Ophthalmology

Tonometry

 

Tonometry is the procedure used to assess intra-ocular pressure. Under local anaesthetic, a specialised probe called a tonometer is gently touched to your pet’s eye which measures the pressure exerted against it by the cornea.

Eye pressure is measured to diagnose glaucoma - an increase in pressure caused by a failure of fluid drainage within the eye. Glaucoma is a markedly painful condition that usually has a sudden onset. Glaucoma can cause damage to the optic nerve and retina, resulting in blindness. Being able to measure eye pressure here at Standish Vets allows us to diagnose glaucoma quickly, as well as assess the efficacy of treatment.

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Enucleation

 

Enucleation is the name for the surgical removal of the eye. The most common reason for the recommendation of enucleation is to relieve uncontrollable pain associated with an eye problem. Reasons for enucleation include glaucoma (increased pressure within the eye), cancer (either within the eye or of the surrounding structures), and severe trauma to the eye that cannot be repaired. Your vet will almost certainly recommend enucleation if your pet has a blind, painful eye. Enucleation will remove the source of pain and is preferable to the long-term use of medication for an eye already unable to see.

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An enucleation requires that your pet have a general anaesthetic. The hair around the eye will be clipped before surgery, and your pet is likely to go home with stitches in the eyelid skin that will be removed after the surgical wound has healed. This surgery most commonly a day procedure, but every animal is an individual and your vet may recommend that your pet is hospitalised overnight.

 

Your pet will go home with antibiotic and anti-inflammatory medication which will be explained when your pet is discharged. Your pet will also go home with a buster collar to prevent them from traumatising the surgical site or pulling their stitches. Your vet will request a post-operative check up appointment, usually two days after surgery.

 

As most enucleations are performed on painful eyes, the majority of patients are actually less painful after surgery than they were before, and most are back to their bright happy selves within a few days. Immediately post-operatively, the skin around the surgical wound will be bruised and swollen. This too will resolve over the following few days. After a few weeks, your pet’s hair will grow back in and the skin over the eye socket will sink a little.

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Cherry Eye

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Cherry eye is the colloquial name for a prolapse of the third eyelid gland, so called for its red bulbous appearance.

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The third eyelid (also called the nictitating membrane) is an extra eyelid that arises from the inside corner of a dog’s eye. It crosses the eye to help protect and spread tears over the eye. At the base of the third eyelid is the third eyelid gland. It is one of the glands responsible for tear production, and it is not normally visible. If the small ligament that holds the third eyelid gland in place breaks, the gland can prolapse and become visible at the corner of the eye.

Although dogs often present to us with only one eye affected by a third eyelid gland prolapse, it is recognised that this condition usually affects both eyes. It is common for the second eye to experience a third eyelid gland prolapse a few weeks or months after the first eye.

 

Cats also have a third eyelid, but prolapse of the associated gland is much more common in dogs. Any breed of dog can develop a “cherry eye”, but some breeds are more at risk. These include English and French Bulldogs, Shih Tzus, Lhasa Apsos, Cocker Spaniels, and Pugs. The gland can prolapse at any time, but it most commonly occurs in young dogs, often before two years of age.

 

The problem with third eyelid gland prolapse arises from lack of tear production. Tears cannot be sufficiently produced when the gland is malpositioned, and so the eye dries out. This can cause irritation to the eye and conjunctivitis.

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Cherry Eye Surgery

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Removal of a prolapsed third eyelid gland is not recommended, as this predisposes the eye to persistent low tear production (‘dry eye’) in later life. ‘Dry Eye’ is a lifelong condition to which some of the same breeds mentioned above are also predisposed, such as Shih Tzus, Cocker Spaniels, Lhasa Apsos, and English Bulldogs.

 

Surgery to replace the prolapsed gland to its rightful position is the recommended treatment for “cherry eye”. The method most often used is called a ‘pocket technique’: a small space is created on the back of the third eyelid into which the gland is placed, before this pocket is closed with fine sutures. Your pet will require a general anaesthetic to undergo this surgery.

 

Complications are possible following any surgery and “cherry eye” surgery is not an exception. While the ‘pocket technique’ surgery has a high success rate, some possible complications include re-prolapse of the gland, suture irritation and infection. Your pet will be discharged with antibiotics and anti-inflammatories to help reduce the risk of postoperative complications, as well as a buster collar, to prevent your pet from traumatising the surgical site.

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