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Ophtho (sophomore) > Dzx of retina and optic nerve (Whitley) > Flashcards

Dzx of retina and optic nerve (Whitley) Flashcards

1
Q

Posterior segment of the eye

A
  • Everything posterior to lens
    • vitreous
    • retina
    • choroid
    • sclera
    • choroid
    • optic nerve
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2
Q

Visual sensory system

A
  • Photoreceptors
    • light energy => electrical energy (Transduction)
  • Modulation of electrical signal by various retinal cells
  • Electrical impulses leave retina by ganglion cell fibers
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3
Q

Retinal vascular patterns

A
  • holangiotic
  • paurangiotic
  • merangiotic
  • anangiotic
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4
Q

Holangiotic vasculature

A
  • most of sensory retina receives direct blood supply from central artery or from cilioretinal arteries
  • Species examples
    • cat
    • dog
    • cow
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5
Q

Paurangiotic vasculature

A
  • Blood vessels within the retina only occur near optic disc
  • Species examples
    • Horse
    • Elephant
    • Rhinoceros
    • Marsupials
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6
Q

Merangiotic Vasculature

A
  • retinal blood vessels are present in a limited portion of retina
    • band of blood vessels and myelinated nerve fibers travers retina in a horizontal plane
  • Species example
    • rabbit
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7
Q

Anangiotic vasculature

A
  • absence of any vasculature within sensory retina
  • species examples
    • birds
    • marsupials
    • bats
    • monotremes
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8
Q

Diagnostics

A
  • Ophthalmic exam
    • direct
    • indirect
  • ERG
  • Physical exam + MDB
  • Neuro exam
  • Imaging
    • CT
    • MRI
    • Ultrasound
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9
Q

ERG

A
  • Electroretinography
    • Assesses retinal function
    • does not asses vision
    • Flashlight, then measurement of electrical response of retina
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10
Q

Optic disk of cat

A
  • non-myelinated
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11
Q

Equine fundus

A

Little dots

-maybe capillaries

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12
Q

Tapetum

A
  • Reflective structure
  • assists or enhances vision in dim light
  • part of the dorsal choroid behind retina
  • develops post-natally
  • variable color
    • associated with age, coat color, breed
    • blue until 8-12 weeks of age
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13
Q

Non-tapetum

(non-tapedal fundus)

A
  • Color depends on degree of pigmentation in RPE
    • if lightly colored may see choroidal vasculature
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14
Q

Optic disc

A
  • variable shape
    • dog: triangular
    • cat: round
    • horse: oval
  • variable degress of myelination
  • vessel margins
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15
Q

Non tapedal species

A
  • pigs
  • primates
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16
Q

Disorders of posterior segment

A
  • Incomplete or improper development
  • limited capacity to respond to dz or injury
  • Inflammation
  • Degeneration
    • thick-thin
    • bright-dull
    • hyper-hypo pigmented
    • hyperemia-pallor
    • absence/displacement of normal structures
17
Q

PHPV

A
  • Persisten hyperplastic primary vitreous
  • embryonal vessel remains present and perfused
    • normally atrophies post-natally
      • 3 wks in dogs
      • 8 wks in cats
      • 2 wks in horses
    • Remnant
      • Mittendorf’s dot
18
Q

Vitreal Degeneration

A
  • Causes
    • age
    • genetic predisposition
    • following inflammation
  • Asteroid hyalosis
    • Calcium-lipid soap complexes
  • Syneresis/Liquifaction
    • snow globe
  • Floaters
19
Q

Congenital disorders of retina

A
  • Retinal dysplasia
  • Retinal detachment
  • Collie Eye Anomaly
20
Q

Retinal Dysplasia

A
  • rosettes/folds in retina
  • variable severity
    • focal or generalized
    • retinal detachments
21
Q

