Examination of eyes

Question 1

How can you dilate the eye to aid your ocular exam?

Answer 1

• Tropicamide = short acting (compared to Atropine)

Question 2

How would you perform an eye exam?

Answer 2

1. History - time of onset, cause, pain, still seeing, general health
2. Hands off, lights on - signs of pain, discharge, asymmetry
3. Stage 2 - lights on = menace response
4. Stage 3 = light off = pupillary light reflex,
   -distant direct ophthalmoscopy
   -close direct ophthalmoscopy
5. Stage 4 = supplementary tests
   -Schirmer tear test
   -local anaesthestic
   -fluorescein

Question 3

Whats the difference between nuclear sclerosis and cataracts?

Answer 3

• Nuclear sclerosis = is a normal aging change and remains transparent from a distance and from close-up. You can see the outline of the nucleus due to retractile difference.
• Cataract = is a genuine opacity which scatters the light

Question 4

What does lens luxation lead to?
What breeds are predisposed?

Answer 4

• Corneal oedema
• Jack Russell

Question 5

How do you treat anterior lens luxation, prior to surgery?

Answer 5

• Antibiotic / steroid combination drops = maxitrol
• Anti glaucoma drops

Question 6

How do you surgically treat anterior lens luxation?

Answer 6

• Anterior dislocation =
  -Surgical lens removal
  -Return the lens to the posterior chamber by external manipulation (“couching”)
  -Then maintain a constricted pupil to keep it there
• Subluxated lens =
  -Surgical lens removal
  -Maintain a constricted pupil with prostaglandin analogues to prevent anterior dislocation

Question 7

What is a cataract?

Answer 7

• Abnormal opacity of lens

Question 8

What is nuclear sclerosis?

Answer 8

• Normal aging change
• Condensation of the nucleus of the lens with age

Question 9

What is the only problem with the vitreous?

Answer 9

• Asteroid hyalosis =
  -snowstorm in the viterous

Question 10

By what age does the tapetum lucidum develop in dogs?

Answer 10

• 12 weeks

Question 11

What does hyperreflectivity indicate in tapetal retinas?

Answer 11

• Thinned retinas - brighter than surrounding area

Question 12

What can cause optic disc swelling?

Answer 12

• Excessive myelination in golden retrievers (normal)
• Optic neuritis / meningitis
• Raised intracranial pressure

Question 13

What do orbital tumours cause?

Answer 13

• Gradual painless displacement of the globe

Question 14

What should be done with prolapse of the globe?

Answer 14

• Replace quickly - GA, alliss tissue forceps on lid margins
• Section lateral canthus if needed
• Suture lids closed for 2 weeks
• Antibiotics + NSAIDs

Question 15

What can prolapse of the globe lead to even with correct management?

Answer 15

• Avulsion of medial rectus muscle (leading to lateral squint / strabismus)
• Traction of the optic nerve (leading to blindness)
• Traction of the trigeminal nerve (leading to loss of corneal sensation)

Question 16

Why do you need to be careful with enucleation of a cat?

Answer 16

• If put traction / pressure on eye during removal can damage optic nerve at chiasm and cause blindness in the other eye