The initial step in amblyopia treatment should be correcting refractive errors, which enhances retinal image quality. In nearly one-third of previously untreated amblyopic children, amblyopia was corrected with just optical treatment after 30 weeks. For those who do not resolve with refractive correction alone, other amblyopia treatments are required. There are treatments available that focus on either the monocular visual acuity impairment or binocular dysfunction and suppression.
In many countries, screening for amblyopia is suggested as part of regular health monitoring for children aged 3–5. Accurate screening procedures that may be used by pediatricians, family care practitioners, nurses, or community groups could detect amblyopia at the earliest possible stage, allowing for the most successful therapy. Accurate screening can also prevent false positives and save time and money by avoiding the need for a full eye exam in non amblyopic children. Early vision screening has been shown to enhance visual outcomes.
Novel monocular treatment approaches for Amblyopia
The current standard treatment focuses on addressing the monocular visual acuity loss by making the amblyopic eye actively work, resulting in normalization of visual cortex function in response to visual input from the amblyopic eye. Patching, atropine, and Bangerter filters are examples of standard approach of care of monocular therapies with strong evidence from randomized clinical trials (RCTs).
Study showed that after achieving stable visual acuity with spectacles, 3- to 8-year-old amblyopic children assigned to patching treatment improved 0.2 to 0.4 logMAR more than children who remained to wear spectacles alone. Within 6 weeks, more than 80% of the improvement with patching had happened. Children under the age of five had considerably better treatment outcomes than children over the age of seven. Nonetheless, even in children 7–17 years old, patching is significantly better than optical correction alone. Moreover, in children aged 3–6 years, atropine penalization has been demonstrated to be as successful as patching in curing both moderate and severe amblyopia. Bangerter filters can help people with moderate amblyopia improve their vision. Despite the fact that the Bangerter group improved slightly less than the patching group, the Bangerter filters were linked to a lower treatment burden and are recommended as a viable therapy for mild amblyopia.
The OccluPad is a newly developed monocular treatment option for occlusion. By removing the polarizing film layer from the liquid crystal display screen of an iPad Air, the LCD display is visible only to the amblyopic eye with the aid of an exactly matched polarizing filter. Meanwhile, the fellow eye is given a neutral density filter to match the luminance seen by the amblyopic eye but, without a polarizing filter, the fellow eye is only able to see the white backlight of the display. As a result, even though the child uses both eyes to view the tablet, images are selectively seen by the amblyopic eye. Playing a game on the OccluPad for half an hour a day twice per week led to significantly more visual acuity improvement than glasses alone.
Novel binocular treatment approaches for Amblyopia
Even after months or years of patching and atropine, many children do not achieve normal visual acuity, and of those who do, up to half will regress. Furthermore, even if normal visual acuity is achieved, normal binocularity (i.e. stereoacuity) is rarely restored, possibly because the eyes are not encouraged to work together during patching treatment.
There has been a shift how amblyopia is viewed over the last few decades. Recent evidence suggests that amblyopia is a binocular disorder rather than a monocular. According to research, there is a strong relationship between the severity of amblyopia and the severity of suppression. Suppression can be reduced by rebalancing the signal between the two eyes, which allows for binocular interaction. This is accomplished by lowering the signal in the other eye (i.e., lowering luminance or contrast) while maintaining a high signal in the amblyopic eye.
We can transfer these findings to reality by using dichoptic games and movies displayed on tablets, computer displays, and virtual reality headsets. There is evidence that visual acuity improvements with binocular treatment occur faster than patching—at least in the beginning—with gains of about 1–2 lines occurring in just 4–8 weeks rather than with 4–6 months of patching. These findings suggest that visual acuity gains may be faster in the short term with binocular treatment than patching. Furthermore, compliance has the potential to be much better than patching.
There have been a lot of short-term evidence for curing amblyopia. However, there is still need for more research on the long-term run. Furthermore, present treatments may be ineffective in treating those with severe amblyopia because they are unlikely to notice all of the game or movie aspects. Finally, smaller children may be unable to comprehend or play the games, or may be uninterested in viewing the movies.
Source: Birch, E. E., Kelly, K. R., & Wang, J. (2021). Recent Advances in Screening and Treatment for Amblyopia. Ophthalmology and Therapy, 10(4), 815–830. https://doi.org/10.1007/s40123-021-00394-7