Direct Intraocular Extension
In contrast to intraocular metastases, direct extension of extraocular tumors into the eye is rare because the sclera is usually an effective barrier to such invasion. Intraocular extension occurs most commonly with conjunctival squamous cell carcinoma and less frequently with conjunctival melanoma and basal cell carcinoma of the eyelid. Only a small minority of carcinomas of the conjunctiva penetrate the globe, and these are often aggressive variants of squamous cell carcinoma: mucoepidermoid, adenoid, and spindle cell carcinoma. These neoplasms usually recur several times after local excision before they invade the eye. For more information on conjunctival tumors, see BCSC Section 8, External Disease and Cornea.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.