Individualized corneal cross-linking, in which UV fluence is adapted to individual stromal thickness, may be an option for stabilizing keratoconus in patients with thin corneas, according to 1-year study results.
“Two years ago, our group at the ELZA Eye Institute in Zurich published a nomogram for adapting UV intensity to individual corneal thickness. Rather than increasing corneal thickness with hyperosmolar riboflavin or by using a contact lens, we change UV fluence. Thinner corneas are treated with a lower dose of UV light,” Emilio Torres-Netto, MD, said at the European Society of Cataract and Refractive Surgeons Winter Meeting.
The individualized protocol was used in 45 eyes with progressive keratoconus and corneas thinner than 400 µm, some just more than 200 µm. Patients were followed up for 1 year after the treatment.
“We measured corneal thickness several times before CXL and calculated with our nomogram the irradiation time required to have the demarcation line at around 70 µm from the endothelium,” Torres-Netto said.
UV irradiation was performed at 3 mW/cm2 with irradiation times between 7 minutes and 25 minutes.
During the follow-up, corneas were examined with Scheimpflug tonometry and anterior segment OCT. No significant changes in visual acuity and refraction occurred over 1 year in the majority of patients, and a median flattening of 2 D was observed. Some of the patients progressed, with a change in keratometry values of 1 D or more at 1 year. Overall failure rate was around 13%, which was higher compared with the 7.6% rate of standard CXL.
“We did expect it to be higher but still consider these results very good and very promising since there was nothing we could do for these corneas before. At least some of these patients may now be able to avoid corneal transplantation,” Torres-Netto said.
Torres-Netto E, et al. Individualized corneal cross-linking in ultra-thin corneas: one year treatment outcomes. Presented at: ESCRS Winter Meeting; Feb. 15-17, 2019; Athens, Greece.
Disclosure: Torres-Netto reports no relevant financial disclosures.
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