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Trabeculectomy outcomes comparable for prior phaco vs. phakic eyes
Survival rates slightly favor clear corneal phacoemulsification over phakic eyes, however.
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Pseudophakic eyes with previous uncomplicated clear corneal phacoemulsification fare just as well as phakic eyes after initial trabeculectomy with mitomycin C, according to a study.
Traditionally, pseudophakic eyes have been considered to be at higher risk for failure after trabeculectomy, Kouros Nouri-Mahdavi, MD, coauthor of the retrospective study in Journal of Glaucoma, told Ocular Surgery News. “However, this may not be true in the clear corneal phaco era.”
To date, studies have not reported trabeculectomy outcomes separately according to the technique used for cataract extraction, Nouri-Mahdavi said. Even so, the choice of which type of glaucoma surgery to undertake may hinge on how the prior cataract surgery affected the eye, particularly whether the superior conjunctiva was dissected.
Study findings
In the current study, the mean preoperative IOP in the 39 eyes of the pseudophakic group was 21.4 mm Hg, which decreased by 9.3 mm Hg at 1 year after trabeculectomy. The 39 eyes in the phakic group, which were matched for surgeon, age, race and time of surgery, had a mean preoperative IOP of 18.6 mm Hg, which decreased by 5.7 mm Hg.
Results were similar at 2 years after surgery.
Kouros Nouri-Mahdavi
The number of postoperative medications was also comparable for both follow-up intervals: a mean 0.54 at 1 year and 0.61 at 2 years for the pseudophakic group vs. 0.46 and 0.58 for the phakic group.
“This is the first study in the literature to specifically look at the outcome of trabeculectomy in eyes that have had prior clear corneal phacoemulsification surgery,” Nouri-Mahdavi said. “This is important because there is the notion in the ophthalmic community that cataract surgery might lead to poorer outcomes when trabeculectomy is performed subsequently.”
Author’s experience
“We expected the outcomes to be the same for both pseudophakic and phakic eyes because, during clear corneal phacoemulsification, we do not touch or manipulate the conjunctiva in any way, therefore causing no scarring at the site of future glaucoma intervention,” Nouri-Mahdavi said. “Still, cataract surgery is followed by mild persistent inflammation for at least a few months.”
In addition, for a patient with cataract and glaucoma simultaneously, “There is always the issue of which surgery should be performed first — cataract or trabeculectomy. Our study shows it probably does not matter. But if you do the cataract surgery first, we recommend waiting 3 to 6 months to schedule trabeculectomy.”
The surgeries in the study were performed between 1997 and 2009. The median follow-up time was 36 months for pseudophakic eyes and 38 months for phakic eyes.
There were no intraoperative complications in either group, and the rate of postoperative complications was fairly low.
However, survival rates for the pseudophakic group tended to be higher overall than the phakic group, although the difference was not statistically significant. Also, pseudophakic eyes were slightly older (75 years vs. 69 years).
After trabeculectomy, 50% of the phakic eyes required cataract surgery.
“Because cataract surgery is a stress to the glaucoma surgical site and causes inflammation, this is probably why the pseudophakic eyes tended to do better. They did not undergo a second surgery,” Nouri-Mahdavi said.– by Bob Kronemyer