No Significant Increase in Trabeculectomy Failure Following Clear-Cornea Phaco

A previous clear-cornea phacoemulsification surgery does not cause a statistically significant differences in trabeculectomy failure rate in patients with open-angle glaucoma (OAG), but there were some clinically relevant differences between phakic and pseudophakic eyes, according to a study published in Clinical Ophthalmology.

“Among patients with OAG, no statistically significant differences were observed in the rate of surgical failure of trabeculectomy when comparing phakic and pseudophakic eyes with prior clear-cornea phacoemulsification. Nonetheless, the relative number of eyes with failure at year 1 and 2 was superior in the pseudophakic group, which might be clinically relevant despite the absence of statistically significant differences,” researchers report. 

The retrospective cohort study examined 82 eyes (58 phakic and 24 pseudophakic) of 82 patients who underwent trabeculectomy between January 1, 2010, and December 31, 2017 with up to 2 years follow-up. Patients in the phakic group were younger than those in the pseudophakic group, (65.8±11.7 vs 76.2±7.9 years, P <.001), and all participants were White. While the most common type of glaucoma in patients studied was primary OAG [59% (n=34) phakic vs 63% (n = 15) pseudophakic], some patients did have exfoliative [35% (n=20) phakic vs 33% (n = 8) pseudophakic] or pigmentary [7% (n=4) phakic vs. 4% (n=1) pseudophakic] glaucoma.

The study measured primary outcome as the probability of surgical failure, defined as IOP higher than 21 mm Hg or reduced by less than 20% from baseline, IOP of 5 mm Hg or less in 3 consecutive visits, need for further glaucoma surgery, phthisis or loss of light perception vision due to glaucoma. Secondary outcome measures were IOP and number of postoperative hypotensive medications at 2 weeks, 1, 3, 6, 9, 12, and 24 months, best corrected visual acuity at 6, 12, and 24 months, number of needling procedures, postoperative complications, and additional glaucoma surgeries.

Researchers found that mean preoperative IOP and number of preoperative hypotensive medications were not significantly different between groups.

They also discovered that the surgical failure rate was not significantly different between groups at 1 year [17% (n=10) phakic vs 29% (n=7) pseudophakic; P =.361] or at 2 years [28% (n=16) phakic vs 46% (n=11) pseudophakic; P =.110]. There were also no significant differences found in postoperative IOP or any secondary outcome measures at 1 and 2 years.

The researchers do point out that​ the relative number of eyes with failure in the first 2 years was superior in the pseudophakic group, which could be considered “clinically relevant,” even if it’s not of statistical significance. 

The study did have limitations: Its small sample size, retrospective design, significant age difference (with younger patients having a higher likelihood of failure, and older patients having a higher rate of complications), and not accounting for prior topical hypotensive treatment. 

“Furthermore, another limitation of our study is the heterogeneity regarding the use of adjuvant antimetabolite [5-FU use in 52 (90%) eyes in the phakic group and 18 eyes (75%) in the pseudophakic group]. Recent evidence suggests that [Mitomycin C, MMC] is more effective in reducing IOP and trabeculectomy surgical failure,” according to the researchers. “As such, in our department, we currently almost only use MMC. Nonetheless, our multivariable regression analysis did not show this heterogeneity to be a significant predictor of failure.”

Reference

Torres-Costa S, Melo AB, Estrela-Silva S, Falcão-Reis F, Barbosa-Breda J. Effect of prior phacoemulsification surgery in trabeculectomy surgery outcomes. Clin Ophthalmol. 2022;16(2):357-367. doi:10.2147/OPTH.S348364