Anterior segment optical coherence tomography of the horizontal and vertical extraocular muscles with measurement of the insertion to limbus distance

Normal Anatomy and Anomalies of the Rectus Extraocular Muscles in Human: A Review of the Recent Data and Findings

“…e four ERMs have a specific attachment to the circular fibrous band located in the apex of the orbit, known as the common tendinous ring, annular tendon, or annulus of Zinn. All four ERMs take origin from this tendinous structure with short proximal tendons [7][8][9][10][11][12][13][14].…”

“…erefore, the content of the ring is nerves and vessels running through above-mentioned spaces, that is, optic nerve and ophthalmic artery (which run through the optic canal), as well as superior and inferior branches (division) of the oculomotor nerve, the nasociliary nerve, and the abducens nerve (which run through the superior orbital fissure). Moreover, the annular tendon is also the place of attachment of the superior oblique muscle and levator palpebrae superioris muscle [7][8][9][10][11][12][13][14]. Zampieri et al [12] indicate that the annular tendon was first described by Antonio Maria Valsalva in his treatise "Opera omnia" published in 1740.…”

“…e average tendon lengths for the IR and SR are 6 mm and 7 mm, respectively. e distal tendons of all four ERMs occupy the anterior position regarding the eyeball's equator and are attached to the sclera [1,[7][8][9][10][11][12][13][14]. However, the insertions of the ERMs also vary in their specific position on the eyeball, their distance from the limbus, and the length of the distal tendon.…”

“…e results of measurements made by various authors on individual ERMs insertions slightly vary ( Figure 1) [1, 8-11, 13, 14]. Pihlblad et al [13] measured distances between the ERMs insertions and the limbus in 46 patients who underwent anterior segment optical coherence tomography. According to results obtained by Pihlblad et al [13] the mean distances between insertion and the limbus measured for each rectus muscle were as follows: 5.7 mm (SD � 0.8 mm, range from 4.3 mm to 7.8 mm) for the MR; 6.0 mm (SD � 0.6 mm, range from 4.8 to 7.0 mm) for the IR; 6.8 mm (SD � 0.7 mm; range from 4.8 mm to 8.4 mm) for the LR; and 6.8 mm (SD � 0.6 mm, range from 5.5 mm to 8.1 mm) for the superior rectus.…”

Agreement Between Three Optical Coherence Tomography Devices to Assess the Insertion Distance and Thickness of Horizontal Rectus Muscles

“…The ability of the OCT to accurately image the extraocular muscles could be useful in the preoperative evaluation of patients with strabismus, especially in those with suspected abnormal muscle insertion, in cases of slipped muscles, or in patients who had previous surgery. 17 Further OCT studies to improve the analysis of the extraocular muscles are needed. Measurements obtained in this study with different devices in healthy patients could be useful to compare those results against different pathologic conditions, such as paralyzed muscles, scarred muscles, or in restrictive strabismus; to investigate the differences in characteristics or measurements; and to facilitate a better approach to different strabismus conditions.…”