Erythromycin (Optryl) 0.5% Ophthalmic Ointment 5g is an antibacterial ointment used to treat eye infections such as conjunctivitis (pink eye) caused by susceptible bacteria. The ointment contains 0.5% erythromycin, a macrolide antibiotic, which works by inhibiting bacterial protein synthesis and preventing the growth of bacteria. It comes in a 5g tube, making it easy to apply directly to the affected eye. Follow the instructions provided by your healthcare provider to ensure proper use and dosage for effective treatment.