Clinical Ophthalmology (Oct 2020)

Horizontal Extraocular Muscle Insertion Site in Relation to Axial Length Using Swept-Source Anterior Segment OCT

  • El-Fayoumi D,
  • Bahgat N,
  • Khafagy M,
  • Hatata R,
  • Sabry D,
  • Allam G,
  • Kasem MA,
  • Sadek S

Journal volume & issue
Vol. Volume 14
pp. 3583 – 3589

Abstract

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Dina El-Fayoumi,1 Nermeen Bahgat,1 Mohamed Khafagy,1 Ragai Hatata,2 Dalia Sabry,3 Ghada Allam,3 Manal Ali Kasem,3 Sherin Sadek2 1Ophthalmology Department, Faculty of Medicine, Cairo University, Cairo, Egypt; 2Ophthalmology Department, Faculty of Medicine, Fayoum University, Fayoum, Egypt; 3Mansoura Ophthalmic Centre, Faculty of Medicine, Mansoura University, Mansoura, EgyptCorrespondence: Sherin SadekFaculty of Medicine, Fayoum University, 2/7 Zahraa EL Maadi, 4th Floor, Dep. 45, Fayoum 11435, EgyptTel +20 1006232012Email [email protected]: The purpose of this study was to correlate between the axial length of the globe and the insertion site of horizontal extraocular muscles using swept-source anterior segment optical coherence tomography (SS-ASOCT), with posing an equation to calculate the muscle insertion site from the axial length.Methods: The study design was observational and cross-sectional. It was performed on 157 eyes of 157 healthy subjects. The distance of the medial rectus (MR) and the lateral rectus (LR) insertion sites from the limbus were measured using SS-ASOCT. The insertion sites’ distances were correlated to the axial length (hypermetropes < 22.5 mm, myopes > 24.5). Correlation between numerical variables was done by Pearson’s correlation coefficient and confirmed by linear regression analysis and scatter diagrams.Results: The mean MR insertion site was 5.47 ± 0.19 mm in hypermetropes versus 5.68 ± 0.23 mm in myopes, whereas the mean LR insertion site was 6.81± 0.23 mm in hyperopes versus 7.08 ± 0.16 mm in myopes. The axial length showed a moderate positive, but significant, correlation to the insertional position for the medial and lateral rectus muscles (MR: r=0.417, p< 0.001; LR: r=0.410, p< 0.001).Conclusion: Comparing the horizontal extraocular muscle insertion site to axial length using SS-ASOCT showed a significant positive correlation. The model equation for MR insertion: MR (mm) = 4.522 + 0.045 (AXL in mm) with an R = 0.437, R2= 0.191, F=12.071, P< 0.001. The model equation for LR insertion: LR (mm) = 5.72 + 0.048 (AXL in mm) with an R = 0.438, R2= 0.192, F=12.116, P< 0.001.Keywords: AS-OCT, axial length, extraocular muscle insertion site, swept-source OCT

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