Collie Eye Anomaly

A
  • Congenital, bilateral, asymmetric anomaly of
    • choroid
    • optic nerve
    • sclera
  • > 85% collies affected
  • Choroidal hypoplasia
  • Posterior pole colobomas
  • Retinal detachment
  • Hyphema
  • Variable vision loss
22
Q

Retinal Detachments

A
  • Congenital
  • Acquired
    • systemic hypertension
    • Inflammatory conditions
    • Vitreal traction
    • Trauma
    • Neoplasia
  • May be partial/complete
  • Rhegmatogenous
    • hole in retina
  • Non-rhegmatogenous
    • no holes

*Sails filled with air

23
Q

Hypertensive retinopathy

A
  • Feline or canine
  • Very common in older cats
  • Clinical signs
    • often present for acute blindness
    • mydriasis
    • poor PLRs
    • Retinal detachments
    • hemorrhage
    • hyphema
  • Usually secondary to
    • renal disease
    • hyperthyroidism
    • cardiac disease
    • neoplasia
  • Therapy
    • treat underlying cause
    • systemic anti-hypertensive meds
      • CCB: amlodipine
      • ACEi: benazepril
  • Prognosis
    • gaurded
24
Q

Chorioretinitis

(Posterior uveitis)

A
  • Inflammation of retinal and choroid
  • Active
    • hyporeflectivity
    • Dark or cellular lesions
    • Borders out of focus
    • Detachments
    • Edema
    • Hemorrhage
  • Inactive
    • Sharp borders
    • Hyperreflectivity
    • Hyperpigmented centers
25
Q

Chorioretinitis

Etiologies

A
  • Sepsis
  • Dogs
    • distemper
    • fungi
  • Cats
    • FIV
    • FeLV
    • FIP
    • Toxo
    • Fungi
  • Horses
    • ERU
    • Herpes
    • Fungi
26
Q

Retinal Degeneration

A
  • Inherited
    • PRA
  • Nutritional
    • Taurine deficiency
  • Post-inflammation
  • Toxic
    • Enrofloxacin
  • SARDS
27
Q

Progressive retinal atrophy (PRA)

A
  • inherited retinal photoreceptor dysplasia or degeneration
  • Loss of rods first, then cones
  • pregressive loss of nigh vision, then day vision
  • thinning of retina = hyperreflectivity
  • then optic nerve atrophy
  • DX
    • Behavior
    • maze test
    • opthalmoscopy
    • ERG
  • TX
    • none
    • gene therapy
    • antioxidants: OcuGlo
28
Q

Enrofloxacin roxicity

A
  • Idiopathic drug reaction
    • also with other fluoroquinalones
  • Dose dependent
    • always use low dose
  • acute blindness following systemic administration
29
Q

SARDS

(Sudden acquired retinal degeneration)

A
  • Acute vision loss
  • unkown etiology
  • initial fundic exam is normal
    • observable degeneration months later
  • Extinguised ‘flat’ ERG
  • No treatment/resolution
30
Q

Congenital Optic Nerve/optic disc anomalies

A
  • Hypoplasia, aplasia
    • non-visual
  • Micropapilla (I think this is a small optic disc)
    • visual
  • Colobomas
31
Q

Optic Neuritis

A
  • Inflammation/swelling
    • optic disc
    • retrobulbar optic nerve
  • CS
    • Mydriasis
    • absent/reduced PLRs
    • Vision loss
    • Variable signs
      • optic papilla swollen
      • hyperemic
      • fuzzy margins
      • hemorrhages
32
Q

Optic Neuritis

Etiologies

TX

A
  • Etiologies
    • systemic infections
    • neoplasia
    • Immune-mediated dz
    • trauma
  • TX
    • directed therapy
    • anti-inflammatory
    • Immunosuppressive
  • Prognosis
    • guarded-poor
33
Q

Optic Nerve Atrophy

A
  • Acquired
  • Often secondary to
    • trauma
    • orbital disease
    • PRA
    • glaucoma
  • Optic disc will appear pale, recessed
  • Vision loss

Ophtho (sophomore) (11 decks)

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