ICT – ICT – Intraoperative Corneal Topography Intraoperative Corneal Topography for image registration purposes for image registration purposes S.Schründer S.Schründer
Dec 28, 2015
ICT – ICT – Intraoperative Corneal TopographyIntraoperative Corneal Topographyfor image registration purposesfor image registration purposes
S.SchründerS.Schründer
Model eye
6mm optical zone
8mm cornealradius
6mm pupil, 4mm below apex
5mm to rotation axis
12mm radiusbulbus
Motivation
Aberrometer
Ablation pattern
Tilted eye
1st wrong pattern
TreatmentDiagnosis
Ablation pattern
Tilted eye
2nd wrong pattern
Eyetracker
Fine registration: Iterative Closest Point
Find corresponding 3d points (via Hough tables)Minimize their distance
Distance Minimization:1. Levenberg-Marquardt
for fast convergence2. Simmulated annealing
to overcome local minima
Line scans
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
1 2 3 4 5 6 7 8 9 10
horizontal cut
vertical cut
100mm sphere
Dimensions in mm
Line scans
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0 1 2 3 4 5 6 7 8 9 10 11 12
vertical cut
horizontal cut
Dimensions in mm
Linear function*
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
lateral shift of tilted movement [mm]
dece
ntra
tion
[mm
]
*8mm corneal radius, 4mm apex/pupil, 13mm apex/rotation axis
Andreas DankertAndreas Dankert
Hendrik FuchsHendrik Fuchs
Saso SpasovskiSaso Spasovski
Coworkers at BioShape