Korean J Ophthalmol.  2012 Dec;26(6):438-445. 10.3341/kjo.2012.26.6.438.

Astigmatic Changes after Horizontal Rectus Muscle Surgery in Intermittent Exotropia

• Hong SW
• Kang NY

• KMID: 1499682
• DOI: http://doi.org/10.3341/kjo.2012.26.6.438

Abstract

PURPOSE
To evaluate the changes of refractive astigmatism after horizontal rectus muscle surgery in intermittent exotropic children.
METHODS
Sixty-nine exotropic patients were retrospectively reviewed. Of those, 35 patients received unilateral lateral rectus recession (BLR group, 35 eyes) and 34 patients received unilateral lateral rectus recession and medial rectus resection (R&R group, 34 eyes). Non-cycloplegic refractions were measured until 6 months postoperatively. Spherical equivalent (SE), J0 and J45 using power vectors were calculated to determine and compare the changes of refractive astigmatism and axis in both groups.
RESULTS
SE significantly decreased after surgery for the first week and did not changed thereafter in both groups (p = 0.000 and p = 0.018, respectively). In BLR group, J0 showed significant changes at the first week and 1 month after surgery (p = 0.005 and p = 0.016, respectively), but in R&R group, J0 changed significantly between 1 week and 3 months postoperatively (p = 0.023 and p = 0.016, respectively). J45 did not change significantly as time passed in both groups (all p > 0.05). There was no statistically significant difference in the magnitude of changes in SE, J0 and J45 between the two groups after the 6-month follow-up (p = 0.500, p = 0.244 and p = 0.202, respectively).
CONCLUSIONS
Horizontal rectus muscle surgery in intermittent exotropic children tends to induce a statistically significant change in astigmatism in the with-the-rule direction and myopic shift in SE. This astigmatism change seems to occur within the first 3 months after surgery. Thus, astigmatism induced by surgery should be checked and corrected at least 3 months after horizontal strabismus surgery.

Keyword

Astigmatism; Horizontal rectus muscle surgery; Intermittent exotropia

MeSH Terms

Adolescent
Astigmatism/*etiology/physiopathology
Child
Child, Preschool
Exotropia/complications/physiopathology/*surgery
*Eye Movements
Female
Follow-Up Studies
Humans
Male
Oculomotor Muscles/surgery
Ophthalmologic Surgical Procedures/*methods
Retrospective Studies
Treatment Outcome
Vision, Binocular/*physiology

Figure

• 

  Fig. 1 Changes of spherical equivalent (SE), J0, and J45 after surgery according to the postoperative time course in bilateral lateral rectus recession (BLR) group (A,C,E) and unilateral lateral rectus recession and medial rectus resection (R&R) group (B,D,F). SE significantly decreased at 1 week postoperatively (p = 0.000 and p = 0.018, respectively) and did not change significantly thereafter in two groups (A,B). In BLR group, J0 showed significant changes until the first month after surgery (p = 0.005 and p = 0.016, respectively) (C). In R&R group, J0 showed significant changes between 1 week postoperatively and 3 months postoperatively (p = 0.023 and p = 0.016 respectively) (D). J45 did not show any significant changes (p > 0.05) in both groups (E,F). POD= postoperative day.

• 

  Fig. 2 Distribution of J0's and J45's before surgery (A,B) and at 6 months postoperatively (C,D) in bilateral lateral rectus recession group (A,C) and unilateral lateral rectus recession and medial rectus resection group (B,D). Non-cycloplegic astigmatism before surgery increased on average after surgery in both groups. Each data point represents the astigmatism component of power vector.

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