Corneal Ulcer

A corneal ulcer is a common problem in dogs and cats and can cause many complications if left untreated. The occurrence of corneal ulcers (ulcerative keratitis) is a condition characterized by damage to one or more corneal layers.

 What is a cornea?

The cornea is a transparent structure on the front segment of the eye that allows the projection of an image to the neurosensory part of the eye (retina). The cornea has no blood vessels and is supplied with oxygen from the tears and intraocular fluid. Due to its structure (thickness is 0.5 mm), the cornea is very sensitive to trauma and insufficient oxygenation. Since many bacteria are normally present on the corneal surface, any damage to its structure can result in a rapid bacterial infection. Ulcers on the cornea can be shallow (only the surface layer is damaged) or they can be very deep, damaging almost all corneal layers. Shallow ulcers are usually treated medically, while deep ulcers may require surgery. 

What are the most common causes of corneal ulcers?

The most common cause of corneal ulcers is poor tear quality or insufficient tear production, which is often present in dogs with seasonal allergies or food allergies. Changes in the anatomy of the eyelids or foreign bodies in the eye are also common causes of corneal ulcers. Symptoms of corneal ulcers usually include blinking, redness of the eyes and discharge from the eyes, sensitivity to light and blurring (cloudy or bluish color of the eye). If recognized early, most ulcers on the cornea will quickly heal with aggressive medical therapy. Deep ulcers are almost always infected and may require hospitalization for several days due to complicated medical treatment. Corneal ulcers, which destroy more than 60-70% of its structure, usually require surgical treatment with the aim of restoring the integrity of the cornea, which prevents eye loss.

Shallow ulcers usually heal within 5-7 days. If complete healing does not occur within 7-10 days, these ulcers become incurable or indolent. Indolent ulcers cannot be cured by medical therapy alone, and require scraping the surface with a needle removing the superficial corneal layer.

It is very important to prevent rubbing of the affected eyes, and this is achieved by using a protective collar. Excessive scratching by the paws of an already injured eye can cause more damage to the cornea and transfer a large number of bacteria from the paws to the eye.