CXL Comparison in the Paediatric Population

Long-term study underscores merits of cross-linking in younger patients. Dermot McGrath reports

Corneal collagen cross-linking (CXL) appears to halt the progression of keratoconus in paediatric patients and results in visual acuity and topographic parameter stabilisation over the long term, a recent study concludes.

“Our results are in line with the published international series for paediatric keratoconus, showing overall good results but with a higher risk of progression than adult patients. Alternative protocols also seem to be equally effective as standard CXL in stopping progression in these younger patients,” said Raquel Félix MD.

Explaining the study background, Dr Félix said there is a need for more studies of CXL in younger patients.

“We know the management of paediatric keratoconus is particularly challenging since younger age has been associated with faster progression and more severe forms of the disease,” she said.

Although the safety and efficacy of CXL in adult keratoconus patients have been established, there are very few studies comparing different CXL protocols in paediatric patients, she added.

Dr Félix’s retrospective cross-sectional study reviewed the data of 44 eyes of 33 patients with progressive keratoconus under the age of 18 who underwent CXL between 2010 and 2021 at two centres in Coimbra, Portugal. The mean follow-up period was 21.9 months, and the mean patient age at the time of treatment was 15 years.

Four different CXL modalities were used, including standard CXL in 9 eyes, accelerated CXL in 14, combined CXL and partial topography-guided photorefractive keratectomy (PRK) in 7, and customised topography-guided CXL in 14. Evaluation included best spectacle-corrected visual acuity (BSCVA), manifest refraction, and Scheimpflug tomography evaluation.

The BSCVA and spherical equivalent for all patients remained stable between preoperative and final follow-up visits—with a significant reduction in the manifest cylinder.

“When analysing the four groups separately, there was a significant improvement in BSCVA in the customised topography-guided CXL group and a significant reduction in the manifest cylinder in the combined CXL and PRK group,” she said.

Mean keratometric values were stable for all patients between preoperative and last follow-up visits. A significant thinnest corneal thickness (TCT) reduction appeared between preoperative and postoperative values. Evaluating the groups separately, all four showed a significant TCT reduction.

The overall success rate was 90.9%, with four eyes showing progression—two from the accelerated CXL group and two from the customised topography-guided CXL group.

Analysing the overall results, Dr Félix noted keratometric and visual acuity values remained stable after CXL and reported the progression rate of 9.1% was slightly better than other paediatric CXL studies, which tend to be in the range of 20% to 24%.

“We found that efficacy in the stabilisation of paediatric keratoconus seems to be similar between different protocols, although combined PRK and CXL and customised CXL resulted in a better improvement in best-spectacle corrected visual acuity. Accelerated CXL with a shorter treatment time may also be considered for paediatric patients, as it was shown to be at least as effective as standard CXL in our study,” she concluded, adding that larger prospective studies are needed to draw firm conclusions regarding the optimal CXL protocol to adopt in paediatric patients.

She presented the study at the ESCRS Virtual Winter Meeting 2022.

Raquel Félix MD is an Ophthalmology Resident at Centro Hospitalar e Universitário de Coimbra (CHUC), Portugal. raquelmaria.felix@gmail.com