Glaucoma: Thinking Outside the OR

Historically, glaucoma patients were maintained for as long as possible on topical medications. If their disease continued to progress on maximal medical therapy, trabeculectomy surgery or a tube shunt were considered. A growing body of research on laser treatment and minimally-invasive glaucoma surgery (MIGS) has already upended traditional protocols, pushing invasive surgery further down the line. For example, we have learned from long-term analyses of the LiGHT (1) and HORIZON (2) trials that laser or surgical interventions can provide better protection of visual field than medical control, even when both strategies achieve the same level of IOP. At the 2024 American Academy of Ophthalmology (AAO) meeting, an analysis of visual field data from the full LiGHT trial showed a 29 percent reduction in the rate of visual field loss with a laser-first vs a drops-first approach despite careful treatment to the same IOPs (3).

New laser advancements just over the horizon are expected to continue this trend of thinking outside the operating room for our patients who are not well controlled and/or not good candidates for surgery.

My approach
 

My personal approach to glaucoma management starts with setting a target pressure for each individual patient based upon their baseline IOP and disease severity, and choosing an intervention (topical drops, laser, or surgery) to achieve that target pressure. Ever since we realized that selective laser trabeculoplasty (SLT) is just as effective at hitting target IOP and more cost-effective than drops (4), my first-line intervention has almost always been SLT. Recent evidence suggests that even if patients have been managed on drops for several years, they still respond well to SLT (5). A repeat SLT is usually my next choice, especially if the patient initially had a good result. After that, a prostaglandin analogue drop would typically be my next intervention.

If at any point the patient develops any visually significant cataract, I would always prefer to offer them phacoemulsification plus MIGS. From the control (phaco only) arms of several MIGS device studies, we know that cataract extraction, by itself, is associated with significant reductions in IOP (6,7,8). Because cataract surgery is a one-time opportunity to also treat glaucoma when you are already entering the eye and exposing it to the risks of surgery, I believe there is a powerful argument for performing phaco+MIGS in any patient with glaucoma undergoing cataract surgery, whether controlled or not.

No matter which IOP-lowering intervention is selected, it must always be evaluated to determine if a) it was successful in reaching the target IOP and b) the established target was sufficient to prevent further optic nerve damage and visual field loss. If we can’t answer “yes” to both questions, the risks and benefits of another intervention have to be weighed.

An unmet need
 

In an ideal world, a couple of SLT laser treatments, phaco+MIGS, and (maybe) one medication would keep our patients’ IOP well controlled and glaucoma progression in check for the rest of their lives. Only the worst cases would ever proceed to tube or trab surgery. Unfortunately, there are many cases that don’t fit neatly into this ideal trajectory, including several large categories of patients who are progressing despite our best efforts, and for whom we currently don’t have great options.

Among these are patients who would benefit from MIGS but are already pseudophakic or haven’t yet developed a cataract. It may be the case that the surgeon or patient doesn’t want to accept the risk (or, in some markets, the out-of-pocket cost) of a standalone MIGS surgery. There are quite a few patients who can’t add another drop – or can’t use most of our available topical medications at all – due to allergies or reactions to the preservatives. This is especially true in the US, where there are fewer preservative-free glaucoma medications available. Finally, we also have a lot of patients who are poor candidates for any surgery due to very advanced age or fragile health, fear of incisional surgery, or difficulty adhering to the intensive follow-up required after conventional surgery due to geographic distance or other medical conditions.

In all these cases, a new incision-free, ab externo laser procedure performed with a femtosecond laser in the clinic or laser suite could be very beneficial in reducing IOP with lower risk. Femtosecond laser image-guided high-precision trabeculotomy (FLIGHT), performed with the ViaLuxe laser system (ViaLase), creates one or more apertures (drainage channels) in the trabecular meshwork (TM), without the need to open up the eye (Figure 1). An intuitive patient interface with touchscreen displays real-time, high-resolution imaging of the trabecular meshwork and Schlemm’s canal with micron precision. This is the first time that a femtosecond laser – already a very mature technology in other areas of ophthalmology – is being applied to glaucoma and it is already delivering surgery-like results. In a published two-year study, 82 percent of eyes achieved a >20 percent reduction and 53 percent of eyes achieved a >25 percent reduction in IOP following FLIGHT treatment (9). Further, the FLIGHT channels remained clearly visible at 24 months under gonioscopic and AS-OCT observation, with no evidence of closure or scarring.

What’s most exciting about FLIGHT is the opportunity to reduce risk. All of medicine is essentially a risk-benefit analysis. Could we lower IOP with filtering surgery? Of course we could. But any penetrating surgical procedure inherently involves the risk of bleeding or infection. With a slow-moving disease like glaucoma, in which patients present with such a wide range of risk factors and severity levels, the benefits of filtering surgery are not always worth the risks. For a relatively fit, healthy 90-year-old who is still driving, for example, I would strongly prefer to avoid tube or bleb-forming surgery. But I also don’t want that patient to lose vision, because I know her quality of life will suffer. If laser and medical therapy have not been successful in reducing her IOP below 30 mmHg, there may not be another viable alternative than to accept standard surgery with all its risks of failure or complications.

Patients like this 90-year-old – and so many others who are not good candidates for invasive surgery or yet more drops – would really benefit from an outpatient procedure that could achieve good IOP-lowering while being less invasive and less burdensome. I’m looking forward to seeing our non-surgical options expand in the future.