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Pseudoexfoliation increases risk for glaucoma damage, cataract surgery challenges
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Pseudoexfoliation is a systemic disease, not just an ocular finding, being present in many organs outside the eye, including the heart, kidneys, liver and brain. It was first described as exfoliation of the lens capsule by John Lindberg of Finland in 1917. Several decades later, the famous pathologist Dr. Georgiana Dvorak Theobald changed the name to pseudoexfoliation to distinguish it from the true exfoliation of the lens capsule that occurs in glass blowers who do not wear protective shields. It occurs more frequently in women than in men, is more common in those older than 70 years, and has a genetic, age-related and likely environmental basis.
The LOXL1 gene is nearly always present, but many patients with this gene do not manifest the disease. Further evidence of a genetic basis is the finding that it is more frequent in certain populations, including those of Scandinavian descent (25.9 per 100,000 in my state of Minnesota) and also unexpectedly very common in the Bantu population, which again suggests a genetic basis in an inbred population that cannot be explained by age, environment, race or diet alone.
Approximately 87% of patients have bilateral findings, and many unilateral cases exhibit clinical findings in the second eye over time. In the Framingham study, 1.8% of the population demonstrated pseudoexfoliation, and in another population study, the incidence at age 50 to 59 was 0.4% and at age 80 to 89 increased to 7.9%, confirming that it is age related. There definitely are unilateral cases, which is rare for an inherited gene-based dystrophy.
The pathology reveals microscopic granular amyloid-like protein fibers deposited on the lens capsule. This is what we see at the slit lamp, and the movement of the pupil pushes these centrally in the classic “bull’s eye” pattern.
The human lens is the only organ in the body where the basement membrane is exposed on the surface, and some believe the findings in the eye represent a chafing of the iris against the anterior lens capsule, mechanically scraping off the amyloid-like protein granules. This makes some sense intuitively, and in addition, pigment from the posterior surface of the iris is chafed and set free in the anterior chamber. Both the amyloid-like pseudoexfoliation material and the iris pigment epithelial cells and granules find their way into the trabecular meshwork, where they can cause a reduced facility of outflow and secondary glaucoma.
So-called pseudoexfoliation syndrome or pseudoexfoliation glaucoma represents 6% to 12% of open-angle glaucoma. As many as 50% of patients with pseudoexfoliation will develop glaucoma damage in their lifetime. In ICD-10 coding, it has its own descriptor, pseudoexfoliation syndrome, and must also be graded as mild, moderate or severe. The glaucoma associated with pseudoexfoliation syndrome is usually more severe than primary open-angle glaucoma, so vigilance in following these patients is critical. Gonioscopy will reveal an open angle with more dense pigmentation. A Sampaolesi pigment line may be seen anterior to Schwalbe’s line. On careful slit lamp examination, there may be dandruff-like pseudoexfoliation material seen on the corneal endothelium, iris and iris margin, lens and zonules and even in the anterior vitreous.
The treatment of pseudoexfoliation syndrome with glaucoma is the same as for any open-angle glaucoma with a few nuances. I start with a topical prostaglandin analogue once daily at bedtime and follow with a topical beta blocker in combination with an alpha agonist and/or carbonic anhydrase inhibitor twice daily. Some like to use a miotic such as pilocarpine to enhance outflow and reduce pupillary movement, thereby reducing pigment dispersion, but I rarely prescribe a miotic in the phakic eye. However, I find a miotic can be very helpful in the pseudophakic eye and also increases depth of focus, rendering many patients spectacle independent. On a positive note, both argon laser trabeculoplasty and selective laser trabeculoplasty perform well in these patients but, for me, rarely provide long-term pressure control.
Tom Samuelson, MD, Brooks Poley, MD, and I found that patients with open-angle glaucoma and elevated IOP despite maximal tolerated medical therapy achieve a significant reduction in IOP with cataract surgery alone. Brad Shingleton, MD, confirmed this finding, and a patient with an IOP higher than 25 mm Hg can see their pressure drop 10 mm Hg or more with phacoemulsification and placement of a posterior chamber IOL. Most of these patients achieve a reduced medication burden as well but still usually require a drop of a prostaglandin analogue every day. The Glaukos iStent works well for me in the patient with pseudoexfoliation glaucoma, and the densely pigmented trabeculum makes visualization of the angle structures and proper placement easier. Areas of increased pigmentation overlying the collector channels can often be recognized, allowing so-called intelligent placement of the iStent, as taught by Ike Ahmed, MD.
Many of us are slightly more aggressive in recommending cataract surgery in the patient with pseudoexfoliation and poor IOP control, but the cataract surgery is also more challenging. The zonules are weaker in patients with pseudoexfoliation and the pupil dilates less well, making cataract surgery more difficult. Pupil expansion and lens capsule support devices are more frequently required. I personally place a capsular tension ring in most patients with pseudoexfoliation, as having practiced in a region with a high incidence of this problem, I have seen many late posterior chamber IOL subluxations. I have found the capsular tension ring useful in many cases for suture to the iris or transscleral when treating these late IOL subluxations.
There is debate as to whether to implant the posterior chamber IOL with the haptics in the sulcus or in the bag to reduce late subluxation. I make this decision on a case-by-case basis, and when the zonules seem secure, I will place a one-piece IOL in the bag. For sulcus placement, a three-piece IOL is required, and I usually perform posterior optic capture. While it may only provide temporary benefit, I also perform more extensive irrigation and aspiration to remove all viscoelastic and as much pseudoexfoliation material and pigment from the eye and angle as possible. I also inject dilute Miostat (carbachol 0.01%, Alcon) and place a drop of Combigan (brimonidine tartrate 0.2%/timolol maleate ophthalmic solution 0.5%, Allergan) on the eye, as post-cataract surgery pressure spikes are more common. In a high-risk patient, a pressure check 4 to 8 hours after surgery may be helpful.
Patients with pseudoexfoliation are very common in my Minnesota practice, and while each patient needs to be treated with an individualized plan, they do share some common issues. I hope some of the data and clinical pearls mentioned above from my experience are useful, as these patients are common and represent a group at higher risk for glaucoma damage and cataract surgery challenges.