The ophthalmic examination

1 The ophthalmic examination


A full ophthalmic examination should be performed on all animals presenting with an ocular complaint. To perform this properly it is important to have a standard approach to all patients together with appropriate facilities and equipment.


The basic parts of the ophthalmic examination are:





Further tests include:






Disposable items required for ophthalmic examination are:













HISTORY


History taking can be divided into general history and that specifically pertaining to the eyes. A general history should consider the following points:










Once a thorough general history has been taken we can move on to the more specific ophthalmic history. This will include asking the owners the following questions:









THE OPHTHALMIC EXAMINATION




Hands-on examination


The first part of the hands-on examination takes place in a well-lit room. The patient should be gently restrained – one hand under the chin and the other behind the back of the head is usually sufficient. A trained nurse is invaluable during ocular examinations – most owners are not very good at restraining their pets in general, and when you are very close to the biting end it is particularly important that the patient is properly held by a confident adult!


A close inspection of the gross appearance of the eyes and face is performed with illumination such as a pen torch. Particular things to consider include the presence of any ocular discharge – the nature of it, whether unilateral or bilateral and the amount of it. Some dogs commonly have a small amount of mucoid discharge at the medial canthus, especially those with doliocephalic conformation such as Dobermanns, and it can be considered a normal finding in such animals. The size of both eyes should be compared – they should be symmetrical but if one is larger than the other it is necessary to establish whether one is enlarged (hydrophthalmic) or if one is shrunken (microphthalmic). In addition to size, the actual position of the eyes should be noted – looking from above the patient directly down on the head can assist in establishing the presence of exophthalmos, enophthalmos or strabismus. General head symmetry and the presence of periorbital swellings should also be noted.


It might be necessary to take samples for laboratory analysis at this stage if indicated. Swabs for bacterial culture and isolation should be taken before any discharges are cleaned away.




Basic vision testing and neurological tests



1. Menace response


A threatening gesture will cause the animal to blink and pull away slightly. The reflex tests the visual pathway (optic nerve, cranial nerve II) and the ability to close the lids (facial nerve, cranial nerve VII), i.e. can the animal see you and, if so, can it react and blink normally? It is important that the stimulus is visual only, and does not generate air currents which would trigger sensory nerve endings on the cornea and skin (trigeminal nerve – cranial nerve V). For this reason some people advocate testing from behind a clear Perspex screen, but in reality this is not really necessary. So long as the hand movements involve just a couple of fingers rather than waving the whole hand in front of the eyes there should not be any confusion over the actual reflex being tested. It is important to stimulate both from directly in front of the eyes and also from other angles – above and below plus medial and lateral. The fellow eye can be covered with your other hand to assess each eye separately.



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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on The ophthalmic examination

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