Glasses as the sole therapy can improve and even resolve the vision of children with strabismic and combined strabismic-anisometropic amblyopia, according to new research.
The findings, published online in the journal Ophthalmology, should encourage clinicians to consider prescribing glasses until their patients stop improving, before resorting to patches or atropine.
Lead author Susan Cotter, a professor at the Southern California College of Optometry in the United States, said the research had already changed the way she practised.
“I used to be the type to put the kids in glasses and patch right away. Now I wait until I don’t see any improvement before I begin occlusion.”
Dr. Cotter and colleagues, who were part of the Pediatric Eye Disease Investigator Group, enrolled 146 children aged from three to almost seven years old. Of these, 52 children had untreated strabismic amblyopia and 94 had combined-mechanism amblyopia.
the bigger surprise was the amount of time that the children’s vision continued improving. Although 90 per cent of the children reached a plateau by 18 weeks, some continued improving for up to 45 weeks.
The researchers prescribed spectacles based on a cycloplegic refraction and measured the patients’ visual acuity using the Ambylopia Treatment Study HOTV chart at baseline and every nine weeks afterward, until there was no improvement in acuity.
After 18 weeks, the children’s amblyopic eye visual acuity had improved a mean of 2.6 logMAR lines (95 per cent confidence interval [Cl], 2.3 – 3.0). Acuity in the amblyopic eyes of 41 children (32 per cent) improved to within one line of fellow eye acuity (95 per cent CI, 24 – 41 per cent), meeting the researchers’ standard for resolution.
Children with strabismic amblyopia improved a mean of 3.2 logMAR lines, which is significantly (P = .003) more than the 2.3-logMAR line improvement seen in those with combined-mechanism amblyopia.
The children with the best stereoacuity at baseline had the most improvement in amblyopic eye visual acuity (3.6 logMAR lines compared with 2.1 logMAR lines in those with the worst baseline stereoacuity; P = .002). However, improvement in amblyopic eye visual acuity was not associated with baseline amblyopic eye visual acuity (P = .34), amblyopic eye spherical equivalent refractive error (P = .07), age (P = .83), anisometropia expressed as vector difference in diopters (P = .17) or as a maximum of vertical or the oblique Jackson cross cylinders (P = .32), or magnitude of strabismus at baseline (P = .88).
Researchers said they were surprised that the size of the strabismus angle did not have a bearing on the success. However, the bigger surprise was the amount of time that the children’s vision continued improving. Although 90 per cent of the children reached a plateau by 18 weeks, some continued improving for up to 45 weeks.