Posters

Objective digitized evaluation of cyclorotation compensation vs none in topography-guided excimer laser corneal refractive treatments

Poster Details

First Author: G. Pamel GREECE

Co Author(s):    A. Kanellopoulos                    

Abstract Details

Purpose:

To comparatively investigate the efficacy of the enhanced Athens Protocol (topography-guided partial PRK normalization combined with higher fluence CXL), which incorporates cyclorotation compensation, in comparison to the previously applied Athens Protocol procedure, in which no cyclorotation compensation was incorporated.

Setting:

LaserVision.gr Clinical and Research Eye Institute, Athens, Greece

Methods:

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.

Results:

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).

Conclusions:

We introduce an objective digitized 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 significantly correlation between targeted and achieved changes, even in very irregular corneas.

Financial Disclosure:

NONE