Increasingly glaucoma subspecialist DR BRETT DRURY and his colleagues are looking beyond medication towards minimally invasive procedures that offer downstream benefits for patients when it comes to the health of their ocular surface.
Every now and then, a patient visits Dr Brett Drury’s rooms and delivers a stark reminder of the consequences of eye drop-driven glaucoma management.
For the Gold Coast anterior segment subspecialist, who undertook a glaucoma fellowship in the UK as minimally invasive glaucoma surgery (MIGS) took root, around 25% of all his cases involve glaucoma. Many of those that require medical therapy are treating their condition with prostaglandin analogs, a mainstay first-line medication option for primary open-angle glaucoma (POAG) and ocular hypertension (OHT).
While he’s cognisant of the “near-universal” ocular surface side effects that come with this approach, it often isn’t until someone returns after unilateral glaucoma surgery that the reality of what patients endure hits home.
“You only have to have one or two patients that become medication-free in one eye post-operatively to see the difference between an eye that’s surgically controlled and one that is medically treated for glaucoma,” says Dr Drury, who practises privately at Outlook Eye Specialists.
“I saw someone like this yesterday who I operated on maybe 12 months ago. In one eye he had surgery for glaucoma and it now looks completely different to the
medication-treated eye. There’s no redness, no periocular pigmentation, no lid margin inflammation.
“Sometimes we lose sight of what people’s eyes normally look like without medication, and, in particular, the longer-term outcomes of prostaglandin analogs are very under-appreciated, to the point where I tend to avoid those medications in younger patients, just because of the sheer number of years they’ll need to be on them.”
Studies show ocular surface disease prevalence in glaucoma can be up to 59%,1 and symptom manifestation has been documented in up to 74% of glaucoma sufferers.2
Dr Drury agrees that ocular surface side effects have probably been “an unfairly accepted part of the deal” for medicated glaucoma patients.
But with a more elegant surgical toolkit, that’s changing.
He notes ophthalmologists are increasingly responding to evidence that selective laser trabeculoplasty (SLT) is on par, if not more effective, as a first-line glaucoma treatment compared with medical therapy. There’s also the ‘interventional glaucoma’ movement that promotes a proactive approach to management, focusing on earlier diagnosis and more aggressive treatments in the initial stages.
Dr Drury remembers the start of his career when the decision was often binary – eye drops and SLT for lower level disease, or a major leap to trabeculectomy.
Now, with more ‘middle ground’ surgical interventions like the iStent infinite and Hydrus Microstent, it’s allowing him and other ophthalmologists to not only provide more consistent lowering of intraocular pressure (IOP) in mild to moderate cases, but to ease patients’ medication burden and restore the quality of their ocular surface.
“I also don’t think medicated glaucoma patients notice the prostaglandin orbitopathy happening. I think they might just associate that with ageing changes, which is just not true,” Dr Drury says.
“Chronic conjunctival injection, tightening of the upper lids, deepening of the upper lid sulcus and periocular pigmentation are very common in long term medically-treated glaucoma patients, particularly with prostaglandin analogues.”
The discomfort. The diminished quality-of-life. These are heavy prices to pay, but are often worth it considering the huge downside of rampant glaucoma.
Treatment adherence is another burden to carry. Many of Dr Drury’s patients will have one or two drops to instil once or twice a day. But whether that actually happens is another story.
“I think we’d all like to believe that adherence is very good, but time and again the research shows that’s not the reality,” he says.
“Patients are immediately faced with redness, stinging, irritation, worsening of their dry eye. The benefits of treating a chronic disease appropriately are sometimes a long way off, so it’s not hard to see why adherence is not 100%.”
So with new technologies, a deeper pool of evidence and a mindset shift towards interventional glaucoma, where does that leave ophthalmologists with their glaucoma patients?
The surgical equation
For Dr Drury, trabecular bypass MIGS first enters the conversation when someone with medically treated glaucoma is undergoing cataract surgery. Often, it provides a window to address three issues at once: their cataract, glaucoma, and dry eye.
“It’s a missed opportunity if you don’t combine MIGS at the time of cataract surgery in these patients.”
It’s also on the table for anyone becoming intolerant of eye drops or those with mild disease whose drops are proving ineffective.
Plus, there’s a smaller cohort with advanced glaucoma for whom he’s trying to avoid more major surgeries due to their age, frailty, or other reasons.
