Coarsened Exact Matching of Phaco-Trabectome to Trabectome in Phakic Patients: Lack of Additional Pressure Reduction from Phacoemulsification

Abstract

PurposeTo compare intraocular pressure (IOP) after trabectome-mediated ab interno trabeculectomy surgery in phakic patients (T) and trabectome with same session phacoemulsification (PT) using Coarsened Exact Matching. Although phacoemulsification is associated with IOP reduction when performed on its own, it is not known how much it contributes in PT.MethodsSubjects were divided into phakic T and PT. Exclusion criteria were follow-up for <12 months and additional glaucoma surgery. Demographics were compared by the Mann-Whitney U test and chi-squared test for continuous and categorical variables, respectively. Multiple imputation was utilized to avoid eliminating data with missing values. Groups were then matched using Coarsened Exact Matching based on age, race, type of glaucoma, baseline IOP, and number of preoperative glaucoma medications. Univariate linear regression was used to examine IOP reduction after surgery; those variables that were statistically significant were included in the final multivariate regression model.ResultsA total of 753 cases were included (T: 255, PT: 498). When all variables except for age were kept constant, there was an additional IOP reduction of 0.05±0.01 mmHg conferred for every yearly increment in age. Every 1 mmHg increase in baseline IOP correlated to an additional IOP reduction of 0.80±0.02 mmHg. Phacoemulsification was not found to be a statistically significant contributor to IOP when comparing T and PT (p≥0.05). T had a 21% IOP reduction to 15.9±3.5 mmHg (p<0.01) while PT had an 18% reduction to 15.5±3.6 mmHg (p<0.01). Number of medications decreased (p<0.01) in both groups from 2.4±1.2 to 1.9±1.3 and from 2.3±1.1 to 1.7±1.3, respectively.ConclusionPhacoemulsification does not make a significant contribution to postoperative IOP or number of medications when combined with trabectome surgery in phakic patients.

Combined analysis of trabectome and phaco-trabectome outcomes by glaucoma severity

“…We included here phaco-trabectome patients, who have a different, mixed indication that often includes visually significant cataract as the primary motivator while presenting with a relatively stable glaucoma. We did so after demonstrating by a rigorous statistical matching method, coarsened exact matching 15 , that phacoemulsification does not contribute significantly to IOP reduction when done at the same time 9 or in a surgery prior to trabectome surgery 16 .…”

“…We recently examined the amount of IOP reduction that is due to phacoemulsification at the time of trabectome surgery and found this to be relatively clinically insignificant 9 . We also noted that trabectome surgery performed after failed trabeculectomy caused patients with more advanced visual field damage to have on average a greater pressure reduction despite similar medications 10 .…”

Recent Developments in Glaucoma Therapy

“…In four of our recent clinical TM ablation studies with up to 1,340 patients, this post-trabecular resistance causes a higher failure rate and a higher postoperative IOP in many individuals with advanced glaucoma. [11][12][13][14] As glaucoma surgeons are well aware, only a small fraction of patients (in our hands about 0.3%) achieve the predicted IOP that would be equal to that of episcleral venous pressure.…”

Impact of Same-Session Trabectome Surgery on Ahmed Glaucoma Valve Outcomes

“…Due to its retrospective nature, patients were not randomized to each treatment group. Although applying different matching methods like coarsened exact [23,30,31] and propensity score matching [28] that we used in our previous studies could reduce the bias due to confounding variables, we were unable to use them here due to relatively small sample size. Additionally, this study was conducted at a single tertiary academic center and cannot easily be generalized to other practices.…”