A corneal perforation happens when there is full-thickness damage to the cornea, the clear window at the front of your dog’s eye. Fluid and tissues located inside the globe will escape out through the deficit. Depending on the size of the deficit, this mostly involves the aqueous fluid from the front chamber of the eye and the iris. Corneal perforations are emergencies, requiring prompt diagnosis and treatment to minimise serious complications, including loss of sight or having to lose the eye. Call a vet without delay if your dog’s eye looks abnormal.
Causes
Trauma - A cat scratch; a sharp object getting in the eye (stick, fireworks, metal fragments).
A deep corneal ulcer - damage to the deepest layers of the cornea, leading to weakening and eventual failure, for example infection or non-healing ulcers.
Risk
Any dog can suffer corneal perforation due to trauma. However the following have greater risk:
Brachycephalic (short-faced) breeds with prominent eyes
Dogs with Keratoconjunctivitis sicca (dry eye) - can affect any dog, but more common in Westies, Cocker Spaniels, English Bulldogs, Pugs
Breeds prone to Indolent ulcers (non-healing) - Boxers, Corgis, Samoyeds, Border Collies
Symptoms
Symptoms develop suddenly.
Signs of pain - Rubbing or pawing the eye; holding the eye partly or fully closed, blinking lots.
Sight loss and sensitivity to light.
Weepy eye, coloured discharge, bleeding or cloudy appearance; red eye
‘Sinking’ of the eye surface or collapse of the front chamber of the eye.
Whitish 'clot’ or iris tissue plug in the corneal puncture.
Diagnosis
Vets diagnose eyelid lacerations based on your dog’s symptoms, a thorough physical exam and further tests, including:
Ophthalmoscope exam - A detailed examination of the eye with a light source and extra magnification
Dye test - Checking the extent and depth of the laceration
Treatment
A corneal perforation is a medical emergency. Treatment depends on the size, location and cause of the corneal perforation.
Eye drops - Antibiotic drops applied every 1-2 hours to combat infection; Eye drops to dilate the pupil, reducing pain and risk of glaucoma.
Non-steroidal anti-inflammatory pain relief by mouth or injection.
An operation - checking for and removing a penetrating foreign body; gently replacing the iris if it has slipped through the perforation; repairing the hole in the cornea with a conjunctival graft, like a natural tissue bandage.
Removal of the eye - This may be necessary when there is irreparable damage to deeper parts of the eye.
What to expect
The chances of recovery depend on how quickly and well the eye is treated, the cause, and how severe the damage is. If treated promptly by a vet, small perforations often heal well, and the eye's sight can be saved. However, larger perforations, damage to tissues inside the eye, or delayed treatment can lead to a worse outcome, with a higher risk of losing sight or even the eye itself.
Complications of corneal perforation include:
Scarring of the cornea; threads of trapped iris tissue attached to the inside of the cornea (synechiae).
Infection and inflammation of the cornea, the inside of the eye (uveitis) and surrounding tissues.
Glaucoma - dangerous increase in pressure within the eye
Sight loss in the eye; loss of the globe itself.
Recurrence - particularly where perforation results from deep and recurring ulcers in affected breeds.
Prevention
It’s impossible to remove all risk of trauma, particularly for dogs who exercise off lead. However, the following measures help to reduce risk:
Don’t let your dog chew or chase sticks
Supervise interactions with unfamiliar cats
Treat eye ulcers promptly and as directed by your vet
Contact your nearest vet if you think your dog has suffered a corneal perforation.