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Exfoliation syndrome: Effects of cataract surgeryon glaucoma

It aint what you dont know that gets you intotrouble; its what you know for sure that just aint so.

Mark Twain

Exfoliation syndrome or pseudoexfoliation (PXF) ischaracterized by the accumulation of fibrillar extracel-lular matrix material on the surface of various oculartissues.1 The material can accumulate on many struc-tures in the anterior segment of the eye as well as onother tissues throughout the body. The PXF materialis composed of a fibrillinglycoprotein skeleton sur-rounded by an amorphous matrix of associated pro-teins. Lens epithelial cells and ciliary epithelial cells

deposit PXF material within their respective basementmembrane lamellae. The material may then accumu-late in the trabecular meshwork,resulting in a blockageof some outflow channels within the eye and leadingto chronic intraocular pressure (IOP) elevation. ThePXF material gradually builds up in the juxtacanalicu-lar tissue, causing progressive glaucomatous damage.

Pseudoexfoliation is now recognized as the mostcommon identifiable cause of open-angle glaucoma(OAG).2 The risk for developing glaucoma is noted tobe 5 to 10 times more common in eyes with PXF thanin those without it. Patients with PXF are twice as likely

to convert from ocular hypertension to glaucoma. Inaddition, when PXF glaucoma is present, it is likelyto progress more rapidly than simple OAG.3,4 Studiesof the natural history of patients with PXF show thatwhen followed for approximately 15 years, 44% ofthese patients received glaucoma therapy.5

The incidence of cataracts also appears to be in-creased in PXF.6 Over the short term, the effect of cat-aract extraction on postoperative IOP in PXF patientsis an increased risk for IOP spikes immediately aftercataract surgery; however, there is preliminary evi-dence that performing cataract surgery in PXF patients

may cause a decrease in IOP over the short term. Re-cent studies of patients with ocular hypertension butno PXF show that phacoemulsification with intraocu-lar lens (IOL) implantation leads to a significantlong-term IOP reduction. Thus, removal of the catarac-tous lens with placement of an IOL may be an effectiveway of lowering IOP in the long term.

Shingleton et al. have followed a series of patientswith PXF who had cataract surgery. The initial report7

comprised 1000 consecutive PXF patients who had cat-aract surgery performed by the same surgeon. Withproper surgical techniques, cataract extraction was

successful, with a minimally significant risk for

complications. The preliminary study also found thatIOP decreased in the early postoperative period.In this issue (pages 18341841), the latest report byShingleton et al. evaluates the long-term effect of pha-coemulsification with posterior chamber IOL implan-tation on IOP in this series of PXF patients. Theretrospective study looked at the results in 1122eyesd882 had no glaucoma and 240 had glaucoma.After approximately 7 years, the PXF with no glau-coma eyes demonstrated a statistically significant re-duced mean IOP compared with the preoperativelevels. Similarly, the PXF with glaucoma eyes had a re-duced mean IOP over this same period of time. A high-

er mean preoperative IOP was associated witha greater reduction in IOP postoperatively in bothgroups. The most important outcome noted in thestudy was that only 2.7% of the PXF with no glaucomaeyes progressed to actual glaucoma requiring medica-tion and only 3.7% of the PXF eyes with glaucoma pro-gressed to needing laser or glaucoma surgery. Thesenumbers are remarkable given the propensity for pa-tients with PXF to convert from ocular hypertensionto glaucoma or to progress rapidly when glaucoma de-velops. Thus, it appears that phacoemulsification withIOL implantation has a protective effect on the devel-

opment or progression of glaucoma in patients withPXF. This effect seemed to persist throughout the rela-tively long follow-up in this group of patients.

The exact mechanism of decreased IOP after re-moval of the cataractous lens is unclear; however,growth of the crystalline lens throughout life hasbeen noted to cause a progressive shallowing of the an-terior chamber, which may cause some forward trac-tion by the zonules in the anterior ciliary body,displacing the uveal track anteriorly and compressingthe outflow of the trabecular meshwork and the canalof Schlemm. Theoretically, removing the thickened

crystalline lens and replacing it with a thin IOL shouldreverse this change and relieve some of the compres-sion of the trabecular meshwork and the canal ofSchlemm.8 Extrapolating these findings to eyes withPXF, it is likely that removing the crystalline lens dur-ing phacoemulsification and replacing it with an IOLwill lead to an increase in outflow through the trabec-ular meshwork and Schlemm canal despite thebuildup of exfoliative material, leading to a decreasein the conversion from ocular hypertension to glau-coma. This may also be instrumental in reducing thenumber of patients with PXF glaucoma who progress

to medication or surgery.

Q 2008 ASCRS and ESCRS

Published by Elsevier Inc.

0886-3350/08/$dsee front matter 1813doi:10.1016/j.jcrs.2008.09.002

FROM THE EDITOR

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Long-term studies that follow a large group of pa-tients are critical when evaluating potential treatmentmodalities for a progressive, long-term condition suchas PXF.

Nick Mamalis, MD

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1814 FROM THE EDITOR

J CATARACT REFRACT SURG - VOL 34, NOVEMBER 2008