Recently, two patients presented requesting more information about some “educational” materials they received. In both instances, the literature was cringe-inducing and underscored the probably vast amounts of misinformation to which patients are exposed.

Stents

The first patient was a 56-year-old woman with primary open angle glaucoma (POAG). She was being treated medically and had to try several medications before finding one without intolerable side effects. The patient, British by birth, brought in a United Kingdom newspaper and shared an article that she wanted to discuss entitled, “The Simple Jab in the Eye that Could Cure Glaucoma.” She questioned why she had to tolerate the adverse effects of chronic topical therapy when there was a simple procedure that could cure her once and for all. The article discussed the Xen Gel Stent (Allergan). The first paragraph began: “Glaucoma can now be cured with a simple injection, according to eye surgeons.” 

The article went on to discuss the procedure, in lay terms, and reported that, while it’s still ‘not perfect,’ it’s much faster than traditional trabeculectomy without the discomfort or complications— though it doesn’t control intraocular pressure (IOP) and costs more than current procedures. 

Stents and shunts, as seen here being implanted, can help glaucoma patients, but they are, by no means, a “cure,” as some news sources have billed them.

However, most readers with glaucoma aren’t going to venture much further than that resonating first sentence about an easy cure. Not a treatment, mind you, but a “cure.”

In the United States, the Xen Gel Stent is currently an investigational device. It is made of a permanent, soft, collagen-derived gel. It is 6mm long and is injected through a small self-sealing corneal incision using a preloaded injector. Like all glaucoma filtration surgeries, it provides drainage from the anterior chamber, through the trabecular meshwork, into the subconjunctival space. It functions similar to conventional drainage implants, albeit with a smaller footprint. Preclinical and human testing shows the implant does not seem to occlude inside the lumen and the implant material does not appear to cause tissue reaction in the eye.¹ The placement of this stent offers a minimally invasive IOP-lowering procedure, with minimum conjunctival tissue disruption, and restricted flow to avoid hypotony.¹ As the implant is not yet available in the United States outside of clinical trials, there is little scientific information available about its effectiveness or complications. 

The information in the patient’s UK newspaper consisted of anecdotal quotes from surgeons beginning to use the procedure. They agreed that it was quicker to perform than trabeculectomy. One surgeon was quoted saying that it probably wasn’t as effective at lowering IOP as trabeculectomy, while another stated that it was as effective without the traditional complications or discomfort. 

A sole report published late last year detailed a patient with a previously uncomplicated Xen Gel Stent implant who developed a hypertrophic bleb and mechanical ectropion. The treatment consisted of draining the hypertrophic bleb following blockage with viscoelastic material of the stent and bleb sealing with a tissue adhesive.²

In our case, the patient was guided through the article to point out the language stating that the procedure reduced IOP, may not be as effective as conventional treatments, and was not available in the United States. She was further educated that, despite the headline, it was not a cure, but merely another IOP reducing therapy. Moreover, she was reminded that POAG cannot be cured; it can be merely controlled by lowering IOP. She seemed satisfied with the explanation.

Selective Laser Trabeculoplasty

The second patient was a 52-year-old woman who recently had been diagnosed with ocular hypertension and sought a second opinion. She was concerned that the previous doctor had spent minimal time with her, didn’t perform a thorough enough evaluation (according to her) to make an accurate diagnosis, and seemed aggressive about performing laser treatment on her as soon as possible.

The patient had no family history of glaucoma that she could recall. She was 20/20 in each eye. Her IOP was 23mm Hg OD and 25mm Hg OS. Her optic discs had robust rim tissue and a C/D ratio of 0.4/0.4 in each eye. There was a healthy appearing retinal nerve fiber layer (RNFL) in each eye. Ultrasound pachymetry revealed a central corneal thickness of 580µm in the right eye and 592µm in the left. Optical coherence tomography showed a normal RNFL and ganglion cell complex in each eye, and threshold perimetry revealed visual fields that were full in each eye. 

SLT is a relatively safe procedure­. However, the claim that it has “no side effects,” as one patient’s literature stated, is innaccurate as clinical studies show several potential—albeit rare—side effects, such as corneal edema, seen above. Click image to enlarge.

The previous diagnosis of ocular hypertension was confirmed and she felt that we had spent enough time and diagnostic testing for her satisfaction. Treatment options were discussed, including observation vs. therapeutic pressure reduction. It was mutually agreed that her risk of conversion to glaucoma was low and she would be followed without treatment. 

