Exposure keratopathy (also known as exposure keratitis) is medical condition affecting 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 ...

eyes 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 con ...

. It can lead to corneal ulceration and permanent loss of vision due to

corneal opacity The human cornea is a transparent membrane which allows light to pass through it. The word corneal opacification literally means loss of normal transparency of cornea. The term corneal opacity is used particularly for the loss of transparency of c ...

. Normally, corneal surface is kept moist by blinking. during sleep, it is covered by lids. Increased corneal exposure to the air due to incomplete or inadequate eyelid closure cause increased evaporation of tear from corneal surface. Increased evaporation of tear cause instability of the tear film and dryness of corneal surface. This will lead to corneal epithelial damage. Both

tear film Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of ...

and corneal epithelium play significant role in corneal protective mechanism. The dryness and epithelial damage will allow micro organism to penetrate cornea and thus

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 ...

occurs.

Signs and symptoms

Symptoms are similar to dry eye. Patients may complain redness, irritation, ocular discomfort, burning, and foreign body sensation. Punctate epithelial defects, epithelial break down and stromal melting may be seen in corneal examination. Corneal ulceration may develop due to bacterial invasion.

Complications

Main complication of exposure keratopathy is permanent vision loss due to corneal opacification. Stromal melting may occasionally lead to corneal perforation.

Causes

Exposure keratopathy may occur due to mechanical eyelid abnormalities or neuro-paralytic corneal anesthesia. It may occur secondary to ocular surgeries like blepharoplasty, ptosis surgery etc. also.

Lagophthalmos

Lagophthalmos Lagophthalmos is the inability to close the eyelids completely. Cline D; Hofstetter HW; Griffin JR. ''Dictionary of Visual Science''. 4th ed. Butterworth-Heinemann, Boston 1997. Blinking covers the eye with a thin layer of tear fluid, thereby p ...

, the inability to close the eyelids completely is the main cause of exposure keratopathy. Common cause of lagophthalmos is

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

(CN VII) palsy. Facial nerve function may affect in several conditions like

cerebrovascular accident A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop funct ...

head trauma A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...

, brain tumors, Bell's palsy etc. Physiological inability to close the eyelids during sleep (nocturnal lagophthalmos) may also cause exposure keratopathy.

Mechanical causes

Chemical or thermal burns to eyelids or

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 epithelium ...

, ocular cicatricial pemphigoid, or symblepharon may cause incomplete or inadequate eyelid closure.

Exophthalmos

Exophthalmos is the unilateral or bilateral bulging of the eye anteriorly out of the orbit causing increased exposure of cornea. It may be seen in many conditions like

Graves' ophthalmopathy Graves’ ophthalmopathy, also known as thyroid eye disease (TED), is an autoimmune inflammatory disorder of the orbit and periorbital tissues, characterized by upper eyelid retraction, lid lag, swelling, redness (erythema), conjunctivitis, and ...

Orbital cellulitis Orbital cellulitis is inflammation of eye tissues behind the orbital septum. It is most commonly caused by an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. It may also occur after trauma. W ...

, Orbital pseudotumor etc.

Surgical

A weak bell phenomenon may result in exposure keratopathy after ptosis surgery. Postoperative lagophthalmos following blepharoplasty is another common cause of secondary exposure keratopathy.

Diagnosis

Fluorescein Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used ...

staining may be used to detect for epithelial defects, corneal infection or perforation of the cornea. Tear break-up time and ocular protection index assessment can be done to reveal

dry eye Dry or dryness most often refers to: * Lack of rainfall, which may refer to **Arid regions **Drought * Dry or dry area, relating to legal prohibition of selling, serving, or imbibing alcoholic beverages * Dry humor, deadpan * Dryness (medical) * ...

. Exophthalmometry can be used to measure degree of exophthalmos.

Prevention

If increased corneal exposure is detected, several preventive measures can be done to prevent keratitis. Aritificial eye drops and eye ointments may be used to keep the eyes moist. Since frequent use of eye drops with preservatives can promote inflammation, it is better to choose preservative free artificial tear drops and lubricating eye drops. Bandage silicone hydrogel or scleral contact lens may be used to protect cornea. But, risk of infection is more with bandage contact lens use. Moisture

goggles Goggles, or safety glasses, are forms of protective eyewear that usually enclose or protect the area surrounding the eye in order to prevent particulates, water or chemicals from striking the eyes. They are used in chemistry laboratories and ...

may also be used to protect cornea. Temporary or permanent tarsorrhaphy may be indicated to treat lagophthalmos. Gold weights can be inserted into the upper eyelid to treat fasial nerve palsy.

Treatment

Treatment of the cause of the exposure is to be done first. For example, in proptosis due to thyroid eye disease, regulation of thyroid hormone levels may be advised. Symblepharon can be treated surgically. If necessary, management of proptosis may be done by orbital decompression. Eyelid taping during sleep may alleviate mild cases of exposure keratopathy. If

corneal ulcer Corneal ulcer is an inflammatory or, more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and the a ...

is detected, it may be treated medically with

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

. If corneal perforation has occurred, immediate treatment measures should be done to restore the integrity of perforated cornea. Tissue adhesive glues, covering with conjunctival flap, bandage

soft contact lens Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic ...

or therapeutic keratoplasty may be indicated to treat perforated corneal ulcer.

References

{{Eye pathology Inflammations Disorders of sclera and cornea Ophthalmology