Purpose: To evaluate and compare a stereo-biomicroscopic technique of ocular torsion measurement with fundus photographic technique.
Methods: This prospective masked observational study included 72 eyes of 36 consecutive subjects with normal ocular motility. The disc-foveal angle was measured by two masked investigators using a slitlamp stereo-biomicroscopic and fundus photographic technique.
Results: The mean age was 13.7 years (6 - 44 years), and 15 (41.6%) were males. The average torsion using the slitlamp technique was 5.5 +/- 3.3 degrees and 6.1 +/- 4.3 degrees with fundus photographic technique. Clinical agreement between the two techniques for 5 degree and 6 degree torsion was 81% and 90% respectively. The average difference between the two techniques was 3.0 +/- 2.6 degrees . The mean inter-ocular difference was 3.3 +/- 2.7 degrees (SD, 2.77) and 5.5 +/- 4.6 degrees using the slitlamp and fundus photographic technique respectively. The Pearson correlation coefficient (r2) was 0.5.
Conclusion: The fundus photographic technique remains the gold standard test for the measurement of ocular torsion. The slitlamp biomicroscopic method can be useful where a fundus camera is unavailable. Further studies are required to test the repeatability of these tests.