From the Guidelines
Proparacaine (0.5%) or tetracaine (0.5%) eye drops are recommended for numbing the eye before inserting a Morgan lens. Apply 1-2 drops to the affected eye and wait approximately 15-20 seconds for the anesthetic effect to begin before inserting the lens. These topical anesthetics work by blocking sodium channels in nerve membranes, preventing the generation and conduction of nerve impulses and providing rapid surface anesthesia 1. The numbing effect typically lasts about 15-20 minutes, which is sufficient for Morgan lens insertion and initial irrigation. Some key points to consider when using topical anesthetics for this procedure include:
- The potential for temporary stinging upon application before the numbing effect begins
- The importance of limiting the use of topical anesthetics to the initial insertion of the Morgan lens, as repeated use can delay corneal healing and potentially cause corneal damage 1
- The need for patients to avoid rubbing their eyes until normal sensation returns, as they may inadvertently damage the cornea without feeling it It's also worth noting that other topical anesthetics, such as oxybuprocaine, may be used in certain situations, but proparacaine and tetracaine are generally preferred for this procedure due to their rapid onset and effective numbing properties 1.
From the FDA Drug Label
Tetracaine Hydrochloride Ophthalmic Solution 0.5% is indicated for procedures requiring a rapid and short-acting topical ophthalmic anesthetic. The topical anesthetic eye drops that should be used for numbing before insertion of a Morgan (lacrimal) lens is tetracaine.
- The recommended dosage is one drop topically in the eye as needed 2.
- It is essential to note that tetracaine is not intended for patient self-administration and should be used under the direct supervision of a healthcare provider 2.
From the Research
Topical Anesthetic Eye Drops for Numbing
- The most commonly used topical anesthetic eye drops are proparacaine, tetracaine, benoxinate (oxybuprocaine), cocaine, and lidocaine 3.
- For numbing before insertion of a Morgan (lacrimal) lens, proparacaine 0.5% eye drops can be used, as it has been shown to provide sufficient patient comfort and avoid complications related to peribulbar anesthesia 4.
- Dilute proparacaine (0.05%) has also been used for the management of acute corneal injuries in the emergency department, providing significant pain reduction without ocular complications or signs of delayed wound healing 5.
- However, it is essential to note that topical anesthetic abuse can lead to permanent corneal scarring and decreased vision, and patients should be carefully instructed on the proper use of these agents 6.
- A study comparing the anesthetic effectiveness of topical levobupivacaine 0.75% and proparacaine 0.5% for intravitreal injections found that proparacaine 0.5% was more effective in preventing pain 7.