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Consider laser trabeculoplasty for treatment of pseudoexfoliation
MLT is especially useful in patients who have trouble with topical glaucoma medications.
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Pseudoexfoliation is the most common cause of secondary glaucoma worldwide and can be difficult to treat. MicroPulse laser trabeculoplasty is an effective treatment that is safe and can be repeated as necessary.
An age-related systemic disease manifesting primarily in the eyes, pseudoexfoliation is characterized by the accumulation of amyloid protein-type material on the surface of the lens. This material then flakes off, resulting in the blockage of the trabecular meshwork, which in turn causes IOP to rise. Studies show between 22% and 50% of people who have pseudoexfoliation will develop glaucoma, although it is more likely to occur by a ratio of nearly 3:1 in elderly women and in those of Scandinavian descent.
The problem
The problem with the glaucoma that develops is that it is not typical primary open-angle glaucoma (POAG). While topical drugs may be beneficial initially, pseudoexfoliation tends to be recalcitrant to medical therapies and can lead to a rapid progression of optic nerve damage. Rises in pressure can still occur over time as the angle structure is being compromised due to the sludging of the pseudoexfoliation material in the trabecular meshwork.
An underdiagnosed condition
Oftentimes, pseudoexfoliation goes unrecognized or undiagnosed. It is important to understand the difference between this condition and typical POAG. Pseudoexfoliation is much more aggressive regarding IOP fluctuations and elevated IOPs. Additionally, a patient who responds to initial treatment but fails suddenly may potentially have pseudoexfoliation, which can usually be identified on slit lamp examination.
Signs of pseudoexfoliation could include:
- A Sampaolesi’s line, which is a pigment deposition anterior to Schwalbe’s line.
- Material on the anterior surface of the lens and at the pupillary border of the iris, which can result in a loss of iris pigment.
- An IOP that tends to escalate faster than those with POAG. This can lead to more rapid optic nerve damage and visual field loss.
- Poor pupillary dilation.
It is also important to be aware that this condition requires more follow-up and more treatment.
Past treatments
Laser trabeculoplasty with argon laser trabeculoplasty and selective laser trabeculoplasty has traditionally been used to treat pseudoexfoliation with good results. However, ALT creates thermal damage within the trabecular meshwork and can then ultimately lead to scarring and synechia. Therefore, while beneficial for a one-time treatment, it is not repeatable. As repeat treatments are necessary, this becomes an issue.
New and improved
Similar to SLT, MicroPulse laser trabeculoplasty (MLT, Iridex) is a procedure that is not as traumatic to the eye as ALT, can be repeated and does well to relieve elevated IOP. MLT procedures have had significant success in treating patients with POAG, and I have found similar results in using this procedure to treat pseudoexfoliation.
While just 4 years ago relatively few physicians knew about MLT, more are now becoming aware of its advantages. Everyone is looking for a better, safer procedure, and MLT has been shown to effectively treat IOP without visible laser-induced tissue damage. This laser modality breaks a continuous wave laser beam into a series of short, repetitive pulses, which allows tissue time to cool between pulses and prevents thermal build-up. This treats the necessary areas without destroying the surrounding tissue, making MLT potentially more titratable than other treatments.
Buying time
It is important to note that while both MLT and SLT carry the advantage of being repeated without causing any damage to the trabecular meshwork, the downside is that the effects do not last several years as they might when treating POAG. In my experience, this treatment is relatively short-lived. After about 6 to 12 months, the patient’s pressure may start to rise again.
I first began utilizing MLT after two of my patients received the treatment and it lowered their IOP. However, at 6 months the pressure returned. Both were re-treated and had similar lowering of IOP, which lasted approximately 6 months again. While repeat treatment is necessary, it does allow patients some relief of their IOP for an ailment that can be resistant to other treatment, or it may assist patients who are unable to tolerate or have compliance issues in using their drops. These patients would simply require regular follow-up with close monitoring of their IOP.
Because MLT does not damage tissue, there is no issue with re-treating patients once their pressure beings to rise again, and you will get an average 25% to 30% reduction in IOP. The biggest effect is generally seen approximately 4 months after treatment. This may buy the patient some time, helping to lower IOP before more definitive surgery. Because MLT has been shown to successfully reduce the need for medication in some patients, it is also advantageous for those who have difficulty using topical medications.
Treatment specifics
I typically treat using a 300-µm spot size, with 300 milliseconds duration and 1,000 mW with a 15% duty cycle. For those who are resistant to treatment at 1,000 mW, you can consider increasing to 1,200 mW to see if you get an effect. There have been no pressure spikes following MLT treatments, nor have I seen inflammation in any of my patients. This is not the case with ALT or even SLT, in which there is potential for transient pressure spikes.
Conclusion
Overall, I feel that MLT can help relieve the symptoms of patients who have pseudoexfoliation, especially those who are unable to use topical medications. I have found my patients do not require pre- or postoperative topical therapies. The procedure shows a nice response after treatment as well as after repeat treatment. It is an excellent option for those who have elevated pressure that needs to be temporally controlled before a definitive surgical procedure.
- References:
- Aasved H. Acta Ophthalmol (Copenh). 1971;doi:10.1111/j.1755-3768.1971.tb02967.x.
- Desai MA, et al. Int Ophthalmol Clin. 2008;doi:10.1097/IIO.0b013e318187e902.
- Fudemberg SJ, et al. Invest Ophthalmol Vis Sci. 2008;49(13):1236.
- Jeng SM, et al. J Glaucoma. 2007;doi:10.1097/01.ijg.0000243470.13343.8b.
- Lavinsky D, et al. Invest Ophthalmol Vis Sci. 2011;doi:10.1167/iovs.10-6828.
- Plateroti P, et al. J Ophthalmol. 2015;doi:10.1155/2015/370371.
- Vujosevic S, et al. Retina. 2010;doi:10.1097/IAE.0b013e3181c96986.
- For more information:
- David D. Gossage, DO, can be reached at Gossage Eye Institute and Optical, 50 W. Carleton Road, Hillsdale, MI 49242; email: eyegoose@yahoo.com.
Disclosure: Gossage reports he has been compensated by Iridex in the past for lecturing, most recently in 2015.