Reproducibility of angle kappa measurements using a modern laser system
Session Details
Session Title: Photoablation
Session Date/Time: Tuesday 13/09/2016 | 14:00-16:00
Paper Time: 14:18
Venue: Hall C2
First Author: : S.Pieh AUSTRIA
Co Author(s): : C. Skorpik G. Schmidinger
Abstract Details
Purpose:
Higher order aberrations corrections are positioned on the pupil centre, whereas the evaluated subjective refraction is centred at the first Purkinje reflex. The detection of the pupil rim using an infrared camera during the determination of the corneal topography allows defining the first Purkinje reflex using polar coordinates based on the distance to the pupil centre. This offset correlates with the angle kappa. Especially in highly aberrated corneas the centration of the ablation profile plays an important role. In a retrospective study 85 eyes that undergone an excimer laser treatment the reproducibility of the angle kappa measurement has been evaluated.
Setting:
Department of Ophthalmology and Optometry, Medical University Vienna
Methods:
In 85 highly aberrated corneas with an RMS HOA (Root-mean-square higher order aberration) from 1,0 to 4,0 µm the variance of the determined offset has been examined. Therefore for each individual case eight determined offsets were compered. Furthermore the mean values and the standard deviation of the preoperative and postoperative offset were evaluated.
Results:
The standard deviation for all evaluated cases were ± 0,11 mm for the offset. In individual cases the standard deviation shows values up to 0,5 mm. This was especially the case in eyes with an incomplete pupil rim detection. Furthermore a change of the offset due to the excimer laser treatment was in mean 0,12 mm ± 0,11 (0,0 – 0,58) and statistically significant.
Conclusions:
The limited reproducibility of the offset and the change of the offset due to the treatment restricts like the light brightness depended pupil shift the accuracy of excimerlaser treatment in highly aberrated corneas
Financial Disclosure:
NONE
