What is the recommended interval between instilling latanoprost eye drops and carbomer 0.2% eye gel?

• A. 1 minute
• B. 15 minutes
• C. 60 minutes
• D. 5 minutes

Answer: (D)

When using more than one topical eye preparation, space their applications to let each medication act and to avoid one influencing the other in the tear film. Latanoprost needs time to be absorbed by the cornea to exert its effect. If a gel is instilled too soon, its viscous vehicle can mix with or dilute the drop, or hinder its absorption due to tear turnover and the gel’s residual presence on the ocular surface. Waiting about 5 minutes after instilling latanoprost before applying carbomer 0.2% eye gel gives the drop a chance to begin acting and reduces the chance of interference, ensuring both medications work as intended. The other intervals are unnecessarily short or long for this purpose.