Abstract
Purpose:
To use enhanced iris images and a proprietary computer software program to quantify ocular torsional changes associated with head tilt.
Methods:
Pixel coordinates of the pupil and different iris landmarks were obtained from enhanced digital images of the right and left iris of 2 subjects with normal extraocular motility. Photographs of the right and left eyes were taken in the straight ahead position and at various degrees of right and left head tilt. A proprietary software computer program converted the x and y pixel coordinates into angles of rotation after averaging multiple points, determining the degree and the direction of torsion for each eye. The degree of head tilt was mathematically calculated from the digital images. The degree and direction of ocular torsion was correlated with the degree and direction of head tilt.
Results:
The average degree of head tilt was 27.5 degees(from 8 to 43 degrees). The average intorsion of the lower eye per degree of head tilt was 0.61 degrees (from 0.54 to 0.65 degrees). The average extorsion of the higher eye per degree of head tilt was 0.56 degrees (from 0.43 to 0.60 degrees). The average ocular torsional changes strongly correlated with the degree of head tilt (Correlation Coefficient = 0.92).
Conclusions:
Computerized iris pattern recognition and analysis of the ocular torsional changes associated with head tilt may provide useful objective means of assessing ocular torsion.
Keywords: 752 vestibulo-ocular reflex •
522 eye movements •
612 neuro-ophthalmology: diagnosis