Abstract
Abstract: :
Purpose:To determine the anatomic variation of the horizontal recti and evaluate its relation to the type and degree of strabismus. Methods: Measurements of the limbus insertion distances and the width of the horizontal recti were made at the time of strabismus surgery in 100 patients (50 esotropic) (50 exotropic). Deviations were further defined as small (≤40pd) and large (>40pd) tropia. Comparisons of the measurements were made between small and large exotropia; small and large esotropia; small esotropia and small exotropia; large esotropia and large exotropia. Results: The average limbus insertion distance and width of the medial recti (MR) in esotropia were 5.43 mm and 8.51 mm, and those in exotropia were 5.58 mm and 8.31 mm (p>0.05). Further, the average limbus insertion distance and width of the lateral recti (LR) in esotropia were 6.52 mm and 7.97 mm, and those in exotropia were 6.32 mm and 8.22 mm (p>0.05). Moreover, when the measurements were compared in the various groups they were not found to be statistically different in any of the groups except when the large angle esotropia was compared to the large angle exotropia. In large angle esotropia, MR was nearer to the limbus (5.43 mm) and thicker (8.65 mm) than in large angle exotropia in which it was further from the limbus (5.93 mm) and thinner (8.16 mm) (p<0.01). Similarly, in large angle exotropia, LR was nearer to the limbus (6.11 mm) and thicker (8.58 mm) than in large angle esotropia in which it was further from the limbus (6.57 mm) and thinner (8.07 mm) (p<0.01). Conclusions: Small angle tropia show no considerable difference in limbus insertion distance and width of the horizontal recti between esotropia and exotropia. However, in large angle tropia the position of the insertion and the width of the horizontal recti suggest their role in the etiology of strabismus highlighting an anatomic basis of heterotropia.
Keywords: anatomy • extraocular muscles: structure • strabismus