Eye examination

Question 1

To begin an eye exam, where do you start

Answer 1

at the healthy eye

(after a thorough anamnesis and observing the patient from afar)

Monitor the movement and behavior of the animal in the room prior to examination.

Question 2

A thorough eye exam should include: (7)

Answer 2

2. Hands-off distant examination of head, eyes, eyelids and skin around the the eyes.
3. Innervation & vision assessment – blinking, Menace response, Pupillary light reflex – direct and consensual, cotton ball/tracking test
4. Schirmer Tear Test (mm/1 min)
5. Fluorescein test – for exluding the corneal ulcer
6. Examination with local light and magnification, local anesthesia if needed, Alcaine 0,5% ®
   (eyelids, distichia, ectopic cilia, spots in cornea, foreign body, anterior chamber, iris).
7. Tonometry (IOP mmHg)
8. Examination of eye fundus with direct ophthalmoscopy without mydriasis at the distance of a straight arm + near ophthalmoscopy ca 10 cm distance from the eye till you see blood vessels, pattern of fundus, optic disc etc.

Question 3

Difference between direct and indirect ophthalmoscopy.

Answer 3

direct is handheld, indirect is a headset/loupes

In direct, the examiner looks directly through the device’s viewing aperture to visualize the fundus (the interior surface of the eye). The light from the instrument illuminates the retina, allowing the examiner to see its details.

Direct ophthalmoscopes provide a limited field of view of the retina, usually around 5-15 degrees. This narrow field of view can make it challenging to examine the entire retina at once.

Direct provides an upright, unreversed image of around 15 times magnification

Indirect consists of a light source mounted on a headband or handheld device, along with a condensing lens. They also require the use of a handheld lens, known as a condensing or viewing lens.

In indirect, the examiner sits at arm’s length from the patient and holds the condensing lens in front of the patient’s eye. The light from the ophthalmoscope is used to illuminate the retina, and the examiner views the magnified image of the fundus through the condensing lens.

Indirect ophthalmoscopes provide a wider field of view compared to direct ophthalmoscopes, typically around 20-30 degrees. This broader field of view allows for better visualization of the peripheral retina and a more comprehensive examination.

produces a reversed, inverted image magnified 2 to 5 times

Question 4

provides an upright, unreversed image of around 15 times magnification and,

provides a limited field of view of the retina, usually around 5-15 degrees

Answer 4

Direct ophthalmoscopy

Question 5

produces a reversed, inverted image magnified 2 to 5 times and,

provides a wider field of view, typically around 20-30 degrees.

Answer 5

Indirect ophthalmoscopy

Question 6

“Extra” eye examinations: (4)

Answer 6

If needed:
- Examination of eye fundus with indirect ophthalmocopy with mydriasis. (Use Tropicamide 0,5-1%)

• Analyses (bacteriology, PCR, gene tests, cytology)
• Examination under general anesthesia
• Cannulation and flushing of naso-lacrimal ducts

When glaucoma is suspected, the pupil should not be dilated, as this narrows the iridocorneal angle.

Question 7

True Ocular Emergencies include: (5)

Answer 7

• Acute onset blindness (eye dz or neuro (like encephalopathies))
• Acute onset of red or cloudy eye
• Acute onset painful eye (squinting or excessive blinking)
• Anything dangling from the eye (including the eye itself – proptosis)
• Trauma of the eye

Question 8

What drug group is especially important for ocular emergencies?

Answer 8

NSAIDs

Basically always give.

You can even recommend the owner give paracetamol in special situations (but not for cats).

Question 9

Ocular emergency Advice for the owner by phone (5)

Answer 9

• The most important thing is that the animal is not allowed to cause further damage-> Elizabethan collars help prevent trauma.
• Rinse the eye gently with artificial tears or special eye cleaning solution, or a sterile saline solution or tap water even.
• Don’t advise to give any „home “ medication (special cases may get paracetamol though)!
• If owner says, or description seems like proptosis of eye: owner should keep the eye moist with saline, water, artificial tears and immediately visit the vet.
• If owner says, or description seems like contact with chemical solution/chemical burns: owner should cleanse eyes with a sterile saline solution, or tap water immediately for at least 20 min and then immediately visit the vet.

Question 10

Equine blepharospasm requires… for exam.

Answer 10

Local blocks as its impossible to manually open.

Question 11

How do you describe red looking sclera?

Answer 11

Its actually bulbar conjunctiva that you see as hyperemic.

Question 12

If you see rhinitis with epiphora and blepharospasm in a feline patient - whats your suspicion?

Answer 12

rhinitis is more typical to feline herpes virus

oral ucleration is more typical to calici

“herpes is epitheliotropic” thus it favors the nose whilst calici more so causes stomatitis

Question 13

Schirmer tear test normal results:

Answer 13

Dog: 15- 25 mm/1 min. Values between 10
and 15 mm may be caused by transiently
lowered tear production because of
stress.

Cat: 12- 22 mm/1 min, but the values may
vary, and cats are difficult to measure.

