Page 93 - WSAVA2018
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A. Sivagurunathan1
1Animal Medical Centre KL, Kuala Lumpur , Malaysia
Tip from experts to maximise your ... Ophthalmic exam
An ophthalmic examination should not be a daunting experience. Interpretation of examination findings may be challenging; however, the examination follows a logical,anatomical order.
In my opinion a basic ophthalmic exam is similar to performing a minimum database ie stool exam , urinalysis and so being I am going to focus on a number of basic and essential examinations in sequential order.
In this presentation I will place more emphasis on simple and objective assessment tools , and non ophthalmic devices that would be applicable the moment you
get back to your practice. Following which I will briefly run through an ophthalmic exam using a number of advanced ophthalmic tools for those interested to refer cases to a veterinary ophthalmolgist.
A. Distance Examination.
We first start off the examination paying close attention to the animal at a distance walking into brightly lit examination room with the client. We pay attention to the size, discoloration, symmetry of the eye and its periocular tissues. The behaviour and mentation of the pet is taken into consideration. Not to mention;, a good history should always be taken.
Ie: prophylactic remedies, ivermectin , etc
B. Vision Evaluation
A blind animal may exhibit high stepping, collision with objects, a stare-like expression, or reluctance to move in a strange environment. The owner’s impression that the animal “sees” well at home must be interpreted cautiously. Animals can “memorize” their own environment. The animal is permitted a few minutes
to adjust to the room and observed as the history is obtained.
The patient’s vision can be further evaluated by noting the response to hand movements (menace reflex), bright lights (dazzle reflex) or to cotton balls tossed into the visual field (tracking reflex). The menace response and the visual placement reaction can also be performed to evaluate the vision. I recommend that each contralateral eye should be evaluated separately by covering the ipsilateral eye it with one hand.
The vision examination should be performed in normal light, then in dim light to assess day and night vision
respectively. If you can see the cotton balls or the obstacles of the maze test, the dog or the cat should be able to see them better than you since their night vision is more developed than ours. Cats generally do not menace test well, but respond well to bright light stimulation, laser lights, and cotton ball testing.
C. Ocular Examination
Based on the sensitivity of each test , an orderly sequence of diagnostic tests must be followed based on the special requirements of each test. For example ;
The evaluation of the tear film (Schirmer tear test) must be done before the eye is manipulated or any drugs are instilled.
Cultures of the external ocular structures must be done before extensive cleaning is done and before drugs are instilled.
The use of mydriatics is necessary for examination
of the lens and posterior segment, but should not be given prior to measuring the intraocular pressure (IOP). The intraocular pressure evaluation requires topical anesthetic and must be recorded before excessive manipulation or before the patient becomes restless and excited.
D. Periocular examination: Orbit and adnexa
Examinations of anatomic structures should begin
with the orbit and other periocular tissues. Orbits
are evaluated for symmetry, eye-orbit relationship, deformities or enlargements. Because of marked variations in eye position of different breeds, one should be acquainted with the various breed characteristics. The extremes of variation in eye position can be represented by the relative enophthalmia of the collie and the exophthalmia of the Pekingese.
The presence or absence of strabismus and nystagmus is noted. Esotropia (crossed-eyes) is inherited in Siamese cats but in dogs may represent severe intraocular or neurological disease. Nystagmus occurs frequently in Siamese, apparently not always associated with clinically detectable vision defects, but in dogs may result from congenital intraocular diseases, or acquired vestibular or cerebellar diseases.
The eyelid position may be helpful in determining relative globe size. Looking from over the top of
the animal’s head helps to estimate globe position. Additional evaluation of the orbit consists of examination of the mouth (floor of the orbit), palpation of orbital
rim, retropulsion of the globe, and evaluation of nasal patency, if necessary.
Special examinations such as standard skull radiography, orbital angiography, ultrasonography, CT and MRI, and surgical exploration may be necessary for a thorough evaluation.
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