Cutting Edge Glaucoma - Issue 2

MINIATURIZATION IN GLAUCOMA MONITORING AND TREATMENT: A REVIEW OF NEW TECHNOLOGIES THAT REQUIRE... • 51  adherence [28]. In South Korea, one-third of the patients suffering from glaucoma were described as nonadherent, and the risk of failure to comply with the ophthalmologist’s recommendations was 1.466 times greater for males than for females, and 1.328-fold greater when the daily number of administrations was increased [14]. In Ethiopia, less than half of the glaucoma patients were considered nonadherent [22]. Nonadherence to pharmacological glaucoma therapy is a global issue. The famous quote by the legendary U.S. Surgeon General C. Everett Koop that drugs don’t work in patients who do not take them fittingly describes a situation that is frustrating to many ophthalmologists. A way out of this dilemma is offered by sustained-release drug-delivery systems that are injected every few months by an ophthalmologist and which reduce the need for patient cooperation practically to zero. A number of such systems have been in clinical practice for some time; they contain steroids to treat different inflammatory processes. In addition to these previ- ously established depots, several sustained-release systems for glaucoma therapy are currently investigational; at the time of writing none of these systems are FDA approved (a pilocarpine- releasing system named Ocusert is just a historic footnote, and was not injected into the eye but rather inserted under the lid, with a considerable degree of irritation in some patients). A sus- tained-release system that seems promising even though it does not meet the definition of minia- turization is the bimatoprost ocular ring; its long-term safety and efficacy have been reported by Brandt et al . [4]. Bimatoprost SR is a sustained-release system developed by Allergan that consists of a bio- degradable implant and is injected into the anterior chamber with a 28-gauge applicator. In a 6-month phase I/II clinical trial, 75 glaucoma patients were administered Bimatoprost SR (6 μg, 10 μg, 15 μg, or 20 μg) intracamerally in the study eye, with the fellow eye receiving topical bimatoprost 0.03% once daily. The IOP reduction from baseline to week 16 in the study eyes was 7.2, 7.4, 8.1, and 9.5 mmHg with the 6-μg, 10-μg, 15-μg, and 20-μg dose strengths in the implant, respectively. The fellow eyes treated with topical bimatoprost showed an average IOP reduction of 8.4 mmHg. When adverse events occured, they tended to appear in study eyes within 2 days after the injection; in general they were transient. Immediately after the injection, the prevalence of conjunctival hyperemia was 24% in the study group, followed in prevalence by foreign body sensation (16%) and eye pain (13.3%). Given that local complications can be a factor in reduced adherence, it seems remarkable that later-onset conjunctival hyperemia was more frequent in eyes treated topically than in those that had received bimatoprost SR (17.3% vs 6.7% of eyes). Asked how likely they would be to recommend the procedure of receiving the bimatoprost implant by intraocular injection, 83% answered likely or very likely [19]. Another prostaglandin, travoprost, is injected intracamerally as a depot with the Envisia ENV515. This is a biodegradable polymer based on a new technology for nano- and micropar- ticle formation. In a phase 2a open-label study over 28 days, an IOP reduction comparable to once-daily topical travoprost was achieved (relevant data were presented at AAO 2017; see the Acknowledgements section). Slightly more invasive than just an injection is the procedure to place a depot drug-delivery system by the name of iDose in the appropriate position. iDose is a 1.8 x 0.5-mm titanium implant