WHAT IS AN INDOLENT ULCER?
The cornea is the transparent front layer of the eyeball. It is less than 1mm thick and consists of several complex layers. An indolent ulcer is a defect in the cornea that is unable to heal due to a layer of denatured tissue on the surface of the eye. The cornea is well supplied with nerves and therefore these ulcers are quite painful.
WHAT CAUSES AN INDOLENT ULCER?
Indolent ulcers are most frequently seen in older dogs. The specific cause is unknown. Normally, when there is a defect or ulcer on the surface of the eye, the cells at the outer edges grow into the centre and healing is complete in about 5-7 days. With an indolent ulcer, these cells growing in from the edges are unable to adhere to the surface of the cornea due to an underlying layer of denatured tissue. Imagine laying sod on pavement – if the grass roots could penetrate the pavement to the soil below, it would survive, since it cannot, the grass dies. Since this layer on the cornea is not allowing the healing edges to root down, the ulcer is unable to heal.
HOW ARE INDOLENT ULCERS TREATED?
There are two methods of treating indolent ulcers:
A short acting sedative and topical anesthetic drops are required to perform these procedures. The loose “flaps” of healing tissue at the edges of the ulcer are gently scraped away and then a small needle is used to either scratch a grid pattern over the surface of the ulcer (striate keratotomy) or to make small puncture holes (punctate keratotomy) through the dead tissue to the healthy cornea below. The intention of the procedures is to create openings through the denatured layer down to the healthy cornea so the healing edges are able to root themselves down. The success rate with these procedures is about 60%. Therefore, if the ulcer still does not heal, a superficial keratectomy (explained below) will need to be performed.
This surgery requires a general anesthetic. Under the operating microscope, a thin layer of cornea is completely removed, including the ulcer and the denatured tissue, leaving only healthy cornea. After surgery, a soft contact lens is placed on the eye (to act as a bandage), and the lids are temporarily held closed with one stitch to protect the eye and hold the contact lens in place. Your pet will also need to wear a plastic head collar for about 1 week (to prevent rubbing at the eye) until the stitch is removed. The success rate for this procedure is very good at 99.9%. Once healing begins, the formation of scar tissue on the cornea is common, this is minimized with a course of anti-inflammatory drops beginning within the first 1-2 weeks after surgery.
WHAT WILL I NEED TO DO AT HOME?
· When using eye drops, be sure the medication is placed directly onto the eyeball. Wait 5 minutes between different drops so as not to flush out the previous medication before it has been absorbed. If you are required to use ointment, always apply it AFTER all the drops have been given.
· Keep the head collar on at all times. It only takes a moment for a rubbing paw to do damage.
Wipe away any discharge from the eye with a clean, moist Kleenex or face cloth.