A study recently published in the Journal of Cataract & Refractive Surgery has shown that an investigational new corneal crosslinking (CXL) protocol—one that avoids epithelial removal—could be safer and provide more rapid visual recovery than current epi-on methods.
The intact epithelium in epi-on procedures reduces oxygen availability and hinders riboflavin penetration into the stroma, both needed for clinical success. But the epi-off method subjects patients to significant post-treatment pain and other potential complications.
Hoping to improve upon epi-on results typical of the established Dresden protocol, researchers used a new riboflavin formulation and application method, plus a pulsed (rather than continuous) dosing of ultraviolet A that “allows oxygen the time to go back into the cornea,” explained study author Doyle Stulting, MD, PhD at the Annual Meeting of the International Society of Refractive Surgery during the American Academy of Ophthalmology meeting in Chicago last week. Dr. Stulting noted that the new protocol can “safely stop progression of ectatic disease in corneas that are as thin as 302nm.”
The new formulation was used to treat 512 eyes with keratoconus or forme fruste keratoconus and 80 eyes with ectasia after LASIK. Treatment involved following the riboflavin formulation with exposure to UV light (365nm) at 4mw/cm2 with on-off cycling for 30 minutes.
Researchers found that mean uncorrected and corrected distance visual acuities improved by 1.0 to 1.5 Snellen lines at one and two years postoperatively. After two years post-op, the total higher-order aberrations and coma decreased 36% and 37%, respectively. Maximum keratometry (Kmax) decreased more than one diopter in three times as many eyes as it increased more than one diopter. The study found that no eyes progressed and there was no loss of effect in year two compared to year one post-op
Dr. Stulting stated that his team saw no complications in the 592 eyes. Pain lasted for 24 hours, blurred vision lasted for two to three days and contact lens wear resumed within a week. He also believes that this new protocol may is able to retreat those who have previously received epithelium-on CXL and have experienced progression.
|Stulting RD, Trattler WB, Woolfson JM, Rubinfield RS. Corneal crosslinking without epithelial removal. J Cataract Refract Surg. 2018;44(11):1363-70.|