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Objective evaluation of cyclorotation compensation in topography-guided treatments

Poster Details

First Author: G.Asimellis GREECE

Co Author(s):    A. Kanellopoulos              

Abstract Details


To comparatively investigate the efficacy of the enhanced Athens Protocol procedure, which incorporates cyclorotation compensation, in comparison to the previously applied Athens Protocol procedure, in which no cyclorotation compensation was incorporated.

Setting: Clinical and Research Eye Institute, Athens, Greece


Two groups were formed. In group-A (‘cyclo’ nA=110 eyes), cyclorotation compensation was applied, while in group-B (‘non-cyclo’ nB=110 eyes), no cyclorotation compensation was applied. Analysis was based on digital processing of Scheimpflug-imaging derived topographic curvature difference maps. Thus we objectively measured differences between targeted (surgical planning) and achieved ablation pattern. We computed the vector (r, ϑ) corresponding to the steepest (peak topographic) corneal point (cone) on the pre-operative surgical planning map (rp, ϑp) and the curvature difference map (rd, ϑd), and calculated the differences between the peak topographic angular data: Δϑ=|ϑp - ϑd| and the weighted angular difference WΔϑ=Δϑ•Δr.


For group-A (cyclo) average Δϑ was 7.18±7.53 (0 to 34) ° and WΔϑ was 3.43±4.76 (0.00 to 21.41) mm. For group-B (non-cyclo), average Δϑ was 14.50±12.65 (0 to 49) ° and WΔϑ was 10.23±15.15 (0.00 to 80.56) mm. The cyclo group-A had on average smaller angular difference as well as weighted angular difference by a statistically significant margin (Δϑ p-value =0.0058 and WΔϑ p-value =0.015).


We introduce an objective technique for evaluation of cyclorotation compensation in excimer laser ablation. The data in this study indicate that incorporation of cyclorotation compensation in customized topography-guided treatments leads to improved correlation between targeted and achieved changes. FINANCIAL DISCLOUSRE: One or more of the authors travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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