An updated review about perceptual learning as a treatment for amblyopia

perceptual learning

Amblyopia is the most prevalent cause of preventable childhood blindness, with a prevalence of 1-5 %. It is also one of the most common causes of unilateral visual impairment that lasts into adulthood. Because of an abnormal binocular vision experience in early childhood, amblyopia is considered a neurodevelopmental disorder of the visual system. Despite the fact that amblyopia results in a variety of monocular deficits (e.g. visual acuity), it has been proven that loss of binocularity is one of the amblyopia defining characteristics. Nowadays, this has led to increased interest in the development of amblyopia treatments that directly address binocular dysfunction by promoting binocular vision and reducing inhibitory interactions within the visual cortex. Perceptual learning (PL from now on) refers to any rather stable change in the perception of a subject as a result of the experience with one or more stimulus.

Dichoptic therapy

Dichoptic Therapy is one of the most common methods for inducing PL in amblyopia treatment (DT from now on). Anti-suppression dichoptic training is a treatment for binocular vision that involves reducing suppression in the visual cortex by presenting stimuli simultaneously that are perceived individually and differently in each eye.

In the subject of visual cognition, various computers programs and video games (VG from now on) have been extensively utilized to increase selective visual attention and some visuospatial skills. For more than a decade, video games of various types (falling blocks, action, and adventure) have been used in the optometry and ophthalmology fields to cure amblyopia. The concept behind using VG to treat amblyopia is that it can help to increase visual functions including VA and stereo acuity.

Recent studies have found some evidence of various types of perceptual learning based amblyopia treatments (monocular training with grating contrast detection tasks, monocular viewing of action movies and video games, anti-suppression DT, stereopsis training, and so on), particularly with the restoration of binocular functions, though these are still under investigation. The major goal of this research was to look at the most recent studies on perceptual learning based amblyopia treatments and try to figure out what role they play in these new treatments. In addition, the findings of recent studies comparing traditional occlusion therapy with new types of perceptive treatment were examined in order to determine whether a perceptual learning strategy in amblyopia is required.

Results of the study on perceptual learning

As a result, the trials published in the last 6 years state some consistent aspects regarding the idea that amblyopia treatment could be aimed at recovering visual functions using new active strategies such as perceptive learning, utilizing technological resources that we now have, such as video games or virtual reality.

Different clinical trials have shown that a notable increase can be accomplished by an extensive range of stimulus, tasks, and length of the perceptual learning based training.

The systematic review of recent studies discovered evidence of a new type of amblyopia treatment that uses dichoptic treatment with or without the use of video games to apparently stimulate the binocular system through perceptual training. In general, studies conducted in the past indicate that this type of treatment is beneficial in enhancing some visual functions including VA in adults who have passed the critical time. This could be due, at least in part, to the format utilized in this type of active therapy, and some researchers have argued that gamification was used to boost patient motivation and compliance.

Nonetheless, additional controlled and random clinical trials might be done to learn more about which visual functions are more efficient and how long the effects of this type of treatment based on perceptual learning would last over time. Based on the findings of many studies, it appears reasonable to prescribe this type of active therapy as a supplement to various passive therapy choices.