MIGS & Cataract Surgery: The ultimate marriage of convenience?
Continuing innovation in the field of MIGS should further increase its usage and potential. Priscilla Lynch reports
Glaucoma treatment is essentially a race against time; lowering intraocular pressure (IOP) to slow down progression in order to preserve quality of vision.
While eye drops remain first-line glaucoma treatment, followed by trabeculoplasty, to reduce IOP and protect the optic nerve, the popularity of minimally invasive glaucoma surgery has risen dramatically over the past few years.
“As compared with trabeculectomy, the reasons for its success are the low variability of the surgical protocols, the more comfortable postoperative period, the quick recovery of vision, the supposed lower incidence of complications,” commented Professor Roberto Bellucci MD, Italy. “However, the reported complications may be the same as those of trabeculectomy when a sudden drop in IOP takes place. On the other hand, MIGS appears to lower IOP at a lesser extent and for a shorter time than trabeculectomy.”
MIGS can essentially be defined as any procedure, generally angle and outflow-based, wherein there is minimal risk of hypotony or other sight-threatening complication, explained Dr Brandon Baartman MD, US, an anterior-segment and glaucoma specialist and expert on MIGS.
“Broadly speaking, it’s considered as a bridge between drops and more invasive, traditional surgery like filters or trabeculectomy. However, as glaucoma specialists have become more comfortable working in the angle and seeing the results of MIGS procedures, we have begun to see a shift to earlier procedural treatment of glaucoma. Even selective laser trabeculoplasty (SLT), with the results of the LiGHT trial (Gazzard G et al 2019), has become somewhat of a first-line therapy for newly-diagnosed glaucoma patients.”
There is now an array of MIGS devices available, as surgical techniques and approach have also refined.
“As for the type of implant, I think all of them work properly and are able to decrease IOP,” said Dr Bellucci. “In some patients a second or a third implant might be required, as it commonly happens for cardiovascular stents. We should get familiar with one or two different types of implants, as it might be difficult to deal with many of them: they are not intraocular lenses and require more time for us to learn what and when, and to evaluate our personal results.”
Dr Baartman said that current MIGS devices such as the “iStent and iStent inject (Glaukos), Kahook Dual Blade (New World Medical), OMNI (SightSciences), Hydrus (Ivantis), and Xen (Allergan) have excellent data behind them and I believe have ushered in the era of treating glaucoma earlier, oftentimes coupled with cataract surgery”.
THE PERFECT COMBINATION
Combining MIGS with cataract surgery makes perfect sense: two conditions can be treated using just one incision, leading to a dramatic improvement in patient vision, consistent lowering of IOP and easing of medicine burden with the removal of drops; a particularly important consideration given the age profile of these patients. Furthermore, glaucoma cases are continuing to rise in line with the growing, ageing population in Western countries and inadequate surgeon numbers. So could MIGS and cataract surgery be the ultimate marriage of convenience? Possibly, according to many in the field. However, when to use MIGS and in whom remains a key question, as it is not the answer for all glaucoma cases.
“One procedure that deviates a bit from the definitive MIGS, but I think of in the same vein, is endocyclophotocoagulation or ECP, which can be used at the time of cataract surgery, with other MIGS devices or in a standalone fashion in pseudophakic patients in order to hopefully delay or avoid entirely the future need for traditional incisional glaucoma surgery,” outlined Dr Baartman. “In short, MIGS is most useful when employed earlier in the disease process in attempt to delay need for additional surgeries.”
Dr Bellucci currently uses MIGS only in pseudophakic eyes or in association with cataract surgery, and only when the target pressure is above 12mmHg.
“Two good examples are high myopia with IOP elevation, and late IOP rise after posterior vitrectomy. I still use trabeculectomy in advanced glaucoma cases, but do prefer MIGS in late-stage glaucoma, where trabeculectomy might resolve in blindness. At present I offer MIGS to pseudophakic patients requiring prostaglandins to control their IOP, to avoid the late anatomical impairment and discomfort of the ocular surface,” said Dr Bellucci.
However, one of the biggest challenges for further widespread adoption of MIGS appears to be financially related, depending on the healthcare system of individual countries.
Cost is a limiting factor in public hospitals in Italy, where MIGS is rarely reimbursed, Dr Bellucci acknowledged.
“In the US, there may be some limitations, based on insurance reimbursement, on which device might be used in which scenario, but data suggests that even as standalone procedures, and sometimes even in phakic patients, these procedures can be safe and effective at controlling IOP and reducing medication burden [thus being cost-effective],” commented Dr Baartman.
STANDARD OF CARE?
So is MIGS the future standard of care, in a healthcare culture driven by making surgery as minimally invasive as possible, against the background of ever-growing demand, a shortage of surgeons and the projected global rise of glaucoma cases?
Yes, according to Dr Bellucci: “I believe MIGS will be the standard of care if the cost problems will be solved. It is important to understand that with MIGS, glaucoma surgery is transitioning from a single event into a surgical protocol that can include two or three surgeries. By decreasing IOP in steps we will probably avoid the complications associated with sudden IOP drop, and will be able to titrate surgery over the entire life span of the patient. In addition, the short surgical times will allow more surgeries, thus facing the increase in the demand for glaucoma care due to the increased life span of an increasingly older European population.”
Dr Baartman also agrees. “Yes, I believe it may be the future standard of care. As mentioned above, I believe we have seen a shift in how we think about, talk about, and manage glaucoma patients, with an emphasis on earlier procedural treatment. Rarely do I see patients in our referral centre on four bottles of ineffective medications to control IOP, and instead, I am seeing these referrals at two bottles and need for additional control with MIGS or SLT. I have appreciated this practice pattern change because it limits drops burden for patients and preserves optionality, both in additional surgical procedures and available medications should additional control be necessary in the future.
“MIGS also has the benefit of being a class of treatments that are generally straightforward in postoperative management and low in complication profile, such that they can often have fewer postoperative visits and return more quickly to their routine glaucoma follow-up schedule.”
There is also continuing innovation in the field of MIGS, which should further increase its usage and potential. “I am looking forward to an expanded arsenal of MIGS treatment options including devices deploying greater numbers of stents (iStent infinite, Glaukos) and even additional subconjunctival MIGS devices in the pipeline (PreserFlo, Santen). I also believe the melding of medication and procedure in the form of sustained drug delivery is a future category of its own we can be excited about,” concluded Dr Baartman.