Comparing the corrective capabilities of selective higher order aberrations using a modern excimer laser system

Session Details

Session Title: Advanced Surface Photoablation

Session Date/Time: Tuesday 10/10/2017 | 09:00-10:20

Paper Time: 09:00

Venue: Room 4.1

First Author: : S.Pieh AUSTRIA

Co Author(s): :    G. Schmidinger   C. Skorpik                 

Abstract Details

Purpose:

Modern excimerlaser systems with a laserspot smaller than 600 µm in diameter and a latency time below 5 ms should allow correcting higher order aberration up to the 6th order. The clinical results remain under this expectations showing that only higher order aberrations up to the 4th order can be improved. The aim is to compare the extend of the correction of each single aberration type of the 3rd and 4th order to increase the preoperative predictability.

Setting:

Department of Ophthalmology and Optometry, Medical University Vienna

Methods:

In 85 patient with highly aberrated corneas, the extend of higher aberration correction of the 3rd and 4th order due to an superficial excimerlaser treatment where evaluated postoperatively and compared. Furthermore the reproducibility of the used target points for the ablation profile centration where analysed.

Results:

The best corrective capability was achieved for the rotatory symmetric spherical aberration followed by the trefoil and coma of the 3rd order. The secondary astigmatism of the 4th order can be improved statistically significant where as a quatrefoil of the 4th order and all other higher order aberrations did not significantly change. The determined entrance pupil centre as one target point for the ablation profile showed a fluctuation of 66 µm ± 49. Furthermore a shift of the coaxially sighted corneal reflex due to the treatment itself was detected and statistically significant.

Conclusions:

Rotatory symmetric corrections that are less sensitive for decentration showed better results than finely detailed aberration corrections. The limited factor for the accuracy of the correction of higher order aberrations is not the laserspot diameter alone but also the precision of the alignment of each single laserspot.

Financial Disclosure:

NONE