The Asia-Pacific Journal of Ophthalmology

Asia-Pacific Journal of Ophthalmology:

Issue 1, January/February 2016 Review Article

Lowering of Intraocular Pressure After Phacoemulsification in Primary Open-Angle and Angle-Closure Glaucoma: A Bayesian Analysis

Thomas, Ravi; Walland, Mark; Thomas, Aleysha; Mengersen, Kerrie

Author Information

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.

Reprints: Ravi Thomas, MD, FRANZCO, Queensland Eye Institute, 140 Melbourne St, South Brisbane 4105, Queensland, Australia.


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.

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