Optical coherence tomography (OCT) has been used to image anterior and posterior structures of the eye, but it has not been used to image structures behind the sclera.1,2 Extraocular muscles, especially when hypertrophied from thyroid eye disease, have been described with OCT anteriorly.3 Patient 1 (Figure 1A) has a large staphyloma created by focal treatment of intraocular retinoblastoma. A horizontal cross-section was taken with Heidelberg Spectralis enhanced depth imaging OCT (EDI-OCT) (Heidelberg Engineering) and revealed details normally masked by the retina and choroid. The sclera (white arrow), Tenon's capsule (red arrow), long posterior ciliary nerve (yellow arrow), and orbital fat (blue arrows) are visualized through the staphyloma, with an area of thinned atrophic retina adjacent to the staphyloma (green arrow). In Patient 2 (Figure 1B), EDI-OCT imaging revealed multiple insertion sites of the inferior oblique muscle. Patient 2 also has a large staphyloma created by focal treatment of intraocular retinoblastoma. Studies have revealed variability in the anatomy of the inferior oblique muscle, showing different insertional patterns and varying number of muscle bellies, ranging from one to four insertion sites.4 The authors postulate that multiple muscle bellies of the inferior oblique are visualized in this patient (red arrows). The inferior oblique muscle inserts approximately 4.63 ± 1.57 mm from the lateral edge of the optic nerve,4 which is approximately where the multiple insertion sites are in this patient.
- Ocak OB, İnal A, Yilmaz İ, et al. Measurement of extraocular horizontal muscle insertion distance via anterior segment optical coherence tomography of healthy children and comparison with healthy adults. Int Ophthalmol. 2019;39(5):1037–1042. doi:10.1007/s10792-018-0903-5 [CrossRef]
- Ohno-Matsui K, Akiba M, Modegi T, et al. Association between shape of sclera and myopic retinochoroidal lesions in patients with pathologic myopia. Invest Ophthalmol Vis Sci. 2012;53(10):6046–6061. doi:10.1167/iovs.12-10161 [CrossRef]
- Häner NU, Dysli M, Abegg M, Zinkernagel MS. Enhanced-depth optical coherence tomography for imaging horizontal rectus muscles in Graves' orbitopathy. Graefes Arch Clin Exp Ophthalmol. 2015;253(9):1569–1573. doi:10.1007/s00417-015-3060-9 [CrossRef]
- Paik DJ, Shin SY. An anatomical study of the inferior oblique muscle: the embalmed cadaver vs the fresh cadaver. Am J Ophthalmol. 2009;147(3):544–549.e1. doi:10.1016/j.ajo.2008.09.012 [CrossRef]