Using contrast acuity and rapid number naming in Huntington’s disease
Reviewed by Claire Howard

This study aimed to evaluate afferent and efferent visual function in Huntington’s disease (HD). HD is often portrayed by abnormal saccadic eye movements and afferent visual pathway involvement however these are poorly characterised and difficult to quantify at the bedside. Participants with manifest HD (n=19) and healthy controls (n=20) performed the King-Devick test, a timed test of rapid number naming. In addition, binocular high and low contrast acuities were measured using low-contrast SLOAN letter charts, and pupillometer recordings made using a handheld NeurOptics pupillometer. Each participant completed the NEI-VFQ-25 questionnaire with neuro supplement as well as the unified Huntington’s disease rating scale. Mean King-Devick time scores were 102.9 seconds in patients with manifest MD and 48.2 seconds in controls (p<0.1, t-test). Binocular high contrast acuity was seven letters lower in manifest HD than controls (p=0.043). This effect was similar for low-contrast acuity, but only low-contrast acuity remained statistically significant after adjusting for covariates. There were no differences in pupillary reactivity or self-reported quality of life. The authors conclude that HD is associated with reduced low-contrast acuity and abnormal performance on the King-Devick test, with these tests being easy to administer.

Contrast acuity and the king-devick test in Huntington’s disease.
Hamedani AG, Bardakjian T, Balcer LJ, Gonzalez-Alegre P.
NEURO-OPHTHALMOLOGY
2020;44(4):219-25.