In pediatric ophthalmology, the most high-profile developments are in myopia and in gene therapy (both mentioned later). However, an emerging new treatment for amblyopia may be just as transformative: dichoptic therapy.
Problems with traditional therapy. Until recently, first-line treatment options for amblyopia have focused on refractive correction with glasses, patching, or pharmaceutical penalization of the better eye, with successful protocols largely established by the Pediatric Eye Disease Investigator Group (PEDIG) investigations.
However, these methods—even when combined—do not always achieve ideal visual acuity outcomes, even when patient adherence is good, which is often not the case. About half of children treated with traditional methods from about age 3 to age 7 have some amblyopia at age 10, and older children demonstrate even greater degrees of residual amblyopia on long-term follow-up.1,2
Further, studies have shown that patching—the gold standard—increases the likelihood of bullying by 37%,3 suggesting that this type of treatment be completed before school age, as bullying may have long-term psychological consequences.4
Pharmacological approaches. Growing in popularity following the PEDIG studies, atropine 1% works as well as patching. However, potential side effects include glare, reversal of amblyopia, and even systemic side effects.5
Investigations are also under way to test pharmacological approaches, including levodopa-carbidopa, dopamine, and citocoline, some of which neurosensitize the brain, enhancing its responsiveness to traditional therapies.
We clearly need new options that are accessible, affordable, and acceptable for both children and adults, given that the prevalence of amblyopia is between 2% and 5%.2 Often considered untreatable in the past, adults are a prime target, particularly given that the lifelong chance of vision loss in the better eye is higher in amblyopes.6
Addressing a Binocular Problem
In a major step forward, amblyopia was recognized as a binocular problem—in that the stronger eye actively suppresses the weaker eye. Activating binocular neural circuits in patients with amblyopia has the potential to “awaken” an amblyopic eye in adults as well as children.1
Dichoptic treatment. A newer type of therapy, dichoptic training, gradually optimizes binocularity by presenting independent stimuli to each eye while the patient with amblyopia looks at a screen. The dominant eye may initially receive less contrast, which is adjusted over time so the nondominant eye improves with training.1
Benefits. Better tolerated than patching, binocular dichoptic training is suitable for anisometropic amblyopia, the most common type seen in clinical practice. The 2015 PEDIG study found that one hour a day was as effective as two hours a day of patching. Although adherence was initially good, children became bored and stopped using dichoptic training because it was limited to a single game, called Falling Blocks, which wasn’t stimulating enough to repeat daily.7
Coming soon? More engaging dichoptic therapies were needed to address this problem. In addition to iPad-based platforms, developers have introduced passive viewing of dichoptic movies, head-mounted virtual reality displays, and shutter glasses paired with dichoptic technology.1
In April 2020, Novartis acquired Amblyotech, a U.S.-based software company, to help pursue a digital therapy for amblyopia. (While I serve on the Amblyotech advisory board, my interest in this approach predates the company’s existence.) It uses active gaming and passive video technology with 3-D glasses and a dichoptic display that presents each eye with different images, gradually training the eyes to work together. With improvement, the lazy eye is forced to work more and more. In both children and adults, early clinical studies demonstrated faster visual improvements than with standard treatments.8,9
Another product called BinoVision (Medisim) offers dichoptic training with similar efficacy, but it uses goggles instead of glasses and manipulates streaming videos to perform audiovisual brain stimulation that increases blood flow and strengthens synaptic connections in the brain to improve the amblyopic eye’s response. It uses brightness/contrast oscillations and flickering, superimposed objects, and audio cues to encourage brain plasticity.10
Given the variety of viewing options available with both devices, chances are greater for maintaining the viewer’s interest and adherence. I predict that dichoptic training will reach its full potential in the near future, becoming a very viable treatment for amblyopia.
1 Kraus CL, Culican SM. Br J Ophthalmol. 2018;102(11):1492-1496.
2 Yen M-L. Taiwan J Ophthalmol. 2017;7(2):59-61.
3 Horwood J et al. Invest Ophthalmol Vis Sci. 2005;46(4):1177-1181.
4 Williams C et al. Br J Ophthalmol. 2006;90(6):670-671.
5 McLendon K, Preuss CV. StatPearls Publishing. 2020. www.ncbi.nlm.nih.gov/books/NBK470551/.
6 Rahi J et al. Lancet. 2002;360(9333):597-602.
7 Manh VM et al. Am J Ophthalmol. 2018;186:104-115.
8 Kelly KR et al. JAMA Ophthalmol. 2016;134(12):14020-1408.
9 Novartis press release. “Novartis acquires Amblyotech, pursuing novel digital therapy for children and adult patients with ‘lazy eye.’” www.novartis.com/news/media-releases/novartis-acquires-amblyotech-pursuing-novel-digital-therapy-children-and-adult-patients-%22lazy-eye%22.
10 BinoVision: “Binocular Treatment—Binovision.” www.bino-vision.com/for-eye-care-professionals/binocular-treatment-binovision/.