Retina and Optic Nerve Flashcards
1
Q
What causes Retinal Dysplasia?
A
- Usually inherited
- can be associated with multiple ocular anomalies
- Other causes:
- maternal viral infections
- canine herpes and parvo viruses
- feline panleukopenia
- Vit A deficiency
- X-ray irradiation
- Drug toxicities
- Intrauterine trauma
- maternal viral infections
2
Q
What are the features of Retinal dysplasia?
A
- Retinal folds
- dots, linear, or V/Y shaped
- dull grey streaks in tapetum
- depigmented or white in non-tapetal
- Geographic retinal dysplasia
- larger, irregular often horseshoe-shaped hyperreflective lesion in tapetal fundus
- Retinal detachment - most severe form
3
Q
What is Hereditary Oculoskeletal dysplasia
A
- Retinal dysplasia in Labrador Retrievers
- Incomplete dominant ocular abnormalities
- cataracts, vitreous strands, persistent hyaloid remnants, retinal folds, retinal dysplasia, rhegmatogenous retinal detachments
- Recessive-skeletal abnormalities
- Short forelimbs and abnormal radius and ulna, hip dysplasia, hypoplasia of anconeal and coronoid processes
- Similar condition in Samoyeds
4
Q
What is Collie Eye Anomaly (CEA)?
A
- Collies
- High prevalence
- reduction due to selective breeding
- Other breeds: shetland sheepdogs, australian shepherds, Border collies
- High prevalence
- Simple autosomal recessive suspected - but condition may be polygenic
- Abnormal mesodermal differentiation
- Choroidal hypoplasia
- Hallmark sign
- Incidentally found (no clinical signs)
- Choroidal hypoplasia
- Optic nerve coloboma
- More severe signs
- Retinal detachment
- hyphema
5
Q
What are the clinical signs of progressive retinal atrophy?
A
- Bilateral - progressive loss of vision - blindness
- Decreased night vision (nyctalopia) usually first sign
- Progressive decrease in PLR
- Larger than normal resting pupil size
- Owner will sometimes report increase in “eye shine”
- Cataract formation in very late stages
6
Q
What is Sudden Acquired Retinal Degeneration Syndrome (SARDS)
A
- Acute photoreceptor death
- Usually middle aged to older dogs
- females overreptresented
- All breed affected
- Associated clinical signs
- may have ‘Cushing’s-like’ signs for weeks or months prior to vision loss
7
Q
What are the clinical signs of SARDS?
A
- Acute vision loss
- Variable PLR
- Chromatic PLR
- Red light negative
- Blue light positive
- Fundic exam
- Normal initially
- Chronic cases
- retinal degeneration
8
Q
How is SARDS diagnosed?
A
- Electroretinogram (ERG)
- May have elevated ALP, or other Cushing’s like changes on blood work
- less commonly diagnosed with Cushing’s via traditional screeding tests
9
Q
What is the treatment for SARDS
A
- No proven treatment
- Permanent blindness
10
Q
What are the effects of Retinal detachments on vision?
A
- Small detachments - no deficit
- large detachments - visual deficit/blindness
11
Q
What is Rhegmatogenous retinal detachment
A
- Retinal tear present which allows liquified vitreous to enter sub-retinal space
- Primary ocular disorder (previous cataract surgery, inherited vitreal degeneration, etc)
12
Q
What is Non-rhegmatogenous retinal detachment
A
- Remains attached at ora ciliaris retinae & optic disc
- Serous sub-retinal fluid-bullous retinal detachment
- Exudative retinal detachments-inflammatory or exudative sub-retinal fluid
- Systemic disease
13
Q
What are the differentials for Non-rhegmatogenous Retinal detachment?
A
- Depends on type of sub-retinal fluid/material
- Exudate (cloudy or discolored, yellow)
- same as chorioretinitis (i.e. posterior uveitis) ⇢ suspect systemic infection
- Transudate (clear)
- Aka Bullous
- Hypertension
- Hypoproteinemia
- Idiopathic (steroid responsive)
- dog specific
- Always perform systemic work-up
- CBC/chemistry panel/UA
- Blood pressure
- CHest radiographs
- Titers/antigen tests
14
Q
How is Retinal detachments repaired?
A
- Only appropriate for rhegmatogenous detachments
- Laser retinopexy
- 2 rows of burns around detachment to create adhesions
- Prophylactic vs. barrier
- Retinal reattachment
15
Q
What are the possible etiologies for Retinal hemorrhages?
A
- Anemia
- COagulopathy
- Systemic hypertension
- Hyperviscosity
- Systemic infections that cause vasculitis
16
Q
What is the diagnostic approach to retinal hemorrhages
A
- Thorough PE
- CBC, Chemistry, UA
- Blood pressure
- Clotting times
- BMBT
- Chest radiographs
- Titers/antigen testing if any suspicion of infectious cause
17
Q
What is Optic neuritis?
A
- Optic nerve inflammation
- Unilateral or bilateral
- Can involve any segment of optic nerve (intraocular vs retrobulbar)
- Associated with sudden blindness, fixed and dilated pupils
- Intraocular involvement:
- disc appears swollen, elevated, and hyperemic, with indistinct margins = papillitis
- Retrobulbar involvement:
- optic disc will appear normal
- need ERG to distinguish from SARDS
18
Q
What are the differentials for Optic Neuritis?
A
- Infectious
- Fungal
- Tick-borne encephalitis or ehrlichiosis
- Protozoal - toxoplasmosis
- Neoplasia
- lymphoma
- orbital/retrobulbar neoplasia
- GME
- Immune mediated
- Idiopathic
- Other:
- Orbital abscess/cellulitis
- Trauma
- Toxins
- Vitamin A deficiency
19
Q
What is the diagnostic approach to Optic Neuritis?
A
- CBC, chemistry panel, USA
- titers/antigen tests for infectious organisms
- Chest radiographs
- MRI or CT scan
- CSG Tap
- Thick of Optic neuritis as a neurologic disease
20
Q
What is the treatment for optic neuritis
A
- Treat primary cause
- Systemic steroids (immunosuppressive dose)
- Oral antibiotics (empiric)
- Prognosis for vision = poor
21
Q
What are the hallmark fundoscopic signs of Progressive Retinal Atrophy?
A
- Tapetal hyper-reflectivity
- Retinal attenuation of blood vessels
- Optic disk pallor
