Lecture 19 4/15/25 Flashcards
(35 cards)
What are the characteristics of feline central retinal degeneration?
-taurine is essential in diet for cats
-cones are most sensitive to inadequate taurine levels
-disease can develop after just 10 weeks of deficiency
-will see focal retinal degeneration temporal to the optic nerve that progresses to a streak across the central retina and then complete retinal degeneration
-treatment with taurine supplementation and diet changes
Which drug is most commonly associated with drug-associated retinal toxicity in cats?
enrofloxacin
What are the risk factors for drug-associated retinal toxicity?
-old age
-renal or hepatic impairment
-high doses
-long durations
-IV admin.
What is the ophthalmoscopic appearance of the retina in drug-associated retinal toxicity?
degeneration of retina; noted as early as 4 days after drug admin
What is the etiology of drug-associated retinal toxicity?
-fluoroquinolones normally cannot access retina due to a transport protein that removes it
-cats do not have this protein, allowing the drugs to reach the retina
-drug reacts with light and causes toxicity
What is the treatment for drug-associated retinal toxicity?
-avoid enrofloxacin in cats
-put cat in the dark if pupils are dilated
-STOP use of the drug causing disease
What are the characteristics of glaucomatous retinal degeneration?
-primary pathology of glaucoma is destruction of retinal ganglion cells
-elevated IOP causes damage to other retinal cell types and leads to complete degeneration
What is chorioretinitis?
-inflammation of retina and choroid
-non-painful
-not obvious unless patient has anterior uveitis or vision compromise
What is the ophthalmoscopic appearance of chorioretinal scars?
-usually focal/multifocal, but can be diffuse
-hyperreflective
-well demarcated if focal
-flat
-not associated with hemorrhage or cellular exudation
-may have pigment clumps at center
What are the characteristics of active chorioretinitis lesions?
-focal/multifocal
-dull gray, white, yellow, or pink in color
-poorly demarcated
-can have “mass” appearance/granulomas, hemorrhage, or engorged vessels
-hyporeflective
-can see retinal detachment
What are the characteristics of inactive chorioretinitis lesions?
-focal/multifocal
-hyperreflective if in tapetum, depigmented if in nontapetum
-well demarcated
-flat
-not associated with hemorrhage
-may have pigment clump in center of lesion
What are the etiologies of chorioretinitis?
-infectious
-immune-mediated
-neoplastic
What is the treatment and prognosis for chorioretinitis?
-treat underlying cause
-use oral steroids; immunosuppressive dose unless infectious in cause
-prognosis depends on extent of lesions; retinal function may or may not return
-active lesions will go on to scar once resolved
Which vascular disorders can affect the retina?
-systemic hypertension
-severe anemia
-hyperviscosity syndrome
-coagulopathies
-infectious dz
-diabetes mellitus
What are the characteristics of systemic hypertension?
-most common in dogs and cats
-small vessels in choroid and retina are highly susceptible to damage from hypertension; become occluded and get ischemic necrosis of vessel walls
-will see retinal hemorrhage, bullous retina detachment, and sometimes hyphema
-diagnosed by taking BP and getting elevated systolic readings
-treated by treating the hypertension; no specific treatment for the retina
What are the characteristics of vascular disorders other than systemic hypertension?
-findings include retinal hemorrhage +/- bullous retinal detachment, dilated vessels, and hyphema and/or anterior chamber fibrin
-diagnosed via BP readings, CBC, chem, coag panel, infectious dz testing
-treatment done by treating underlying disorder
What is retinal detachment?
-separation of neurosensory retina from underlying RPE
-results in marked vision loss and potentially complete blindness
-peracute presentation
What are the types of retinal detachment?
-bullous: separation due to accumulation of fluid or cells between retina and RPE
-rhegmatogenous: separation begins as a tear and detachment progresses as vitreal fluid accumulates between retina and RPE
What are the ophthalmoscopic findings in retinal detachment?
bullous: anterior ballooning of retina with hazy/murky/bloody subretinal fluid
-tear: draped veil hanging over optic nerve
What are the ultrasound findings in retinal detachment?
bullous: seagull wing appearance
tear: veil shape
What are the etiologies of bullous retinal detachments and their treatments?
*systemic hypertension: treat disorder
*chorioretinitis: treat disorder
*retinal dysplasia/CEA: no treatment
*immune-mediated: corticosteroids
-steroid-responsive
-uveodermatological syndrome
*nonunion
What are the etiologies of rhegmatogenous retinal detachments and the treatment?
-post-cataract surgery
-spontaneous/genetic
-trauma
-secondary to coloboma
treatment only through reattachment surgery
What are the characteristics of the optic nerve?
-not truly a cranial nerve, but a white matter tract of the diencephalon composed principally of the axons of retinal ganglion cells
-axons project without synapses from retinal nerve fiber layer through optic chiasm and optic tracts
-fibers go to either the lateral geniculate nucleus, superior colliculus, hypothalamus, or pretectal nucleus and other midbrain centers
What are the four regions of the optic nerve?
-intraocular optic nerve: within the globe and sclera
-intraorbital optic nerve
-intracanalicular optic nerve
-short intracranial optic nerve that merges into optic chiasm
