Take-home message: The time for refractive surgery for special needs children seems to be at hand, considering that advancements in laser and IOL technologies have been proven to be efficacious. Correcting a special needs child’s vision can reduce fearfulness and improve their behavioral challenges.
St. Louis —Most medications and devices that are used on a routine basis to treat pediatric patients are used off-label. These medications and devices were not developed to treat children but rather were adapted from innovations that were designed to treat adults. If the innovations prove to be effective and safe in children, they may become part of standard practice.
The time for this in refractive surgery seems to be at hand, considering that advancements in laser and IOL technologies have been proven repeatedly to be efficacious, according to Lawrence Tychsen, MD, who described his approach to treating select spectacle-noncompliant visually impaired pediatric patients with anisometropic amblyopia and isoametropic blur-induced blindness.
Most of these children, he pointed out, have neurobehavioral disorders, such as cerebral palsy, autism, Down syndrome, and developmental encephalopathies and are not compliant with spectacle wear and cannot wear contact lenses.
“Bilateral high ametropia can trap these patients in a cocoon of visual blur that promotes fearfulness and blunted social interactions that exacerbate the behavioral disorder,” Dr. Tychsen explained. He is the John F. Hardesty, MD, Distinguished Professor of Ophthalmology and Visual Sciences, Pediatrics and Neurobiology, St. Louis Children’s Hospital, Washington University, St. Louis.
To treat myopia of –8 D or less, hyperopia of +5 D or less, and astigmatism of 2.5 D or less, he performs excimer laser PRK (608 patients in this study). In children with refractive errors above these limits, he prefers to implant a Visian or Ophtec-Artisan spherical or toric phakic IOL (174 patients in this study). In children with small anterior chambers less than 3.2 mm and small corneas under 11 mm, he performs lensectomy (58 patients in this study).
The preoperative examination done to obtain precise measurements frequently must be carried out with the patients under brief general anesthesia, as are all surgeries, which are all outpatient procedures. The procedures are performed not only on children from the St. Louis region, but also nationally and inter-nationally.
The refractions targeted in these patients vary by age, but Dr. Tychsen pointed out typically 1 D of overcorrection. He reported that regression after PRK can be up to 0.85 D annually in some children with high myopia, which is considered greater than 8 D. Applying mitomycin C intraoperatively can reduce the level of regression but does not eliminate it.
“This is the reason that we prefer to implant phakic IOLs in children with high myopia and high hyperopia,” he commented.
In a study of the efficacy of refractive surgery in this challenging patient population, the primary outcome is the gain in the uncorrected VA, which is the important measurement in children who are noncompliant with glasses. The children are assessed using optotype Early Treatment Diabetic Retinopathy Study charts or the Preferential Looking method and Contrast Acuity Cards. Improvements in eye tracking and visual evoked potentials are recorded in their Pediatric Visual Diagnostic Laboratory.
Dr. Tychsen reported that following a refractive procedure the patients with myopia gained an average of 1 log unit or 10 lines of vision; the patients with hyperopia gained an average of more than three lines of vision.
“These gains,” he said, “are comparable to those reported in other North American and western European case series as reviewed in our paper with Paysee et al.”
Other factors can limit the gains in visual acuity. However, Dr. Tychsen emphasized that comorbidities, such as neurobehavioral disorders (52%), amblyopia (72%), nystagmus (43%), and optic neuropathy (12%), should not be deterrents. “For individual children with a comorbidity, the visual acuity gain may be substantial,” he stated.
In children with high myopia and sufficient anterior chamber depth, he implants a Visian ICL (Staar Surgical Company). For high hyperopic and astigmatic errors, he implants an Artisan hyperopic or toric phakic IOL (Ophtec). These IOLs are enclaved to the iris at the 3 and 9 o’clock fixation points.
“The virtue of the phakic IOL is stable correction of extreme ametropia. The mean refractive error in this study population was 15 D,” he said. Patients implanted with a phakic IOL gained 13 lines of vision compared with preoperatively.
Another important finding in this patient group was that half of the children who underwent a refractive procedure gained some binocular fusion, ranging from level 1 (restoration of a positive prism vergence fusional response) to level 5 (100 arc sec stereopsis).
Induced corneal haze is the biggest concern with excimer laser keratectomy. In this group, the severities ranged from grade 0 (none) to grade 4 (severe). Dr. Tychsen reported that 83% had no haze, 8% had grade 1 haze, 5% grade 2 haze, and 2% each grades 3 and 4 haze. No child has developed corneal ectasia.
Traumatic de-enclavation was the most common complication associated with Artisan IOL implantation in 4.6% of patients, followed by endothelial cell loss exceeding 2% annually in 3.6% of patients, and retinal detachment in 1.1%.
Patient quality of life
A visual function questionnaire was used to gauge the impact of the surgery on patient quality of life. The parental responses to the questionnaire indicated how important a refractive procedure was to the patients’ families.
“When asked how many years of the child’s life he or she would give up to obtain good vision, the parents indicated that they would give up 12% or 10 years of the child’s life and endure a 13% chance that the surgery would be blinding,” Dr. Tychsen said.
When considering the cost effectiveness of ophthalmic interventions and treatments, pediatric refractive surgery ranked in the top two to eight positions among all medical interventions.
“With more than 10 years of follow-up, refractive surgery is moving beyond the stage of proof of concept and may become standard of practice in the decade ahead for special needs children,” Dr. Tychsen concluded. “With this technology, we have the ability to make these children more fully alive.”