Surgical Management of Pseudoexfoliation Glaucoma

Helen L. Kornmann, MD, PhD Steven J. Gedde, MD



Introduction

Pseudoexfoliation (PXF) syndrome is an age-related systemic condition that is characterized by an abnormal accumulation and deposition of extracellular matrix material throughout the anterior segment of the eye,1 most notably along the pupillary border and on the anterior lens capsule. Although these deposits are the most consistent and important diagnostic feature of this condition, other ocular manifestations include weakened zonules predisposing patients to narrow angles and lens subluxation/dislocation, poor pupillary dilation, posterior synechiae formation, iris transillumination defects, cataract formation, and secondary open-angle glaucoma.2 PXF syndrome is the most common identifiable cause of open-angle glaucoma worldwide, although prevalence rates vary extensively.2 In some countries it accounts for the majority of glaucoma,3 with the highest prevalence reported in Scandinavian countries.4 Single nucleotide polymorphisms in the lysyl oxidase-like-one (LOXL1) gene have recently been identified as major risk factors for the development of PXF,5 suggesting a genetic susceptibility in certain populations. PXF glaucoma (PXFG) is thought to result from obstruction of the trabecular meshwork by exfoliation material causing elevation of intraocular pressure (IOP), although abnormalities in the lamina cribrosa relating to elastic tissue may also play a role in the development of glaucoma.6,7 PXFG has a worse prognosis than primary open-angle glaucoma (POAG). The reasons for this are multifactorial and may be related to higher IOP, worse visual field damage, and greater optic nerve head cupping at the time of diagnosis. In addition, PXFG is often more resistant to medical therapy than POAG, responds for a shorter period INTERNATIONAL OPHTHALMOLOGY CLINICS Volume 54, Number 4, 71–83 r 2014, Lippincott Williams & Wilkins

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of time, and frequently fails.8–10 As a result, patients with PXFG often require surgical intervention.1 The traditional surgical options for managing PXFG are similar to those for POAG and include laser trabeculoplasty, filtering surgery, and tube shunt implantation. With the advent of minimally invasive glaucoma procedures, either alone or in combination with cataract surgery, newer techniques have also been developed for the management of PXFG. This article reviews the current literature regarding the surgical treatment options for PXFG.



Laser Trabeculoplasty

If medical management fails to sufficiently lower IOP, laser trabeculoplasty is a useful treatment in open-angle glaucoma.11 Because the trabecular meshwork is more heavily pigmented in PXF, argon laser trabeculoplasty (ALT) may be particularly effective in these patients. Historically, patients with PXF have responded well to ALT12,13; however, the IOP-lowering effect is frequently short lived and failure occurs at a faster rate than in POAG patients.14–16 For instance, the 2year success rate of primary ALT in PXFG was reported as high as 80% compared with 77% in POAG, but declined to 36% in PXFG versus 67% in POAG after 8 years of follow-up.17 Selective laser trabeculoplasty (SLT) is being increasingly accepted as an alternative to ALT, and it has been shown to be safe and effective in several forms of open-angle glaucoma.18 In a multicenter randomized clinical trial (RCT) comparing ALT and SLT in patients with PXFG, both procedures were equivalent in terms of IOP lowering up to 6 months posttreatment, achieving a decrease in IOP of 7.7 ± 7.12 mm Hg in ALT and 6.8 ± 5.4 mm Hg in SLT (P = 0.56).19 The number of glaucoma medications decreased minimally in the SLT group (0.16 ± 1.21), whereas there was no decrease in the ALT group (0.00 ± 1.01; P = 0.59). IOP spikes were not observed in either group. Other studies have demonstrated that the effect of SLT in PXF is comparable to POAG and results in a 20% to 35% reduction in IOP from baseline.20–22 A recent prospective study by Goldenfeld et al23 examined the effect of SLT in PXFG and reported a mean IOP decrease from 26.01 ± 2.5 to 17.8 ± 2.8 mm Hg (P20% IOP reduction, and 59% with >30% reduction from baseline 1 year after treatment. They also found that both 180- and 360-degree SLT were more effective than 90 degrees of treatment, concluding that 90-degree SLT is generally ineffective. Other studies have suggested that 360-degree treatment is more effective than 180 degrees with IOP reductions reportedly as high as 9.08 mm Hg (35% reduction from baseline) 2 years after 360-degree SLT.26 Baseline IOP also seems to affect the overall reduction in IOP and may serve as a predictor for response to 360-degree SLT. In a study by Shibata et al,27 pretreatment IOPZ21 mm Hg resulted in a more dramatic decrease in IOP compared with a baseline IOP

Surgical management of pseudoexfoliation glaucoma.

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