[Assessment of retention and drug-release of ophthalmic ointment on the ocular surface].

PURPOSE: The dynamics of ophthalmic ointment on the ocular surface were investigated using a fluorescent ointment. METHODS: Ten healthy volunteers were enrolled. Ointment (1.0 cm length, 0.05 g) containing 0.1% flavin adenine dinucleotide sodium was squeezed out from the tube and placed in the left lower conjunctival sac. The eyes were then closed for 30 seconds and permitted to blink naturally. Two examinations including observation of tear film lipid layer interference pattern and fluorophotometric measurement of fluorescence intensity, both at the center of the cornea, were performed before examination and at 1, 3, 6, 9, 12, 15, 30, 60 minutes after instillation. RESULTS: In all cases, even 1 hour after instillation, tear film interference patterns were observed, and fluorescence intensity greater than before instillation, was present. CONCLUSION: Ointment placed in the conjunctival sac is thought to remain and release agents on the ocular surface for at least one hour.