By Robert J. Noecker, MD, Special to Ophthalmology Times
There is a shift in mindset happening in regard to glaucoma. It is a chronic disease, and like most chronic diseases, treatment is not a one procedure that controls the disease for the remainder of the patient’s life. The advent of low-risk surgical options is moving this from a pharmaceutically managed disease to one controlled via a series of surgical procedures, and the outcome appears to be highly beneficial for patients.
Though topical glaucoma medications have excellent results in clinical studies, in the real world less than 50% of patients use their medications as prescribed.
Essentially, the result is a therapy in which the physician has zero control, and the tendency is to sit back and wait until there is serious damage to the optical nerve before proposing a risky surgical alternative. Finding myself in a similar mode, I deliberately embraced the myriad low-risk surgical therapies for glaucoma.
I regularly perform MicroPulse laser trabeculoplasty (MLT, Iridex) for patients in the early stages of glaucoma. Similar to selective laser trabeculoplasty, MLT lowers IOP about the same as a single prostaglandin1, but the laser causes no anatomical changes to the trabecular meshwork.2
If a glaucoma patient needs cataract surgery, I will always consider performing a combination procedure and implant a device (iStent Trabecular Micro-Bypass, Glaukos) at the same time. As experience with this stent has increased, surgeons have seen dramatic improvements in results compared with the pivotal trials.
A study by Tobias Neuhann, MD, followed patients for 36 months who received the stent in conjunction with small-incision cataract surgery and found a mean reduction in IOP from 24.1 mm Hg at baseline to 14.9 mm Hg.3
This was accompanied by a reduction in mean medications from 1.8 at baseline to 0.3 medications at 3 years, with no intraoperative or postoperative complications typically seen with conventional glaucoma surgeries. The upside is very good, and the downside is very small, so it is always my next step in intervention.
The trabecular meshwork is dynamic and is always adjusting in response to changes in pressure with new configurations of cells and structures. The problem with glaucoma is that the system starts to stiffen up a little, and no longer responds as easily to changes in pressure. The trabecular meshwork is a system that needs continuous flow to keep the cells and sensors within it open and functioning.
If fluid is shunted away to another space, studies have found that the system starts to atrophy, thus losing its elasticity and ability to move aqueous away from the anterior chamber.4
Recent studies also demonstrate that treatment with trabecular bypass stents after trabecular meshwork disuse atrophy can re-establish conventional outflow.5
Whenever possible I try to maintain an active trabecular meshwork before moving on to other treatments to mitigate the risk of a post-fibriotic pressure spike.