Table 1.

Topical chemotherapy for ocular surface squamous neoplasia (OSSN)

Most common OSSN treatment options	Formulation	Dosage	Side effects
IFN-a2b	Topical: 1 MIU/ml (Alternative: 2–3 MIU/ml), Subconjunctival injections: 3 million IU/0.5 ml (Alternative: 10 MIU/month)	Topical: 4 times a day drops continuously, Subconjunctival: Weekly injections until resolution (typically 4–5 weeks)	Minimal side effects for drops, flu-like malaise with injections
5-FU	Topical: 1% drops	4 times a day for 1 week with 3 weeks off (Alternative: 4 times daily for 2 days to 4 weeks)	Mild pain, lid edema, epitheliopathy
MMC	Topical: 0.02–0.04% drops	4 times a day for 1 week followed by 2–3 weeks off until the eye is quiet. Usually 3–4 cycles until resolution (Alternative: 7–14 day cycles)	Pain, keratopathy, punctal stenosis, LSCD

LSCD= limbal stem cell deficiency; MIU= million international units; LSCD= limbal stem cell deficiency; MIU= million international units; IFN-a2b= interferon alpha 2b; 5-FU= 5-fluorouracil; MMC= mitomycin C