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Exfoliation syndrome: Effects of cataract surgery on glaucoma
FROM THE EDITOR
Exfoliation syndrome: Effects of cataract surgery on glaucoma It ain’t what you don’t know that gets you into trouble; it’s what you know for sure that just ain’t so. Mark Twain Exfoliation syndrome or pseudoexfoliation (PXF) is characterized by the accumulation of fibrillar extracellular matrix material on the surface of various ocular tissues.1 The material can accumulate on many structures in the anterior segment of the eye as well as on other tissues throughout the body. The PXF material is composed of a fibrillin–glycoprotein skeleton surrounded by an amorphous matrix of associated proteins. Lens epithelial cells and ciliary epithelial cells deposit PXF material within their respective basement membrane lamellae. The material may then accumulate in the trabecular meshwork, resulting in a blockage of some outflow channels within the eye and leading to chronic intraocular pressure (IOP) elevation. The PXF material gradually builds up in the juxtacanalicular tissue, causing progressive glaucomatous damage. Pseudoexfoliation is now recognized as the most common identifiable cause of open-angle glaucoma (OAG).2 The risk for developing glaucoma is noted to be 5 to 10 times more common in eyes with PXF than in those without it. Patients with PXF are twice as likely to convert from ocular hypertension to glaucoma. In addition, when PXF glaucoma is present, it is likely to progress more rapidly than simple OAG.3,4 Studies of the natural history of patients with PXF show that when followed for approximately 15 years, 44% of these patients received glaucoma therapy.5 The incidence of cataracts also appears to be increased in PXF.6 Over the short term, the effect of cataract extraction on postoperative IOP in PXF patients is an increased risk for IOP spikes immediately after cataract surgery; however, there is preliminary evidence that performing cataract surgery in PXF patients may cause a decrease in IOP over the short term. Recent studies of patients with ocular hypertension but no PXF show that phacoemulsification with intraocular lens (IOL) implantation leads to a significant long-term IOP reduction. Thus, removal of the cataractous lens with placement of an IOL may be an effective way of lowering IOP in the long term. Shingleton et al. have followed a series of patients with PXF who had cataract surgery. The initial report7 comprised 1000 consecutive PXF patients who had cataract surgery performed by the same surgeon. With proper surgical techniques, cataract extraction was successful, with a minimally significant risk for Q 2008 ASCRS and ESCRS Published by Elsevier Inc.
complications. The preliminary study also found that IOP decreased in the early postoperative period. In this issue (pages 1834–1841), the latest report by Shingleton et al. evaluates the long-term effect of phacoemulsification with posterior chamber IOL implantation on IOP in this series of PXF patients. The retrospective study looked at the results in 1122 eyesd882 had no glaucoma and 240 had glaucoma. After approximately 7 years, the PXF with no glaucoma eyes demonstrated a statistically significant reduced mean IOP compared with the preoperative levels. Similarly, the PXF with glaucoma eyes had a reduced mean IOP over this same period of time. A higher mean preoperative IOP was associated with a greater reduction in IOP postoperatively in both groups. The most important outcome noted in the study was that only 2.7% of the PXF with no glaucoma eyes progressed to actual glaucoma requiring medication and only 3.7% of the PXF eyes with glaucoma progressed to needing laser or glaucoma surgery. These numbers are remarkable given the propensity for patients with PXF to convert from ocular hypertension to glaucoma or to progress rapidly when glaucoma develops. Thus, it appears that phacoemulsification with IOL implantation has a protective effect on the development or progression of glaucoma in patients with PXF. This effect seemed to persist throughout the relatively long follow-up in this group of patients. The exact mechanism of decreased IOP after removal of the cataractous lens is unclear; however, growth of the crystalline lens throughout life has been noted to cause a progressive shallowing of the anterior chamber, which may cause some forward traction by the zonules in the anterior ciliary body, displacing the uveal track anteriorly and compressing the outflow of the trabecular meshwork and the canal of Schlemm. Theoretically, removing the thickened crystalline lens and replacing it with a thin IOL should reverse this change and relieve some of the compression of the trabecular meshwork and the canal of Schlemm.8 Extrapolating these findings to eyes with PXF, it is likely that removing the crystalline lens during phacoemulsification and replacing it with an IOL will lead to an increase in outflow through the trabecular meshwork and Schlemm canal despite the buildup of exfoliative material, leading to a decrease in the conversion from ocular hypertension to glaucoma. This may also be instrumental in reducing the number of patients with PXF glaucoma who progress to medication or surgery. 0886-3350/08/$dsee front matter doi:10.1016/j.jcrs.2008.09.002
