The Importance of Binocular Vision Therapy in Treating Amblyopia

Amblyopia or lazy eye is a low visual impairment syndrome that is a cause for concern in many parents, especially those with toddlers. Amblyopia occurs when there is inadequate stimulation of one of the eyes during the critical period of its development, leading to suppression of vision in that eye, usually first detected in early childhood. In this regard, most recently developed methods of amblyopia therapy have focused on binocular amblyopia treatment in the case when this peculiar feature of development has already been overcome.

In this blog post, we will emphasize why it is crucial to treat the condition more than just monocularly and explain why this treatment is a revolution in the measures taken to binocular amblyopia treatment and improve vision in its patients.

Understanding Binocular Vision and its Role in Amblyopia

The capability of associating the two eyes together to achieve depth perception and visualize objects in their volume is known as binocular vision. It is integral to performing basic tasks, for example, estimating distances, interception of flying objects, or reading comfortably. People with amblyopia usually experience problems with binocular vision and therefore suffer from a reduced or complete lack of depth perception and other visual impairments. This means that the cross inhibition of the eyes compounds the management of amblyopia and therefore calls for amblyopia treatment to be done using a more specialized amblyopia therapy.

What is Binocular Summation ?

When both eyes work in harmony, there is an improvement in visual performance, which is known as binocular summation. However, in amblyopic patients, such binocular summation is often lacking or reduced in most cases. Nevertheless, studies have demonstrated that the normal range of binocular summation can be regained if the stimulus of the affected eye is amplified. This means shunting and increasing the visual input presented to the weaker eye through contrast enhancement.

Suppression in Amblyopia

Amblyopia refers to the condition in which the dominant reply eye suppresses the visual response of the non-dominant eye or amblyopic eye. This is possible to avoid diplopia and also confusion of visual images. However, this plays a very important role in the enhancement of amblyopia. Experts believe that suppression plays an important role in the progression and maintenance of amblyopia, which is why it is critical to opt for therapeutic strategies that aim at correcting binocular dysfunctions.

What is dichoptic training ?

Dichoptic training is a new therapeutic technique for the treatment of amblyopia that provides controlled use of binocular amblyopia treatment techniques. Such training employs special goggles (red and green-tinted goggles are often used) designed in such a way that different images are displayed to each eye. Peripheral visual processing, in which one eye is used at a time without the exclusion of both eyes at the same time, is stimulated by dichoptic training to improve binocular vision and the processing of visual information.

Dichoptic Training and Its Impact on the Adult Amblyopic Brain

Researchers have proposed that the use of dichoptic training is so beneficial to the adult amblyopic brain in training and adaptation. For instance, Li et al. (2013) examined the effectiveness of dichoptic training versus monocular training (where only one eye is used). Both groups trained for one hour a day for two weeks, whereupon improvements in visual acuity were noted in both groups. Nevertheless, the vocal accuracy and stereopsis of those who had undergone dichoptic training improved even more, compared to those who had received only monocular training. Most importantly, there were also important changes in suppression with the approach, showing that it is more efficient to treat amblyopia with both eyes than just the affected eye.

Key Benefits of Binocular Vision Therapy for Amblyopia

Binocular vision therapy plays an important role in enhancing the overall binocular capabilities of the patient, as well as the depth sense, by encouraging the activity of both visual receptors at the same time. This way of treatment, called dichoptic treatment, proves to be very helpful for patients who find it difficult to comply with amblyopia treatment. A few statements are provided below to support the validity of amblyopia binocular treatment :

Improvement in Childhood Amblyopia Without Breaking Suppression

In research by Bossi et al. (2017), in which a family-centered binocular amblyopia treatment system was analyzed, it was shown that covered bilateral treatment of amblyopia enhanced the vision without completely alleviating the interocular suppression. This means that it is possible to improve the vision with some level of suppression or intervention for adults with anisometropic amblyopia, and so this method can be adapted for children, making it possible for them to improve their vision at home rather than in the hospitals alone.

Primary Intervention for Adults with Anisometropic Amblyopia

The effect of dichoptic training on anisometropic amblyopia adults was investigated by Murali et al. (2022). As a result, the best-corrected visual acuity (BCVA) and near acuity increased significantly after three months of treatment. In addition, improvement in stereopsis was seen in 24% of participants, suggesting that there is scope for meaningful outcomes even in anisometropic adults with amblyopia.

Enhanced Contrast Sensitivity in Adults

Hess and Thompson (2015) mention studies in which binocular stimulation has been found to enhance contrast sensitivity in amblyopic adults. Such enhancement is essential as it contributes to the overall enhancement of visual functioning and its quality in performing various activities.

Rescue of Suppression

Repeated exposure to dichoptic training, as reported by Li et al. (2011), helped in a marked reduction of suppression in adults suffering from amblyopia. Thus, both the visual acuity and the stereopsis undergo significant improvements that help in the enhancement of the quality of vision.

Dichoptic Training vs. Monocular Training : Which is Better?

Drawing comparisons between binocular amblyopia treatment (dichoptic) and traditional amblyopia therapy such as patching, it is apparent that the former has a few advantages. Monocular training, as a typical amblyopic treatment, does train the weaker eye behind the convex lens after the healthy eye has been occluded, but it does not encapsulate the need to integrate both eyes. On the contrary, dichoptic therapy involves both eyes, encouraging visual motor coordination and subsequently, neural adaptation.

Binocular Therapy as a Game-Changer in Amblyopia Treatment

The idea of incorporating both eyes’ use in therapy effectively helps combat amblyopia more radically than it is currently done. Many treatments in the past, such as patching, could be used to improve the use of the amblyopic eye and its vision acuity. However, such techniques did not offer much improvement in binocular vision and stereopsis. On the other hand, binocular amblyopia treatment vision training overcomes these limitations by involving two eyes similar to depth perception practice, which results in the improvement of visual coherence, improvement of perception, and its combination with acuity vision.

Moreover, having both eyes working together becomes dominant in the apex of the brain, encouraging dominance, which leads to neuroplasticity, which is an essential capability for facilitating learning and making adjustments. This is advantageous because it allows for binocular therapy to be effective on adults who are far beyond the so-called ‘critical period’ of vision development. Detrimental eye suppression being reduced and inter-eye coordination being emphasized gives hope through dichoptic training to those who have had very few options in the past for treatment.

Conclusion

Binocular amblyopia treatment has changed the paradigm of amblyopia therapy as it not only aims at improving the vision of the affected eye but also seeks to enhance the neurosensory responses associated with stereopsis as well as minimizing suppression. Training of this sort also has the added benefit of being particularly directed at the use of both eyes as opposed to aggravating the eye, which is most dominant, hence more effective results than just training one eye. There is an improvement in the visual ability of the individual as well as in perceiving three-dimensional images and lessening the effect of the dominant eye, which leads to better vision.

In recent years, there has been a strong body of evidence showing the advantages of employing binocular therapy in amblyopia treatment; therefore, it could be said that this represents a paradigm shift in its treatment. Be it addressed to children or adults, the application of binocular approaches, such as dichoptic training, could serve the purpose of solving this fairly common problem more successfully, both in terms of visual acuity and the ability to perform the activities of daily living.

By informing the readers on the aspects of effective binocular vision therapy, the solutions to the problems of those suffering from amblyopia can be found in their improvements of vision even after a childhood period.