Based on data from earlier published studies, investigators at a tertiary clinic in India hypothesized that patients with glaucoma are in a state of chronic stress, potentially leading to “allostatic overload,” or physiologic consequences of exposure to chronic environmental stressors.
Study Design
This was a case-control study that included 50 patients with primary open-angle glaucoma (POAG) and 50 age-matched controls. Allostatic load was estimated based on 13 different variables, including blood pressure, lipid levels, body mass index, cortisol, glycosylated hemoglobin (HbA1c), creatinine clearance, and C-reactive protein. One point was assigned to each variable that was above predefined biologic cutoff values, and a score of ≥4 points was considered high allostatic load.
Outcomes
Patients with POAG had significantly higher mean allostatic load scores than controls (4.68 vs 3.32, respectively). These trends continued after adjusting for age, sex, and socioeconomic status. Higher allostatic load was associated with significantly worse mean Humphrey visual field deviation and thinner retinal nerve fiber layer thickness. Patients with glaucoma were also more likely to have elevated HbA1C and homocysteine levels and low high-density lipoprotein levels.
Limitations
This study does not establish causality and can only assess association. There is likely a 2-way relationship between glaucoma and allostatic load, with glaucoma leading to heightened stress and increased cortisol levels (which can in turn increase IOP) which in turn leads to higher allostatic loads. This cycle may then promote vascular dysregulation, which can impair optic nerve perfusion. More discussion was needed on potential links between social determinants of health (e.g., class) and chronic disease, including glaucoma.
Clinical Significance
Results of this study may be helpful when counseling patients regarding certain nonpharmacologic adjunct treatments for glaucoma that could lower allostatic load. Physical activity, yoga with breath control exercises, and meditation have all been shown to reduce physiologic stress and positively impact allostatic load parameters. Meditation has also been shown to lower IOP. These are low-risk interventions which may improve patient quality of life, give patients a sense of control, and reduce risk of glaucoma progression.
Financial Disclosures: Dr. Gillian Treadwell discloses no financial relationships.