Personality and stress influence vision restoration and recovery in glaucoma and optic neuropathy following alternating current stimulation: implications for personalized neuromodulation and rehabilitation
Authors: Sabel B. A. , Wang J. , Fähse S. , Cárdenas-Morales L. , Antal A. 
Published: April 2020

Abstract
Purpose
Identifying factors that affect recovery or restoration of neurological function is a key goal of rehabilitation in neurology and ophthalmology. One such factor can be prolonged mental stress, which may be not only the consequence of nervous system damage but also a major risk factor, or cause, of neural inactivation. Using the visual system as a model of neural injury, we wished to study how patients’ stress and personality profiles correlate with vision recovery as induced by therapy with alternating current stimulation (ACS) in patients with optic nerve damage.

Methods
Personality and stress questionnaires were sent retrospectively to a clinical convenience sample of patients who suffer low vision due to optic nerve damage, which had previously been treated with ACS. The questionnaires included the NEO Five-Factor Inventory (NEO-FFI), the Trier Inventory of Chronic Stress (TICS), and the Flammer syndrome (FS) checklist, which probes signs of vascular dysregulation (VD). These scores were then correlated with the extent of ACS-induced vision restoration as recorded 1–3 years earlier by perimetric visual field tests.

Results
Two NEO-FFI personality factors (lower neuroticism, higher conscientiousness) and the presence of physiological Flammer signs were associated with greater recovery as were individual items of the factors openness and agreeableness. Single NEO-FFI item analysis revealed that recovery relates to greater extraversion (optimistic and happy), openness (less guided by authorities for decisions on moral issues), and agreeableness (argue less, like working with others, thoughtful, considerate) as well as the presence of FS signs (cold hands/feet, hypotension, slim body shapes, tinnitus). This suggests that patients with better recovery were more calm, peaceful and secure, hard-working, and reliable, and with high organizational skills. In contrast, patients with poor recovery had a tendency to be emotionally unstable, anxious, unhappy and prone to negative emotions, impulsive, careless, and unorganized. Chronic stress assessed with TICS did not correlate with recovery.

Conclusion
Vision restoration induced by ACS is greater in patients with less stress-prone personality traits and those who show signs of VD. Prospective studies are now needed to determine if personality has (i) a causal influence, i.e., patients with less stress-prone personalities and greater VD signs recover better, and/or (ii) if personality changes are an effect of the treatment, i.e., successful recovery induces personality changes. Though the cause-effect relationship is still open, we nevertheless propose that psychosocial factors and VD contribute to the highly variable outcome of vision restoration treatments in low vision rehabilitation. This has implications for preventive and personalized vision restoration and is of general value for our understanding of outcome variability in neuromodulation and neurological rehabilitation.