Individualised corneal cross-linking in ultra-thin corneas: treatment outcome after one year

Session Details

Session Title: Cross-Linking

Session Date/Time: Tuesday 25/09/2018 | 14:00-16:00

Paper Time: 15:32

Venue: Room A3, Podium 3

First Author: : S.Kling SWITZERLAND

Co Author(s): :    E. Torres   F. Hafezi                 

Abstract Details

Purpose:

The standard Dresden Corneal Cross-linking (CXL) protocol is only recommended for corneal thicknesses of >400µm limiting 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 predicted penetration depth up to 70µm distance to the endothelium. The purpose of the current study was to analyze, if individualized CXL with shorter irradiation times is still able to stop keratoconus progression up to 12 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 Institute AG, Dietikon (Switzerland).

Methods:

A total of 18 progressive keratoconus eyes with corneal thicknesses ranging from 300 to 389µm 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 tonometery at pre-op, 1 and 12 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:

2 of 18 eyes showed progression within 12 months. A significant correlation between the demarcation line depth and changes in densitometry (r=-0.53, p=0.041) was found, however not between irradiation time and densitometry (r=0.17, p=0.549). A borderline correlation was observed between demarcation line depth and CDVA at 6 months post-op (r=+0.47, p=0.079) and at 1 year post-op (r=+0.51, p=0.051). On average, there was a significant change from baseline at 12 months in thinnest thickness (-12±22 µm, p=0.036) and Kmax (-0.85±1.5 D, p=0.034), but not in densitometry (-0.25±2.0 GSU), CDVA (0.09±0.33), sphere (0.67±1.7D) and cylinder (-1.8±6.9D).

Conclusions:

Individualized CXL treatment with shorter irradiation times did show promising preliminary results in halting keratoconus progression. The observed failure rate is higher than with standard CXL treatment (11% vs 7.6%). 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:

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