Exposure keratopathy

Exposure keratopathy (also known as exposure keratitis) is medical condition affecting the cornea of eyes. It can lead to corneal ulceration and permanent loss of vision due to corneal opacity.

Exposure keratopathy
Other namesExposure keratitis
SpecialtyOphthalmology
SymptomsDryness, irritation, redness, eye pain and photophobia.
ComplicationsCorneal opacity
CausesLagophthalmos, CN VII paralysis
Diagnostic methodEye examination
PreventionPrevention of increased corneal exposure

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 and corneal epithelium play significant role in corneal protective mechanism.[1][2] The dryness and epithelial damage will allow micro organism to penetrate cornea and thus keratitis occurs.

Signs and symptoms

Symptoms are similar to dry eye.[3] 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.[3] 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.[3]

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.[3]

Lagophthalmos
Main article: Lagophthalmos

Lagophthalmos, the inability to close the eyelids completely is the main cause of exposure keratopathy. Common cause of lagophthalmos is facial nerve (CN VII) palsy. Facial nerve function may affect in several conditions like cerebrovascular accident, head trauma, brain tumors, Bell's palsy etc. Physiological inability to close the eyelids during sleep (nocturnal lagophthalmos) may also cause exposure keratopathy.[4]

Mechanical causes

Chemical or thermal burns to eyelids or conjunctiva, ocular cicatricial pemphigoid, or symblepharon may cause incomplete or inadequate eyelid closure.

Exophthalmos
Main article: 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,[5] Orbital cellulitis, Orbital pseudotumor etc.[6]

Surgical

A weak bell phenomenon may result in exposure keratopathy after ptosis surgery.[3] Postoperative lagophthalmos following blepharoplasty is another common cause of secondary exposure keratopathy.[7]

Diagnosis

Fluorescein staining may be used to detect for epithelial defects, corneal infection or perforation of the cornea.[8] Tear break-up time and ocular protection index assessment can be done to reveal dry eye. 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.[3] 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.[7] Bandage silicone hydrogel or scleral contact lens may be used to protect cornea.[3] But, risk of infection is more with bandage contact lens use.[7] Moisture goggles may also be used to protect cornea.[9] Temporary or permanent tarsorrhaphy may be indicated to treat lagophthalmos. Gold weights can be inserted into the upper eyelid to treat fasial nerve palsy.[9]

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.[3] Eyelid taping during sleep may alleviate mild cases of exposure keratopathy.[3]

If corneal ulcer is detected, it may be treated medically with antibiotics. 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 or therapeutic keratoplasty may be indicated to treat perforated corneal ulcer.

See also

References
  1. Zasloff, Michael (1 October 2012). "Defending the cornea with antibacterial fragments of keratin". The Journal of Clinical Investigation. 122 (10): 3471–3473. doi:10.1172/JCI65380. ISSN 0021-9738. PMC 3461931. PMID 23006322.
  2. McDermott, Alison M. (December 2013). "Antimicrobial Compounds in Tears". Experimental Eye Research. 117: 53–61. doi:10.1016/j.exer.2013.07.014. ISSN 0014-4835. PMC 3844110. PMID 23880529.
  3. John F., Salmon (2020). "Cornea". Kanski's clinical ophthalmology : a systematic approach (9th ed.). Edinburgh: Elsevier. p. 242. ISBN 978-0-7020-7713-5. OCLC 1131846767.
  4. Tsai, Shawn H.; Yeh, Shu-I; Chen, Lee-Jen; Wu, Chien-Hsiu; Liao, Shu-Lang (1 June 2009). "Nocturnal Lagophthalmos". International Journal of Gerontology. 3 (2): 89–95. doi:10.1016/S1873-9598(09)70027-4. ISSN 1873-9598.
  5. Bahn, Rebecca S. (2010). "Graves' Ophthalmopathy". New England Journal of Medicine. 362 (8): 726–38. doi:10.1056/NEJMra0905750. PMC 3902010. PMID 20181974.
  6. Goldman, Lee (2012). Goldman's Cecil Medicine (24th ed.). Philadelphia: Elsevier Saunders. pp. 2430. ISBN 978-1437727883.
  7. "Exposure Keratopathy - EyeWiki". eyewiki.aao.org.
  8. Mathenge, Wanjiku (2018). "Emergency management: exposure keratopathy". Community Eye Health. 31 (103): 69. ISSN 0953-6833. PMC 6253321. PMID 30487689.
  9. "Lagophthalmos Evaluation and Treatment". American Academy of Ophthalmology. 1 April 2008.
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