In the current study, Diniz-Filho and colleagues1 report on an important and practical issue for clinicians who care for patients with glaucoma, namely, trying to determine the influence of cognitive decline on perimetric testing. Specifically, they hypothesized that cognitive decline was associated with increased visual field (VF) variability, a finding that could lead to delayed or false detection of disease occurrence and progression. The effect of cognitive decline on glaucoma testing is important to understand, as the prevalence of both conditions increases with age.2,3 In the Salisbury Eye Evaluation,2 the prevalence of glaucoma among white individuals increased from 3.4% at age 73 to 74 years to 9.4% among those 75 years and older; the increase in prevalence among black individuals was even greater, with glaucoma affecting 5.7% of 73- to 74-year-olds and 23.2% of those 75 years and older. Cognitive impairment follows a similar age-related pattern in the United States, with 16.0% of those 71 to 79 years old and 29.2% of those 80 to 89 years old affected.3

Visual field testing remains one of the primary methods of assessing visual function in glaucoma. However, VF variability is a well-described phenomenon, with 85.9% of abnormalities in the Ocular Hypertension Treatment Study not confirmed on repeat testing.4 Taking a VF test requires patients to remain attentive, fixate on a target, and translate visual stimuli into motor responses-all tasks that may be affected by cognitive dysfunction. In fact, the authors of this study1 found that there was a significant association between cognitive decline and VF variability, even after adjusting for sociodemographics, baseline cognition, and baseline VF mean deviation. While these findings may not be surprising, the results highlight the importance of considering nonvisual factors, such as cognitive dysfunction, when caring for patients with glaucoma, many of whom may be at high risk for multiple medical and neuropsychiatric comorbidities.

This study1 contributes to the literature on cognitive impairment in glaucoma.5,6 A study by Harrabi and colleagues5 found that people aged 65 and older with glaucoma, Fuch corneal dystrophy, and age-related macular degeneration all had lower cognitive scores than age-matched controls. The authors assessed cognition using a format of the Mini-Mental State Examination that does not depend on visual cues and they suggested that vision loss itself may contribute to cognitive decline.5 Likewise, examining the impact of VF loss on falls, Coleman et al6 showed that VF reliability was better among individuals with higher cognitive function. The current study by Diniz-Filho et al1 goes a step further than prior investigations by exploring the implications of cognitive dysfunction on the management of glaucoma. Consequently, this study represents a relatively important step toward understanding the cognitive factors that impact the measurement of visual function among patients with glaucoma.

The study by Diniz-Filho and colleagues1 provides evidence that cognitive decline is likely to occur in the course of caring for patients with glaucoma and that this may affect the variability of VF test results. However, the study is not able to establish a definitive cause-effect relationship and a number of plausible confounding factors might be associated with the measured cognitive decline. The authors assessed cognition using the Montreal Cognitive Assessment, which is a well-validated instrument with adequate psychometric properties. However, visual decline could have impacted Montreal Cognitive Assessment scores independent of cognitive dysfunction because the instrument relies on interpretation of visual objects to score its executive function, visuoconstructional skills, and attention domains. Additionally, although Montreal Cognitive Assessment scores are reported in this study as a linear scale, the distance between scores is unlikely to be even and this could have impacted measurement reliability and precision.

Glaucoma and cognitive decline are both progressive conditions that can result in marked functional impairment. In the Study of Osteoporotic Fractures, Coleman and colleagues6 found that older women with binocular VF loss were at greater risk for frequent falls. Although adjusting for cognitive function attenuated this association, women with severe VF loss still had 50% higher odds of frequent falls compared with women without VF loss. Similarly, Ramulu et al7 determined that individuals with glaucoma had a greater fear of falling than those without glaucoma. They showed that fear of falling increased with the severity of VF loss and that this association was stronger than for a number of other risk factors such as decreased contrast sensitivity, living alone, being unemployed, and the presence of cataract or medical comorbidities.

The current study1 corroborates the importance of detecting both glaucomatous VF loss and cognitive impairment. Indeed, because of ongoing and frequent contact with patients with glaucoma, vision care clinicians may be positioned to detect not only ocular disease, but also conditions such as cognitive impairment that can impact our patients' well-being and our ability to optimally care for their vision. With the population of the United States aging at a rapid pace, the incidence and cost of caring for glaucoma and comorbid systemic and neuropsychiatric conditions is also likely to increase considerably. This study1 suggests that to effectively monitor glaucoma, it may also be important to screen for neuropsychiatric decline and refer identified patients for appropriate care. Increased rates of falls, depression, motor vehicle crashes, and use of hospital services have all been associated with glaucoma and justify considerable investment in its detection and treatment. In summary, this study is part of a growing body of literature that points to the opportunity for vision care clinicians to improve health outcomes and better understand factors that impact the healthy aging of our patients.