Effect of pulsed collagen cross-linking technique on the depth of demarcation line in keratoconus


Aim: To compare the depth of demarcation line developing in the cornea after the standard Dresden protocol compared to accelerated, pulsed, epithelium-off corneal cross linking (18 minutes of pulsed UVA, pulsed profile 1 second on, 2 seconds off).

Corneal collagen cross-linking (CXL) is a well-established treatment method used to increase the strength of the cornea and to arrest keratoconus progression. The Dresden protocol, which was the CXL technique initially described, involves 30 minutes of ultraviolet-A (UVA) irradiation at an intended irradiance of 3.0 mW/cm2 with a total surface dose of 5.4 J/cm2. Several new commercially available CXL devices use the Bunsen-Roscoe law of reciprocity to offer higher UVA irradiation intensity in shorter periods of time. Corneal stroma demarcation line has been described to develop after CXL with the Dresden protocol and it can be visualized with slit lamp biomicroscopy, confocal microscopy and anterior segment optical coherence tomography (ASOCT)
as soon as 2 weeks after treatment. 

The depth of the demarcation line has been suggested to represent the effectiveness of CXL treatment and marks the border of the corneal stroma denuded from keratocytes. The purpose of this study was to compare the depth of corneal stroma demarcation line developing after the Dresden protocol and accelerated, epithelium-off CXL using AS-OCT. Refractive laser ablation was used in some of our patients if indicated according to surgeon preference. 

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Source: ESCRS