By July 2019, there were no complement-specific therapeutics indicated for ocular surface use registered on www.clinicaltrials.gov (search strings: ‘complement’ / ‘C3’ / ‘C5’ / ‘eculizumab’ AND ‘cornea’, ‘conjunctiva’, ‘dry eye’, ‘keratitis’, OR ‘ocular surface’). The gene discussed is C3; the disease is dry eye syndrome.