Corneal ulcer overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
A 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 agrarian societies. In developing countries, as well as in Florida, corneal ulcer is frequently the cause of great morbidity as well as economic loss to the person and family. Children afflicted by Vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes, which may persist lifelong, causing tremendous & avoidable loss to the person and the society.
Causes
Corneal ulcers are a common human eye disease. They are caused by trauma, particularly with vegetable matter, chemical injury, contact lenses, and infections. Other eye conditions can cause corneal ulcers, such as entropion, distichiae, corneal dystrophy, and keratoconjunctivitis sicca (dry eye).
Risk Factors
People with poor eye hygiene and contact lens abusers (e.g. those who wear contact lenses overnight) are at an increased risk of developing corneal ulcers. Corneal ulcers are a common condition in humans, particularly those living in the tropics and in agrarian societies. In developing countries, children afflicted by vitamin A deficiency are at a high risk for corneal ulcer and may become blind in both eyes, which may persist lifelong if not treated.
Diagnosis
History and Symptoms
Corneal ulcers are painful due to nerve exposure, and can cause tearing, squinting, and vision loss of the eye. There may also be signs of anterior uveitis, such as miosis (small pupil), aqueous flare (protein in the aqueous humour), and redness of the eye. An axon reflex may be responsible for uveitis formation — stimulation of pain receptors in the cornea results in release inflammatory mediators such as prostaglandins, histamine, and acetylcholine.
Laboratory Findings
Diagnosis is done by direct observation under magnified view of slit lamp revealing the ulcer on the cornea. The use of fluorescein stain, which is taken up by exposed corneal stroma and appears green, helps in defining the margins of the corneal ulcer, and can reveal additional details of the surrounding epithelium. Herpes simplex ulcers show a typical dendritic pattern of staining. Rose-Bengal dye is also used for supra-vital staining purposes, but it may be very irritating to the eyes. In descemetoceles, the Descemet's membrane will bulge forward and after staining will appear as a dark circle with a green boundary, because it does not absorb the stain. Doing a corneal scraping and examining under the microscope with stains like Gram's and KOH preparation may reveal the bacteria and fungi respectively. Microbiological culture tests may be necessary to isolate the causative organisms for some cases. Other tests that may be necessary include a Schirmer's test for keratoconjunctivitis sicca and an analysis of facial nerve function for facial nerve paralysis.
Treatment
Surgery
Surgery in the form of corneal transplantation may be needed in few cases to save the eye.
Primary Prevention
Contact lens wearers must be sure to wash their hands and pay very close attention to cleanliness while handling their lenses to prevent corneal ulcers. Also, contact lenses should not be worn overnight or when swimming, and eye lubricants should be used prior to lens removal to avoid scratches due to dryness. Prompt, early attention by an ophthalmologist or optometrist for an eye infection may prevent ulcers from forming.