An epibulbar (limbal) dermoid is a choristoma composed of fibrofatty tissue covered by keratinized epithelium; it may contain hair follicles, sebaceous glands, or sweat glands. The dermoid often straddles the limbus (typically inferotemporally) or, less frequently, resides more centrally in the cornea. It is typically less than 10 mm in diameter, with minimal postnatal growth. The dermoid may extend into the corneal stroma and adjacent sclera but seldom encompasses the full thickness (Fig 21-5). Often, a lipoid infiltration of the corneal stroma is noted at the leading edge. Sometimes the lesion is continuous with epibulbar dermolipomas that involve the lateral quadrant of the eye.
Epibulbar dermoids may be seen in Goldenhar syndrome (see also Chapter 18). Patients with Goldenhar syndrome may have one or more of a variety of anomalies, including ear deformities or periauricular tags, maxillary or mandibular hypoplasia, vertebral deformities, eyelid colobomas, or Duane retraction syndrome.
Epibulbar dermoids can produce astigmatism with secondary anisometropic amblyopia. Large epibulbar dermoids can block the visual axis. Surgical excision may be indicated if they cause ocular irritation or amblyopia, but the procedure may result in scarring and astigmatism, which can also lead to amblyopia. Although excision will not eliminate the preexisting astigmatism, surgery may be useful for treating very elevated lesions. Tumor removal involves excising the episcleral portion flush with the plane of surrounding tissue. In general, the surgeon need not remove underlying clear corneal tissue, mobilize surrounding tissue, or apply a patch graft over the resulting surface defect; however, because some lesions extend into the anterior chamber, tissue should be available in the event that a patch graft is required. The cornea and conjunctiva heal within a few days to several weeks, generally with some scarring and imperfect corneal transparency; nevertheless, the appearance can be improved considerably.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.