She asked if laser treatment would be a viable option should her IOP need to be lowered and was informed that trabeculoplasty would be a suitable alternative to medications. She then proffered an educational brochure on selective laser trabeculoplasty (SLT) that had been given to her at her previous office. The brochure, entitled, “SLT: The Gentle Alternative for Glaucoma Therapy,” was prepared not by the previous doctor’s office, but by a medical information company. The majority of the information was accurate and easy for patients to understand. However, there was one statement that was even more cringe-worthy than the previous example. It stated, “SLT is painless and there are no side effects to worry about.” A claim of no side effects is tempting to patients, but all physicians know that there is no therapy that is entirely devoid of adverse events.

SLT results in selective absorption of energy by trabecular pigmented cells, enhancing aqueous outflow. In contrast to argon laser trabeculoplasty, there is no thermal damage imparted to the trabecular meshwork. Clinical studies suggest that SLT is efficacious in lowering IOP, as the initial treatment option or when medical therapy is insufficient, with response rates after one year ranging from 59% to 96%.³ Indeed, SLT is a current and effective treatment for lowering IOP; adverse effects are uncommon, mild and transient in nature in most cases. The most common post-procedure adverse effects are inflammation and subsequent IOP rise, both of which are typically self-limiting or easily managed with topical medications.³

However, there are well-known severe complications that can occur as a result of SLT. Macular edema has been reported to occur following SLT.^4-6 The genesis of the macular edema is unknown, but may be related to prostaglandin induction in the inflammatory cascade initiated by SLT. While treatment is usually quite effective in resolving macular edema, the condition can persist for months.⁵

Other reported side effects potentially occurring from SLT are corneal edema, haze and thinning. In the majority of cases, topical steroid treatment resolved the edema within several weeks, but in several cases patients were left with mildly reduced visual acuity due to stromal haze.^7-9 It is not known what factors predispose patients to these corneal changes following SLT. Commensurate with these corneal changes, several patients had hyperopic refractive shifts. One report noted shifts of nearly 2.0 to greater than 6.0 diopters in eyes that were moderately to highly myopic prior to SLT.⁹ 

We have personally witnessed a patient develop severe corneal edema with folds in Descemet’s membrane following SLT. This individual required a protracted course of topical steroids with a subsequent elevation in IOP, placing him at risk for further glaucomatous damage.

Other rare complications from SLT have been documented. In one case, a patient developed a significant anterior chamber reaction, shallow anterior chamber and choroidal effusion.¹⁰ In another, the patient developed hyphema after the procedure.¹¹ While SLT has been shown to be a safe and effective pressure-lowering treatment overall, it would be irresponsible for any physician or educational piece to suggest that, “there are no side effects to worry about.”

Mythbusting

Education about diseases and therapeutic options are a paramount part of the doctor-patient relationship. However, it can become an uphill struggle when patients are exposed to false and misleading statements about their treatments. 

1. Lewis RA. Ab interno approach to the subconjunctival space using a collagen glaucoma stent. J Cataract Refract Surg. 2014;40(8):1301-6. 2. Fernández-García A, Romero C, Garzón N. “Dry Lake” technique for the treatment of hypertrophic bleb following XEN Gel Stent placement. Arch Soc Esp Oftalmol. 2015;90(11):536-8. 3. Barkana Y, Belkin M. Selective laser trabeculoplasty. Surv Ophthalmol. 2007;52(6):634-54. 4. Ha J, Bowling B, Chen S. Cystoid macular oedema following selective laser trabeculoplasty in a diabetic patient. Clin Experiment Ophthalmol. 2014;42(2):200-1. 5. Wu Z, Huang J, Sadda S. Selective laser trabeculoplasty complicated by cystoid macular edema: report of two cases. Eye Sci. 2012;27(4):193-7. 6. Wechsler D, Wechsler IB. Cystoid macular oedema after selective laser trabeculoplasty. Eye (Lond). 2010;24(6):1113. 7. Moubayed SP, Hamid M, Choremis J, Li G. An unusual finding of corneal edema complicating selective laser trabeculoplasty. Can J Ophthalmol. 2009;44(3):337-8. 8. Regina M, Bunya VY, Orlin SE, Ansari H. Corneal edema and haze after selective laser trabeculoplasty. J Glaucoma. 2011;20(5):327-9. 9. Knickelbein JE, Singh A, Flowers BE, et al.  Acute corneal edema with subsequent thinning and hyperopic shift following selective laser trabeculoplasty. J Cataract Refract Surg. 2014;40(10):1731-5. 10. Kim DY, Singh A. Severe iritis and choroidal effusion following selective laser trabeculoplasty. Ophthalmic Surg Lasers Imaging. 2008;39(5):409-11. 11. Shihadeh WA, Ritch R, Liebmann JM. Hyphema occurring during selective laser trabeculoplasty. Ophthalmic Surg Lasers Imaging. 2006;37(5):432-3.