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, 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. Sometimes, however, the ulcer may become very deep, and in severe cases the eye may rupture. These deep or ruptured corneal ulcers may require surgery in the form of a 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).
What does the CCT graft procedure involve?
CCT grafting is performed with the patient under general anaesthetic, and with the aid of an 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 suture material (see diagram). Depending on the case, additional procedures such as a third eyelid flap or temporarily stitching the eyelids partially closed may be performed to help protect the graft and eye.
What happens after the operation?
The patient is usually kept in our hospital for a few days to ensure that the eye is healing satisfactorily. When they go home they usually need to wear a Buster collar for a week or two so that they cannot rub at the eye. We give a course of pain-relieving tablets and antibiotic eye drops. The eye is usually a little uncomfortable and itchy, but this settles over a week or two.
You will need to keep your pet relatively calm and quiet for a few 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 check-up examination with our veterinary ophthalmology team around 3-4 weeks following the surgery to ensure that the eye is healing satisfactorily. In some cases a brief general anaesthetic is required at this stage to remove the stitches, although this is not always necessary.
Does the graft need removing, and what is the effect on vision?
This type of graft is not removed and 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 more peripheral to this. To reduce scarring, we often dispense a course of eye ointment (‘Optimmune’) for a month or two following the surgery.
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