In the search for better post-surgical results and quicker recovery times, eye surgeons have begun to use a new class of procedures known as minimally invasive glaucoma surgeries (MIGS). Devices in this category include the iStent, made by the Glaukos Corp, which is a tiny stent used in glaucoma surgery to bypass obstructions in the eye, and allow damaging excess fluid to drain away.


Global glaucoma


Worldwide, glaucoma is the leading cause of irreversible blindness, affecting over 65 million people. When it comes to treating glaucoma, the primary goal is to reduce the raised intraocular pressure (IOP) that results from excess fluid in the eye. The normal first-line treatment is with eye drops but when these fail, surgery is often the next step.

"Glaucoma is the leading cause of irreversible blindness."

The traditional surgical procedure is a process known as a trabeculectomy, in which the surgeon removes obstructed pathways in the eye. But this process has its shortcomings. According to Gus Gazzard, a consultant ophthalmic surgeon and leading researcher in eye care based in London’s Moorfields Eye Hospital and in private practice, trabeculectomy can result in excessively low IOP, which can cause problems such as cataract and pain. It can also require high frequency medication with drops after surgery to help control the risk of scarring. “Even when the operation goes well, it can leave patients with altered vision and in some, the sensation of a foreign body in the eye,” he says.


The tiny iStent, pictured here on top of a 1 cent coin

Minimally invasive glaucoma surgeries


Since its development in 2001, MIGS has been subject to significant research and this has led experts to consider that devices such as the iStent could also have an application in the treatment of cataracts in patients with raised IOP. Studies show that when inserted during cataract surgery, iStent can achieve superior reductions in IOP than cataract surgery alone, and at around six months post-surgery it can reduce, even remove, the need for IOP-lowering medication.

"9 out of 10 patients would rather have simple surgery rather than use drops."

Mr Gazzard says this is popular with patients. “They tell us just how much they dislike [drops]; nine out of ten patients would rather have simple surgery rather than take drops. They don’t like the idea of being medicated, they dislike the routine, and the side effects of red eye, irritation discomfort and dry eye. Long-term drops can cause permanent damage to the eye and can cause whole-body side effects such as wheeze and sleepiness.”

As a result, around one in three patients won’t take eye drops as prescribed, which has a huge cost both to the patient and also to the health service paying for a drug that is wasted.

The iStent close-up

Stand-alone care


Recent studies suggesting that MIGS can extend the benefits of cataract surgery for up to three years have excited researchers. The use of the device as a standalone treatment for glaucoma is similarly exciting. Even though the jury is still out on this discussion, it is clear that eye surgeons are keen to find new procedures that improve outcomes for patients. The hope is that as MIGS will be there to usher in the new era of care.


A graphic of the iStent at work in the eye