Surgical pearls for CXL treatment of keratoconus, corneal ectasia

Take-home message: On the heels of the recent FDA approval of corneal collagen crosslinking, some surgical pearls are provided for the treatment of progressive keratoconus and corneal ectasia.

By Peter S. Hersh, MD, Special to Ophthalmology Times

Teaneck, NJ-Corneal collagen crosslinking (CXL) is a treatment designed to decrease the progression of keratoconus, a disease typified by distortion of the normal corneal optical dome secondary to biomechanical structural weakening. CXL aims to mitigate the progression of this distortion by strengthening the corneal stroma.

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This year, the CXL procedure was approved by the FDA for the treatment of progressive keratoconus in patients > 14 years of age as well as for ectasia after refractive surgery. Approval was granted to Avedro, using its riboflavin products Photrexa Viscous and Photrexa. Photrexa comprises riboflavin 5’-phosphate 0.146% in solution containing 20 % dextran. It is used for riboflavin loading and during UV exposure. Photrexa is riboflavin 5’-phosphate 0.146% without dextran and is used for corneal swelling after the loading phase in corneas which have an intraoperative thickness <400 um. The riboflavin drops are used in conjunction with the Avedro KXL System, which operates at 365 nm UVA at a power of 3mW/cm².

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The approved procedure is similar to the method used internationally for many years:

1.      The eye is prepped and draped in the usual fashion and a lid speculum is placed.

2.     A 9.0 mm removal of the central epithelium is performed per the surgeon’s preference. Usually, either a spatula or 20% alcohol is used to remove the epithelium.

3.     With the lid speculum removed, riboflavin with dextran (Photrexa Viscous) is applied topically every 2 minutes for 30 minutes. The patient is instructed to keep eyes closed between drops.

4.     After 30 minutes, confirm adequate riboflavin uptake by slit lamp examination. Uptake is confirmed by a homogeneous green fluorescence throughout the corneal stroma and by the presence of a yellow/green flare in the anterior chamber. If uptake is not adequate, additional riboflavin is administered until flare is observed. (Figure 1)

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