Insertion of Horizontal Rectus Muscles in Strabismus

ABSTRACT

An anatomical evaluation of the limbus-insertion distance and width at insertion of the horizontal rectus muscle had been measured on enuclated eyes from normal adult cadavers by several authors. We measured the variation in the limbus-insertion distance and width of 214 horizontal rectus muscles in 111 strabismus patients, composed of 38 esotropes and 73 exotropes. We also evaluated their relation to strabismus. The results were as follows 1. The average limbus-insertion distance of medial rectus was 4.38 +/- 0.45 mm and lateral rectus was 5.56 +/- 0.84 mm and the average width of medial rectus at insertion was 9.19 +/- 0.78 mm and that of lateral was 8.32 +/- 1.00 mm. 2. The largest values for limbus-insertion distance and width of medial rectus were found in esotropes in the 8 to 13 years old age group(9.76 +/- 0.12 mm and 4.53 +/- 0.44 mm respectively), and those of lateral rectus in exotropes in the 13 to 18 years old age group(8.66 +/- 0.95mm and 6.09 +/- 0.45mm respectively). 3. The limbus-insertion distance and width at insertion was larger in male than in female and it was especially significant in the medial rectus muscle of esotropes(p<0.001). 4. The limbus-insertion distance and width tended to be larger in horizontal deviation greater than 40 delta. as compared to those of 40 delta or less.