Patients with subthreshold amblyopia may experience restoration to 20/20 vision in both eyes and improved stereopsis following traditional amblyopia treatment, according to a study published in the American Journal of Ophthalmology. These patients, who have visual acuity better than 20/40 that is not correctable to 20/20, may represent a sizable proportion of those treated for amblyopia, the report shows.
Researchers performed a retroscopic chart review of 2311 pediatric patients who were diagnosed with amblyopia at Boston Children’s Hospital between 2010 and 2014. While published amblyopia studies frequently include individuals with visual acuity worse than 20/40, this investigation assessed children with visual acuity better than 20/40 in both eyes but not correctable to 20/20 in 1 or both eyes. The main outcome measure was the complete resolution of amblyopia, defined as visual acuity of 20/20 or better in both eyes and stereopsis at the final follow-up visit.
Of the 2311 patients with amblyopia, a total of 464 patients (20.1%; median age, 6.3 years; 234 boys) had subthreshold amblyopia. The majority fulfilled the criteria for an amblyogenic mechanism (61.7%), which was most commonly anisometropia (32.8%).
The patients were followed for a median of 3.1 years after the initial visit and almost all (97.5%) were treated. Common treatments included spectacles (93.7%), patching (38.4%), and atropine (5.7%). Among the 318 patients who returned for follow-up, 47.8% experienced complete resolution, including 55.7% of treatment-naïve patients and 62.5% (5 of 8 patients) of those offered observation alone. In patients who achieved amblyopia resolution, log stereopsis improved from 4.50 at the first visit to 3.91 at the final visit.
The report shows that a longer time of follow-up was significantly associated with resolution of subthreshold amblyopia (odds ratio [OR], 1.38; 95% CI, 1.22-1.57; P <.001).
“This study is important because clinicians caring for a child with subthreshold amblyopia may have difficulty deciding whether there is reason to require families to endure the burden of continuous glasses wear or patching for a child who technically does not meet diagnostic criteria for amblyopia,” according to the researchers. “We provide evidence that with treatment many patients (including 33.9% of those who had undergone prior treatment) will recover 20/20 vision, with improved stereopsis.”
Study limitations include a retrospective nature and lack of control group participants who did not undergo treatment.
Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or clinical research organizations. Please see the original reference for a full list of authors’ disclosures.
Michalak SM, Chinn RN, Shoshany TN, Bishop K, Staffa SJ, Hunter DG. Subthreshold amblyopia: characterization of a new cohort. Am J Ophthalmol. Published online December 18, 2022. doi:10.1016/j.ajo.2022.12.015