Anterior segment OCT and confocal microscopy findings in atypical corneal intraepithelial neoplasia.

To report a case of biopsy-proven corneal intraepithelial neoplasia (CIN) diagnosed and followed clinically using high-resolution anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM). Observational case report. A 57-year-old man presented with decreased vision in the right eye for 2 months before presentation. His best-corrected visual acuity was 20/70 in the affected eye, and the slit-lamp examination revealed superficial opacification of the anterior cornea originating from the temporal limbus with a "leopard-spot" pattern more centrally. The lesion was excised at his 2-month follow-up, and the histological examination revealed squamous dysplasia consistent with CIN. Visual acuity improved, and the slit-lamp examination revealed barely visible residual disease at the temporal limbus. However, AS-OCT showed a thicker and highly reflective epithelial layer near the temporal limbus, similar to initial presentation, highlighting this residual disease. IVCM demonstrated dysplastic cells consistent with residual disease. Therefore, we treated the patient with topical interferon alpha-2b (1 million IU/mL) 4 times daily in the affected eye. At 3-month follow-up, the patient's best-corrected visual acuity was 20/20 in the affected eye with persistent but improved residual disease adjacent to the temporal limbus. In the mid-periphery of the inferonasal cornea, focal areas of iatrogenic linear scarring were confirmed to be limited to the anterior stroma by AS-OCT and IVCM at 6-month follow-up. AS-OCT and IVCM are noninvasive techniques that can be used to diagnose and aid in the management of CIN, which may present as subclinical disease through slit-lamp biomicroscopy alone.