Invasive conjunctival melanoma can arise de novo, from nevus or from melanoma in situ. The literature reports that after treatment of invasive conjunctival melanoma more than 50% of patients develop local tumor recurrence, with 20% eventually requiring orbital exenteration and 20-30% developing fatal metastasis. Our results have improved since we replaced adjuvant cryotherapy with radiotherapy and topical chemotherapy. There is scope for multicenter clinical trials and translational research, but these require consistent staging and grading of disease. We propose that the term 'primary acquired melanosis' should only be used clinically, when the histology is not known. We have devised a clinical system for mapping conjunctival melanocytic lesions and a system for scoring the histological grade of atypia of conjunctival melanocytic intra-epithelial neoplasia/melanoma in situ. We anticipate that these measures will improve outcomes after treatment of conjunctival melanoma in situ and invasive melanoma.