Practical techniques for eye exams

Question 1

Schirmer tear test

Answer 1

60 seconds in the ventral conjunctival fornix between the lower lid and the third eyelid.
Do not touch the notched end with your fingers
If you like to fold, do it PRIOR to removing from the plastic package.
Always perform on BOTH eyes!

Question 2

STT, species references..

Canine

Answer 2

18.84 +- 4.47
23.90 +- 5.12
21 +- 4.2
<10 = suspicious for KCS
<5- diagnostic for KCS

Question 3

STT specie references..

Feline

Answer 3

14.3 +- 4.7
16.92 +- 5.73
Normal cats can have <5-10

Question 4

Equine STT values

Answer 4

20.6 +- 6.5
24.8 +- 4.8
<10 = diagnostic for KCS

Question 5

Explain the purpose of the STT.

Answer 5

?

Question 6

Name the medical condition associated with an abnormally LOW STT

Answer 6

Research appropriate medical management options for the condition.
Recognize appropriate surgical management options for the condition including advantages and disadvantages of the procedure.
Review risk factors for the development of the condition.

Question 7

Fluorescein test

Technique

Answer 7

1. Fluorescein is a water-soluble, ophthalmic dye that is typically impregnated into sterile strips.
2. Moisten a strip with a drop of sterile saline
3. Allow a drop of dye to then fall upon each eye. In the event that you need to touch the strip to the eye, touch the strip to the sclera so that you do not artificially create what appears to be an area of fluorescein uptake on the surface of the cornea
4. Now flush the eye gently with eye wash so as to rinse off the excess.
5. If the cornea is intact, the dye will not stick.
6. If the cornea is damaged, the fluorescein will adhere to the stromal layer.
7. Observing fluorescein uptake is enhanced by using a blue light – either a Wood’s lamp or a filter on your standard direct ophthalmoscope.
8. Note: Descemet’s membrane does not uptake fluorescein. Therefore, a clear area at the base of a deep defect in the cornea is a bad sign: it means that the ulcer is deep and in danger of rupturing.

Question 8

Alternative flur. stain method..

Answer 8

Note: An alternate approach to fluorescein staining is to place the fluorescein strip in a 3cc syringe that is capped at the needle end. You then add sterile saline to the syringe, replace the plunger, and give a gentle shake to the syringe to create a slurry of dye that can then be squirted onto the each eye after the needle has been removed from the syringe.

Question 9

ID…

Answer 9

desemetocele

Question 10

Appreciate what a normal fundus looks like for both a dog and cat:

Answer 10

practical techniques paper

Question 11

Feline fundus - normal-

Answer 11

practical techniques paper

Question 12

What are the four structures you can ID when performing a fundic exam?

Answer 12

• optic disc
• retina
• tapetum
• retinal and choroidal vasculature

Question 13

Identify what category of ophthalmic drugs you could use to facilitate the fundic examination by inducing pupillary dilation. Name two drugs that fit into this category, and be able to classify each as either short-acting or long-acting

Answer 13

Category of Ophthalmic Drug: Mydriatics

Two Types of Drugs in this Category:
o Atropine sulfate 1% (long-acting)
o Tropicamide 0.5% or 1% (short-acting)

Question 14

The more negative (red) the diopter setting

Answer 14

the more DIVERGING power the lens possesses, and you are able to focus more posterior / caudally

Question 15

The more positive (green) the diopter setting

Answer 15

the more CONVERGING power the lens possesses, and you are able to focus more anterior / cranially

Question 16

in the eye a distance of 3 diopters equals..

Answer 16

1 mm

Question 17

Image orientation by direct ophthalmoscope..

Answer 17

upright and more magnified with a smaller field of view

Question 18

To perform indirect ophthalmoscopy, the clinician begins by

Answer 18

standing at a flexed arm’s length from the patient. The clinician then places a strong light source at eye level alongside his head. With the light source maintaining its position alongside his head, the clinician should direct the light at the patient’s eye to catch the tapetal reflection. Once the tapetal reflection is captured, the clinician must bring the lens in between himself and the patient. For stability, the clinician may rest the hand that is holding the lens against the patient’s brow.
With the lens in place and perpendicular to the light source, the fundic image should be visible albeit inverted.
The clinician may then adjust his view by moving the lens towards and away from the eye until the eyelids and iris disappear from view, allowing the fundic image to fill the lens.

Question 19

the image orientation that is produced by an indirect ophthalmoscope

Answer 19

The view is upside-down and backwards, less magnified with a larger field of view.

Question 20

Normal tonometry measurements dog:

Answer 20

Normal, dog: 15-25mmHg

Question 21

Normal tonometry measurements cat:

Answer 21

Normal, cat: 15-30mmHg

Question 22

Equine normal tonometry measurments..

