CORNEAL ULCERS
(by Dr Jason Smith 2005)
The cornea is the transparent membrane which makes up the front of the eyeball. Think of it as a clear window consisting of 3 layers - namely, the epithelium, stroma and Descemet’s membrane. A corneal ulcer is an erosion through the entire epithelium and into the stroma. Deep ulceration into the Descemet’s membrane may result in leakage of the fluid within the eyeball resulting in eye collapse and irreparable damage can occur.
How does a corneal ulcer occur?
The most common cause of ulceration is trauma, other causes may include a laceration from a cat scratch, chemical burn of the cornea and infectious organisms such as bacteria, viruses and fungi.
Corneal ulceration may result from a diseases originating from the eye or develop secondary to disease elsewhere in the body. Examples of underlying causes include:
Ectopic cilia and distichiasis - abnormal hairs rubbing on the corneal surface.
Keratoconjunctivitis Sicca (KCS) - a drying of the cornea due to abnormal tear formation.
Endocrine diseases such as diabetes mellitus, hyperadrenocorticism, hypothyroidism and inherited diseases.
What are the symptoms of a corneal ulcer?
A corneal ulcer is very painful and most pets rub the affected eye, squint or close the lids and produce excessive tears.
How are corneal ulcers treated?
Most superficial corneal ulcers take 3-5 days to heal with correct diagnosis and treatment. Treatment involves antibacterial therapy and medication to relieve spasm and pain.
Deep corneal ulceration may involve placement of a contact lens, 3rd eyelid flap surgery or specialist referral for ophthalmic surgery (e.g. conjunctival graft). Persistent or non-healing corneal ulcers require further diagnostic further work-up in order to address the underlying disease/cause.
