Exposure keratopathy refers to that surface disorder of the eye in which absence of an adequate tear film results in breakdown of the corneal epithelium. This may produce disruption of corneal epithelium, ulcer formation, super added infection, thinning and even perforation of eyes in severe cases.
Exposure keratopathy is broadly divided into two main categories viz.
- Exposure due to primary or secondary corneal anaesthesia or hypoaesthesia: Corneal sensation plays an important role in the maintenance of healthy corneal epithelium. It is presumed that nerve growth factors released by corneal nerves mediate epithelial cell proliferation. Thus, corneal anaesthesia results in a surface which is more vulnerable to injury, delayed healing of corneal epithelium, and progressive keratopathy. Reduced corneal sensation may be congenital or acquired, and may be complete or partial.
- Exposure produced by mechanical eyelid abnormalities such as lagophthalmos:Lagophthalmos is the inability to close eyelids completely. Lagophthalmos may be divided into three main groups e.g. Proptosis causing excessive ocular surface exposure, palpebral (eyelid) insufficiencysecondary to physiologic, congenital or acquired conditions, and idiopathic lagophthalmos. Lagophthalmos with or without exposure keratopathy may be present at night in some healthy individuals (nocturnallagophthalmos).
Exposure of cornea from any cause may lead to thickening, xerosis (dryness), and scarring of epidermis.
Exposure keratopathy may produce symptoms such as
- Irritation of eyes.
- Foreign body sensation.
- Blurring of vision.
- Photophobia (increased sensitivity to light).
- Corneal vascularisation.
- Corneal ulceration.
Exposure keratopathy has numerous causes such as
- Fifth intracranial nerve palsy.
- Cerebro-vascular accident.
- Herpes simplex.
- Herpes zoster.
- Multiple sclerosis.
- Intracranial seventh nerve palsy.
III. Malposition of lids
Diagnosis depends upon clinical history and evaluation.
Clinical history: To determine the aetiology, history should elucidate any recent trauma, surgery, or any infection. History of Bell’s palsy should be taken. A family history of corneal anaesthesia or lagophthalmos should be elicited.
Clinical examination: The position of eyelids in a relaxed open and closed position as well as inter-palpebral distance should be assessed. Appositional closure of the eyelids with each blink should be recorded. Slit-lamp examination may be done to exclude any obscure lagophthalmos. Obscure lagophthalmos may be due to when the upper and lower eyelashes meet, preventing complete closure of the lids, or obscures view of the true eyelid position. The upper eyelid may also overhang the lower lid, giving the appearance of total closure, however, eyelid margins may not oppose. Bell’s phenomenon should be recorded.
Conjunctiva is examined for any areas of scarring or cicatrisation.
Corneal sensations are evaluated by using wisp of cotton or an aesthesiometer.
Staining with Fluorescein sodium dye may reveal any punctuate epithelial erosions, frank epithelial defects, or ulceration.
A complete neurological examination is also conducted including assessment of cranial nerves.
Management should be carried out under medical supervision.
Management of exposure keratopathy depends upon underlying aetiology i.e. whether the disease is primarily related to corneal anaesthesia or lagophthalmos.
I. Corneal anaesthesia: In these cases, the mainstay of treatment is lubrication with
- Preservative-free artificial tears.
- Eye ointment at night.
Other treatment includes
- Bandage contact lenses: Short term use of bandage contact lenses may be effective in promoting healing by epithelial cell migration and adhesion to the stroma.
- Anti-inflammatory agents: Agents such as corticosteroids must be used with caution since they may precipitate stromal lysis and perforation.
- Tetracyclines: These may be effective in cases of stromal necrosis.
- Autologous serum: It is a valuable adjunt in the treatment ofneurotrophic keratopathyand persistent corneal epithelial defects.
- Punctal occlusion: Punctal occlusion with punctal plugs or cauterisation of the puncta may be helpful.
- Tarsorrhaphy: Partial stitching of the eyelids together to protect cornea.
- Amniotic membrane transplantation: Amniotic membrane act as basement membrane scaffold upon which epithelium may migrate and adhere.
- Cyanoacrylate glue: Cyanoacrylate glue may be applied with a bandage contact lens for the treatment of small corneal perforations.
- Lamellar/penetrating keratoplasty: Lamellar/penetrating keratoplasty may be required for larger perforations.
Mild epitheliopathy: The following treatment is given if there is no ulceration and only mild epitheliopathy is present. It includes
- Preservative-free artificial tears.
- Lubricating ointment at night.
Moderate to severe corneal involvement but no ulceration: In these cases, expected duration of lagophthalmos is important.
- If lagophthalmos is expected for six weeks: Management includes patching of eyes with ointment or temporary tarsorrhaphy.
- If lagophthalmos is expected for longer than six weeks: Management includes permanent tarsorrhaphy, gold lid weight surgery, recession of levator palpebrae superioris muscle, or full thickness graft, depending upon the aetiology.
Lower eyelid lagophthalmos may be treated with lateral tarsal strip or lower lid spacing graft.
Friedman Neil J, Kaiser Peter K. Essentials of Ophthalmology First Edition. Saunders Elsevier 2007. P 180.
Traboulsi Elias I, Utz Virginia Miraldi. Practical Management of Pediatric Ocular Disorders and Strabismus – A Case-Based Approach. Springer Science+Business Media, LLC 2016. P 129- 134.