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Observational Study
. 2016 Apr 14;11(4):e0153585.
doi: 10.1371/journal.pone.0153585. eCollection 2016.

Glaucoma Surgery Calculator: Limited Additive Effect of Phacoemulsification on Intraocular Pressure in Ab Interno Trabeculectomy

Ashley E Neiweem  1 , Igor I Bussel  2 , Joel S Schuman  2 , Eric N Brown  2   3 , Nils A Loewen  2
Affiliations
Observational Study

Glaucoma Surgery Calculator: Limited Additive Effect of Phacoemulsification on Intraocular Pressure in Ab Interno Trabeculectomy

Ashley E Neiweem et al. PLoS One. .

Abstract

Purpose: To compare intraocular pressure (IOP) reduction and to develop a predictive surgery calculator based on the results between trabectome-mediated ab interno trabeculectomy in pseudophakic patients versus phacoemulsification combined with trabectome-mediated ab interno trabeculectomy in phakic patients.

Methods: This observational surgical cohort study analyzed pseudophakic patients who received trabectome-mediated ab interno trabeculectomy (AIT) or phacoemulsification combined with AIT (phaco-AIT). Follow up for less than 12 months or neovascular glaucoma led to exclusion. Missing data was imputed by generating 5 similar but non-identical datasets. Groups were matched using Coarsened Exact Matching based on age, gender, type of glaucoma, race, preoperative number of glaucoma medications and baseline intraocular pressure (IOP). Linear regression was used to examine the outcome measures consisting of IOP and medications.

Results: Of 949 cases, 587 were included consisting of 235 AIT and 352 phaco-AIT. Baseline IOP between groups was statistically significant (p≤0.01) in linear regression models and was minimized after Coarsened Exact Matching. An increment of 1 mmHg in baseline IOP was associated with a 0.73±0.03 mmHg IOP reduction. Phaco-AIT had an IOP reduction that was only 0.73±0.32 mmHg greater than that of AIT. The resulting calculator to determine IOP reduction consisted of the formula -13.54+0.73 × (phacoemulsification yes:1, no:0) + 0.73 × (baseline IOP) + 0.59 × (secondary open angle glaucoma yes:1, no:0) + 0.03 × (age) + 0.09 × (medications).

Conclusions: This predictive calculator for minimally invasive glaucoma surgery can assist clinical decision making. Only a small additional IOP reduction was observed when phacoemulsification was added to AIT. Patients with a higher baseline IOP had a greater IOP reduction.

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Conflict of interest statement

Competing Interests: The authors have read the journal's policy and have the following competing interests: Nils Loewen has received honoraria for wet labs and lectures by Neomedix, Inc. The other authors have declared that no competing interests exist. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Trabectome Surgeries.
Cases analyzed after accounting for exclusion criteria (AIT, ab interno trabeculectomy; phaco-AIT, AIT combined with phacoemulsification; IOP, intraocular pressure; POAG, primary open angle glaucoma; SOAG, secondary open angle glaucoma).
Fig 2
Fig 2. IOP and medication plots.
Preoperative and postoperative intraocular pressure (IOP; left) and number of glaucoma medications (Meds; right) over the 12 month follow-up for both groups. Represented as mean ± standard error. Statistically significantly different at all time points for both plots (p<0.05).
Fig 3
Fig 3. Phaco-AIT and AIT Scattergrams.
Scattergrams of AIT and phaco-AIT after 1 month (left) and 12 months (right). Baseline IOP plotted against IOP at 1 month and 12 months with x = y line. Red line represents linear fit.
See this image and copyright information in PMC

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