Broad and long-lasting vision improvements in youth with infantile nystagmus after home training with a perceptual learning app

Abstract

Current treatments for infantile nystagmus (IN), focused on dampening the oscillating eye movements, yield little to no improvement in visual functioning. It makes sense, however, to treat the visual impairments associated with IN with tailored sensorimotor training. Recently, we therefore developed a letter discrimination training embedded in an eye movement task. This training improved visual performance of children with IN, but most children had not reached plateau performance after 10 training sessions (3,500 trials). Here, we test the effects of prolonged visual perceptual learning (14,000 trials) in 7-18-year-old children with IN, targeting visual crowding as an important bottleneck in their visual functioning. Children (n=36) were assessed before and after training and we performed follow up measurements after 6 months. The training program not only improved performance on the trained letter-discrimination tasks (uncrowded and crowded acuity improvement 0.08±0.03 logMAR and 0.19±0.05 logMAR, respectively; reduction crowding extent 0.31±0.05 logMAR). It also improved visual acuities measured with clinical vision charts at distance (5m, uncrowded 0.15±0.02 logMAR; crowded 0.18±0.02 logMAR) and at near (40cm, uncrowded 0.09±0.02 logMAR, crowded 0.10 ± 0.02 logMAR). We also observed transfer of training effects to untrained tasks such as reading (improvements in reading acuity and reading speed 0.07±0.02 logMAR and 16±2 wpm respectively) and even stereopsis (improvement of 0.22 ± 0.06 log10arcsec). In addition, we found that the training effects translated into improvements of daily-life functioning (as assessed with a functional vision questionnaire), and that they were long lasting (no significant decline after 6 months). The transfer to untrained conditions did not result from improved contrast sensitivity. We conclude that training with an engaging perceptual learning app at home elicits broad and long-lasting vision improvements in youth with IN. Improvements on self-reported functional vision scores underline the clinical relevance of perceptual learning with e-health apps for individuals with IN.