Posters

Individualized corneal cross-linking in ultra thin corneas: 2 year follow-up

Poster Details

First Author: H.Abdshahzadeh SWITZERLAND

Co Author(s): F. Gilardoni   E. Torres-Netto   S. Kling   N. Hafezi   F. Hafezi        

Abstract Details

Purpose:

The standard Dresden Corneal Cross-linking (CXL) protocol is only recommended for corneal thicknesses of >400μm, limting the treatment to early stages of keratoconus. Recently, we have developed a nomogram for ultra-thin corneas to individually determine the irradiation time required for safe CXL treatment, with a peredicted penetration depth up to 70μm distance to the endothelium. The purpose of the current study was to analyze whether individualized CXL with reduced individualized fluence is able to stop keratoconus progression up to 24 months after treatment.

Setting:

The study was conducted jointly at the Ocular Cell Biology Laboratory, Center for Applied Biotechnology and Molecular Medicine at the University of Zurich (Switzerland) and the ELZA Instute AG, Diekon (Switzerland).

Methods:

A total of 45 progressive keratoconus (KC) eyes with corneal thicknesses between 305 μm and 398 μm at the time of UV irradiation were enrolled. UV irradiation was performed at 3 mW/cm2 with irradiation times between 7 and 25 min. CDVA, manifest refractive sphere and cylinder were evaluated at pre-op, 6- and 12-months post-op. Kmax, thinnest corneal thickness and densitometry were evaluated with Scheimpflug tonometry at pre-op,1-,12-, and 24-months post-op. Corneal demarcation line was assessed with anterior segment OCT at 1 month after surgery. Keratoconus progression was defined as increase of Kmax by >1.0 D within 1 year.

Results:

5 of 45 eyes showed progression within 12 months. A significant correlation was found between the demarcation line depth and changes in densitometry (r=+0.321, p=0.041) and between the demarcation line depth and irradiation time (r=+0.391, p=0.012). On average, there was a significant change from baseline at 12 months in thinnest thickness (-19±80 μm, p<0.001), in Kmax (-1.20±1.60 D, p<0.001) and in densitometry (+2.18±1.79 GSU). No significant changes were found in CDVA (p=0.868), sphere (p=0.951) and cylinder (p=0.878).

Conclusions:

Individualized CXL standardizes the treatment protocol in ultrathin corneas and halted KC progression with a success rate of 89% at 12 months and 82% at 24 months. Demarcation line depth did not predict treatment outcome and hence is likely not related to the extent of CXL-induced corneal stiffening, but rather to the extent of induced wound healing.

Financial Disclosure:

None