A keratoconus study out of Sydney has found the potentially quicker pulsed corneal crosslinking (CXL) protocol is likely to be at least as effective as the standard method involving continuous UV exposure.
Findings of the Pulsed corneal crosslinking in the treatment of keratoconus: A systematic review and meta-analysis have been published in the latest edition of Graefe’s Archive for Clinical and Experimental Ophthalmology.
In it, authors Ms Maria Qureshi, Dr Himal Kandel and Professor Stephanie Watson OAM conducted a comprehensive analysis of existing studies assessing pulsed CXL to draw “meaningful conclusions” regarding its overall efficacy, and importantly – whether or not it performs better for patients than continuous CXL.
“The options available for crosslinking are increasing, so the aim was to assist clinicians with gaining clarity and confidence in what treatment benefit their patients,” said Qureshi, lead author, of the Save Sight Institute.
In progressive keratoconus, CXL is now described as the treatment of choice for preserving corneal shape, thickness and visual acuity.
To carry out the procedure, riboflavin eye drops are applied to the cornea and then a UV light shone to produce a chemical reaction that strengthens the cornea. The chemical reaction produces reactive oxygen species to make bonds in the cornea such that oxygen is needed during the procedure.
To improve patient outcomes from CXL, the authors noted the procedure has been performed in various ways to increase patient comfort and/or reduce overall treatment time.
Pulsed CXL is one such protocol. It uses intermittent pulsing (on and off) UV light rather than the continuous UV exposure of standard CXL protocols.
“It is a clinical approach that has gained popularity as it may allow CXL to be done faster by allowing enough oxygen to reach the cornea during the faster treatment time,” the Sydney research team said.
They said pulsed CXL protocols have evolved over time by treating patients with higher energy levels, and adding supplemental oxygen to further boost its effects. In some cases, it has been delivered with topographical guidance by using the patient’s corneal curvature as a guide to optimise the UV light delivery.
The study found that measures in visual acuity and corneal parameters such as corneal shape (keratometry) and thickness (pachymetry) improved or were stable in both pulsed and continuous cross-linking groups at 12 months post-procedure.
Differences in these outcomes were not statistically significant between the pulsed CXL group and the continuous exposure group. Studies that could demonstrate meaningful superiority over standard CXL involved topographically-guided pulsed CXL.
Prof Watson said pulsed CXL was likely to be at least as effective as standard CXL for keratoconus.
“To inform clinicians and patients we need to perform more studies that compare treatments to really understand the potential benefits and risks of newer CXL protocols such as pulsing,” she said.
The researchers hope these findings will help clinicians gain confidence when informing their patients of CXL options, as well as deciding between pulsed and continuous modalities of CXL offered in their practice.
Dr Kandel recommended clinicians could use the Save Sight Keratoconus Registry to monitor their CXL outcomes.
“The registry is in use globally and enables collection of data on crosslinking from everyday practice and for clinicians to generate outcomes reports or their treatments and benchmark their data against global data,” he said.
More reading
A new school in corneal collagen cross-linking
CAIRS Plan tool to streamline keratoconus surgical procedures
Keratoconus: A frank discussion with Abi Tenen
