Fundus Flashcards
What are the components of the fundus?
Sclera Choroid (vascular) Tapetum Retinal pigment epithelium (RPE) Neurosensory retina (rods, cones, and retinal blood vessel)
T/F: lacking pigmented epithelium or the tapetum from the retina can be a normal variation
True
Occurs in light blue eyed dogs (husky)
T/F: the optic nerve is myelinated in dogs and cats
False
Myelinated in dogs
Absent in cats —> optic disc appears dark, round and small
What are hallmarks of retinal disease?
Retinal hemorrhage Retinal detachment Vascular changes Altered tapetal reflectivity Altered pigmentation Altered optic nerve Head appearance
What are possible causes of retinal hemorrhage?
Anemia Systemic hypertension Hyperviscosity Diabetes mellitus Chorioretintitis Coagulopathy Trauma Retinal detachment
Where can retinal hemorrhage be localized?
Pre- retinal (keel boat)
Within nerve fiber (flame-shaped)
Within retina (dot-blot)
Sub-retinal (diffuse, irregular)
What initial diagnostic work up do you do if you have a patient with retinal hemorrhage?
CBC/Chem
PT/PTT
Blood pressure
What are causes of retinal detachment?
Retinal degeneration Vitreous disease Congenital malformation Lens luxation Neoplasia Intraocular inflammation — chorioretintitis Trauma Vascular disease — hypertension
What is retinal detachment ?
Separation of neurosensory retinal from RPE
Remains attached at ONH and oral ciliaris
Bulbous detachment of the retinal is an early sign of __________________ disease in cats
Feline hypertensive retinopathy
What is the treatment for bulbous retinal detachment associated with feline hypertensive retinopathy?
Antihypertensive therapy —amlodipine
What is retinal dialysis/
Compete retinal detachment AND tear
No longer attached at ora ciliaris
Retinal dialysis is a common occurrence with primary vitreous degeneration. What breeds are predisposed ?
Shih Tzu
Havanese
Chinese crested
How does the retina appear with retinal dialysis?
Tapetum is hyper-reflective because no overlying retina is there to absorbed light and the retinal is folded over the optic nerve
What is the treatment for retinal dialysis?
Partial detachments - retinopexy
Complete detachments
- re-attachment surgery
- poor visual success rate
Increased tortuously of the vascular retina is associated with ??
Hypertension
Hyperviscosity (polycythemia)
In what cases can you get increased reflectivity of the tapetum?
Retinal thinning
- degeneration/scarring
- retinal detachment/tear
In what cases can you have decreased reflectivity of the tapetum?
Increased retinal thickening
- folding
- edema
- inflitrates
- effusion
What are disorders of retinal degeneration?
Progressive retinal atrophy
Sudden acquired retinal degeneration syndrome
Feline central retinal degeneration
Drug-associated rental degeneration
What is progressive retinal atrophy?
Bilateral and symmetrical degeneration
GRADUAL Photoreceptor degeneration — causing night blindness initially then progressing to gradual loss of vision
What is the treatment for progressive retinal atrophy?
None
Clinical signs of progressive retinal atrophy?
Slow/incomplete PLR
Narrowing and loss of retinal blood vessels = attenuation
Tapetal hyper-reflectivity
Optic nerve atrophy
Non-tapetal pigmentary changes
Secondary cataract formation
What is sudden aquired rental degeneration syndrome (SARDS)?
Bilateral and symmetrical
ACUTE photoreceptor death
-dilated pupils but fundus appears normal
SARDS is associated with what signalment?
Middle aged/older dogs
Obesity/weight gain
PU/PD/PP
CBC and biochem are suggestive of hyperadrenocortisim but most cases do not have cushings
What is feline central rental degeneration?
Initial degeneration confined to ellipical area dorsolateral to ONH
Feline central retinal degeneration may be associated with what nutrional deficiency?
Taurine
What antibiotic can cause retinal degeneration in cats
Enrofloxacin
—- functional defects in ABCG2 allows drug to cross blood-retinal barrier
What is chorioretintitis?
Inflammation of the chronic (uvea) and retinal
Gray-white ares of edema or cellular infiltrate in the retina
Can aslo have retinal detachment, rentinal hemorrhage, vitreous haze, impaired vision, anterior uveitis
What work up will you do for chorioretintitis ?
PE
CBC/biochem/UA/thoracic rads
Serology (fungal and tick titers)
Treatment for chorioretintitis?
Address specific causes
Anti-microbial
Anti-inflammatory — if infectious diseases excluded
