Why Your Eye Doctor Uses Anaesthetic Drops

by Mar 18, 2023

There are eye drops which can numb the front surface of the eyes. These eye drops are called ocular anaesthetic drops. The three most common medications in this group are proparacaine, tetracaine, and benoxinate. These numbing eye drops have uses in eye procedures including gonioscopy, applanation tonometry, corneal surgery, and can also be used to reduce pain from an eye injury. These medications are never prescribed for continued use as there is a high risk of potential side effects.


How Numbing Drops Work

The numbing eye drops are able to numb the cornea and front of the eye by prevent nerve impulses.

The cornea has many free nerve endings which are very sensitive to pain or contact.

A numbing eye drop acts as a sodium channel blocking in these nerves.

The nerves in the cornea, as well as all nerves, rely on sodium channels to create and send an impulse signal of pain.

The numbing eye drops have a medication component that binds to these sodium channels and prevents the functioning for up to fifteen minutes.

During this time, no sensations of pain or contact can be felt as there are no nerve signals from the area.

Since the numbing eye drops work through direct contact with the nerve endings, there is no associated numbness throughout the body.

The ocular anaesthetics only numb the front of the eye, even the eyelid retains sensation, though the inside of the eyelid will be numbed.


Uses of Numbing Eye Drops

Numbing eye drops are used in clinics or medical settings but not as a prescription to be taken home.

For eye procedures that involve contacting the front of the eye with an instrument or lens, a numbing drop is used prior to the procedure.

Among these procedures are gonioscopy which is used to view the drain of the front of the eye and monitor for glaucoma.

In gonioscopy, a special lens is placed directly on the eye to allow viewing of the structures.

Another in office procedure is applanation tonometry. Tonometry is used to measure the eye pressure and check for signs of glaucoma or eye inflammation.

In applanation tonometry, a numbing drop and drop of yellow dye are put in the eye and then a probe gently contacts the eye to measure the pressure of the resistance.


Uses for Numbing Drops for Injuries

Numbing drops can also be used to reduce pain and improve comfort during an exam on an eye that has been injured.

A scratch, or abrasion, on the front of the eye is one of the most painful eye conditions.

If there is an abrasion, a numbing drop can alleviate the pain enough to allow a thorough examination of the wound.

While the numbing drop provide short term relief, it will not be prescribed as a treatment even in cases of eye injuries.


Side Effects of Numbing Eye Drops

The concerning side effect of numbing eye drops is developing a condition called corneal melt syndrome.

Corneal melt syndrome can occur if there is prolonged use of numbing drops for more than one day consecutively.

The numbing drops soften the cornea and can lead to the entire cornea sloughing off if not used sparingly.

This is why numbing drops are used in office only and are not prescribed.


Our eye doctors at Perception Eyecare + Eyewear in Richardson, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrists at 972-250-0700 or schedule an appointment online if you would like to learn more about anaesthetic eye drops. Our optometrists provide the highest quality optometry services and eye exams in Richardson, TX and the surrounding vicinities of Garland, University Park, Sachse, and Highland Park.

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