Describing his wish list for this GAP therapy, Dr. Kahook said it should be patient-independent, physician-administered and monitored, and it should have a safety profile equal to or better than prostaglandin analogue topical therapy, a long duration of action (at least 6 months), and be repeatable over the patient’s lifetime.
GAP platforms in development include punctal plugs, subconjunctival depot injections, ocular surface inserts, and intraocular injectable depots. Reviewing the pros and cons of these approaches based on current iterations, Dr. Kahook concluded that none fulfills all of his wish list criteria.
“They are all able to provide 100% adherence and are patient-independent and physician-administered,” Dr. Kahook said. “Safety is an issue with the more invasive techniques, however, and long duration of efficacy is one of the biggest concerns.”
Regarding punctal plugs, the non-invasive nature of this approach is an advantage. However, retention has been an issue for most devices in this space, and based on publicly available data, punctal plug delivery of glaucoma medications has been less effective than topical timolol for lowering intraocular pressure (IOP).
“There are also questions about the long-term safety of a punctal plug,” Dr. Kahook said. “Considering all of these issues, this approach is not a perfect solution.”
The category of ocular surface devices includes the bimatoprost-laden silicone ocular surface ring (Helios, Allergan) that was shown in a phase II trial to have good retention and sustained IOP-lowering activity over 6 months.
“Discomfort does not seem to be a big issue because patients acclimate to the ring after a few days,” Dr. Kahook said. “An advantage of this device compared with punctal plugs is that patients will realize if the ocular surface ring falls out. A big unanswered question, however, is whether it can be as effective as a topical prostaglandin analogue.”