Answer 22

12-28 mmHg

Question 23

TonoPen works via

Answer 23

applanation tonometry: the TonoPen measures the force required to flattan, or applanate a constant area of cornea. Pressure = force / area
(softer blue rubber tip)

Question 24

TonoVET works via..

Answer 24

TonoVet works via rebound tonometry: a small probe is rapidly propelled from a fixed distance to contact the cornea before returning (rebounding) to the instrument. The rebound characteristics are assessed to determine IOP.
small ball tip

Question 25

High intraocular pressure?

Answer 25

?

Question 26

Low intraocular pressure?

Answer 26

?

Question 27

Name two antibiotics (or antibiotic combination products) that are used topically as ophthalmic prescription drugs

Answer 27

``` o Aminoglycosides  Tobramycin sulfate 0.3%  Gentamicin 0.3% o Triple antibiotic combo  NeoPolyBac o Multiple antibiotic + steroid  NeoPolyDex  NeoPolyBac with Hydrocortisone o Fluoroquinolones  Ofloxacin 0.3% o Tetracyclines  Oxytetracycline HCl and Polymyxin B Ophthalmic Ointment (containing oxytetracycline 5mg/g; polymyxin B sulfate 10,000 units/g; white petrolatum, and liquid petrolatum.) in 3.5 g ointment tubes --- Terramycin® o Macrolides  Erythromycin 0.5% ```

Question 28

Aminoglycosides

Answer 28

i. Bactericidal ii. Concentration-dependent iii. Interfere with protein synthesis 1. To reach the ribosome, these drugs must first cross the lipopolysaccharide layer (in gram-negative organisms), the bacterial cell wall, and finally the cell membrane. 2. Because of the polarity of these compounds, a specialized active transport process is required. 3. Anaerobic bacteria are generally resistant, because they lack appropriate transport systems iv. Synergism is common when aminoglycosides and β-lactam antibiotics (penicillins and cephalosporins) are used in combination. The cell-wall injury induced by the β-lactam compounds allows increased uptake of the aminoglycoside by the bacteria because of easier accessibility to the bacterial cell membrane.

Question 29

Fluoroquinolones

Answer 29

i. Bactericidal ii. Inhibit nucleic acid synthesis. 1. Bind to the DNA gyrase-DNA complex to induce defects in supercoiling 2. This renders the bacteria unable to multiply and survive.

Question 30

Macrolides

Answer 30

i. Generally bacteriostatic, but may be bactericidal at high concentrations or if there are a low number of a highly susceptible bacterial organism ii. Inhibit protein synthesis. 1. Macrolides reversibly bind to 50S subunit of the ribosomes and inhibit transpeptidation and translocation processes 2. This results in premature detachment of incomplete polypeptide chains.

Question 31

Polymixins

Answer 31

i. Bactericidal ii. Inhibit cell membrane function. 1. Disrupt the structure of cell membrane phospholipids and increase cell permeability by a detergent-like action, causing cell death. 2. Polymixins have also been shown to neutralize endotoxins.

Question 32

Tetracyclines

Answer 32

i. Bacteriostatic ii. Inhibit protein synthesis. 1. Reversibly binds to receptors on the 30S ribosomal subunit of the bacteria 2. This prevents the addition of amino acids to the elongating peptide chain, preventing synthesis of proteins

Question 33

Identify the circumstance(s) under which the ophthalmic use of corticosteroids is contraindicated and be able to explain why:

Answer 33

a. When a corneal ulcer is present i. Corticosteroids can impair corneal wound healing by inhibiting epithelial proliferation and migration; suppressing local immune factors; and promoting collagenase enzyme production. ii. Administering corticosteroids in the face of a corneal ulcer can lead to catastrophic corneal “melting”

Question 34

Identify the circumstance(s) under which the ophthalmic use of NSAIDS is contraindicated and be able to explain why

Answer 34

a. When a patient has glaucoma or is predisposed to glaucoma i. Topical NSAIDS in dogs has been shown to increase intraocular pressure by decreasing aqueous outflow through the iridocorneal angle

Question 35

Name one ophthalmic anti-inflammatory drug and explain when you might prescribe it

Answer 35

a. Flurbiprofen 0.03% b. Diclofenac 0.1% c. May be indicated to manage blepharitis, conjunctivitis, keratitis, uveitis, or as prophylaxis for lens-induced uveitis

Question 36

Name a topical ophthalmic anesthetic used in veterinary medicine and explain when it might be advisable to use this product?

Answer 36

a. Proparicaine HCl 0.5% b. Prior to certain methods of tonometry, i.e. Tonopen c. Prior to certain procedures, i.e. grid keratotomy