“Someone I’d consider on maximal medical therapy with an IOP above target, would be considered for surgical glaucoma management in my clinic, as well as those who, despite having seemingly well controlled pressure, show changes in their structural and functional parameters – those are the two classic scenarios.”
Dr Drury was conducting his glaucoma fellowship in Manchester in 2017 roughly around the same time as Glaukos’ first version of the iStent, that opened the MIGS category, was gaining widespread use.
Over the years, the procedure has demonstrated significant improvements in ocular surface disease and quality-of-life combined with cataract surgery, including reduced Ocular Surface Disease Index (OSDI) scores and medication use.3,4
In terms of IOP, a subgroup analysis of the Collaborative Initial Glaucoma Treatment Study demonstrated that over eight years of follow-up, patients with greater visual field loss at baseline who were treated with surgery experienced less visual field loss versus those treated with medications.5
In 2024, the Australian Therapeutic Goods Administration approved Glaukos’s fourth generation iStent infinite, offering several upgrades.
The biggest of those include a new three-stent procedure – up from two – allowing the surgeon to inject stents across a span of up to approximately six clock hours around Schlemm’s canal. Plus, surgeons now get an unlimited number of delivery attempts – upgraded from four.
Dr Drury expects improved outcomes. Surgeons can be more particular about their placement.
“Particularly for someone starting out, because if one stent is malpositioned, then the other two may still work, offering a greater chance of success,” he says, noting that optimal stent placement is the next frontier in MIGS research.
“The infinite attempts at injecting probably takes the anxiety out for some people, especially if they’re new to the learning curve, because they can be confident that if they’re not happy with the position, they can take it back out and reload. You’ll end up with better placement, because people don’t have to accept when it’s not placed in the perfect spot due to having no shots left.”
Aside from these surgical behavioural changes, the data also paints a positive picture.
In a pivotal trial of the iStent platform implanted at the time of cataract surgery, it was observed that 84% Of patients were medication-free at 23 months.6 Plus, an independent study on iStent showed that after five years, on average, patients maintained a 40% reduction in IOP and a 71% reduction in medication burden.7 And a third study showed a 72% reduction of patients with severe ocular surface disease symptoms such as dry eye through three months post-operatively.8
It computes with what Dr Drury sees in his clinic: “If someone has a surgically controlled IOP with no medication requirement, I’m more confident that person is going to lose less visual field over time than someone who has the same pressure with medication requirement.”
But if reduced IOP is the number one objective, becoming medication-free is a close second.
“It’s an immediate and a big improvement from the patient perspective,” he adds.
“I think sometimes the happiest patients are ones that I’m referred and can perform simple, safe procedures that allow them to be medication-free – that’s actually one of the most rewarding things in glaucoma: lifting that medication burden and seeing the eye recover.”
References
1. Leung EW, Medeiros FA, Weinreb RN. Prevalence of ocular surface disease in glaucoma patients. J Glaucoma. 2008;17(5):350–5.59%
2. Mylla Boso AL, Gasperi E, Fernandes L, et al. Impact of ocular surface disease treatment in patients with glaucoma. Clin Ophthalmol. 2020; 14:103–11.
3. Schweitzer JA, Hauser WH, Ibach M, et al. Prospective Interventional Cohort Study of Ocular Surface Disease Changes in Eyes After Trabecular Micro-Bypass Stent(s) Implantation (iStent or iStent inject) with Phacoemulsification. Ophthalmol Ther. 2020 Dec;9(4):941-953.
4. Jones L, Maes N, Qidwai U, et al. Impact of minimally invasive glaucoma surgery on the ocular surface and quality of life in patients with glaucoma. Ther Adv Ophthalmol. 2023 Feb 13
5. Musch DC, Gillespie BW, Lichter PR, et al. Visual field progression in the Collaborative Initial Glaucoma Treatment Study: the impact of treatment and other baseline factors. Ophthalmology. 2009;116(2):200–207
6. https://www.aaojournal.org/article/S0161-6420(18)31990-0/fulltext
7. https://link.springer.com/article/10.1007/s12325-021-02039-4
8. Schweitzer JA, Hauser WH, Ibach M, et al. Prospective interventional cohort study of ocular surface disease changes in eyes after trabecular micro-bypass stent(s) implantation (iStent or iStent inject) with phacoemulsification. Ophthalmol Ther. 2020;9(4):941-953.)
