A New Spray Device to Deliver Topical Ocular Medication: Penetration of Fluorescein to the Anterior Segment

PURPOSE: To measure the penetration of fluorescein into the anterior ocular compartments after exposure of the cornea to a mist of aerosol droplets.

METHODS: This was an open-label proof-of-principle trial. Eighteen healthy volunteers were asked to participate. A conventional (50 μL) drop of fluorescein solution (20 mg/mL) was administered to the right eye; an ocular mist (10 μL) of the same solution was applied to the left eye. Autofluorescence (photons/s) was measured in the cornea, the anterior chamber (AC), and the lens before administration and at 1, 2, 5, 10, 20, 50, and 100 min thereafter. The area under the curve (AUC) was calculated. For the vitreous cavity, measurements were performed at baseline and after 100 min.

RESULTS: All participants completed the study. AUC (mean±SD) for the cornea was (363±431)×10(4) photons after drop application and (154±265)×10(4) photons after the mist (P=0.005). For the AC, these values were (6.9±10.3)×10(4) and (2.9±5.4)×10(4) photons, respectively (P=0.14). Autofluorescence data obtained in the lens did not allow reliable AUC calculations. Autofluorescence in the vitreous at 100 min did not significantly exceed the level at baseline.

CONCLUSION: It was demonstrated that fluorescein applied to the ocular surface with the spray device enters the AC. The total amount of fluorescein molecules reaching the ocular surface by the 2 methods of administration, however, is not equivalent. Therefore, no definitive conclusions on relative bioavailability can be drawn from this experiment.