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PHILADELPHIA - Simultaneous cataract and filtering surgery is safe and effective for the challenging population of patients with pseudoexfoliation (PEX) glaucoma, according to a study presented at the annual ASCRS symposium on Cataract, IOL and Refractive Surgery. Researchers at the Massachusetts Eye and Ear Infirmary, in the second stage of a two part study evaluating the risks and outcomes of cataract surgery in patients with PEX, compared two groups of eyes undergoing combined surgery: 156 eyes with PEX and 99 control glaucomatous eyes without PEX. They found no significant between-group differences in efficacy of the filtering surgery, as measured by reductions in IOP and glaucoma medication use, refractive and visual outcomes or rates of various postoperative complications. However, intraoperative complications were more common in the PEX group and those events were related to zonular weakness. Among eyes with PEX, zonular weakness was noted in 10 and vitreous loss occurred in five of those eyes. None of the eyes experienced capsular rupture, according to a study conducted by James M. Heltzer MD at Harvard University, Boston, US. He said PEX syndrome affects 10% of the Boston glaucoma clinic population. Its role as a risk factor in both the formation of cataract and the increased risk of complications during cataract surgery is well recognised. While zonular weakness is cited as a primary factor for intraoperative and postoperative complications, some reports have focused on the contribution of capsular weakness, Dr Heltzer explained. "Our findings from this stage of the investigation, coupled with our data from the initial portion of the study in which there were 10 cases of zonular weakness and only one case of capsular weakness among 297 PEX patients undergoing cataract surgery alone, suggest that zonular weakness is the primary cataract surgery safety issue in this population. "It definitively addresses the question of whether zonular weakness or capsular rupture plays the greater role in intraoperative complications," he said. The eyes included in the phacotrabeculectomy study were operated on between June 1986 and December 1999. Baseline IOP was 20.8 mm Hg in the PEX glaucoma eyes and 21.0 mm Hg in the controls. Achieved mean decreases in IOP postoperatively were 7.0 mm Hg in the PEX glaucoma group and 6.5 mm Hg in the controls. The difference was not statistically significant. The PEX glaucoma patients decreased their glaucoma medication use from an average of 1.8 medications per patient to 0.2. For the controls, average medication use declined from 2.0 to 0.4 medications per patient. Cataract surgery was performed using phacoemulsification in 93% of PEX eyes. Only one of those cases, which developed phacodonesis intraoperatively, was converted to extracapsular cataract extraction. In the remaining eyes, extracapsular cataract extractions or pars plana lensectomies were conducted because of dense nuclei or the presence of frank preoperative phacodonesis. Eyes with zonular weakness which underwent phacoemulsification were implanted with large optic, polymethyl methacrylate posterior chamber IOLs. Anterior chamber IOLs were used in those eyes with vitreous loss, and scleral-fixated lenses were placed after pars plana extractions. Visual and refractive outcomes were similar in eyes with and without PEX. BCVA improved from 20/80 to 20/30 in the PEX eyes and from 20/60 to 20/30 in the controls. There was no significant difference between groups in the final spherical equivalent (SE). The groups were also similar in incidences and types of postoperative complications, including rates of corneal oedema, iritis and fibrinoid reactions. The only lens dislocation occurred several weeks into the postoperative period in a patient with PEX who suffered a fall. There were no cases of late lens decentration or dislocation. "Previous literature would indicate that IOL stability and risk of late dislocation are significant concerns in eyes with PEX. "In contrast to our expected findings, visual and refractive outcomes were not adversely affected in our population nor did we encounter any problems with late IOL dislocation," Dr Heltzer said. As a secondary objective, the researchers characterised preoperative features of a group of 364 PEX glaucoma patients who underwent 453 cataract procedures, either alone or in combination with trabeculectomy and compared them with a control group of 409 patients without PEX glaucoma who underwent 425 cataract procedures. Those analyses found no significant differences between the groups in age, race, IOP or number of glaucoma medications. However, significantly more PEX patients underwent combined surgery versus cataract extraction alone. In addition, both diabetes and hypertension were significantly more common in the normal population (11.5% and 49.6%, respectively) compared with the PEX group (4.9% and 38.4%, respectively). "Various studies have reported that PEX is associated with an increased risk of systemic vascular diseases, including cardiac disease, cerebrovascular accidents, aortic and abdominal aneurysms. "Therefore, it was interesting to see in our population that both diabetes and hypertension were less common among patients with PEX glaucoma relative to the controls," Dr Heltzer observed. |
