This article is part of Optometry Advisor’s conference coverage from the 2021 meeting of the American Academy of Optometry, held in Boston from November 3 to 6, 2021. The team at Optometry Advisor will be reporting on a variety of the research presented by the primary eye care experts at the AAO. Check back for more from the AAO Optometry 2021 Meeting..

Following corneal crosslinking (CXL) treatment for keratoconus (KC), worsening of at least 1.00 D may signal KC regression, researchers reported in a case study they presented at the American Academy of Optometry 2021 meeting in Boston.


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Epithelium-off (Epi-off) CXL, which the US Food and Drug Administration approved in 2016, has become the top US treatment to address KC progression. Studies have indicated the treatment is beneficial for patients. Epithelium intact (epi-on), which is not FDA approved, may lower infectious risks and lead to quicker recovery. Previous research has, however, indicated that leaving the epithelium intact prohibits riboflavin and oxygen permeation and reduces efficacy. Post-CXL monitoring is essential. The objective of the current case report was to add to the body of research that promotes guidelines for identifying KC regression after CXL.

A Hispanic male patient presented with KC in both eyes (mild in right eye) after lack of success with hybrid and corneal gas permeable lenses. He had functional vision with eyeglasses. At the time researchers performed bilateral epi-on CXL on December 20, 2016, the patient was 26 years old. In February 2021, he presented again, with subjective vision loss, with left eye > right eye. He said he had not rubbed his eyes or undergone other ocular surgery.

Manual KSteep (right eye -1.12D left eye -1.38D), Topography KSteep (-0.5D; -0.7D), astigmatism (-1.13D; -2.25D), topography corneal astigmatism (-0.8D; -1.8D), and refractive astigmatism (-2D, OD-only) had worsened.

The researchers recommended epi-off CXL since insurance covered the procedure and the patient had experienced early regression after 2 years following epi-on CXL.

“Serial comparisons of Scheimpflug tomography can detect early KC progression but are not accessible in all clinical settings. As a result, clinicians may be unable to rely on maximum keratometry, pachymetric distribution or elevation profiles to detect CXL failure,” the researchers said. “Thus, at 6 to 12 months after CXL when corneas stabilize, any subsequent and repeatable worsening of ≥1D in manual or topography KSteep, corneal or refractive astigmatism may help suspect post-CXL regression.”

They recommended CXL patients avoid eye rubbing and be monitored at least annually, especially if they tend to rub their eyes, undergo CXL when they are young, or undergo epi-on CXL to swiftly address any regression.

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Reference

Barnett M, Merchant K. Detecting clinical regression after cornea collagen cross-linking in keratoconus patients. Presented at: American Academy of Optometry 2021 Annual Meeting; November 3-6, 2021; Boston. Board #45.