Abstract
Amblyopia, predominated by reduced visual acuity, loss of contrast sensitivity and depth perception, occurs when the brain favors one eye over the other. The non-preferred (amblyopic) eye is suppressed to allow for better visual interpretation of the surroundings. It is suggested that selective visual attention is involved in amblyopic suppression mechanisms (Hou et al., 2016). In this study, we hypothesize that training adult amblyopes with high-attention demand tasks improves their contrast sensitivity. To test this, we compared two training programs in adult amblyopes using a dichoptic approach: a high-attention task group compared to a low-attention task group. The high-attention task consisted of quickly searching and counting the vertical Gabors presented in the amblyopic eye while simultaneously being presented with distractors (horizontal Gabors) in the non-amblyopic eye. It is well known that searching and counting features require rapid shifts in attention and are considered high-attention demand tasks (Egeth et al., 2008; Anobile et al., 2012). The low-attention task was to report a simple horizontal and/or vertical rectangle that was presented to each eye, which needs little attentional effort. The two groups of amblyopes were randomly assigned into the two training programs. Both programs were about two visits per week and two hours per visit for two months. Contrast sensitivity was measured before and after training. Our training results show that for the majority of amblyopes in both groups, the contrast thresholds were decreased after their corresponding training, suggesting contrast sensitivity improvement from both training programs. However, the average contrast sensitivity improvement percentage was twice as large in the high-attention training group than it was in the low-attention training group. Our results support the view that training with high-attention demand tasks may provide important insight for treating amblyopia and perhaps other cortical dysfunctions.