Cutting Edge Glaucoma - Issue 2

52 • CUTTING EDGE - GLAUCOMA containing a reservoir of travoprost capped by a membrane to allow continuous but gradual release. Just like the same manufacturer’s iStent and iStent inject trabecular microbypass stent, iDose is surgically inserted into the trabecular meshwork and is supposed to be kept in place by a rather sharp scleral anchor at the peak of the small device. According to a press release by Glaukos, iDose was tested in a 154-patient, multicenter, randomized, double-blind phase II trial that was designed to evaluate two different versions of the iDose delivery system with two differ- ent elution rates of the IOP-lowering drug travoprost. Eyes in the control group received topical 0.5% timolol ophthalmic solution. The primary efficacy endpoint of the study was noninferiority to topical timolol. The phase II results were from an available interim cohort of 74 patients. An iDose travoprost was implanted into 49 of them, while 25 patients were assigned to the timolol comparator group. Average IOP reductions observed in this cohort of implant patients during the first 12 months showed that iDose Travoprost achieved an approximate 30% reduction in mean IOP vs. baseline IOP. After 12 months, the number of glaucoma medications ranged on average from 0.54 to 0.56 in the fast and slow iDose Travoprost elution implant groups, respectively. In the control group treated with topical timolol, the mean number of medications was 0.72. There were reportedly no adverse events of hyperemia to date in either elution group (Glaukos press release, January 10, 2018). While intraocular drug delivery systems hold promise for overcoming the adherence problem, it remains to be seen if patients are willing to undergo repeated injections. Besides concern about the repeated interventions, economic factors will probably figure prominently in the acceptance or rejection of this new form of treatment. In a recent survey in the U.S., 24% of participating glaucoma patients were ready to use such a new delivery system when the annual cost was $500. Paying $1000 per year reduced the proportion of patients willing to give intraocular drug depots a try to 18%. Recommendation by an ophthalmologist increased the willingness to use such a system by 6–12%; patients of an advanced age (65 years and older) and individuals with a low income were more likely to remain on eye drops [32]. Minimally Invasive Glaucoma Surgery Over the last several years, glaucoma surgery has seen the addition of a number of procedures with a minimally invasive approach. The termMIGS (minimally invasive glaucoma surgery, sometimes termed micro-incisional glaucoma surgery) refers to a group of surgical procedures that have five distinct characteristics in common: a surgical approach that in most cases is ab interno (a new device, InnFocus, is inserted by an external approach) through a clear corneal incision which spares the conjunctiva from incision; does minimal damage to target tissue such as the trabecular meshwork; presents an IOP reduction efficacy that makes the technique a viable alternative to other more established procedures; has a good safety record that reduces the risk of serious com- plications; and facilitates a rapid recovery with minimal impact on the patient’s quality of life [40]. Since MIGS was the subject of a recent major review in this journal [2], we will only outline a few general principles and share some significant data here. Basically, there are three groups of minimally incisional interventions: procedures that target the trabecular outflow; those that