Diquafosol Delivery from Silicone Hydrogel Contact Lenses: Improved Effect on Tear Secretion

Purpose: The aim of this study was to evaluate the ability to uptake and to deliver diquafosol from commercial contact lenses (CLs) and its effect on tear secretion. Methods: For both in vitro and in vivo experiments, two commercial silicone hydrogel (Si-Hy) CLs (comfilcon A and balafilcon A) were used. The CLs were soaked overnight for 12h in diquafosol solution and control CLs were soaked in saline solution (NaCl 0.9%). The CLs were introduced into a new well container with 1mL of saline solution, and aliquots of 100L were extracted at different times during a period of 6h to measure the diquafosol release. For in vivo experiments, nine male New Zealand white rabbits were used. CLs soaked in diquafosol were inserted in the eye and compared with control CLs and diquafosol topical instillation. Schirmer's tests were performed to evaluate tear secretion and diquafosol release at different times during the 6-h period. Results: For in vitro experiments, the largest amount of diquafosol was released during the first 24h for both CL materials under study, without statistical differences between them (P<0.05). The topical application showed the maximum release at 1min after instillation, meanwhile the release from both CL materials was at 30min of insertion. The effect on tear secretion was higher with CL delivery compared with topical instillation (P<0.05), being 300min for both CLs and 90min for topical application. Conclusion: The use of CLs increases the residence time of diquafosol on the ocular surface with a concomitant enhancement in tear secretion during longer periods.