Traumatic Eye Injuries - Birds
Eyelid Injuries
The skin over the whole of the skull in most birds is not very elastic and is adherent to bone. Any wound more than a few days old tends to contract and fibrose.
The lower eyelid of birds is the most mobile and special care should be taken to restore its anatomy if it has been traumatised. Even small wounds should be treated surgically under local anaesthesia using monofilament non-absorbable suture material.
Nictitating Membrane Injuries
It is well developed, and if damaged, can have severe consequences due to its role in 'spreading the pre-corneal tear film, protective blinking and cleaning of the corneal surface.
It is commonly traumatised in birds of prey, and should be evaluated in raptors with slow-healing corneal problems.
Lesions should be surgically corrected under general anaesthesia.
Foreign bodies can also become lodged between the lower eyelid and the nictitating membrane, and can easily be removed under local anaesthesia.
Eye Globe and Corneal Injuries
The eye globe is very large in birds with a large posterior segment and a small anterior segment and cornea.
Corneal injuries and keratitis occus in raptors during accidental collisions, and in other birds during transport.
Severe corneal injuries might benefit from a temporary tarsorrhaphy.
Iris and Uvea Injuries
Tears in the iris and uvea are commonly seen in raptors after trauma. Hyphema and vitreous haemorrhage can be extensive and the screlar ossicles can occasionally fracture.
Secondary cataract will develop if iridal tissue damage is extensive. It should be differentiated from congenital cataract associated with microphthalmus, inherited cataract and cataract associated with old age.
Treatment is possibly via extracapsular cataract extraction, but vision is not always fully restored.
Lens Luxation
This is usually seen in very severely traumatised eyes. It leads to further uveitis due to leakage of the lens protein into the anterior chamber and phacoemulsification might be necessary to remove the lens if there is no response to non-steroidal anti-inflammatory medication.
Retinal Trauma
Retinal detachment and tearing can be seen after accidents and gun shot wounds.
The temporarily blind bird should be isolated in a cage and given corticosteroids to halt any inflammatory processes. Trauma to the posterior segment of the eye is usually treated conservatively and conditions such as vitreous haemorrhage may take weeks to dissolve.
Enucleation
This might be necessary in a severely damaged eye and is performed following lateral canthotomy by collapsing the glove through corneal incision and removal of the lens and vitreous.
Care should be taken to avoid the interorbital septum and the optic nerve of the other eye.
Profuse bleeding from the medial plexus can be controlled by inserting haemostatis sponges.
Wild birds with reduced vision cannot be safely released back into their natural habitat and will have to adapt to a life in captivity. This might be especially difficult in birds of prey.
| Traumatic Eye Injuries - Birds Learning Resources | |
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Avian Medicine Q&A 17 |
References
Coles, B. (2007) Essentials of avian medicine and surgery John Wiley and Sons
Doneley, R. (2010) Avian medicine and surgery in practice: companion and aviary birds Manson Publishing
Samour, J. (2000) Avian medicine Elsevier Health Sciences
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