Innovation Spotlight - Refractive Surgery

Refractive Surgery

Some children may be candidates for refractive surgery

By Jonathan M. Davidorf, MD

While the surgical treatment of adult ametropias has gained increasing acceptance in the ophthalmic community, experience with the surgical correction of pediatric and adolescent ametropias is limited. Indications for performing refractive surgery in the pediatric and adolescent populations may be divided into the obligatory, functional, or elective categories.

Obligatory indications

Pediatric patients under 7 years of age with anisometropic amblyopia should be considered for refractive surgery if contact lens intolerance develops. Treatment options would be limited to procedures capable of correcting higher amounts of myopia, hyperopia, or astigmatism.

Although LASIK has shown the most promise of the refractive corneal surgical procedures for higher corrections, the requisite intraoperative fixation poses challenges in young children. In one PRK series, the necessary sedation precluded fixation and pediatric patient cooperation, so the authors centered the ablation over the pupil and demonstrated improved best spectacle-corrected visual acuity (BSCVA) following PRK in patients as young as 5 years old.1
I think LASIK is preferable to PRK in children under 7 years of age because:

• PRK may induce more corneal haze in children than in adults.


• LASIK has demonstrated better predictability and stability compared to PRK for higher corrections.


• The postoperative care for the LASIK patient is considerably easier.

In contrast to refractive corneal surgery techniques, phakic IOL implants obviate the need for patient cooperation during the procedure, and the IOLs may correct higher ametropias. Additionally, phakic IOLs are exchangeable in cases of improper power calculations, sizing errors, or progressive untoward refractive changes. In addition, LASIK or PRK may be performed should further treatment be desired.2

Because of difficulties in postoperative care in infants and younger children, a foldable phakic IOL that can be implanted through a self-sealing, astigmatically neutral incision would be recommended.3

While major potential complications of phakic IOL surgery include glaucoma, cataract formation, and even endophthalmitis, the risk of not treating a young child with dense anisometropic amblyopia is lifelong reduced vision in that eye.4-6

Functional indications

Pediatric patients over the age of 7 are at minimal risk of developing further amblyopia, but patients may still have functional indications for undergoing refractive surgery. Examples include contact lens-intolerant patients with:

• Significant anisometropia.


• Refractive accommodative esotropia.


• Higher refractive corrections.

PRK, LASIK, or phakic IOL surgery may improve these patients' overall visual performance and can enable some to participate in recreational or sporting activities, which should have a positive impact on their social development.

Hyperopia is particularly amenable to surgical treatment in pediatric patients. Because hyperopia does not tend to progress through adolescence, and because even moderate amounts of hyperopia are well tolerated by children, the target refractive endpoint when treating hyperopia need not (and, perhaps, should not) be emmetropia.

A year and a half ago, I performed LASIK on a 16-year-old girl who was glasses- and contact lens-intolerant and had +7.25 D of hyperopia and 20/70 uncorrected visual acuity (UCVA). Because the patient's full correction was outside the limit of safety for hyperopic LASIK, a +5.25 D correction was performed, which left the patient with +1.75 D of residual hyperopia and 20/25 UCVA. The patient is now in college and still functioning without glasses.

Elective indications

Patients who are capable of wearing contact lenses or are obtaining adequate vision in glasses certainly have no medical necessity for refractive surgery. Such patients must be considered a frontier in pediatric and adolescent refractive surgery. The need is for a procedure that is safe and adjustable, particularly for myopia.

Although LASIK has some adjustable attributes, lifting the flap or creating a new flap poses some risk. Additionally, the induced corneal thinning may preclude further enhancement surgery. Intrastromal corneal rings (Intacs, KeraVision) may be useful for myopia of -4 D or less (about 75% of myopia), but experience on explantation of the intracorneal segments after several years is limited. Phakic IOL surgery offers the potential benefits of exchangeability and the ability to perform LASIK for residual refractive errors. Adjustable IOLs may even one day allow laser fine-tuning of postoperative refractive errors.

As we gain experience with the obligatory situations, the safety of refractive surgery, the compatibility of phakic IOLs, and the viability and safety of periodic IOL exchanges or LASIK enhancements in pediatric eyes will be determined. After thorough clinical studies with such eyes, then we may begin to consider moving into the territory of surgically correcting the more functional and elective types of problems.

References

1. Alio JL, Artola A, Claramonte P, Ayala MJ, Chipont E. Photorefractive keratectomy for pediatric myopic anisometropia. J Cataract Refract Surg 1998;24:327-330.
2. Zaldivar R, Davidorf JM, Oscherow S, Ricur G, Piezzi V. Combined posterior chamber phakic intraocular lens and laser in situ keratomileusis: bioptics for extreme myopia. J Refract Surg 1999;15:299-308.
3. Leseur LC, Arne JL. Phakic posterior chamber lens implantation in children with high myopia. J Cataract Refract Surg 1999;25:1572-1575.
4. Zaldivar R, Davidorf JM, Oscherow S. Posterior chamber phakic intraocular lens for myopia of -8 to -19 diopters. J Refract Surg 1998;14:294-305.
5. Davidorf JM, Zaldivar R, Oscherow S. Posterior chamber phakic intraocular lens for hyperopia of +4 to +11 diopters. J Refract Surg 1998;14:306-311.
6. Greenwald MJ, Parks MM. Amblyopia. In: Tasman W, Jaeger EA eds. Duane's Clinical Ophthalmology, Vol 1. Philadelphia:
JB Lippincott Company 1994, p. 1-22.
7. Maloney RK, Jethmalani J, Sandstadt C, Grubbs R, Kornfield J, Schwartz D. Laser adjustable IOL. International Society of Refractive Surgery Annual Meeting, Orlando, FL, October 1999.

Jonathan M. Davidorf, MD, is in private practice at the Davidorf Eye Group, West Hills, CA, and Maloney Vision Institute, Los Angeles. He is on the teaching faculty at the Jules Stein Eye Institute, UCLA.

George O. Waring III, MD, editor of this column, is professor of ophthalmology and director of refractive surgery at Emory University, Atlanta

Ophthalmology Times / APRIL 15, 2000