EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/76185
Cataract editor's corner of the world Is cataract surgery alone enough? July 2012 by Enette Ngoei EyeWorld Contributing Editor ver the past decade, the fields of cataract surgery and refractive surgery merged with the advent of refractive IOLs and the use of femtosecond lasers. Similarly, the fields of glaucoma and cataract surgery are merging with the introduction of minimally invasive glaucoma surgery (MIGS) performed during lens extraction by comprehensive ophthalmolo- gists and glaucoma specialists alike. When treating patients with cataracts and glaucoma, the question of when to perform a combined procedure versus separate procedures is still a difficult one. The review by David Friedman, M.D., on this subject in 2002 is an often-quoted article. Recently, Peter Ta Chen Chang, M.D., et al reported in the Journal of Cataract & Refractive Surgery on the long-term effect of phacoemulsification on IOP. EyeWorld spoke with both lead authors about their findings. O Bonnie An Henderson, M.D., cataract editor EyeWorld talks to the authors of two important papers on lowering IOP with cataract surgery S afety and efficacy in per- forming combined proce- dures on patients with cataract and glaucoma have led many surgeons to do separate surgeries. David S. Friedman, M.D., Alfred Sommer Professor, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, and author of the study "Surgical strategies for co- existing glaucoma and cataract; an evidence-based update," said that in cases where patients have significant cataract and borderline pressure con- trol, many clinicians are now taking out the lens only and performing glaucoma surgery later. When surgeons think of combined procedures they like to think "save the conjunctiva," Dr. Friedman said, because "the results of our [2002] literature review showed that when you look at the overall outcomes of combined tra- beculectomy and cataract surgery, the pressure lowering effect is less than trabeculectomy alone." The question is, will taking out the cataract now and doing the tra- beculectomy in 3 months produce better results? No one has done a trial comparing that approach to the straight combined approach, said Dr. Friedman, but there are arguments for the former being better because after that period of time, the inflam- mation should go down and bring pressure back to baseline levels. The ongoing debate about whether cataract surgery alone is enough to bring about a significant decrease in IOP is an important one. In 2002, Dr. Friedman and colleagues assessed short- and long- term control of IOP with different surgical treatment strategies for co- existing cataract and glaucoma. Pub- lished in Ophthalmology, the study was mainly a large case series, look- ing at IOP pre- and post-op. The study reported that evidence was good that long-term IOP is lowered more by combined glaucoma and cataract operations than by cataract operations alone. EW CATARACT 21 An eye with both a cataract and elevated IOP. A recent study examines the long-term effect of phacoemulsification on IOP Source: Pekka Virtanen On average, Dr. Friedman said, patients with angle-closure glau- coma who had cataract surgery alone had a pressure decline of about 1 mm Hg or 1.5 mm Hg at about 1 year. "As there weren't a lot of studies about patients with open-angle glau- coma, the actual number of those is harder to tell, but it seemed like it was also in a similar range," he said. Higher pressure, larger effect "In terms of angle-closure, there's been a wide variability in reports about how much cataract surgery controls eye pressure. My take on a lot of the literature is if the patient starts at a higher pressure, surgery tends to bring the pressure down a bit," Dr. Friedman said. He described a large study from Hong Kong that compared pha- coemulsification alone versus combined phacotrabeculectomy in medically controlled chronic angle- closure glaucoma (CACG) with coexisting cataract. Published in Ophthalmology in 2008, the randomized clinical trial showed that there was pressure low- ering post-op and in the 1-1.5 mm Hg range, but those patients started with a baseline pressure of around 18. Dr. Friedman said, "So again when you start relatively low, there's not that far to go. Removing the lens isn't going to make [IOP] go down a lot in those patients." Dr. Friedman described a study by Bradford J. Shingleton, M.D., and colleagues that looked at the ef- fect of phacoemulsification with posterior chamber IOL implantation performed by a single surgeon on IOP and glaucoma medication requirements in pseudoexfoliation (PFX) eyes with or without glau- coma. The study showed very large declines in pressure especially in instances where the pressure was high, Dr. Friedman said, and there was an association with the amount of pressure decline with the level of IOP elevation pre-op. Mixed evidence According to Peter Ta Chen Chang, M.D., Vanderbilt Eye Institute, Nashville, Tenn., "The most com- pelling evidence of the IOP-lowering effect of cataract surgery is in the population of untreated ocular hypertensive patients (patients with elevated IOP without evidence of progressive optic nerve damage), as demonstrated by the recent publica- tion by Dr. Mansberger and the Ocular Hypertension Treatment Study Group." Dr. Chang, lead author of an important recently published study that investigated the long-term ef- fect of phacoemulsification on IOP in patients with ocular hypertension and open-angle glaucoma, said that outside of this untreated ocular hypertensive patient population, the evidence on the IOP-lowering effect of cataract surgery is mixed. Dr. Chang's study retrospec- tively reviewed the medical records of 29 individuals with either open- angle glaucoma or ocular hyperten- sion in both eyes who had uncomplicated phacoemulsification in one eye; the other eye remained phakic for at least 3 years, he said. continued on page 22