Expansile Gas Concentration in Primary Pseudophakic Retinal Detachment Repair, Effect on Intraocular Pressure and Outcomes; the Manchester Pseudophakic Retinal Detachment Study

Purpose: To investigate the effect of isovolumetric and expansile gas tamponade concentrations on single surgery anatomical success (SSAS) and day 1 intraocular pressure (IOPD1) following pars plana vitrectomy (PPV) for mild-moderate complexity primary pseudophakic rhegmatogenous retinal detachment (PRD).

Methods: We conducted a single-centre retrospective continuous and comparative study on eyes that had undergone small-gauge PPV using isovolumetric versus expansile gas for PRD repair between 2011 and 2020 at a single tertiary vitreoretinal centre in UK. We performed propensity score matching (PSM) using preoperative findings as covariates to account for relevant confounders. Significant risk factors such as proliferative vitreoretinopathy C or giant retinal tears were excluded.

Results: From 456 eyes, PSM analysis matched 240 eyes with 120 in each group. The median (interquartile range) follow-up was 96 (59 to 218) days. The SSAS was 229/240 (95.8%) overall; 115/120 (95.8%) and 114/120 (95.0%) in isovolumetric and expansile groups, respectively (p = 1.000). Relative to the isovolumetric group, the expansile group had lower proportion of eyes with IOP ≤ 21 mmHg (odds ratio, 95% confidence interval, 0.40 [0.23-0.68], p < 0.001); but significantly higher number of eyes with IOP ≥ 22 mmHg (2.53 [1.48-4.34], p < 0.001), ≥ 25 mmHg (2.77 [1.43-5.33], p < 0.001), ≥ 30 mmHg (2.90 [1.28-6.58], p = 0.006) and ≥ 40 mmHg (p = 0.029, isovolumetric: 0 [0%] vs expansile group: 6 [5%]). There was only one case of hypotony (≤ 5 mmHg) 1/240 (0.4%) which occurred in the expansile group.

Conclusions: Expansile gas concentration does not impact SSAS but is associated with significantly raised IOPD1 with no reduction in hypotony rates following PPV for primary PRD.