This article discusses how refractive surgery has been used successfully to treat severe anisometropia and isoametropia associated with amblyopia in children who cannot wear standard spectacles or contact lenses. The authors review how and when to use each technique, and their risks and benefits. They also introduce newer techniques currently being used in adults that may someday be used in children.
Extraocular techniques used in children include photorefractive keratectomy, laser-assisted subepithelial keratomileusis, and laser-assisted in situ keratomileusis. Intraocular techniques include refractive lensectomy and phakic intraocular lenses.
The authors say that although refractive surgery has been shown to be effective for improving vision and reducing refractive error in children, it is important to remember that it is appropriate only in special circumstances for a few pediatric subpopulations.
They note that conventional amblyopia therapy consists of the following steps: (1) clearing the ocular media if there is a visual obstruction such as a leukoma, visually significant cataract, or vitreous hemorrhage; (2) correcting significant refractive error with either spectacles or contact lenses; and (3) occlusion or pharmacologic and/or optical penalization of the fellow eye. While these steps are successful in the majority of children with amblyopia, there are several subsets of the pediatric population in which conventional therapies are often ineffective:
- Children with high-magnitude isoametropia who are spectacle-noncompliant or -intolerant. These children typically have neurobehavioral abnormalities related to genetic mutations, autism, cerebral palsy, or prematurity;
- Children with severe anisometropia who are noncompliant or intolerant of spectacle and contact lens wear; and
- Children with high ametropia, either anisometropia or isoametropia, who have other special circumstances, such as craniofacial anomalies, ear deformities, or neck hypotonia that preclude the use of refractive correction.
In the past, no other treatment options existed for these patients, resulting in varying levels of visual impairment and, with continued lack of treatment, degradation of functional vision (uncorrected visual acuity) up to 20/3400 (i.e., counting fingers) in the affected eye(s), tantamount to functional blindness in bilateral cases. Refractive surgery can normalize refractive error in these children and, the authors say, in bilaterally affected children, improves their development and social skills.
Untreated severe refractive error in young children can also result in severe amblyopia akin to deprivation amblyopia occurring with dense congenital cataract or leukoma. The authors say that surgery can treat high refractive error and appears to be safe at medium-term follow-up (10 years); it is thus an appropriate treatment for these conditions when standard therapy fails and the alternative will be certain functional blindness in the affected eye(s). Refractive surgery in the future may even be used to prevent refractive amblyopia.
The authors note that interventional case series and case-control studies of excimer laser refractive surgery, phakic IOLs, and refractive lens exchange in children have demonstrated improvements in uncorrected and best-corrected visual acuity, and developmental and social functioning, in addition to reduced refractive error with few complications.
They conclude that while the majority of children with either unilateral or bilateral refractive error do well with contact lenses or spectacles, for the subset of children who do not, refractive surgery is reasonable and the last option to prevent a lifetime of severe visual impairment. Randomized clinical trials would be helpful to confirm or disprove efficacy.