Remove small foreign objects from the uppermost layer of the cornea or conjunctiva. The deeper and the larger a foreign object which should be removed lies within the cornea and the more complicated it is to remove it, the more drops of topical anesthetic are necessary prior to the removal of the foreign object to numb the surface of the eye with enough intensity and duration.
In dentistry, topical anesthetics are used to numb oral tissue before administering a dental local anesthetic due to the entry of the needle into the soft tissues of the oral cavity. Some topical anesthetics are also used in otolaryngology. Topical anesthetics are now commonly used in the temporary relief of premature ejaculation when applied to the glans of the penis. Benzocaine or lidocaine are typically used for this purpose as they are available as over-the-counter drugs.
Duration of topical
The duration of topical anesthesia might depend on the type and amount applied, but is usually about half an hour.
When used excessively, topical anesthetics can cause severe and irreversible damage to corneal tissues and even loss of the eye. The abuse of topical anesthetics often creates challenges for correct diagnosis in that it is a relatively uncommon entity that may initially present as a chronic keratitis, masquerading as acanthamoeba keratitis or other infectious keratitis. When a keratitis is unresponsive to treatment and associated with strong ocular pain, topical anesthetic abuse should be considered, and a history of psychiatric disorders and other substance abuse have been implicated as important factors in the diagnosis. Because of the potential for abuse, clinicians have been warned about the possibility of theft and advised against prescribing topical anesthetics for therapeutic purposes. Some patients who suffer from eye pain, which is often considerably strong neuropathic pain caused by the irritation of the nerves within the cornea and/or conjunctiva, try to illegally obtain oxybuprocaine or other eye anesthetics and use the substance to numb their eye pain, often ending up with irreversible corneal damage or even destruction. Often, such patients finally require corneal transplantation. In case of prolonged or chronic eye pain, especially neuropathic eye pain, it is highly advisable to use centrally acting substances like anticonvulsants or antidepressants. Even very small amounts of an anticonvulsant and/or an antidepressant can almost completely stop eye pain and does not damage the eye at all.
