The US Food and Drug Administration (FDA) has approved Allergan’s drug-releasing implant, Durysta, for administration within the cavities of the eye to reduce intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension.
Measuring just 0.2mm by 1mm, the tiny polyester plug gradually releases bimatoprost, a drug already found in eye drops often prescribed to treat the condition. However, more than seven in ten patients fail to use their drops properly — reducing the drug’s benefit — while others struggle with side-effects.
It is hoped the implant will improve treatment and slow down progression of the disease.
In glaucoma, there is damage to the optic nerve (which sends information from the eye to the brain for processing into images), leading to a loss of vision.
Most common in people in their 70s and 80s, it is usually caused by fluid building up in the front part of the eye, due to either too much of it being made or it not draining away properly. This increases the pressure in the eye and squeezes the optic nerve, killing some of the fibers it needs to transmit information to the brain.
The damage can’t be reversed, but treatment to lower the pressure can slow or prevent further loss of vision.
Eye drops are the mainstay of treatment and need to be administered up to four times a day. They lower the pressure by reducing the amount of fluid the eye makes, or by making it easier to drain away.
However, a 2017 study from the University of Sao Paulo in Brazil, in which people with glaucoma were watched as they put in their drops, found that 72 per cent struggled to administer them properly.
Other research has shown that many people simply forget to put in their drops or don’t take them because of side-effects such as eye irritation.
The new Durysta implant, made by Allergan, is loaded into a pen-like applicator before being injected just below the cornea, the eye’s protective outer layer, by a doctor. Nestled against the iris, the colored part of the eye, the implant slowly dissolves over time, releasing bimatoprost as it does so.
Bimatoprost works by mimicking the activity of prostaglandins, naturally occurring compounds that help fluid drain out of the eye.
In two trials involving more than 1,100 patients, the implant cut the pressure inside the eye by up to a third over three months — similar to regular eye drops. Side-effects included blurred vision, eye pain and headaches. In rare cases, the implant can damage the cornea, leading to permanent loss of vision.
The implant’s benefits last around eight months. A patient can currently only have one fitted, but it is hoped that, in future, they will be able to have replacements when needed. The device was cleared for use in the U.S. earlier this year and Allergan plans to apply for approval in other countries..