Effect of phacoemulsification on blebs

February 1, 2012

Study shows that phaco can cause IOP increase and alteration to bleb morphology

"Phaco could be detrimental to the function of the fistula by causing an increase in intraocular pressure (IOP) and can cause considerable alteration to the morphology of the filtering bleb," asserted Prof. Tomasz Zarnowski (Chair of Ophthalmology and Eye Hospital, Medical University, Lublin, Poland) during his presentation at the 2011 ESCRS meeting in Vienna, Austria.

Most frequent complication

"Trabeculectomy is still the gold standard in the surgical treatment of glaucoma," continued Prof. Zarnowski, "however, cataract is the most frequent complication of this treatment." He went on to explain that in some cases, cataract surgery can be particularly challenging. So, he and his colleagues performed a study to analyse the effect of phacoemulsification with posterior chamber lens implantation on IOP and function of filtering blebs in patients that have undergone successful trabeculectomy.

"We measured the IOP and evaluated the bleb in times of 24 hours, 10 days and 6, 12 and 18 months," added Prof. Zarnowski. "In comparing the groups, we noticed that in our study group the IOP was elevated. The elevation was around 2 mmHg... it reached statistical significance during the follow up."

Correlation with IOP and phaco

A correlation between IOP before and after phaco was found, which is not so important according to Prof. Zarnowski. However, there was a difference found between the group of patients that had undergone phaco and those that had not. "So, it was demonstrated that there was no change in IOP in 50% of the patients that had undergone trabeculectomy only whereas this was only true for 12% of the patients that had undergone phaco," stated Prof. Zarnowski.

"There is a reverse correlation between phaco after trabeculectomy and IOP," continued Prof. Zarnowski, "In other words if we perform phaco later, after trabeculectomy, we expect lower IOP measurements." However, in eyes with functioning filtering blebs Prof. Zarnowski recommended modifying the technique so that the conjunctiva and filtering bleb are not disturbed during the procedures.

"Even with a modified technique there are nominal cases of detrimental effect on the functioning filtering bleb. So performing phaco not only impacts the IOP but also the bleb morphology in all periods of observation," he concluded.

Professor Tomasz Zarnowski is (chairman) Chair of Ophthalmology and Eye Hospital, Medical University, Lublin, Poland. He may be reached by E-mail: zarnowskit@poczta.onet.pl

Prof. Zarnowski has indicated no financial interests in the subject matter.