Open angle glaucoma is one of the most common reasons the elderly seek eye surgery. It is a chronic debilitating condition that can lead to blindness. In terms of glaucoma treatment, what works for one person may not necessarily be applicable to all. This is why beyond what you read on the internet or the successful eye surgery your friend tells you about, you should look to your doctor to guide your treatment decision. But of course it does not hurt to know your options. Having an intelligent discussion with your glaucoma specialist will make your glaucoma surgery less daunting.
For decades, patients were limited to essentially two main choices- a lifetime of glaucoma eye medications or trabeculectomy. The classic glaucoma surgery is called trabeculectomy, well known for its potency in lowering intraocular pressures. The surgeon treats aqueous fluid overload by creating a fistula (or hole in the eye) leading to a blister-like pocket on the surface of the eye. This blister, or “bleb”, contains the excess fluid and allows it to seep into the surrounding veins.
Although trabeculectomy is very effective and used even up to this day, it is also notorious for its many post-operative complications. These include overtreating the eye pressure (hypotony) resulting in loss of vision, chronic irritation or eye pain, bleeding in the eye, increased lifetime risk of infection as well as other risks. These were the risks that all patients opting for glacoma surgery faced until surgeons developed a less traumatic procedure called canaloplasty.
With canaloplasty, an eye surgeon can drain the fluid by inserting a flexible catheter through the eye’s natural drainage duct (Schlemm’s canal). This surgery does not require the creation of a fistuala or a bleb. Instead it enhances the natural process of the anatomical drainage of the eye.
Over the last few years, several groups of doctors have independently published their successes with canaloplasty. One of these studies by Lewis and colleagues published in 2010 found that most patients who had canaloplasty required no after-care medications once they had healed from surgery. Serious post operative complications such as infections or chronic hypotony were rare. (1 Favorable results were also noted even in the glaucoma high-risk groups such as African Americans who are known to have a higher risk with trabeculectomy surgery. (2)
Trabeculectomy or Canaloplasty?
A head to head comparison between canaloplasty and trabeculectomy has been published. A study by Ayyala and his colleagues in 2011 showed similar reduction in IOP for both surgeries. There was also little difference between post surgical failure rates and rate of post-medication use between the two.(3)
Despite its generally excellent results, not all glaucoma surgeons are ready to abandon or replace trabeculectomy with canaloplasty. At the 22nd annual American Glaucoma Society meeting, Dr Adam Reynolds reviewed more than 200 cases of glaucoma eye procedures done in eight different health facilities in the US who received either trabeculectomy or canaloplasty.
Although IOP lowering was significant for both trabeculectomy and canaloplasty, Dr Reynolds observed that trabeculectomy appears to have about a 2 mmHg advantage in terms of IOP lowering compared to canaloplasty. Whether this will matter in the long run for most patients with open angle glaucoma, remains to be seen. Considering the significant additional risk of trabeculectomy, a 2mmHg difference may be a price worth paying for the added safety of canaloplasty. Additionally, many glaucoma specialists contend that canaloplasty is an ideal treatment for patients with mild to moderate glaucoma both for its safety and because these patients would not require and extreme amount of IOP lowering. (3)
Dr Reynolds adds: “With canaloplasty, there is less of a chance I’m going to get the IOP targets I want without medication, but the procedure has fewer complications and is less invasive.”(3)
In summary, compared to trabeculectomy, one cannot dispute canaloplasty’s superior safety profile. IOP lowering ability appears to be similar to trabeculectomy (though there may be a small IOP advantage with trabeculectomy). Additionally, early surgical intervention with canaloplasty can often relieve one of using daily eye drops while avoicing the significant risks of trabeculectomy.(4)
- Lewis RA et al. Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg. 2011 Apr;37(4):682-90.
- Grieshaber MC et al. Canaloplasty for primary open-angle glaucoma: long-term outcome.Br J Ophthalmol 2010;94:1478-1482
- American Glaucoma Society 22nd Annual Meeting: Abstract 8. Presented March 2, 2012.http://www.medscape.com/viewarticle/760075?src=rss
- Ayyala RS. Comparison of surgical outcomes between canaloplasty and trabeculectomy at 12 months’ follow-up. Ophthalmology. 2011 Dec;118(12):2427-33.
Looking for an Ophthalmologist in California?
Dr. David Richardson is taking new patients at his office in San Marino, CA., and is always willing to provide a second opinion for those who would like the peace-of-mind that such a consultation would provide.