Pediatric refractive surgery in evolution.

With the advent of corneal refractive surgery using excimer laser technology, treatment for corneal and refractive disorders have advanced tremendously and become very precise and predictable. The use of these techniques in the treatment of corneal and refractive disorders in children, especially during the amblyogenic ages, would be invaluable. Numerous reports on refractive surgery in children have demonstrated that it can be performed safely and efficaciously in the pediatric population. However, controversy still exists whether it should be done in this population. We explore the available published data to address this controversy.

INTRODUCTION

Refractive surgery was initially used to treat asymmetric or unilateral high myopia in children with ablyopia, who where refractory to conventional treatments such as spectacles, contact lenses, or traditional patching or penalization therapy. These studies showed that laser-assisted in situ keratomileusis (LASIK) and Photorefractive keratectomy (PRK) could be performed safely and effectively in children.1–5 However, these studies only treated older children, mostly over the age of eight years. One of the limiting factors that did not allow younger children to be treated was the need for general anesthesia. Despite reporting successful treatment, these authors also reported the limited effects on the final visual outcomes, attributed to the fact that they were treating children outside the amblyogenic ages.

EARLY TREATMENT

Successful visual recovery in children with refractive disorders requires early visual rehabilitation. It is generally accepted the earlier the intervention the better the outcome. This is especially true if children fail the current established treatment such as spectacle correction, contact lenses, and patching or penalization.

Anisekonia due to retinal disparity in children with significant anisometropia, greater than three diopters, is a major problem in a child that cannot wear contact lenses.6 Corneal refractive surgery offers on the corneal plane treatment, aiding in the anisekonia. Initial studies aimed at treating the anisometropia by correcting the difference in the refractive disorders. Other studies have used refractive surgery in children to treat bilateral high myopia7 and accommodative esotropia.8–10

TECHNIQUES

Both LASIK and PRK have been used in children as young as two years of age.71112 LASEK (Laser subepithelial keratomileusis) has also been used with good success.1213 Topical anesthesia with self-fixation can be employed in older, cooperative children.351415 Premedication with anxiolytic agents such as midozolam or diazepam has also been used.1416 In young children, general anesthesia with IV sedation or laryngeal mask can be used.17

OUTCOMES

The first refractive study in children was published in 1995.2 PRK, although effective initially, has been hampered by corneal haze. Corneal haze has been reported at a rate as high as 25% and has been associated with failure to comply with longer term steroid regimen postoperatively.2716 In one study, severe corneal haze was found in 2.5% of the patients in two month and in 7 % after seven months, especially in high myopic treatments.16 In one study, a three-year follow-up on a cohort of patients treated with PRK, with myopia up to - 15D and hyperopia up to + 5D, found stable refraction and improvement in visual acuity and stereopsis, with minimal corneal haze.11

Myopic regression after PRK in children was noted at a level as high as 69% of the patients, with a shift toward myopia at a rate of 1D per year.18 This was attributed to an axial myopic shift related to normal growth patterns of the eye and partly to the more rapid healing response observed in children.

Persistent corneal haze formation in LASIK is seldom seen in children and adults, and has been reported in one child.4 LASIK flap complications have been reported, including epithelial ingrowth, wrinkles, diffuse lamellar keratitis, and free flaps, at a rate similar to adult LASIK surgery.41419 Despite early flap-related complications numerous studies have shown LASIK to be safe and effective even in children as young as two years of age.41420 Visual acuity outcome data is limited, given the younger age of children and ongoing treatment of amblyopia. Authors report the desired postoperative outcomes with patients remaining orthophoric, with residual refractive error of less than ± 0.375 with regression of 1.19D after one year.11421

CONCLUSION

Pediatric refractive surgery based on the current available data appears to be safe and effective. Current indications for refractive surgery include anisometropia, bilateral high myopia, and accommodative esotropia. Corneal haze is certainly a major concern in children receiving surface ablation, especially in high myopic treatments. Initial reports on the use of phakic intraocular lenses may be a good alternative in these cases.2223 In LASIK, surgery flap complication rates, although appear similar to those in adults, is still a concern. Myopic regression is seen with both procedures, whether it is secondary to aggressive healing or natural growth of the eye is still to be determined. Prospective controlled clinical trials are still needed to better demonstrate long-term safety and efficacy.