The Amsler Grid Use Study (AGUS): Amsler Grid Nonadherence is Driven by Forgetfulness and Health Beliefs But Not Age

Purpose The Amsler grid is a widely prescribed home-monitoring tool used to detect vision changes associated with ocular disease. Despite poor adherence being considered a major challenge in its administration, studies examining adherence rates are lacking, limiting the development of evidence-based solutions. Therefore, this study aimed to quantify current adherence levels of Amsler grid use and explore factors that may influence nonadherence. Methods A mail-out survey containing items adapted from validated questionnaires, collecting adherence, self-efficacy and beliefs towards Amsler grid use, was distributed via a modified Dillman’s Total Design method to 300 individuals who attended a large referral-only eye clinic and were prescribed an Amsler grid. Responses scored adherence levels (high, moderate and low), determined reasons for nonadherence and behaviours of adherence/nonadherence. Results Most respondents demonstrated moderate (61.0%; 75/123) or low adherence (30.9%; 38/123) to the Amsler grid, with forgetfulness being the most common nonadherence reason (89.4%; 110/123). Unintentional nonadherence was the most frequent behaviour (48.8%; 60/123), while purposeful nonadherence was uncommon (1.6%; 2/123). A higher concerns beliefs score was the only significant predictor of poorer adherence scores ( p = 0.03). Contrarily, regular use of the Amsler grid ( p = 0.03) and a higher necessity beliefs score ( p = 0.01) were associated with greater adherence scores. Higher necessity beliefs were also significantly associated with moderate and high Amsler grid adherence (OR = 1.340, 95% CI = 1.044–1.720) and indicated a greater likelihood of unintentional nonadherence rather than combined unintentional and purposeful nonadherence (OR = 1.237, 95% CI = 1.009–1.516). Non-modifiable factors such as age and gender were not significantly associated with adherence outcomes. Conclusions Amsler grid nonadherence was primarily unintentional and mostly due to forgetfulness. Poor adherence was associated with greater concerns in Amsler grid use, indicating modifiable factors that can be addressed to improve adherence.