Horizontal Extraocular Muscle and Scleral Anatomy in Children: A Swept-Source Anterior Segment Optical Coherence Tomography Study

Abstract

PurposeTo evaluate the efficacy of anterior segment swept-source optical coherence tomography (SS-OCT) for examining horizontal extraocular muscle thickness, distance from the corneal limbus to the insertion of the horizontal extraocular muscle (limbus to insertion distance), and scleral thickness in Korean pediatric strabismus patients.MethodsThis study included pediatric strabismus patients between 5 and 10 years of age. Children with any ocular disease other than strabismus or a history of ocular surgery were excluded. SS-OCT was used to measure horizontal extraocular muscle thickness, limbus to insertion distance, and scleral thickness. Eyes were classified into subgroups by sex, spherical equivalent of the refractive error (measured with cycloplegic refraction), and fixating/deviating eye.ResultsOne patient initially included in this study was excluded due to poor cooperation. Of the remaining 35 eyes of 20 patients, 19 eyes (54.3%) were from male patients and 16 eyes (45.7%) were from female patients. The mean patient age was 7.86 ± 1.38 years. Lateral scleral thickness was greater in male eyes than in female eyes (p = 0.048). No other differences were noted between male and female children. Additionally, there were no statistically significant differences between fixating and deviating eyes or among spherical equivalent groups for any parameter examined.ConclusionsAnterior segment SS-OCT can successfully and comfortably measure horizontal extraocular muscle and scleral anatomy in children. These measurements may be helpful for treatment and follow-up of pediatric strabismus patients.

Optical coherence tomography in paediatric clinical practice

“…Han et al analysed extraocular muscle and scleral anatomy using swept‐source OCT in 20 children with strabismus offering a more comfortable, cost‐effective, low‐radiation alternative to magnetic resonance imaging or computed tomography, without requirement for anaesthetic. Specifically, the distance from the limbus to the insertion point of the horizontal extraocular muscles, as well as scleral thickness, were able to be successfully measured …”

Do rectus muscle parameters vary between emmetropes and myopes?

“…While previous studies investigated EOM parameters (especially muscle insertion distance and thickness) using instruments such as Vernier callipers, ultrasound B-scan, magnetic resonance imaging and optical coherence tomography (OCT), these either estimated the distances in cadaveric eyes or did not involve humans with varying degrees of myopia. [19][20][21][22][23][24][25][26][27][28] The paucity in the literature in exploring the association of medial (MR) and lateral rectus (LR) muscle parameters with varying degrees of myopia warrants investigation to understand this relationship, especially considering that the biomechanical properties of the eye, similar to structural properties, may also differ between emmetropes and myopes. 24,25,27,29,30 With this background on the significant role of EOMs during convergence, and in turn the association of prolonged nearwork with myopia, it is of interest to explore whether the EOM parameters show any association with myopia akin to thinning/atrophy of various ocular structures with ocular stretching.…”

Shape analysis of rectus extraocular muscles with age and axial length using anterior segment optical coherence tomography

“…Recent advances in anterior segment optical coherence tomography (AS-OCT) have made it possible to visualize not only the cornea, anterior chamber, and iris but also the extraocular muscles (EOMs) [1][2][3][4][5][6][7][8][9]. However, these reports only involved the evaluation of tomographic images of the EOMs, and most of them were related to muscle insertion.…”