Page 2294 - Cote clinical veterinary advisor dogs and cats 4th

1138 Ophthalmic Examination

examination without injuring the patient or its whiskers and other senses to navigate? ○ Gently wipe away very large clumps of
examiner. Is it easily startled by obstacles? Does vision discharge if they will obstruct placement
VetBooks.ir Equipment, Anesthesia • Test vision by dropping cotton balls or ○ Keeping the proximal end of the STT
appear to be worse on one side than the
of the tear test strip, without touching
other?
the lid margins or ocular surface.
• Exam table in a quiet room that can be
darkened
Place the folded tip between the lower
• Bright focal light source (well-charged Finoff gauze into different areas of the visual field. strip in the package, fold at the notch.
Functional vision can also be tested using an
transilluminator or otoscope without a cone) obstacle course in an enclosed area. The best lid and globe. Close lids if necessary, keep
• Schirmer tear test (STT) strips obstacles are relatively large, safe to bump strip in for 60 seconds, and immediately
• Fluorescein dye–impregnated strips into, and free of odor. Vary the course during replace if blinked out.
• Rose Bengal dye–impregnated strips the test. Do not provide excessive nonvisual ○ Low is < 10 mm/min, borderline is
(optional) guidance (sound, food). Repeat in dim light 10-15 mm/min, normal is > 15 mm/min
• Sterile saline/eye irrigating solution if indicated. wetting in dogs and cats (sometimes even
• Topical anesthetic (e.g., 0.5% proparacaine), • Looking at the face head-on in room light, lower for many normal cats).
often refrigerated assess the overall appearance and symmetry ○ If a corneal herpetic lesion is suspected,
• Tonometer (e.g., Schiøtz, Tono-Pen, of the head and orbits, resting pupil size, and apply Rose Bengal dye. Place a drop of
TonoVet) globe size, position, and motility. Note any sterile saline to a Rose Bengal–impregnated
• 1% tropicamide (optional) ocular discharge or tear staining. strip, and lightly touch (or allow a drop to
• Magnifying or fundic lens (lens strength of ○ Evaluate the eyelid shape and conforma- fall on) to the dorsal bulbar conjunctiva.
20-28 diopters [D] or a 2.2 lens good for tion before manipulating the head. Allow the lids to blink. Examine the
general use) or direct ophthalmoscope ○ Palpate the muscles of mastication, and cornea with focal white light for dye reten-
• Muzzle for aggressive patients assess the degree of globe retropulsion tion, indicating the presence of nonvital
• Sedation and/or anesthesia are generally through the closed lids. Palpate both eyes epithelial cells, and for a characteristic
not necessary and may hinder a good simultaneously to best assess symmetry. dendritic dye uptake pattern.
examination. ○ Retropulsing each eye individually elevates • If corneal ulceration (p. 209) is suspected,
the nictitans, which can then be evaluated apply fluorescein. Place a drop of sterile saline
Anticipated Time for presence, shape, coloration, motility, or proparacaine on a fluorescein strip, and
About 10-20 minutes (longer if mydriatics and abnormalities. lightly touch the strip (or allow a drop to fall
are used) • Assess the cranial nerves bilaterally (p. 1136) on) to the dorsal bulbar conjunctiva. Allow
○ Menace response (II afferent, VII efferent): the lids to blink. Flush excess fluorescein
Preparation: Important covering one eye, perform a menacing with saline to prevent false-positive results
Checkpoints gesture to the open eye to elicit a blink, (ocular discharge, epithelialized but irregular
• Adequate restraint greatly aids examination without stimulating the vibrissae or face. corneal surfaces). Examine in a darkened
and is generally best performed by one or Hold your hand flat and vertical with its room, ideally with cobalt light/Wood’s lamp.
more assistants, not the owner. Muzzle dogs lateral aspect toward the animal’s eye or Fluorescein uptake indicates an absence of
if necessary. use just one finger to allow testing of corneal epithelium.
• Examine the animal at eye level (on exam smaller areas of the visual field while ○ In 1-5 minutes, fluorescein may appear
table); large dogs may be examined on the minimizing air motion. at the nostril(s) or mouth, indicating
floor, sitting up, and if necessary, backed ■ Cerebellar disease may cause absence nasolacrimal patency (positive Jones test).
into a corner. of the menace response without loss of NOTE: a negative Jones test result does
• Cats especially can become enophthalmic vision. not necessarily indicate nasolacrimal duct
during examination; frequent repositioning ■ Very young puppies and kittens obstruction.
of the body or the use of other stimuli are normally do not menace. • Retroilluminate the eyes to identify opacities
often necessary to reduce enophthalmos. ○ Palpebral reflex (sensory V afferent, VII in the visual axis.
efferent): lightly touch the lateral and ○ Hold the transilluminator above your ear,
Possible Complications and medial canthi to stimulate blinking. and shine it into the animal’s eyes. Adjust
Common Errors to Avoid Observe for completeness of blinking. your position (usually to below the level
• Fragile eyes (ruptured eyes, descemetoceles) ■ In cases where the lids are unable to of the animal) until you see the tapetal
should be handled extremely gently, if at all. close but sensation is present (e.g., reflection. Opacities in the clear ocular
NOTE: do not palpate, retropulse, or measure facial paralysis, exophthalmos), globe media will appear silhouetted.
intraocular pressure in these eyes. retraction and nictitans elevation (± III, • Carefully examine the surface and anterior
• Perform STT before any topicals are applied IV, VI efferent) or head withdrawal may segments of the eyes in dim light with a
(these alter the wetness of the ocular surface); be seen instead. bright focal light or transilluminator. Note
assess fluorescein staining before tonometry ○ Dazzle reflex (II afferent, VII efferent): the lid margins, nasolacrimal puncta, bulbar
(tonometry may give false appearance of rapidly apply a very bright focal light to and palpebral conjunctivae, cornea and
corneal lesions); assess pupillary motion one eye. This should cause the eye to blink anterior chamber, iris surface, pupil, and
before pharmacologic mydriasis. NOTE: do (subcortical pathway). An intact dazzle anterior lens.
not give mydriatics if glaucoma (p. 387) is does not alone signify vision so much as ○ Holding the light from the side (across
a possibility. some degree of retinal and optic nerve the plane of the iris) will aid greatly in
• Patient fear/anxiety and/or a weak light function. accentuating the three-dimensionality of
source are common causes for an apparently ○ Pupillary light reflex (II afferent, III anterior chamber structures.
weak pupillary light response (PLR). efferent): apply a bright light to one eye, • Examine the fundus, noting the optic nerve,
and observe ipsilateral (direct PLR) and retinal vessels, tapetum, and nontapetum.
Procedure contralateral (indirect or consensual PLR) ○ A drop of tropicamide may be given
• Grossly assess functional vision as the animal pupillary constriction. Note the degree for mydriasis (contraindicated if there is
walks to/in the exam room: Does the animal and speed of pupillary constriction. any suspicion of glaucoma). Wait 20-30
navigate confidently, easily avoiding objects? • If mucoid ocular discharge is present, measure minutes after applying; effects will last
Does it walk slowly and cautiously, using tear production. for 2-4 hours.

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