mm Hg decrease in IOP (and other levels) was calculated. Depending on the prior, the probability of achieving a greater than or equal to 5 mm Hg reduction in IOP in POAG varied from 0.1% to 3%. Confidence in a greater than or equal to 6 mm Hg decrease required a prior belief that phacoemulsification produces a mean decrease of 7 mm Hg. The probability of a decrease in IOP was greater in PACG: approximately 50% probability of a greater than or equal to 5 mm Hg decrease in PACG uncontrolled on medications. Phacoemulsification in POAG has a high probability of producing a small decrease in IOP that may be useful in early, well-controlled disease. The probability of a clinically significant decrease of greater than or equal to 5 to 6 mm Hg-required for advanced/uncontrolled disease-is low. Results support the role of phacoemulsification in PACG.
authors.affiliation: From the *Queensland Eye Institute; †University of Queensland, Brisbane, Queensland; ‡Glaucoma Investigation and Research Unit, Royal Victorian Eye & Ear Institute, Melbourne, Victoria; and §Discipline of Mathematical Sciences, Queensland, University of Technology, Brisbane, Queensland, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Thomas
authors.forename: Mark
authors.initials: M
authors.lastname: Walland
authors.forename: Aleysha
authors.initials: A
authors.lastname: Thomas
authors.forename: Kerrie
authors.initials: K
authors.lastname: Mengersen
mesh_terms: D001499:Bayes Theorem; D015812:Glaucoma, Angle-Closure / Q000503:physiopathology / Q000601:surgery*; D005902:Glaucoma, Open-Angle / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D018918:Phacoemulsification; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies