EyeWorld Asia-Pacific March 2016 Issue

March 2016 Glaucoma treatment 28 EWAP SECONDARY FEATURE How doctors in the Asia-Pacific approach glaucoma treatment by Ivan Goldberg, MD, Shamira Perera, MD, and Wang Ningli, MD Experts discuss their own approaches to glaucoma treatment, considering duration, the wide variety of glaucoma medications, and patient adherence Ivan Goldberg, MD On ‘Extending the duration of glaucoma medications’ Medical therapy for reduction of intraocular pressure (IOP) only succeeds if the active agent reaches its target receptor(s) at an appropriate concentration and with the required regularity. With the current need for physical instillation of eye drops, this necessitates patient or patient–carer involvement in regular accurate administration over the long-term. Adherence to and persistence with medical therapy is an ongoing challenge for all patients receiving often life-long treatments for chronic, incurable conditions, particularly those that do not elicit immediate warning symptoms of disease progression or disease under-treatment. Glaucoma is a classic model for this situation. To exacerbate this status quo, instillation of eye drops can fall victim to physical barriers (dyscompliance) such as tremor, arthritis (particularly of shoulder, arm, neck, and fingers) and weakness. Hence, there is active research under way into other methods of drug delivery for current (as well as future) IOP-lowering drugs, methods which, if effective, would “remove the patient from the treatment program”, side-stepping patient adherence, persistence, and dyscompliance challenges. As Drs. Kahook, Lewis, and Novack have explained, any considered alternative drug delivery system needs to demonstrate several attributes. Firstly, effectiveness: with different rates of drug penetration to the receptors compared with eye drops (pharmacodynamics), dose response curves change for each of the various medication classes. Secondly, tolerability: as well as the drug molecule(s) shown to be acceptable, so must be any delivery device or carrier, whether it be a punctal plug, a conjunctival ring or an injected depot. Thirdly, reliability: will the device (if there is one) be retained? What is its risk of dislocation? Fourthly, sustainability: the period over which the new delivery system is effective is critical to delivery of eye care, determining frequency of visits. And finally, safety: intraocular injected depots clearly pose a greater invasiveness than subconjunctival, which in turn is more invasive than externally fitted hardware (plugs and rings). When all these considerations allow commercial availability of an alternative drug delivery system, how to incorporate their implementation into the practical day-to-day running of clinics, offices, and practices will require adjustments that could be major for patient service. Given the difficulties posed by current medical treatment regimens, it is exciting to contemplate these challenges. On ‘Navigating through the Sea of Glaucoma Medications’ Once physical barriers have been addressed that may otherwise interfere with successful self- instillation of drops, non-adherence to and failure to persist with glaucoma medications are the major hurdles for long-term medical management success. Minimizing the inconvenience of the treatment program (mainly by decreasing the number of bottles used and by reducing the frequency of instillation) plays a significant role to encourage adherence. Hence, once-daily beta blockers and/or prostaglandin analogues have assumed first- and secondline treatment options if there are no contraindications and they prove effective and tolerated. Hence, too, the popularity of fixed-dose combinations, that decrease both the number of bottles used and the number of dropping times required as well as halving the dose-exposure of the ocular surface to preservatives. Availability of these fixed-dose combinations differs in various countries; outside the U.S., most of our patients have access to prostaglandin–beta- blocker, carbonic anhydrase– beta-blocker, alpha-agonist–beta- blocker and now, more recently, carbonic anhydrase–alpha-agonist combinations. That means for suitable patients, access to two agents in one bottle once daily and up to four agents in two bottles, one once daily, the other twice daily. This streamlining of the number of bottles required also reduces regular medication costs. If costs are a concern for a patient, even if a health system subsidizes them to some extent, cheaper alternatives like generic products might offer savings. However, as there are differences in the chemical composition of generic solutions compared with name brands, as well as differences in bottle make-up and structure, individual patients might respond differently to one of these alternatives. They cannot be assumed to be identical in efficacy or tolerability. Selective laser trabeculoplasty (SLT) remains an option for patients at every stage of non-incisional eye pressure reduction treatment: at initiation and whenever a second, third or even fourth agent are being considered. Choices available for an continued on page 30