Laser Refractive Surgeries Can Decrease Anisometropia

Laser refractive surgery has mixed results in treating children with anisometropic amblyogenic refractive errors, according to a literature review published in Ophthalmology. The findings indicate that, while the procedures can decrease anisometropia and may address amblyogenic refractive errors for these patients, evidence that they can improve amblyopia has yet to be elucidated. 

Researchers conducted a PubMed search in October 2021 to review the efficacy and safety of laser refractive surgeries to treat amblyopia in children. The first author reviewed 137 abstracts, of which 69 full articles were reviewed. The researchers found 12 articles that met the inclusion criteria and were included in the final assessment, 2 case-control studies and 10 case series. 

The reports reviewed relied on 4 different surgical interventions — laser-assisted in situ keratomileusis (LASIK), laser epithelial keratomileusis (LASEK), photorefractive keratectomy (PRK), and refractive lenticule extraction⁄small incision lenticule extraction (ReLEX/SMILE). For all patients, clinicians recorded best corrected visual acuities and spherical equivalents, however, many other study parameters varied. The most common metric to measure success was the percentage of patients who achieved a residual refractive error of 1 diopter (D) or less of the target refraction.  

Five studies enrolled patients with anisometropic myopia only (mean age range, 6.7 to 9.04 years; mean follow-up range, 8.17 months to 4 years). The researchers note refractive success in these patients between 43.7% and 89%. 

Another 2 studies enrolled patients with hyperopia only (mean age range, 8.0 to 10.3 years; mean follow-up range, 20.1 months to 7 years). Refractive success in this group ranged between 38% and 47%. 

The remaining studies had a mix of both patient populations (mean age range, 6.1 to 10.3 years; mean follow-up range, 17 months to 6.5 years). Refractive success for these patients ranged between 27.2% to 50%.

Laser refractive surgery shows the ability of children to achieve target refraction within 1 D; however, the percentage of this success varies between children and their conditions, the researchers explain. Multiple factors, including age, regression of refractive error, and previously failed therapy, play a role in success after surgery. 

“The available data from the level III evidence reviewed in this assessment demonstrate that the ability to achieve target refraction within 1 D using laser refractive surgery to address anisometropic amblyogenic refractive error in children are variable, but the magnitude of anisometropia appears to be decreased,” the researchers report.

The primary limitations of the review were the difference in methodology, lack of standardization between studies, and small sample size.