What is a melting ulcer?
A melting ulcer, or keratomalacia, occurs when the cornea starts to lose its solid structure and becomes ‘jelly’ like. They can rapidly progress to rupture of the eye within 24 hours and are therefore an ocular emergency.
What is the cause?
The collagen which maintains the structure of the cornea is broken down by enzymes called collagenases. These are secreted by bacteria when ulcers become infected. The eye reacts to the infection by secreting enzymes to fight the bacteria, however these also contribute to the ongoing breakdown of collagen.
How are they diagnosed?
Melting ulcers have a characteristic cloudy and jelly-like appearance. Your veterinary ophthalmologist may take a swab of the cornea to identify any bacteria that might be present. This allows the most effective treatment to be determined as the bacteria involved can sometimes be resistant to commonly used antibiotics.
How are they treated?
It is important that melting ulcers are treated quickly and intensively using one or more of the following:
- Medication – An intensive regime of eye drops applied every 1- 2 hours for the first 24 – 48 hours. Antibiotic and anti-collagenase drops are used alongside antibiotic tablets and painkillers.
- Corneal cross-linking – This is a procedure performed under anaesthetic which uses riboflavin (B2) drops to soak the cornea before activating it with ultra-violet light. This procedure helps to kill any infectious organisms and stabilises the collagen to prevent further melting. This can also be used to stabilise the cornea prior to placing grafts if required.
- Corneal grafting – If the ulceration is over 50% depth the eye becomes fragile and is at risk of rupture. A corneal or conjunctival graft may be placed over the cornea in order to stabilise it.
