Page 2295 - Cote clinical veterinary advisor dogs and cats 4th

Ophthalmic Examination 1139

• If the eye is red or cloudy, the pupil is
abnormal, or there is vision loss, perform
VetBooks.ir the fingers alone is inadequate to measure
tonometry. Palpation of the globes with
intraocular pressure (IOP). Referral is neces-
sary if you cannot perform tonometry when
K
indicated. Apply a drop of topical anesthetic
A B (may not be necessary with TonoVet tonom-
F G eter). Avoid pressure on the ventral neck,
lids, or globes.
○ Schiøtz: assemble the tonometer and
C clean the footplate. Test the tonometer
by placing it on the included test block
(gives a scale reading of 0). Position the
animal with iris plane parallel to floor
(dorsal recumbency or sitting up with nose Procedures and Techniques
L
J pointed up). Holding the tonometer by
D E H I M the handles and keeping it vertical, gently
rest the footplate on the central cornea
OPHTHALMIC EXAMINATION Selected equipment and materials that may be used during an ophthalmic (not the third eyelid or sclera) until a
examination. A, Sterile eye irrigating solution. B, A 0.5% proparacaine solution. C, Schirmer tear test (STT) strips single reading is produced. Repeat two
in packaging. D, Rose Bengal strip in packaging. E, Fluorescein strip in packaging. F, Otoscope head on base to three times, and use included chart
of direct ophthalmoscope. G, Direct ophthalmoscope head. H, A 28 diopter (28D) fundic lens with case. I, A 2.2 to get actual IOP. If IOP is > 25 mm
fundic lens with case. J. Schiøtz tonometer with box, weights, test block, and conversion chart. K, Tono-Pen Hg, repeat with next additional smallest
Avia tonometer. J, Tono-Pen tonometer. M, TonoVet tonometer (no probe tip loaded). weight. Record IOP in mm Hg (not as
scale readings). Clean after use.
○ Tono-Pen: Properly fit a clean tip cover,
turn on, and calibrate if necessary. Gently
○ Indirect ophthalmoscopy: the preferred from 2-6 inches (5-15 cm) from the touch the instrument tip to the cornea,
method because it provides a wider view animal. View as many areas as possible. making brief contact and keeping it
that is easier to interpret and is safer for Adjust the focus if needed by changing perpendicular to the corneal surface; it
the examiner: diopter settings, which allow focusing does not need to be horizontal. Repeat
Using a fundic lens and bright focal at different depths when used at a fixed
■ several times until a long beep is heard.
light or transilluminator, position your- distance and any correction required by A bar over the 5% value at the bottom
self as for performing retroillumination your eyes. The image is a direct image indicates a statistically acceptable reading
(described above), an arm’s length away (not reversed). in mm Hg.
from the animal. The assistant should ■ If blepharospasm or resistance on the ○ TonoVet: Properly insert a new probe tip.
hold the lids open. If using an aspheric part of the animal is seen, dim the Turn on and ensure that proper species
fundic lens, hold the lens’ flatter side light, apply the polarizing filter, or calibration is on. Holding the instrument
(white rim) toward the animal. Place use a smaller circle size. horizontal with the tip 4-8 mm from and
the lens 1-2 inches from the animal’s ■ The crosshairs in the fixation aperture perpendicular to the cornea, repeatedly
eye, and then move it toward you may be used for measuring fundic press the button to take readings until
slightly until the fundic view (inverted structures. Size comparison may also a long beep is heard. A nonblinking d
and backward) fills the lens. Examine be made to the size of the optic nerve before the reading indicates a statistically
the whole fundus, adjusting as if the head. significant, dog-/cat-calibrated reading.
fulcrum of the line of sight is at the ■ The red-free (green) filter allows for ○ Normal IOP in dogs and cats is 15-25 mm
animal’s lens (e.g., move laterally for a differentiation between fundic blood, Hg.
more medial view). which appears black, and melanin,
○ Direct ophthalmoscopy: provides a highly which appears brown. Postprocedure
magnified view of very small areas of the ■ An optional cobalt filter may be used for Flush corneas of excess fluorescein if necessary.
fundus, with the examiner very close to detecting fluorescein-positive corneal Protect eyes from light if mydriatics were used.
the patient lesions.
To allow the widest area to be examined, The slit-beam (thin, long rectangle) AUTHOR: Jane Cho, DVM, DACVO
■ ■
use your right eye to examine the setting may help in detecting three- EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
animal’s right eye, and use your left dimensionality of anterior segment Thompson, DVM, DABVP
eye to examine the animal’s left eye. lesions. View the beam on the eye
With the largest white circle setting directly and not through the ophthal-
■
and the diopter dial set on 0, focus moscope window.
on the fundus by viewing the eye

www.ExpertConsult.com