A tactile pain evaluation scale for persons with visual deficiencies

Pain evaluation scales often rely on the sense of sight. There is so far no pain assessment scale designed specifically for persons with visual impairment.

This study aims to validate a tactile pain evaluation scale, Visiodol (Copyright Prof Pickering), in blind or visually impaired persons, by correlation with a numeric pain scale.

The study took place at University Hospital Clermont-Ferrand, France.

Pain intensity for a range of thermal stimuli (Pathway Medoc) was evaluated with Visiodol and a numeric pain scale. Secondary outcomes, including pain thresholds, catastrophizing, emotion, and quality of life, were compared in persons who were blind or visually impaired and in sighted persons. Lin's concordance correlation coefficient was estimated. Weighted Cohen's κ accounted for degrees of disagreement between scales with 95% confidence intervals (95% CI).

Sixteen healthy sighted and 21 healthy nonsighted volunteers (n = 13 congenital, n = 8 acquired) were included.

Lin's correlation coefficient for repeated data was 0.967 (95% CI, 0.956-0.978; P < 0.001) for visually impaired participants, with a good agreement at each temperature plateau. A weighted Cohen's κ of 0.90 (95% CI, 0.84-0.92) and 92.9% percentage of agreement for visually impaired participants were satisfactory. Pain perception, psychological components, and quality of life were more impaired in persons who were blind or visually impaired than in sighted persons.

This study validates Visiodol, a tactile scale for persons who are blind or visually impaired, and addresses health care inequalities in the context of pain evaluation. Visiodol will now be tested in a larger population of patients to give the millions of persons worldwide who are blind or visually impaired an option for pain intensity evaluation in clinical situations.

French National Agency for the Safety of Medicines and Healthcare Products (2018-A03370-55) and www.ClinicalTrials.gov (NCT03968991).