Answer
Remove soft lenses before applying the drops and wait at least 15 minutes before replacing them. The preservative can be absorbed by and discolour soft lenses.
Sources for this answer
- Azelastine hydrochloride 0.5 mgml Eye drops solution — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.