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
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
3
Q
Retinal vascular patterns
A
- holangiotic
- paurangiotic
- merangiotic
- anangiotic
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
5
Q
Paurangiotic vasculature
A
- Blood vessels within the retina only occur near optic disc
- Species examples
- Horse
- Elephant
- Rhinoceros
- Marsupials
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
7
Q
Anangiotic vasculature
A
- absence of any vasculature within sensory retina
- species examples
- birds
- marsupials
- bats
- monotremes
8
Q
Diagnostics
A
- Ophthalmic exam
- direct
- indirect
- ERG
- Physical exam + MDB
- Neuro exam
- Imaging
- CT
- MRI
- Ultrasound
9
Q
ERG
A
- Electroretinography
- Assesses retinal function
- does not asses vision
- Flashlight, then measurement of electrical response of retina
10
Q
Optic disk of cat
A
- non-myelinated
11
Q
Equine fundus
A
Little dots
-maybe capillaries
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
13
Q
Non-tapetum
(non-tapedal fundus)
A
- Color depends on degree of pigmentation in RPE
- if lightly colored may see choroidal vasculature
14
Q
Optic disc
A
- variable shape
- dog: triangular
- cat: round
- horse: oval
- variable degress of myelination
- vessel margins
15
Q
Non tapedal species
A
- pigs
- primates
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
- normally atrophies post-natally
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
Chorioretinitis
Etiologies
* Sepsis
* Dogs
* distemper
* fungi
* Cats
* FIV
* FeLV
* FIP
* Toxo
* Fungi
* Horses
* ERU
* Herpes
* Fungi
26
Retinal Degeneration
* Inherited
* PRA
* Nutritional
* Taurine deficiency
* Post-inflammation
* Toxic
* Enrofloxacin
* SARDS
27
Progressive retinal atrophy (PRA)
* 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
Enrofloxacin roxicity
* Idiopathic drug reaction
* also with other fluoroquinalones
* Dose dependent
* always use low dose
* acute blindness following systemic administration
29
SARDS
| (Sudden acquired retinal degeneration)
* Acute vision loss
* unkown etiology
* initial fundic exam is normal
* observable degeneration months later
* Extinguised 'flat' ERG
* No treatment/resolution
30
Congenital Optic Nerve/optic disc anomalies
* Hypoplasia, aplasia
* non-visual
* Micropapilla (I think this is a small optic disc)
* visual
* Colobomas
31
Optic Neuritis
* Inflammation/swelling
* optic disc
* retrobulbar optic nerve
* CS
* Mydriasis
* absent/reduced PLRs
* Vision loss
* Variable signs
* optic papilla swollen
* hyperemic
* fuzzy margins
* hemorrhages
32
Optic Neuritis
Etiologies
TX
* Etiologies
* systemic infections
* neoplasia
* Immune-mediated dz
* trauma
* TX
* directed therapy
* anti-inflammatory
* Immunosuppressive
* Prognosis
* guarded-poor
33
Optic Nerve Atrophy
* Acquired
* Often secondary to
* trauma
* orbital disease
* PRA
* glaucoma
* Optic disc will appear pale, recessed
* Vision loss
