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Photographs of a pterygium and various grades of ocular surface squamous neoplasia: pterygium (A), conjunctiva intra-epithelial neoplasia (CIN) 1 (B), CIN 3 (C), carcinoma in situ (D), squamous cell carcinoma (SCC) grade 1 (E), SCC grade 2 (F), SCC grade 3 (G), and SCC with orbital invasion (H).
