People with Down Syndrome have a disproportionately higher risk of developing keratoconus than the general population, and many go on to receive corneal cross-linking (CXL) to stop keratoconus from progressing. Despite this, except for a few case reports, no studies have been published to date on the effectiveness of CXL in patients with keratoconus and Down Syndrome.
Prof. Farhad Hafezi, Medical Director of the ELZA Institute, was part of an international study group that performed a randomized clinical trial of two CXL protocols in 27 people aged between 10 and 20 years with Down syndrome and progressive keratoconus in both eyes. They compared the effectiveness of the standard “Dresden protocol” (DP) CXL with an accelerated CXL (A-CXL) protocol. One protocol was randomly selected for the patient’s right eye, and the patient’s left eye received the other protocol. Both protocols involved the removal of the corneal epithelium and saturation of the structural layer of the cornea below, the stroma, with riboflavin. The riboflavin is activated by UV light, which cross-links together the molecules in the stroma, which results in a stronger cornea, which should stop the keratoconus from progressing further. Where the protocols differed is that the DP-CXL arm received the traditional 3 mW/cm² ultraviolet (UV) light irradiation for 30 minutes, to deliver a total UV dose (fluence) of 5.4 J/cm², whereas the A-CXL arm received a UV intensity that was threefold higher (9 mW/cm²) delivered over a three-times shorter period (10 minutes).
Three years after the procedures, what did the investigators find? A- and DP-CXL resulted in a similar flattening effect, but DP-CXL was better able to maintain corneal stiffness in weaker corneas. Despite A-CXL showing stable results for 2 years, there was decreased corneal stiffness in the third year – meaning that following these patients for an even longer term is worthwhile.
Read the paper here.
Hashemi H, Roberts CJ, Ambrósio R, et al. Comparative contralateral randomized clinical trial of standard (3 mW/cm²) versus accelerated (9 mW/cm²) CXL in patients with down syndrome: 3-year results. J Refract Surg. 2022;38(6):381-388.