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FROM THE EDITOR
Long-term studies that follow a large group of patients are critical when evaluating potential treatment modalities for a progressive, long-term condition such as PXF. Nick Mamalis, MD REFERENCES 1. Ritch R, Schlo¨tzer-Schrehardt U. Exfoliation syndrome. Surv Ophthalmol 2001; 45:265–315 2. Ritch R. Exfoliation syndromedthe most common identifiable cause of open-angle glaucoma. J Glaucoma 1994; 3:176–178 3. Bengtsson B, Heijl A. A long-term prospective study of risk factors for glaucomatous visual field loss in patients with ocular hypertension. J Glaucoma 2005; 14:135–138
4. Grødum K, Heijl A, Bengtsson B. Risks of glaucoma in ocular hypertension with and without pseudoexfoliation. Ophthalmology 2005; 112:386–390 5. Jeng SM, Karger RA, Hodge DO, Burke JP, Johnson DH, Good MS. The risk of glaucoma in pseudoexfoliation syndrome. J Glaucoma 2007; 16:117–121 6. Schlo¨tzer-Schrehardt U, Naumann GOH. Ocular and systemic pseudoexfoliation syndrome [perspective]. Am J Ophthalmol 2006; 141:921–937 7. Shingleton BJ, Nguyen BK, Eagan EF, Nagao K, O’Donoghue MW. Outcomes of phacoemulsification in fellow eyes of patients with unilateral pseudoexfoliation: single surgeon series. J Cataract Refract Surg 2008; 34:274–279 8. Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes. J Cataract Refract Surg 2008; 34:735–742
J CATARACT REFRACT SURG - VOL 34, NOVEMBER 2008
Exfoliation syndrome: Effects of cataract surgery on glaucoma It ain’t what you don’t know that gets you into trouble; it’s what you know for sure that just ain’t so. Mark Twain Exfoliation syndrome or pseudoexfoliation (PXF) is characterized by the accumulation of fibrillar extracellular matrix material on the surface of various ocular tissues.1 The material can accumulate on many structures in the anterior segment of the eye as well as on other tissues throughout the body. The PXF material is composed of a fibrillin–glycoprotein skeleton surrounded by an amorphous matrix of associated proteins. Lens epithelial cells and ciliary epithelial cells deposit PXF material within their respective basement membrane lamellae. The material may then accumulate in the trabecular meshwork, resulting in a blockage of some outflow channels within the eye and leading to chronic intraocular pressure (IOP) elevation. The PXF material gradually builds up in the juxtacanalicular tissue, causing progressive glaucomatous damage. Pseudoexfoliation is now recognized as the most common identifiable cause of open-angle glaucoma (OAG).2 The risk for developing glaucoma is noted to be 5 to 10 times more common in eyes with PXF than in those without it. Patients with PXF are twice as likely to convert from ocular hypertension to glaucoma. In addition, when PXF glaucoma is present, it is likely to progress more rapidly than simple OAG.3,4 Studies of the natural history of patients with PXF show that when followed for approximately 15 years, 44% of these patients received glaucoma therapy.5 The incidence of cataracts also appears to be increased in PXF.6 Over the short term, the effect of cataract extraction on postoperative IOP in PXF patients is an increased risk for IOP spikes immediately after cataract surgery; however, there is preliminary evidence that performing cataract surgery in PXF patients may cause a decrease in IOP over the short term. Recent studies of patients with ocular hypertension but no PXF show that phacoemulsification with intraocular lens (IOL) implantation leads to a significant long-term IOP reduction. Thus, removal of the cataractous lens with placement of an IOL may be an effective way of lowering IOP in the long term. Shingleton et al. have followed a series of patients with PXF who had cataract surgery. The initial report7 comprised 1000 consecutive PXF patients who had cataract surgery performed by the same surgeon. With proper surgical techniques, cataract extraction was successful, with a minimally significant risk for Q 2008 ASCRS and ESCRS Published by Elsevier Inc.