Question 14

Sheila, 8 y, female cavalier king charles spaniel,
chronic blepharitis, inflammation of conjunctiva and cornea, totally pigmented, not transparent cornea.

Answer 14

keratoconjunctivitis sicca

Question 15

Answer 15

Nnormal vein in part of bulbar conjunctiva.

Question 16

Episcleral and scleral blood vessels congestion
+/- conjunctival blood vessel congestion/conjunctival hyperemia can indicate?

Answer 16

Signs of intraocular diseases.

Pictured eye has high intraocular pressure - glaucoma.

Question 17

typical cat breed for entropion

Answer 17

maine coon

Question 18

3 light source and magnification options for eye exams:

Answer 18

focal light source
biomicroscope
loupes

Question 19

What is PVR assessment?

Answer 19

PVR in this context likely stands for “Pattern Visual Response”.

It refers to a type of test used to assess the function of the visual pathway from the eyes to the brain.

This test helps in localizing abnormalities in vision-related neural pathways and detecting issues in the central nervous system (CNS), such as optic nerve disorders and neuro conditions etc.

Question 20

Explain the PLR and why you test it.

Answer 20

The pupillary light reflex (PLR) is a neurological test used to assess the integrity of the visual and autonomic pathways controlling pupil constriction. It evaluates both the direct and consensual (indirect) responses of the pupil to light stimulation.

This test is particularly useful in veterinary ophthalmology and neurology to detect lesions affecting the eyes, optic nerves, brainstem, or autonomic pathways.

Question 21

Neural Pathways Involved in the Pupillary Light Reflex

Answer 21

The pupillary light reflex follows a pathway, involving both afferent (sensory) and efferent (motor) components:

Afferent
- Light enters the eye and is detected by the retina.
- Signals travel via the optic nerve (cranial nerve II) to the optic chiasm, where some fibers cross to the opposite side, others remain on the same side.
- Processed in the midbrain.

Efferent
- parasympathetic fibers via the oculomotor nerve (cranial nerve III)
- Short ciliary nerves then innervate the iris sphincter muscle, causing pupillary constriction (miosis).

Question 22

Clinical Interpretation of Abnormal Reflexes:
Absent direct & consensual PLR in one eye,
normal in the other.

Answer 22

Possible causes:
Optic nerve (CN II) lesion in the affected eye (e.g., optic neuritis, retinal disease).

Question 23

Clinical Interpretation of Abnormal Reflexes:
Absent direct PLR but present consensual PLR.

Answer 23

Possible causes:
Oculomotor nerve (CN III) or iris sphincter dysfunction in the affected eye.

Question 24

Clinical Interpretation of Abnormal Reflexes:
Absent consensual PLR but present direct PLR.

Answer 24

Possible causes:
Optic nerve lesion in the opposite (non-stimulated) eye.

Question 25

Clinical Interpretation of Abnormal Reflexes: Absent consensual PLR but present direct PLR.

Answer 25

Possible causes: Optic nerve lesion in the opposite (non-stimulated) eye.

Question 26

Clinical Interpretation of Abnormal Reflexes: Both pupils dilated, unresponsive to light.

Answer 26

Possible causes: Brainstem lesion affecting the midbrain (e.g., herniation, trauma, toxins).

Question 27

Clinical Interpretation of Abnormal Reflexes: Anisocoria (unequal pupils), one pupil does not respond.

Answer 27

Possible causes: CN III, oculomotor nerve dysfunction (e.g., Horner’s syndrome, trauma, or tumors affecting autonomic pathways).

Question 28

a normal PLR in a blind animal suggests

Answer 28

cortical blindness

Question 29

Topical anesthesia options for eyes. (5)

Answer 29

Tetracaine 0.5% Proxymetacaine (Proparacaine) 0.5% (Alcaine) Oxybuprocaine (Benoxinate) 0.4% Lidocaine 2% Gel Chloroprocaine 3% Gel Topical anesthesia, if spastic/painful eye. For simple examinations one drop is applied. The effect approximately one minute after application. ## Footnote Topical anesthetics are not indicated as treatment in painful conditions, due to their tissue toxicity,

Question 30

In animal with spastic eye (blepharospasm) you must exclude:

Answer 30

* Foreign body in conjunctiva, cornea, under eyelids, and under nictitans membrane * Aberrant cilia or hair (distichia or ectopic cilia) Also Evaluate by staining with Fluorescein-Na solution for detecting corneal ulcer.

Question 31

What are ectopic cilia?

Answer 31

abnormal hair follicles develop and grow through the conjunctiva, usually on the upper or lower eyelid, and can contact the cornea. These misplaced cilia can cause irritation, discomfort, corneal ulcers, and even vision impairment due to chronic mechanical trauma. Treatment typically involves surgical excision of the affected hair follicles to prevent recurrence. ## Footnote Symptoms include excessive blinking (blepharospasm), tearing (epiphora), redness, and corneal ulcers.

