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Ophthalmology > Retina, Optic Nerve and Vision > Flashcards

Retina, Optic Nerve and Vision Flashcards

1
Q

Retina - 9 layers *** (name 4)

A

Ganglion cells
Photoreceptors
RPE (retinal pigment epithelium)
Tapetum

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2
Q

Glaucoma starts with what cells? ***

A

Glaucoma starts with the ganglion cells in the retina. (The retinal reactions end with the ganglion cells that are the cell bodies for the optic nerve’s axons.)

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3
Q

Fundus in dog or cat? difference in shape/vasculature

A

Dog: round or triangular, vascular
Cat: round, no vessels in centre

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4
Q

Normal variance in the retina, name 7 things

A

Excessive myelin
Retinal vasculature pattern
Pigment islands in tapetum or tapetal islands in non-tapetum
Absence of tapetum
Partial or sub-albinotic fundus
Conus: hyper reflective area surrounding optic nerve head
(Puppy tapetum colour change at 4, 8, 13, 18 weeks)

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5
Q

Congenital: Collie Eye Anomaly (CEA) can involve what 3 things? What is most common?

A

– Chodoidal hypoplasia (most common)
– Optic nerve coloboma
– Retinal detachment & hemorrhages

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6
Q

Congenital: Retinal dysplasia - what causes it, what happens? sequelae?

A 
inherited, toxic or infectious cause
 Malformation of retinal layers
 Retinal folds or rosettes
 Geographical areas -> Predisposed to retinal detachment 
 Genetic blood test available (Optigen)
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7
Q

Developmental/Acquired: Progressive retinal degeneration/atrophy

A
  • Degeneration or atrophy
  • Progressive history
  • Inherited
  • Night vision
  • Tapetal hyper reflectivity
  • Attenuation of arterioles
  • ERG, genetic blood test
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8
Q

Developmental/Acquired: Sudden acquired retinal degeneration

A

Acute
Will look normal. PLR present & normal fundus
Only way to diagnose is an electro-retinogram.
Controversial treatments - IV immuno-globulins

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9
Q

Developmental/Acquired: Retinal Detachment

3 causes

A
  1. Retinal tear leads to influx of vitreous into sub retinal space (small dogs)
  2. Exudate from choroid due to inflammation or hypertension
  3. Tractional from fibrous tissue in the vitreous secondary to inflammation or genetics
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10
Q

Chorioretinal lesions

A

– Posterior uveitis: infectious

– Asymmetrical presentation if bilateral – Systemic prednisone

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11
Q

Retina: Detachment: ocular exam, work-up, treatment

A 
• Partial: vision present
– Complete: blindness 
• Ocular exam
– Dilate pupil
• Work-up underlying cause
– Blood work, BP...
• Treat underlying cause
• Retinal surgery – Retinal tears
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12
Q

Optic nerve Coloboma. What is it? Causes? Predisposition to?

A

A malformation where you have a hole in the optic nerve. If the periphery is affected, fluid will run underneath.
Causes: Congenital, part of the Collie eye anomalies, or inherited in Basenjis
at 6 o’clock
Predispose to retinal detachment
Prophylactic Treatment: Laser retinopexy may prevent retinal detachment

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13
Q

Optic nerve hypoplasia:

A

PLR not working, no optic nerve head to be seen
+/- vision
Can be inherited/congenital

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14
Q

Optic nerve neuritis

A 
• Inflammation
• GME (Granulomatous
meningoencephalitis)
• Blindness (likely)
– No PLR, menace
• MRI
• CSF tap
• Systemic anti-inflammatory – dexamethasone
Systemic immunosuppressive drugs (azathioprine)
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15
Q

Scotopic vision (dogs)

A 
• Vision in dim illumination
• Rod dominated retina
• Better motion vision in dim light
• Tapetum – reflects light 2nd time
• Threshold of light to see image is lower
DB

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16
Q

Photopic vision (humans)

A

• Vision in bright light mediated by cones
• Tapetum scatters light – decreases visual acuity • Less ganglion cells – grainy image
• Hemeralopia (day blindness): Malamute


17
Q

Hyperopia

A
  • Refractive state of the eye in which the parallel rays of light would come to focus behind the retina if not intercepted by it
  • Australian Shepherd, Malamute, English Springer Spaniel
18
Q

Myopia

A
  • Refractive state of the eye in which parallel rays of light come into focus in front of the retina
  • German Shepherd, Rottweiler, Min. Schnauzer, Toy Poodle, Labrador, English Springer Spaniel, Collies
19
Q

Strabismus

A

– Condition in which the two eyes are not simultaneously

direct at the same object in a coordinated fashion – Deviated eye turns inward

20
Q

Nystagmus

Abnormal nystagmus in what breeds?

A

– Oscillatory movement of the eye
– Siamese, Himalayans, Birman


21
Q

Developmental/Acquired: Retinal Detachment

Diagnosis & Treatment

A 
Diagnosis: fundic exam
o If opacity of lens or chambers: ocular ultrasound o ERG: will be diminished
o Work-up underlying cause
     CBC, serum biochemistry
     Blood pressure
Treatment: treat underlying cause 
o Hypertension: amlodipine
o Uveitis: see uveitis section 
o Traction bands and Tears
 ASAP vitrectomy and laser retinopexy 
 Guarded prognosis for vision
22
Q

Name the 2 congenital retinal anomalies and the 4 developmental/acquired retinal diseases

A
  1. Retinal dysplasia
  2. Collie eye anomaly
  3. Progressive retinal degeneration
  4. Sudden acquired retinal degeneration syndrom (SARDs)
  5. Retinal detachment
  6. Chorioretinal lesions: Uveitis causing retinal issues
23
Q

Treatments for retinal diseases

A

Only two that can really be treated are chorioretinal lesions (underlying cause & prednisone) and retinal detachments (underlying cause, if tear - vitrectomy/laser retinopexy)

24
Q

Optic nerve diseases

Name 2 congenital and 1 acquired

A
  1. Nerve coloboma (laser), optic nerve dysplasia

2. Optic neuritis (treat with anti-inflammatory/immuno suppressive drugs -> dex/azathioprine)

25
Q

If you are treating anything at the level of the retina/optic nerve/fundus, can you use drops?

A

A drop will never get to the level of the retina, so for any thing in the fundic level etc, you need oral/systemic treatments.

26
Q

Inflammation at the back of the eye - how can we treat?

A

You’ll need steroids. e.g. chorioretinal lesions -> Systemic prednisone

27
Q

Fundic conus

A

hyper reflective area surrounding optic nerve head

28
Q

Fundus - blood supply

A

a. There are 3 - 4 large veins that run into disk and anastomose (forming venous ring) in the optic disk.
b. There are 12 or so smaller arteries that emerge at periphery of disk and carry blood to retinal periphery.
c. The area centralis (macula) is a relatively avascular area lateral to optic disk. Mediates sharpest vision.

29
Q

Granulomatous meningoencephalitis

A

Inflammatory disease of the CNS (dogs rarely cats)
2nd most common encephalitis (most common is CDV -> inflammatory disease of the canine CNS)
Female young toy dogs more common
Rapid onset
White matter of the cerebrum, brainstem, cerebellum, and spinal cord.
Noninfectious idiopathic cause, perhaps immune mediated or abnormal response to an infectious agent.

Ophthalmology (9 decks)

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