Compliance refers to the patient’s fulfilling the instructions given by the physician. Compliance is a comprehensive term that can be applied to prescribed personal behavior (e.g., diet, exercise), avoidance (e.g., alcohol), and medication. With regard to medications, it is inclusive of all steps involved from purchase through administration.

Adherence is an alternative term for describing how closely the patient follows instructions.

Compliance and adherence rates differ based on patient-related factors (e.g., age, education, ability to afford the treatment), disease duration (e.g., acute vs. chronic), disease severity (e.g., early vs. advanced), disease impact (e.g., asymptomatic vs. life threatening), mode of treatment (e.g., oral, parenteral, behavioral), and complexity of regimen (e.g., once a day vs. many times daily).⁸ It is the result of complex, multi-factorial behaviors. It is also affected by fear of side effects, individual psychosocial variables, and physician–patient relationship.⁸

Persistence is the term used for long-term therapies when emphasis is being placed on the duration of compliance or adherence: compliance and adherence enable persistency. Compliance, adherence, and persistence can be total, partial, erratic, or nil.

Gurwitz et al.⁹ found that of 2,440 Medicaid patients over 65 years of age, more than 23% were nonadherent to prescribed medication. This calculation was based on the number of prescriptions filled and the computed days without medication. Nordstrom et al.,¹⁰ using data from health insurance claims, found that nearly half of Medicaid patients were totally nonadherent to all topical ocular hypotensive medications by 6 months, and only 37% of patients were refilling their prescriptions at 3 years.

The presumption is that with better persistency there will be less damage from disease.¹¹

Urquhart¹² has developed a classification of where and how the failure in medication dosing occurs. He states that when a medication has not worked as expected, the potential mechanism for its failure falls among three categories:

Compliance with patching has always been thought to be a major factor in the success of occlusion therapy for amblyopia.¹³ Similar to findings in other conditions, (weight loss, other types of physical rehabilitation), it has been shown by Gottlob et al.¹⁴ that the main changes in visual acuity occur in the first 5 weeks of patching. However, the exact amount of compliance with occlusion regimens is almost impossible to assess by researchers; even with hospitalized patients the tendency to “cheat,” and the ability to do so, is very real, and the fact that the effect of occlusion is inversely related to age¹⁵ complicates the analysis.

Why is compliance with amblyopia therapy in children so difficult? Probably because (a) parents are required to treat the child, and (b) the parents are therefore subject (and susceptible) to the stress of the child’s tension, external judgments of their child, the child “looking different,” or the child’s less-than-perfect behavior while patched.^16,17 and (c) the parents get worn out. Noncompliance in amblyopia therapy therefore has an extra level of responsibility, that of treating the parents in addition to the child!

A device is available that can be used to measure patching compliance: the Occlusion Dose Monitor (ODM). It is attached to the occlusion patch with double-sided adhesive, and measures the temperature difference between the front and back of the ODM every 2 minutes.¹⁸ Menon et al.¹⁹ found that compliance with patching, measured with the occlusion monitors in a 15-month study, was the major variable in success of treatment.

In a study done in Holland,²⁰ where the investigators had previously validated the ODM instrument, compliance was measured in 310 newly-diagnosed amblyopic children. Researchers visited the homes, maintaining two groups, one with an intervention (stickers, cartoons, parent education) vs. no intervention (a picture to color). Compliance was positively associated with parental fluency in language, level of education, and initial acuity of the child, with overall better compliance in the intervention group.

Beliefs about amblyopia and patching play a role in compliance, as assessed by Norman et al.²¹ Perceived vulnerability and response costs were significant predictors of response behavior. Self-reported compliance of 151 parent–child units revealed that only 54% were patching as instructed. Perceived self-efficacy was positively associated with compliance, and perceived prohibition of the child’s activities was negatively associated with compliance.²² It was remarkable, however, that past behavior (compliance) accounted for the greatest proportion of explained variance in individuals’ compliance with patching.

Parental weariness may certainly play a great part in the abandonment of amblyopia therapy. Novel techniques for increasing compliance are reported in the literature: arm splints and casts, combined patching, atropine penalization, and oral levodopa to allow parents to control their children.¹⁷ In the 18 months that followed the admission to one study,²³ hospitalization with supervised patching combined with intensive parental education, and improved compliance, was associated with patients gaining at least one line of acuity.²³ Gluing the patch to the child’s face,¹⁷ or even suturing a translucent plastic patch to the skin with 3-O nylon²⁴ (skin scars were judged “acceptable” to parents, patients and investigators) have been suggested as well, and no doubt all of these efforts can increase compliance, but at what cost? Repka¹⁷ notes that it needs to be demonstrable to both parent and child that an increase in quality of life justifies the costs and the potential psychological effects of these more invasive interventions.

In ophthalmology, elevated intraocular pressure remains the condition most frequently requiring long-term drug treatment. Ocular hypotensive therapy prevents or delays progression of glaucomatous nerve fiber–layer and visual field defects.^25,26 It is understandably difficult, however, for patients with asymptomatic disease, as glaucoma may be until late in its course, to maintain excellent compliance The costs of medication and potential complexity of dosing regimens are additional challenges. Because of the change in ophthalmic treatment, away from miotic agents and individual drugs to new classes of agents frequently used in combinations, this review emphasizes information published since 2005.

Noncompliance in glaucoma has been estimated to range from 24% to 83%.^27,28 Many physicians do not recognize the extent of the problem. In one study, of 500 physicians, most believed that 75% to 100% of patients were compliant, whereas 34% of the patients admitted to noncompliance.²⁹

Another issue is related to which medication the patient is prescribed. Once-a-day prostaglandins are now the first line of treatment.³⁰ Many studies have shown that prostaglandin therapy has better persistence than that of other drugs.¹⁰ Schwartz et al.³¹ showed, in a retrospective study of almost 1,500 patients, comparing treatment with a prostaglandin to treatment with a beta-blocker, that the patients prescribed timolol were 39% more likely to discontinue therapy. Others have shown similar statistics.^{32,33,34,35,36} It has been shown³⁰ that more complex regimens (e.g., twice daily beta-blocker dosing) result in 37% dosing errors (either under- or overadherence, for example, >12 hours or <10 hours between doses).