Question 32

Describe the FLUORESCEIN TEST

Answer 32

Place dye strip in syringe of NaCl or place a drop of NaCl directly onto end of strip. One drop of the stain is applied on the cornea and excess stain is rinsed off. In areas with loss of corneal epithelium Fluorescein-Na will penetrate into the stroma causing a green stain. Deep ulcers may go all the way down to the Descemet's membrane.

Question 33

Answer 33

Deep ulcers may go all the way down to the Descemet's membrane. The membrane will not stain but will present as a clear spot in the middle of the green stained walls.

Question 34

Tonometry is the measurement of intraocular pressure (IOP), mmHg. Indications: (6)

Answer 34

* Painful eye * Red eye * Cloudy eye * Vision impairment * Enlarged eye * In breeds predisposed to glaucoma ## Footnote beagle, husky, etc.

Question 35

Normal intraocular pressure in dogs? in cats?

Answer 35

dogs is 15-25 mmHg in cats 15-30 mmHg ## Footnote Normal IOP diff between eyes ≤ 8mmHg.

Question 36

Normal IOP diff between eyes

Answer 36

≤ 8mmHg.

Question 37

IOP of > 30 mmHg over several days damages

Answer 37

the optic nerve and retina. * IOP > 40 mm is painful and causes enlargement of the globe (buphthalmos). ## Footnote Normal in dogs is 15-25 mmHg, in cats 15-30 mmHg.

Question 38

enlargement of the globe

Answer 38

buphthalmos ## Footnote IOP > 40 mm is painful and causes enlargement of the globe (buphthalmos).

Question 39

IOP > 40-50 mm causes what to happen?

Answer 39

paralyses the sphincter muscle of the iris and causes mydriasis. ## Footnote Normal in dogs is 15-25 mmHg, in cats 15-30 mmHg.

Question 40

Lowered IOP indicates

Answer 40

intraocular inflammation (uveitis). ## Footnote Normal in dogs is 15-25 mmHg, in cats 15-30 mmHg.

Question 41

3 options for vision testing

Answer 41

obstacle course (with owner or treats at the end) cotton ball test swinging light test (look for head or eye movements)

Question 42

The optic nerve is the afferent path both for vision and pupillary light reflexes. In the cat and dog, about two-thirds of the optic nerve fibres cross in the optic chiasm to the opposite side of the brain. In the optic tract, about 80% of the nerve fibres project via the lateral geniculate nucleus to the visual cortex of the cerebrum, whereas about 20% go to the midbrain. Normal function of the optic nerve can be tested in many ways. Practical testing includes: (4)

Answer 42

* The menace response * The visual placing reaction (forelimbs onto tabletop) * The pupillary light reflexes * The dazzle reflex

Question 43

A normal menace response requires

Answer 43

a normal visual pathway, (the sensory pathway), as well as a normal facial nerve (VII), the motor pathway. ## Footnote note that the menace reaction can be absent in animals with cerebellar or facial nerve lesions, without the animal being blind, and that seriously ill animals may react poorly to the stimulus.

Question 44

Signs of Collie Eye Anomaly

Answer 44

blindness microphthalmia enophthalmia coloboma aka retinal hypoplasia (which can cause retinal detachment)

Question 45

Answer 45

iris cyst, benign balls of iris tissue

Question 46

Answer 46

persistent pupillary membrane

Question 47

Many dog breeds are predisposed to glaucoma. Inspection of the iridocorneal angle, the drainage angle between the cornea and iris, may be indicated. In horses and cats the angle is easily visible, in dogs vision is obscured by the sclera. So how is this examined in dogs?

Answer 47

gonioskopia An extra curved lens, a gonioscopy lens, can be placed on the cornea after topical anesthesia for inspection of the iridocorneal angle in the dog. However, this is not part of routine examination.

Question 48

Answer 48

iris coloboma aka missing iris tissue, benign but can cause light sensitivity

Question 49

classic signs of uveitis

Answer 49

blepharospasm. episcleral or conjunctival hyperemia. diffuse corneal edema. miosis. aqueous flare (indicative of protein or cells in the anterior chamber) fibrin in the anterior chamber. hypopyon. hyphema. ## Footnote In uveitis, production of aqueous is diminished, and the IOP is lowered.

Question 50

Uveitis complications in horses.

Answer 50

Uveitis may be recurrent with variation in severity. This is of special importance in the horse where recurrent uveitis is a major cause of blindness. Because of the intimate connection between the iris and the lens, untreated uveitis will lead to adherences. The aqueous is not able to drain through the pupil and will accumulate behind the iris pushing it forwards. The iris will then block the drainage angle, and the eye develops secondary glaucoma finally leading to blindness. Posterior uveitis affecting the choroid will show less dramatic signs, but the eye is red, and examination of the fundus (the back of the eye) will reveal pathologic changes.

Question 51

What is the fundus reflex.

Answer 51

refers to the (varying color) reflection of light from the back of the eye, or fundus, observed when using an ophthalmoscope or retinoscope.

Question 52

What is schiotzi?

Answer 52

old-fashioned tonometry

Question 53

Normal IOP in horses.

Answer 53

10-37 mmHg (wider normal range than other species)