For corneal abrasions in dogs and cats, see Corneal ulcers in animals.

Corneal abrasion is a medical condition involving the loss of the surface epithelial layer of the eye's cornea

Cornea

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

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Symptoms and signs

Symptoms of corneal abrasion include pain, photophobia

Photophobia

Photophobia is a symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical photosensitivity of the eyes, though the term...

, a foreign-body sensation, excessive squinting, and a reflex production of tears

Tears

Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....

. Signs include epithelial defects and edema

Edema

Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

, and often conjunctival injection, swollen eyelids, large pupils and a mild anterior-chamber reaction. The vision may be blurred, both from any swelling of the cornea and the excess tears. Crusty build up from excess tears may also be present.

Cause

Corneal abrasions are generally a result of trauma to the surface of the eye. Common causes include jabbing a finger into an eye, walking into a tree branch, getting grit in the eye and then rubbing the eye or being hit with a piece of projectile metal. A foreign body

Foreign body

A foreign body is any object originating outside the body. In machinery, it can mean any unwanted intruding object.Most references to foreign bodies involve propulsion through natural orifices into hollow organs....

 in the eye may also cause a scratch if the eye is rubbed. Injuries can also be incurred by "hard" contact lenses that have been left in too long. Damage may result when the lenses are removed, rather than when the lens is still in contact with the eye. In addition, if the cornea becomes excessively dry, it may become more brittle and easily damaged by movement across the surface.

Corneal abrasions are also a common and recurrent feature in people who suffer specific types of corneal dystrophy, such as lattice corneal dystrophy. Lattice dystrophy gets its name from an accumulation of amyloid deposits, or abnormal protein fibers, throughout the middle and anterior stroma. During an eye examination, the doctor sees these deposits in the stroma as clear, comma-shaped overlapping dots and branching filaments, creating a lattice effect. Over time, the lattice lines will grow opaque and involve more of the stroma. They will also gradually converge, giving the cornea a cloudiness that may also reduce vision. In some people, these abnormal protein fibers can accumulate under the cornea's outer layer--the epithelium. This can cause erosion of the epithelium. This condition is known as recurrent epithelial erosion. These erosions: (1) Alter the cornea's normal curvature, resulting in temporary vision problems; and (2) Expose the nerves that line the cornea, causing severe pain. Even the involuntary act of blinking can be painful.

Diagnosis

Although corneal abrasions may be seen with ophthalmoscopes, slit lamp microscopes provide higher magnification which allow for a more thorough evaluation. To aid in viewing, a fluorescein

Fluorescein

Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....

 stain that fills in the corneal defect and glows with a cobalt blue-light is generally instilled first.

A careful search should be made for any foreign body, in particular looking under the eyelid

Eyelid

An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...

s. Injury following use of hammers or power-tools should always raise the possibility of a penetrating foreign body into the eye, for which urgent ophthalmology

Ophthalmology

Ophthalmology is the branch of medicine that deals with the anatomy, physiology and diseases of the eye. An ophthalmologist is a specialist in medical and surgical eye problems...

 opinion should be sought.

Treatment

Although small abrasions may require no specific treatment, larger abrasions are typically treated for a few days with a topical antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 to prevent infection and sometimes a topical cycloplegic to reduce pain and improve comfort.. A single large study by John W King, et al.; showed that only 0.7% of corneal abrasions actually become infected without antibiotic drops, questioning the necessity of such practice. The cycloplegic may also reduce a secondary inflammation of the iris known as an iritis. A 2000 review however found no good evidence to support the use of cycloplegics/mydriatics. It is often believed that eye pads used in "pressure patching" may improve comfort and promote healing by preventing repeated eyelid blinking that may cause further physical distruption to the cornea. Controlled studies have however not supported this assertion.

Due to the introduction of newer contact lens materials, mainly silicone hydrogels, pressure patch treatment is being phased out and replaced by "bandage contact lenses". These newer materials provide much more oxygen to the cornea and can be fitted tightly (providing minimal movement) with a low risk of corneal hypoxia and oedema. These lenses greatly decrease the patients pain and allow the patient to administer drops.

For recurrent corneal erosions, treatment may be had with a laser surgery called phototherapeutic keratectomy

Phototherapeutic keratectomy

Phototherapeutic keratectomy is a type of eye surgery that uses a laser to treat various ocular disorders by removing tissue from the cornea. PTK allows the removal of superficial corneal opacities and surface irregularities...

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Topical anesthetic

Topical anesthetic

A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area. Topical anesthetics are available in creams,...

s are not to be used for continued pain control as they can reduce healing and cause secondary keratitis

Keratitis

Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...

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Complications

Complications are the exception rather than the rule from simple corneal abrasions. It is important that any foreign body be identified and removed, especially if containing iron as rust

Rust

Rust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...

ing will occur.

Occasionally the healed epithelium may be poorly adherent to the underlying basement membrane

Basement membrane

The basement membrane is a thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs including skin, or the endothelium, which lines the interior surface of blood vessels.- Composition :...

 in which case it may detach at intervals giving rise to recurrent corneal erosion

Recurrent corneal erosion

Recurrent corneal erosion is a disorder of the eyes characterized by the failure of the cornea's outermost layer of epithelial cells to attach to the underlying basement membrane...

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