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Accelerated cross-linking limits keratoconus progression in children

Study finds the treatment halts disease progression, with an improvement in visual acuity.

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Children with progressive keratoconus who underwent accelerated corneal cross-linking achieved a significant improvement in visual acuity, according to a study.

“Our experience in accelerated corneal collagen cross-linking (CXL) in adults using the new CXL procedures from Avedro yielded promising results for progressive keratoconus,” co-author Necip Kara, MD, an assistant professor of ophthalmology at Gaziantep University School of Medicine in Turkey, said. “Based on these outcomes, we decided to perform the procedure in the pediatric population.”

The authors noted that previous clinical studies have demonstrated that standard cross-linking in children is an effective and safe modality for halting disease and improving visual and topographic outcomes, but that there have been limited findings using accelerated cross-linking in pediatrics.

In the current study, cross-linking treatment was performed in 44 eyes of 38 patients at the Beyoglu Eye Research and Education Hospital in Istanbul, as reported in the Journal of Refractive Surgery. All patients were 18 years or younger (mean age, 15.3 years; range, 9 to 18 years) and were observed for at least 24 months (1, 6, 12 and 24 months).

Procedure

“The surgical procedure consists of first inserting an eyelid speculum and instilling topical anesthesia (proparacaine hydrochloride ophthalmic solution), followed by corneal epithelium removal with a blunt spatula. Next, before irradiation, 0.1% riboflavin eye drops are applied to the corneal bed for 15 minutes, at a frequency of one drop every 2 minutes. Accelerated CXL is then performed with 4 minutes of continuous ultraviolet A 365 nm light (KXL system, Avedro) at an irradiance of 30 mW/cm2 (7.2 J/cm2),” Kara told Ocular Surgery News. The light covers a 9-nm diameter circular spot centered on the cornea, as recommended by the manufacturer.

In contrast, standard CXL treatment employs ultraviolet A light with a 30 mW/cm2 (5.4 J/cm2) radiation for 30 minutes.

A bandage contact lens is placed at the end of the procedure, and the speculum is removed. Patients were prescribed moxifloxacin 0.5%, artificial tears and fluorometholone acetate 0.1%.

Results

At the final visit, the flat keratometry value decreased from a baseline of 46.4 D to 46 D, and the steep keratometry value decreased from 50.6 D to 50.1 D. Total higher-order aberrations, coma and astigmatism values also significantly decreased.

At 2 years after treatment, uncorrected visual acuity improved from 20/63 to 20/50, and best corrected visual acuity improved from 20/50 to 20/40. Mean spherical and cylindrical refractions were not significantly altered.

“The mean uncorrected vision did not improve significantly at 1 month but was significantly better at all subsequent visits,” Kara said. “Corrected vision, likewise, was about the same at 1 and 6 months but was significantly improved at 12 and 24 months.”

No serious postoperative complications were noted, although 34 patients reported minor to moderate ocular pain, which lessened 2 to 3 days after treatment. The authors were surprised by the lack of haze.

“Although haze formation after CXL treatment is commonly seen, we did not see any haze in this pediatric population,” Kara said.

Accelerated cross-linking offers shortened treatment time, which is an advantage for patients who need general anesthesia or have low compliance to prolonged treatment, according to Kara.

Because pediatric keratoconus cases are more aggressive than keratoconus in adults, children should be monitored for a longer period of time, Kara said. – by Bob Kronemyer