complications. The preliminary study also found that IOP decreased in the early postoperative period. In this issue (pages 1834–1841), the latest report by Shingleton et al. evaluates the long-term effect of phacoemulsification with posterior chamber IOL implantation on IOP in this series of PXF patients. The retrospective study looked at the results in 1122 eyesd882 had no glaucoma and 240 had glaucoma. After approximately 7 years, the PXF with no glaucoma eyes demonstrated a statistically significant reduced mean IOP compared with the preoperative levels. Similarly, the PXF with glaucoma eyes had a reduced mean IOP over this same period of time. A higher mean preoperative IOP was associated with a greater reduction in IOP postoperatively in both groups. The most important outcome noted in the study was that only 2.7% of the PXF with no glaucoma eyes progressed to actual glaucoma requiring medication and only 3.7% of the PXF eyes with glaucoma progressed to needing laser or glaucoma surgery. These numbers are remarkable given the propensity for patients with PXF to convert from ocular hypertension to glaucoma or to progress rapidly when glaucoma develops. Thus, it appears that phacoemulsification with IOL implantation has a protective effect on the development or progression of glaucoma in patients with PXF. This effect seemed to persist throughout the relatively long follow-up in this group of patients. The exact mechanism of decreased IOP after removal of the cataractous lens is unclear; however, growth of the crystalline lens throughout life has been noted to cause a progressive shallowing of the anterior chamber, which may cause some forward traction by the zonules in the anterior ciliary body, displacing the uveal track anteriorly and compressing the outflow of the trabecular meshwork and the canal of Schlemm. Theoretically, removing the thickened crystalline lens and replacing it with a thin IOL should reverse this change and relieve some of the compression of the trabecular meshwork and the canal of Schlemm.8 Extrapolating these findings to eyes with PXF, it is likely that removing the crystalline lens during phacoemulsification and replacing it with an IOL will lead to an increase in outflow through the trabecular meshwork and Schlemm canal despite the buildup of exfoliative material, leading to a decrease in the conversion from ocular hypertension to glaucoma. This may also be instrumental in reducing the number of patients with PXF glaucoma who progress to medication or surgery. 0886-3350/08/$dsee front matter doi:10.1016/j.jcrs.2008.09.002
1813
1814
FROM THE EDITOR
Long-term studies that follow a large group of patients are critical when evaluating potential treatment modalities for a progressive, long-term condition such as PXF. Nick Mamalis, MD REFERENCES 1. Ritch R, Schlo¨tzer-Schrehardt U. Exfoliation syndrome. Surv Ophthalmol 2001; 45:265–315 2. Ritch R. Exfoliation syndromedthe most common identifiable cause of open-angle glaucoma. J Glaucoma 1994; 3:176–178 3. Bengtsson B, Heijl A. A long-term prospective study of risk factors for glaucomatous visual field loss in patients with ocular hypertension. J Glaucoma 2005; 14:135–138
4. Grødum K, Heijl A, Bengtsson B. Risks of glaucoma in ocular hypertension with and without pseudoexfoliation. Ophthalmology 2005; 112:386–390 5. Jeng SM, Karger RA, Hodge DO, Burke JP, Johnson DH, Good MS. The risk of glaucoma in pseudoexfoliation syndrome. J Glaucoma 2007; 16:117–121 6. Schlo¨tzer-Schrehardt U, Naumann GOH. Ocular and systemic pseudoexfoliation syndrome [perspective]. Am J Ophthalmol 2006; 141:921–937 7. Shingleton BJ, Nguyen BK, Eagan EF, Nagao K, O’Donoghue MW. Outcomes of phacoemulsification in fellow eyes of patients with unilateral pseudoexfoliation: single surgeon series. J Cataract Refract Surg 2008; 34:274–279 8. Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes. J Cataract Refract Surg 2008; 34:735–742
J CATARACT REFRACT SURG - VOL 34, NOVEMBER 2008