Nitrous oxide cryotherapy for intraepithelial epithelioma of the conjunctiva.

Nine patients were treated with the nitrous oxide eyelid cryoprobe for large or recurrent intraepithelial epithelioma of the conjunctiva or cornea. Nitrous oxide cryotherapy is more convenient for ocular cryosurgery than liquid nitrogen therapy and seems to be as effective for intraepithelial epithelioma. Surgical debulking of the lesion is recommended before cryosurgery. An obvious advantage of cryosurgery over surgical modalities for intraepithelial epithelioma is that large areas of tumor as well as surrounding tissues can be treated. This procedure results in a higher cure rate and avoids grafting and symblepharon formation. The complications of light cryosurgery seem to be minor even when the cornea is treated. Heavy cryosurgery may result in severe iritis, posterior synechiae, and corneal scarring. A biopsy-proved diagnosis of intraepithelial epithelioma can be misleading and does not rule out the presence of underlying malignant disease.