A topical anesthetic is a

local anesthetic A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general an ...

that is used to numb the surface of a body part. They can be used to numb any area of the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

as well as the front of the

eyeball Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

, the inside of the

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next pass ...

, ear or

throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebrae. It contains the pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the trachea (windpi ...

, the

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...

and the genital area. Topical anesthetics are available in creams, ointments, aerosols, sprays, lotions, and jellies. Examples include

benzocaine Benzocaine, sold under the brand name Orajel amongst others, is an ester local anesthetic commonly used as a topical pain reliever or in cough drops. It is the active ingredient in many over-the-counter anesthetic ointments such as produ ...

butamben Butamben is a local anesthetic. Proprietary names includes Alvogil in Spain and Alvogyl in Switzerland. It is one of three components in the topical anesthetic Cetacaine. Chemistry It is the ester of 4-aminobenzoic acid and butanol.drugs.c ...

, dibucaine,

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, li ...

oxybuprocaine Oxybuprocaine (INN), also known as benoxinate or BNX, is an ester-type local anesthetic, which is used especially in ophthalmology and otolaryngology. Oxybuprocaine is sold by Novartis under the brand names Novesine or Novesin. Safety for use in p ...

, pramoxine,

proxymetacaine Proxymetacaine (INN) or proparacaine ( USAN) is a topical anesthetic drug of the aminoester group. Clinical pharmacology Proxymetacaine is a local anesthetic which on topical application penetrates sensory nerve endings in the corneal tissue. Me ...

(proparacaine), and tetracaine (also named amethocaine).

Usage

Topical anesthetics are used to relieve

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

and

itch Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasant ...

ing caused by conditions such as sunburn or other minor burns, insect bites or stings, poison ivy,

poison oak Poison oak refers to two plant species in the genus '' Toxicodendron,'' both of which can cause skin irritation: *''Toxicodendron diversilobum'' or Western poison oak, found in western North America *''Toxicodendron pubescens ''Toxicodendron pu ...

poison sumac ''Toxicodendron vernix'', commonly known as poison sumac, or swamp-sumach, is a woody shrub or small tree growing to 9 metres (30 feet) tall. It was previously known as ''Rhus vernix''. This plant is also known as thunderwood, particu ...

, and minor cuts and scratches.DrLinhart.com
/ref> Topical anesthetics are used in

ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a med ...

and

optometry Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. Optometrists are health care professionals who typically provide comprehensive primary eye care. In the Un ...

to numb the surface of the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

(the outermost layers of the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

and

conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epitheli ...

) to: * Perform a contact/applanation tonometry. * Perform a

Schirmer's test Schirmer's test determines whether the eye produces enough tears to keep it moist. This test is used when a person experiences very dry eyes or excessive watering of the eyes. It poses no risk to the subject. A negative (more than 10 mm of moi ...

(The Schirmer's test is sometimes used with a

topical A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of class ...

eye anesthetic, sometimes without. The use of a topical anesthetic might impede the reliability of the Schirmer's test and should be avoided if possible.). * 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 Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions ...

, topical anesthetics are used to numb oral tissue before administering a dental

due to the entry of the needle into the soft tissues of the oral cavity.''Local Anesthesia for the Dental Hygienist,'' Logothetis, Elsevier, 2012 Some topical anesthetics (e.g.

) are also used in

otolaryngology Otorhinolaryngology ( , abbreviated ORL and also known as otolaryngology, otolaryngology–head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT)) is a surgical subspeciality within medicine that deals with the surgical a ...

. Topical anesthetics are now commonly used in the temporary relief of premature ejaculation when applied to the glans (head) of the penis. Benzocaine or lidocaine are typically used for this purpose as they are available as

over-the-counter drug Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid presc ...

Duration of topical

The duration of topical anesthesia might depend on the type and amount applied, but is usually about half an hour.

Abuse when used for ocular pain relief

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 Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired e ...

, masquerading as acanthamoeba keratitis or other

infectious keratitis An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

. 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 have eye pain, which is often considerably strong

neuropathic pain Neuropathic pain is pain caused by damage or disease affecting the somatosensory system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli ( allodynia). It may have continuo ...

caused by the irritation of the nerves within the cornea and/or conjunctiva, try to illegally obtain oxybuprocaine or other eye anesthetics (for example by

stealing Theft is the act of taking another person's property or services without that person's permission or consent with the intent to deprive the rightful owner of it. The word ''theft'' is also used as a synonym or informal shorthand term for som ...

them at their

ophthalmologist Ophthalmology ( ) is a surgery, surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Followin ...

optometrist Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. Optometrists are health care professionals who typically provide comprehensive primary eye care. In the Un ...

, by

forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at whi ...

medical prescription A prescription, often abbreviated or Rx, is a formal communication from a physician or other registered health-care professional to a pharmacist, authorizing them to dispense a specific prescription drug for a specific patient. Historica ...

s or by trying to order it via an

online pharmacy An online pharmacy, internet pharmacy, or mail-order pharmacy is a pharmacy that operates over the Internet and sends orders to customers through mail, shipping companies, or online pharmacy web portal. Online pharmacies include: * Pharmacy ben ...

) and use the substance to numb their eye pain, often ending up with irreversible corneal damage or even destruction (which is a

vicious cycle A vicious circle (or cycle) is a complex chain of events that reinforces itself through a feedback loop, with detrimental results. It is a system with no tendency toward equilibrium (social, economic, ecological, etc.), at least in the short r ...

and causes more pain). Often, such patients finally require

corneal transplantation Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft). When the entire cornea is replaced it is known as penetrating keratoplasty ...

. In case of prolonged or chronic eye pain, especially

neuropathic eye pain Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...

, it is highly advisable to use centrally acting substances like

anticonvulsants Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of ...

(

pregabalin Pregabalin, sold under the brand name Lyrica among others, is an anticonvulsant, analgesic and anxiolytic medication used to treat epilepsy, neuropathic pain, fibromyalgia, restless leg syndrome, opioid withdrawal and generalized anxiety ...

gabapentin Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication primarily used to treat partial seizures and neuropathic pain. It is a first-line medication for the treatment of neuropathic pain caused by diab ...

and in more serious cases

carbamazepine Carbamazepine (CBZ), sold under the trade name Tegretol among others, is an anticonvulsant medication used primarily in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medi ...

) or

antidepressants Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, heada ...

(for example

SSRI Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions. SSRIs increase the extrace ...

s or the

tricyclic antidepressant Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants, which is important for the management of depression. They are second-line drugs next to SSRIs. TCAs were discovered in the early 1950s and we ...

amitriptyline Amitriptyline, sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat cyclic vomiting syndrome (CVS), major depressive disorder and a variety of pain syndromes from neuropathic pain to fibromyalgia ...

). 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.

Notes

External links

Principles of Office Anesthesia: Part II. Topical Anesthesia
{{Anesthesia

Local anesthetics Anesthesia

Usage

Duration of topical

Abuse when used for ocular pain relief

See also

Notes

External links