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Excimer custom treatment with asymmetric centration: integrating pupil and corneal vertex information

Session Details

Session Title: Surface Ablation II

Session Date/Time: Tuesday 08/10/2013 | 16:30-18:00

Paper Time: 16:36

Venue: Main Lecture Hall (Ground Floor)

First Author: : P.Vinciguerra ITALY

Co Author(s): :    F. Camesasca   S. Arba- Mosquera           

Abstract Details

Purpose:

Success in excimer laser refractive surgery is strictly related to perfect centration of the ablation. Visual axis is not always coincident with corneal vertex or axis of the pupil. Traditionally, excimer lasers feature a centration based on the pupil center (pupil rim) or on the coaxial light reflex (corneal vertex). We present an innovative strategy for asymmetric centration aimed at correcting refractive components and high-order aberrations (HOA).

Setting:

Istituto Clinico Humanitas, Milan, Italy.

Methods:

A novel ablation profile - Asymmetric Offset (AO) - was developed with Schwind CAM aspheric profiles by combining high-order aberrations as referred to the pupil center (line-of-sight) and manifest refraction values referred to the corneal vertex (visual axis). AO was developed to cover the pupil aperture and maintain the corneal vertex as the ablation optical axis.

Results:

With AO sphere and cylindrical (refractive) components are centered to corneal vertex if pupil offset (difference between pupil axis and corneal vertex position) is necessary, and the ablation axis is on the visual axis. When combined with HOA ablation plan, asymmetric offset leads to spherical components influencing HOA coma components, while astigmatic components influences HOA trefoil components. With AO, HOA are referenced to the pupil center and will not be shifted. This leads to an ablation map itself that is concentric to the pupil, and with the edges of the optical zone concentric to the pupil boundaries.

Conclusions:

AO ablation profiles provides a simple method to combine pupil and corneal vertex information for ablation. Clinical studies are undergoing to prove the theoretical results, demonstrate the reduction in HOAs, as well as define safety, predictability, and long term stability of results with asymmetric offset ablation profiles.

Financial Interest:

... is employed by a for-monetary company with an interest in the subject of the presentation