Abstract
Purpose: :
Little is known about the influence of viewing distance on vertical deviations (Graf et al. 2004; Thomas et al. 2005). We investigated the influence of viewing distance in a group of patients with 4th nerve palsy.
Methods: :
Fifty–three patients with 4th nerve palsy were retrospectively studied in an effort to record their vertical deviation at 1/3m and 6m.Deviation was measured by the alternating cover test at both distances in the primary position of gaze. In addition deviations including cyclotorsion at 2.5m were measured with a tangent screen (Harm's Wall)
Results: :
27 out of the 53 (50.94%) patients had a vertical deviation, which measured more at 1/3m than at 6m (mean vertical deviation±SD, 11.6±8.9 at 1/3m, 6.2±6.3 at 6m), 18 (33.96%) patients had a vertical deviation which was more at distance (6.9±6.5 at 1/3m, 10.1±7.2 at 6m), Only in 8 (15.09%) patients the vertical deviation remained the same irrespective of the distance (9.9+–10.4 at 1/3 and 6m). 23 out of the 53 (43.39%) patients had an associated exodeviation (mean vertical deviation +– SD, 9.4±8.0 at 1/3m, 8.8±7.6 at 6m), 23 patients (43.39%) had no horizontal deviation (10.5±9.8 at 1/3m, 7.7±8.3 at 6m), and only 7 patients out of 53 (13.21%) had an associated esodeviation (8.3±6.7 at 1/3m, 7.0±3.9 at 6m),. Measurements from the tangent screen showed that mean excyclotorsion was larger with the affected eye fixing in most positions of gaze.
Conclusions: :
Vertical deviation of patients with superior oblique palsy varies in most patients between near and distance fixation, and was most commonly higher at near. This could be explained by adduction during convergence. Difference in vertical deviation needs to be considered for surgical planning. Secondary torsional deviation was greater than primary torsional deviation.
Keywords: strabismus • eye movements