BLOG: Sustained-release glaucoma devices a viable alternative to drops
We are fortunate to have many options for the treatment of glaucoma, including several classes of glaucoma medications, selective laser trabeculoplasty and minimally invasive glaucoma surgery.
By far, the most common starting point for patients is topical drops. We have always known that perfect compliance with drop regimens is challenging, and the data on this front is actually quite discouraging. A retrospective analysis of more than 1,200 newly diagnosed patients in a managed health care plan found that even in the first year on topical IOP-lowering therapy, about a third of patients never refilled their prescription or had poor adherence to the drop regimen — only 20% could be classified as having “persistently good adherence” (Newman-Casey et al.).
There are many reasons patients fail to comply with drops, including cost, physical or cognitive limitations, and complexity of the regimen. Sustained-release (SR) technologies hold great potential to reduce the burden on patients to remember their drop regimen and actually instill the drops correctly every day. These technologies could save patients money and reduce the preservative load on the ocular surface as well.
To date, Durysta (bimatoprost intracameral implant, Allergan) is the only SR technology approved in the U.S. The implant is injected by an ophthalmologist as a standalone procedure and provides IOP-lowering effects for several months before dissolving. Studies have shown that it can lower IOP in patients with glaucoma or ocular hypertension by up to 33% from baseline (Medeiros et al., Bacharach et al.).
A few surgeons in my area are using this implant, although, so far, they have reserved it largely for patients who have already shown they can tolerate and will respond to a topical prostaglandin analogue but are noncompliant and/or have difficulty squeezing the bottle due to rheumatoid arthritis or other conditions. A challenge with Durysta is that it currently is only approved for a single injection, rather than the repeat injections that would be needed over time to permanently eliminate one or more topical medications.
In following these patients after implantation, the tiny (1 mm in length), rodlike Durysta implant is visible in the anterior chamber. I typically see these patients at 1 week to monitor for complications (conjunctival hyperemia being the most common), then again after 3 to 4 months to determine whether the implant is still functioning. Once that pressure starts to climb a little bit, we reinitiate drops or determine another course of action to maintain IOP control.
There are several other SR technologies in development, including drug-eluting rings, punctum plugs, contact lenses and other implantable devices. The furthest along in the development pipeline is iDose TR (sustained-release travoprost implant, Glaukos), which is in phase 3 clinical trials. The device is designed to stay in the eye for at least 1 year. According to company press releases, IOP reductions of 32% to 33% from baseline have been achieved through 12 months, and the device has been shown to have a good safety profile through 36 months. Additional results are expected this year.
While it is helpful to stay abreast of clinical trial news, our patients really cannot take advantage of these technologies until they are cleared by the FDA. That is when it becomes most important to dive into what the published data show and what is available in your area. It is wonderful to know that we have more options on the horizon, because the need for sustained-release technologies is so great.
References:
- Bacharach J, et al. Drugs. 2021;doi:10.1007/s40265-021-01624-9.
- Medeiros FA, et al. Ophthalmology. 2020;doi:10.1016/j.ophtha.2020.06.018.
- Newman-Casey PA, et al. Ophthalmology. 2015;doi:10.1016/j.ophtha.2015.06.039.
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