ADVICE

Corneo conjunctival transposition (CCT) grafts

Corneo conjunctival transposition grafts are used to treat deep corneal ulcers.

What is a corneal ulcer?

The cornea is the transparent structure at the front of the eye that allows light to enter. Traumatic injury, most commonly a scratch or foreign body, but also eyelid diseases (entropion), eyelash disease (ectopic cilia or distichiae), infectious agents, or dry eye, can damage the surface of the cornea and expose the underlying tissue to cause an ulcer.

If the ulcer is shallow, then it will usually heal on its own within a few days or with medical treatment (antibiotic drops, anticollagenase drops, topical lubricant and pain relief by mouth). Sometimes, however, the ulcer may become very deep, and in such cases there is a risk that the eye may rupture. These deep corneal ulcers may require surgery in the form of a corneo conjunctival transposition (CCT) graft.

What is a CCT graft?

A CCT graft is a form of ‘sliding’ graft in which healthy cornea adjacent to the ulcer is slid across to aid repair. This healthy cornea is attached to the conjunctiva, so this is also slid across towards the site of damage (the conjunctiva is the pale pink tissue that covers the ‘white’ of the eye and is a thin, relatively strong tissue containing many blood vessels. These properties make it a useful graft material).

CCT grafting is performed with the patient under general anaesthetic and with the aid of a surgical operating microscope. Using microsurgical instruments, a half-thickness area of cornea is dissected from one edge of the ulcer and extended to the edge of the cornea. Further dissection is then performed to free an area of conjunctiva. This results in a flap of cornea connected to conjunctiva which remains attached to the margin of the eye. This flap is then slid across to cover the ulcer and is stitched in place using very fine reabsorbable suture material.

Depending on the case, additional procedures, such as placing a soft bandage contact lens and temporarily stitching the eyelids partially closed, may be performed to help protect the graft and the cornea while it is healing.

What happens after the operation?

The patient might stay hospitalised for a day or two to ensure that the eye is healing satisfactorily or might go home the same day. When they go home, they need to wear a Buster collar for around a week or two so that they cannot rub at the eye. We give a course of pain-relief tablets and antibiotic eye drops. The eye is usually a little uncomfortable and itchy, but this settles after a week or two.

You will need to keep your pet relatively calm and quiet for two to three weeks following the surgery to allow the eye to heal. Usually, this means lead or garden exercise only, no boisterous play, and trying to reduce excitement and barking as much as possible. We will usually recommend a recheck examination one week after surgery and another recheck three to four weeks following the surgery to ensure that the eye is healing satisfactorily.

Does the graft need removing, and what is the effect on vision?

This type of graft is not removed. The area where the original ulcer was should ultimately be relatively transparent with reasonable vision, although there will be some pigmentation and scarring of the cornea. To reduce scarring, we often dispense a course of eye ointment (Optimmune or tacrolimus) for a month or two following the surgery.