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Refractive outcomes following the Athens protocol in keratoconic eyes with coincident vs non-coincident keratometric and refractive axes

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Session Details

Session Title: Cross-Linking Protocols

Session Date/Time: Monday 24/09/2018 | 14:00-16:00

Paper Time: 14:52

Venue: Room A3, Podium 3

First Author: : T.Rodrigues PORTUGAL

Co Author(s): :    A. Martins   M. Oliveira   E. Costa   M. Quadrado   A. Rosa   J. Murta     

Abstract Details


Collagen cross-linking combined with anterior surface normalization by topography-guided excimer ablation (the Athens Protocol) is an emerging treatment alternative for progressive keratoconus. Whether the refractive, in addition to the keratometric axis, should be taken into account for surgical planning is still unclear. Here, we aimed to compare refractive and keratometric postoperative outcomes of keratoconic eyes treated with the Athens Protocol with preoperative coincident vs. non-coincident keratometric and refractive axes.


Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra (CHUC)


Retrospective case series. Best-corrected visual acuity (BCVA), manifest refraction and topographic measurements (Orbscan IIz system, Bausch & Lomb), including simulated corneal astigmatism and thinnest pachymetry, were evaluate pre- and postoperatively. Surgical planning took the keratometric axis into account. Paired t-tests were used to evaluate postoperative changes in outcomes. A preoperative difference greater than 20┬║ between the axis of the manifest negative cylinder (refractive axis) and the axis of the flat K (topographic axis) was used to stratify the sample. Unpaired t-tests were used to compare outcomes between patients in different strata. P<0.05 were considered statistically significant.


We included 32 eyes of 32 patients (mean[SD] age 30.53[9.31] years; 58.38% male). Mean[SD] follow-up time was 6.32[3.50] months. Postoperative BCVA improved significantly (P=0.0005), while both manifest refractive cylinder (P<0.0001) and topographic steep K (P<0.0001) were significantly decreased. The postoperative change in spherical equivalent was not significant (P=0.1876). On stratified analysis, we included 19 patients in the coincident axes group and 13 patients in the non-coincident axes group. We did not find significant differences regarding BCVA (P=0.0903), refractive cylinder (P=0.9097), steep K power (P=0.5652), nor spherical equivalent (P=0.4269) between groups.


Our results suggest that postoperative outcomes following the Athens Protocol are not significantly affected by preoperative agreement between the refractive and keratometric axes. Such lack of agreement was previously shown to be a poor prognosis factor for intrastromal corneal ring (ISCR) implantation, an alternative treatment for progressive keratoconus. Thus, the Athens Protocol may become the privileged treatment modality for keratoconic eyes with non-coincident refractive and topographic axes.

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