Glaucoma and Compliance with Therapy: Strategies for and Barriers to Success
Glaucoma is the leading cause of blindness worldwide, affecting more than 70 million people. Early and consistent therapy is crucial for the preservation of remaining vision in patients with the disease. However, there are many factors that can lower compliance rates and cause non-adherence to treatment plans, which has reported rates of 30-80%. 
Beliefs and Lack of Knowledge about Glaucoma and Treatment Methods
Many studies have found that patients diagnosed with glaucoma may not truly understand the potential for severe, vision-threatening consequences with inadequately treated disease, and the potential benefits of adherence to the treatment plan developed by the ophthalmologist.      As a largely asymptomatic disease, it may be difficult for patients to appreciate disease progression with non-adherence or conversely preservation with appropriate use of therapy. This leads to a lack of trust and faith in the treating physician, which can increase the likelihood that a patient will be non-adherent to their medications.   
The low level of knowledge by the general public about the manifestations of glaucoma and the threat of vision loss that comes along with the disease also plays an important role in the low rates of adherence that is seen among these patients. This also can be attributed to poor health literacy, which is seen among patients dealing with a wide array of conditions, but especially glaucoma patients.   
Difficulty with Obtaining and Administering Eye Drops
Another important factor that affects adherence rates is the difficulty that is reported by patients when trying to obtain glaucoma medications. Cost is a significant barrier to accessing care for many patients, and this has been seen in multiple settings and patient populations.     Even when patients are able to obtain their medications, many experience difficulties with administering drops. This can be attributed to difficulties reading the print on the bottle, forgetfulness, the effects of other chronic conditions increasing the difficulty of managing glaucoma,    and difficulties with applying the correct amount of force and having adequate visual acuity and dexterity to only get the number of drops desired,   among other factors.
Strategies and Interventions to Increase Adherence
There have been many studies into interventions and strategies that have been shown to improve adherence to a glaucoma treatment plan. Most of these work to specifically address barriers discussed above. For example, incorporating discussions of beliefs about glaucoma and treatment methods will help to address misinterpretations of the disease and also help to build trust in the patient-physician relationship, especially when patient-centered communication is used, leaving the patient feeling like an active participant in their own healthcare.  
Another method to improve adherence involves improving health literacy as a whole in this patient population, especially among those newly diagnosed or those struggling with non-compliance. This has been completed using videos discussing glaucoma, including the anatomy of the eye and examples of what vision loss in glaucoma looks like, and also the potential treatment options available and instructions for their use.  
Difficulties with medication bottles, whether reading the print or just forgetting to use them, are common and multiple interventions have been successful in combatting this. Some options include personalized mail and phone call reminders of appointments and medication administration times. One important development of note in this area involves the development of the EyePhone© App, which provides notifications and reminders of current medical treatment, and it has been found to significantly increase glaucoma treatment adherence and improve quality of life.
Another issue that can be addressed through upcoming technological interventions is the struggle of administering only one drop at a time. A contributing factor is the significant variability that has been noted between bottles in terms of the amount of force needed to produce one drop. This can lead to multiple drops being used, and thus early exhaustion of drop supply, which has been found to be fairly common in a pilot study of glaucoma patients. A team from University of California – San Diego is working to establish the use of a smart electronic eyedrop bottle that measures the number of single- and multiple-drop deliveries and provides a potential solution for remote glaucoma eyedrop monitoring. Another promising development in this space is the use of a nose-pivoted drop delivery device, which was found to improve eye drop delivery success, reduce bottle tip contact, and decrease the number of eye drops wasted, leaving it strongly preferred by patients over a traditional drop delivery system.
Lastly, it is important to mention a shift in treatment protocol for glaucoma away from the medication-first model to the early and repeated use of selective laser trabeculoplasty (SLT). SLT involves the use of a Nd:YAG laser to improve drainage through the trabecular meshwork, thus lowering intraocular pressure (IOP). In a recent systematic review, SLT was proven to be effective at lowering IOP with high success rates, even after a single treatment, and has the added benefit of being independent of a patient’s capacity to remain compliant with a treatment plan. The Clarifying the Optimal Application of SLT Therapy (COAST) Trial is being initiated to determine the utility of low-energy SLT conducted annually as primary treatment for mild to moderate open angle glaucoma.
In summary, treatment non-adherence is frequently seen among glaucoma patients, and is associated with lack of understanding of the threat to vision from glaucoma, mistrust of the treatment plan and the potential benefits of adhering to it, and difficulty affording and using drops. There are many interventions to address these barriers, including “smart” eyedrop bottles to provide remote monitoring of adherence and proper usage of drops, smartphone apps to give personalized reminders of when to use medication, and educational videos to improve health literacy and knowledge about glaucoma and dispel common misconceptions about the disease. Laser treatments are increasingly being advocated as an alternative first line therapy where available, and future therapeutics will likely also consider the difficulties and barriers to frequent eyedrop administration.
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