Impact of Phacoemulsification on Trabeculectomy Bleb Function and Morphology in Primary Angle Closure Glaucoma: A Comparative Study of the Visco-Cushion Effect

Purpose This study evaluates the impact of phacoemulsification on trabeculectomy bleb morphology and intraocular pressure (IOP) control in patients with primary angle closure glaucoma (PACG). The study also evaluates possible alterations in these effects by intra-operative blocking of internal sclerostomy by high-density viscoelastic (visco-cushion). Methods This is a single-center, interventional, prospective study including patients with PACG who underwent phacoemulsification post-trabeculectomy. This study also evaluated the effect of sodium hyaluronate 1.4% as a cushion to block the sclerostomy site. Patients were divided into two groups: group A received this intervention, while group B did not. Postoperative IOP and the number of glaucoma medications at week 2, month 1, and month 4 were assessed as a measure of bleb function. Bleb morphology was analyzed at these timepoints using the Indiana Bleb Appearance Grading Scale (IBAGS) and anterior segment optical coherence tomography (AS-OCT). Results The study included 35 patients with a mean age of 59.91 ± 7.59 years. The mean interval between trabeculectomy and phacoemulsification was 6.83 ± 5.57 years (range: 1-20 years). Mean preoperative IOP was 15.43 ± 2.62 mm Hg, with 12 eyes needing anti-glaucoma medications (AGMs). Mean IOP at postoperative month 4 was 12.69 ± 2.32 mm Hg (p<0.001, chi-square test), with one eye needing AGM. IOP reduction was significantly lower in the visco-cushion group (p<0.05, ANOVA test). By the end of four months, 97.14% of patients showed complete success as compared with 65% preoperatively. Bleb morphology was noted to be maintained in up to 66% patients in terms of bleb height and extent on IBAGS, as well as bleb internal reflectivity and the number of microcysts, as noted on AS-OCT. The group without a visco-cushion exhibited a significant decrease in qualitative bleb height and microcystic spaces, along with an increase in bleb vascularity (p<0.05, Fischer exact test). Thirty patients (87.5%) showed a >20% decline in bleb height on AS-OCT, which was greater in group without visco-cushion (p<0.05, Mann-Whitney U test). Conclusion Use of a visco-cushion during phacoemulsification in PACG eyes with prior functioning trabeculectomy resulted in the retention of healthy bleb morphology parameters except bleb wall thickening. However, this protective effect on bleb morphology did not transcribe into IOP reduction. On the contrary, conventional phacoemulsification despite bleb height reduction, increased bleb vascularity, and decreased microcystic spaces resulted in better IOP control in the first four months after surgery. Longer follow-up of these cases is suggested to examine eventual fate of these bleb morphological alternations.