The surgical correction of refractive errors in children is not new, but it remains a debatable topic in ophthalmological societies worldwide. The experience with pediatric cataract surgery, intraocular lens implantation, and corneal transplantation has revealed major, often sight-threatening, differences in the pediatric response to surgery compared with that in adult patients having the same procedures. In the pediatric eye, the problems include refractive treatment stability, uncorrected and best corrected visual acuity, predictability, anesthesia, corneal status, and centration of the ablation zone. For this reason, refractive surgery, which is estimated to have been performed in over 18 million adult eyes, has not been widely introduced in children. However, one condition, anisometropia, has been treated by excimer surgery for several years to improve the chances for amblyopia in the young child.
As summarized by Paysse,1 the prevalence of amblyopia in the United States population is estimated to be 2% to 5%. Amblyopia is the most frequent cause of unilateral visual impairment in children and young adults in the U.S. and Western Europe. It is even more prevalent elsewhere in the world. If the amblyopia is severe and bilateral, an affected person can be functionally blind from the condition. Vision screening is recommended between the ages of 3 years and 5 years and is usually done in schools or by primary care physicians. Amblyopia is most often detected during this routine vision screening. Despite these facts, adequate screening is believed to occur in only 21% of preschool children in the U.S. Treatment of amblyopia is less likely to be successful in children older than 6 years. Recently, however, there have been hints that success may be achieved later.2
Anisometropic amblyopia is the most frequent form of amblyopia, and because the affected child is usually asymptomatic, late diagnosis is common. Problems with traditional treatments for anisometropic amblyopia are well-known and include poor compliance and psychosocial stress for families and patients that may continue into adulthood. Treatment success for anisometropic amblyopia is achieved in about two thirds of cases. Consideration of alternative treatments less dependent on patient/family compliance, such as refractive surgery, has been shown to be reasonable.3
In this issue, Astle et al. (pages 2028–2034) assess the refractive, visual acuity, and binocular results of laser-assisted subepithelial keratectomy (LASEK) for anisomyopia, anisohyperopia, and anisoastigmatia in 53 children with various levels of amblyopia secondary to anisometropic causes. To date, most studies have reported a small number of patients and rarely provided data on stereopsis. Astle et al. found that of 33 children, 39.4% had positive stereopsis preoperatively and 87.9%, 1 year after LASEK. They concluded that LASEK is an effective surgical alternative to improve visual acuity in anisometropic children unable to tolerate conventional methods of treatment or in whom these methods fail.
Although still controversial, the use of corneal excimer laser surgery in anisometropia can be an important option in children with amblyopia. A child who is not compliant with traditional treatment options, such as spectacles, contact lenses, and occlusion or penalization of the sound eye, may have a chance to develop a binocular visual system if excimer surgery is applied. If the long-term results that have been reported3 prove to be valid and major complications as summarized above do not occur, refractive surgery may be a good, even the best, method to help these children.
1. Paysse EA. Photorefractive keratectomy for anisometropic amblyopia in children. Trans Am Ophthalmol Soc. 102. 2004. 341-371. Available at: http://www.aosonline.org/xactions/2004/1545-6110_v102_p341.pdf
. Accessed October 15, 2007.
2. Fronius M, Cirina L, Cordey A, Ohrloff C. Visual improvement during psychophysical training in an adult amblyopic eye following visual loss in the contralateral eye. Graefes Arch Clin Exp Ophthalmol. 2005;243:278-280.
3. Paysse EA, Coats DK, Hussein MAW, et al. Long-term outcomes of photorefractive keratectomy for anisometropic amblyopia in children. Ophthalmology. 2006;113:169-176.