Abstract
Purpose: Disruptions in visuomotor behavior are common in individuals with neuro-ophthalmic conditions but rarely assessed at point-of-care locations. This study uses a simple visuomotor reading task to evaluate visuomotor function and determine whether this test can effectively distinguish patients with optic neuropathies from healthy controls.
Methods: We performed a retrospective analysis of reading time during King-Devick (KD) test in the neuro-ophthalmology clinic. This test involves reading 120 irregularly spaced single-digit numbers aloud as fast as possible from left-to-right (“Irregular LR”). It has been used to assess visuomotor behavior in different neurological conditions. Additionally, we recorded visuomotor behavior using infrared oculography (Tobii, Inc) during number reading using the Irregular LR and variations of the KD test called “Regular LR” (same numbers as the KD test but regularly spaced and read left-to-right), “Regular RL” (regularly spaced KD numbers read right-to-left), and “Paragraph” (continuous text).
Results: Rapid number reading time was assessed in 442 neuro-ophthalmic clinic patients. Patients with visual acuity of 20/40 or worse in the better-seeing eye had significantly longer reading times (91±37s, p<0.001) compared to controls (52±15s), while no difference was found for patients with visual acuity better than 20/40 (56±23s, p=0.12). We analyzed fixation and saccade parameters from infrared oculography during reading in 55 participants (39 patients, 16 controls) and found that reading as indicated by total fixation duration was significantly slower by ~30% in patients with optic neuropathies across stimulus types: Irregular LR (p=0.007), Regular LR (p=0.001), and Regular RL (p=0.002). The random forest model showed good predictive performance (F1=0.84, Accuracy=0.75, AUC=0.8), with total fixation duration in the Regular LR and RL paradigms as the top predictors of optic neuropathy.
Conclusions: Number reading tests are easily and rapidly administered at the busy eye clinic. Infrared oculography assessing different reading paradigms revealed significantly worse oculometrics corresponding to slower reading in patients with optic neuropathies.