By Dr. Nicholas R. Rader
Glaucoma is the second leading cause of blindness worldwide, behind cataracts. It is sometimes called the “silent thief” of vision because in its most common form — the one that affects 90% of glaucoma patients — there may be no symptoms until very late in the disease.
By that time, damage can be severe and irreversible. This is why regular eye exams are so important to detecting the disease in its earliest stages.
Although eye drops have been the mainstay of glaucoma treatment for many years, since the late 1960s the surgical procedure of choice has been trabeculectomy. With trabeculectomy, a surgical drain (fistula) is created so fluid can drain from inside the eye to a blister, or bleb, created on the surface of the eye.
Although you can greatly reduce pressure with trabeculectomy, there are many complications associated with this surgery. These include discomfort from the bleb, cosmetically unacceptable appearance of the eye, late infection that could lead to blindness, leakage of the bleb, failure of the bleb and the not-infrequent need for additional surgery.
Add to this the need for frequent follow-up visits and lifestyle limitations — many surgeons advise their patients against swimming and other physical activities after trabeculectomy — and it’s little wonder that surgeons have sought better, less invasive alternatives.
These newer procedures are designed to take advantage of the eye’s natural drainage mechanism. They are usually referred to as minimally invasive glaucoma surgery or MIGS.
Canaloplasty is one such procedure that has changed my own approach to glaucoma surgery. I performed my first canaloplasty shortly after the procedure was approved by the FDA in June of 2008, and it quickly became my preferred procedure for many reasons.
Rather than create a hole in the eye to relieve pressure, canaloplasty uses a small, 200 micron fiber optic catheter to re-open the normal outflow channels of the eye. It’s very similar to the way angioplasty opens the blocked vessels of the heart.
Since this does not involve creating a fistula to allow fluid to exit the eye, it eliminates the risks of infection, wound leakage and excessively low pressure associated with trabeculectomy. By expanding the eye’s existing drainage mechanism, canaloplasty controls the eye’s intraocular pressure in a physiologic manner.
Recovery is faster, fewer office visits are needed and costs are reduced. Best of all, the patient can more quickly resume normal activity.
Spawned by the success of the canaloplasty procedure, efforts are now underway to develop new procedures designed to take advantage of the internal drainage system of the eye.
Trabeculotomy, for instance, is a delicate electro-surgical procedure that has been available in the United States since 2006. It uses discrete electrocautery to open the internal access to the eye’s drainage system. I have found this to be useful in patients requiring mild reductions in pressure. Like canaloplasty, trabeculotomy can be performed in conjunction with standard cataract surgery.
In June 2012, the iStent was approved for use in the United States. At the time, it was the smallest device ever approved by the FDA. With this procedure, a microscopic drain is inserted to provide internal access to the eye’s existing drainage system. The results seem to be similar to those obtained with trabeculotomy, but continued modifications of the device may result in even better pressure control.
These are exciting times for eye surgeons. As we combine better understanding of the mechanisms behind glaucoma with creative developments in surgical equipment, we are able to fight the disease using the eye’s natural pressure control mechanisms.
I believe we can look forward to improved surgical outcomes for glaucoma with reduced risk of complication and less interference with our patients’ active lifestyles.