Term
| What are the parts of the fundus? |
|
Definition
-retina
-choroid
-optic n
-sclera |
|
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Term
| What is normal in regards to a fundic examination? |
|
Definition
-tapetal fundus is always superior
-no tapetuc can be a normal variation
-amount of RPE and choroidal pigment vary with coat color
-all structures should appear CLEAR and CRSIP |
|
|
Term
| Why is the choroid pigmented? What is its normal color? |
|
Definition
-inc melanocytes
-dark brown |
|
|
Term
| What does mild color dilution of the choroid look like? In which animals does it occur? |
|
Definition
-orange/brown due to less pigment + choroidal vessels showing through
-animals with red coat color and chocolate labs |
|
|
Term
| What does a blue iris look like? In which animals does it occur? |
|
Definition
-choroidal vessels against white sclera; red appearance and usually atapetal
-huskies |
|
|
Term
| Does a feline have an oddly large or small tapetal area? |
|
Definition
|
|
Term
| Generally describe the retina. |
|
Definition
| -semi-transparent, thin, neurosensory tissue |
|
|
Term
| Can we normally see the retinal blood vessels? |
|
Definition
|
|
Term
| What would indicate elevation of the retina? What is the one exception to this rule? |
|
Definition
-bulge in retinal vessels when visually followed
-exception = horse |
|
|
Term
| Where does the retina attach? Why is this clinically significant? |
|
Definition
-only attached around the optic disc and peripherally where the retina meets the ciliary body
-large potential space for fluid and/or cell accumulation leading to retinal detachment & can tear and fall off the choroidal surface |
|
|
Term
|
Definition
| -the visible portion of the optic nerve |
|
|
Term
| What does a typical feline optic disc look like? |
|
Definition
-non-myelinated (small, dark, round)
-vessels do not cross the disc |
|
|
Term
| What does a typical canine optic disc look like? |
|
Definition
-myelin varies (round to traingular & dark to white)
-vessels cross the disc |
|
|
Term
| What does a typical equine optic disc look like? |
|
Definition
|
|
Term
| What does a typical ruminant optic disc look like? |
|
Definition
-dark, tannish color causing it to blend into background, to cream colored depending on species
-extremely large overlying vessels |
|
|
Term
| What is hyperreflectivity? What does it indicate? |
|
Definition
-the tapetum appears hyperreflective when the overlying retina is thin
-indicates retinal atrophy due to inactivity |
|
|
Term
| What is hyporefflectivity? What does it indicate? |
|
Definition
-the tapetum appears hyporeflecive when there is fluid and/or cells b/n the tapetum and retina
-indicates active disease |
|
|
Term
| What are the causes of a non-tapetal fundus in general? What do they look like? |
|
Definition
-retinal atrophy/degeneration (inactive): apears depigmented
-active disease: appears blurry, out of focus with fluid beneath retina (hemorrhage or exudate) |
|
|
Term
| What does an electroretinogram measur? What is its purpose? |
|
Definition
-measures respone of the photoreceptors to light
-tests for retinal degeneration |
|
|
Term
| What does an ocular ultrasound do? What does it specifically diagnose? |
|
Definition
-images the position of the retina if it is not visible on fundic exam
-diagnostic for retinal detachment |
|
|
Term
| How does retinal disease usually affect the PLRs? |
|
Definition
|
|
Term
| Between what two layers does retinal detachment occur? |
|
Definition
| -occurs b/n the RPE layer of the retina an dthe neurosensory retina |
|
|
Term
| What causes progressive retinal atrophy (PRA)? Is it bilateral, unilateral, or varies? |
|
Definition
-genetic
-always bilaterally symmetrical |
|
|
Term
| At what age does PRA usually begin? |
|
Definition
| -5 years of age and blind by 8-9 years of age |
|
|
Term
| What is the physiology behind PRA? |
|
Definition
| -gradual degeneration of photoreceptors from rods to cones |
|
|
Term
| What is the first clinical sign of PRA? |
|
Definition
|
|
Term
| What clinical signs do we see on fundic exam of PRA? |
|
Definition
-diffuse atrophy visible
-hyperreflectivity
-retinal vasculature attenuation
-pale optic disc |
|
|
Term
|
Definition
| -Sudden Acquired Retinal Degeneraiton Syndroe |
|
|
Term
| What animals are affected by SARDS? |
|
Definition
| -middle-aged to older dogs |
|
|
Term
| What is the clinical sign of SARDS? |
|
Definition
| -ACUTE onset of blindness (always bilateral) |
|
|
Term
| How does SARDS affect the PLRs? |
|
Definition
|
|
Term
| How does the fundus appear on examination with SARDS? How do we diagnose it? |
|
Definition
-normal
-diagnosed bia electroretinogram |
|
|
Term
|
Definition
|
|
Term
|
Definition
| -Progressive Retinal Atrophy |
|
|
Term
| Is PRA acquired or genetic? Bilateral or unilateral? |
|
Definition
|
|
Term
| At what age does PRA commonly present? What is the age of onset? Why are these two values different? |
|
Definition
-presents by 8-9 years
-onset at about age 5 y
-progresses over years |
|
|
Term
| How do the photoreceptors change over the course of PRA? HOw does this affect vision in the patient? |
|
Definition
-rods to cones gradually
-night blindness first folled by day vision loss |
|
|
Term
| What kind of retinal degeneration commonly affects dogs with access to large animal dewormers? |
|
Definition
|
|
Term
| What are the clinical sings of Ivermectin toxicity evident on an optho exam? |
|
Definition
-acute blindness with dec PLRs
-also see neuro signs if a greater overdose
-fundus appears normal |
|
|
Term
| How do we treat the visual deficits that occur with lowergrade Ivermectin toxicity? Explain the reasoning behind it. |
|
Definition
-no treatment
-b/c vision returns normally within 48 hours (light vision then night vision) |
|
|
Term
| What is the doctor term for light vision? |
|
Definition
|
|
Term
| What is the doctor term for dark vision? |
|
Definition
|
|
Term
| In which species do we usually see visual issues due to Enrofloxacin toxicity? |
|
Definition
|
|
Term
| What are the clinical signs see due to Enrofloxacin toxicity seen on an optho exam? |
|
Definition
| -acute, irreversible blindness due to retinal degeneration |
|
|
Term
| What is the physiologic cause of retinal degeneration due to retinal detachment? |
|
Definition
| -separated from the choroid (its nutrient source) |
|
|
Term
| What are the typical signs of retinal atrophy? |
|
Definition
-hyperreflectivity
-retinal vasculatrue attenuation
-depigmentation in non-tapetal fundus
-pale optic disc if the retinal atrophy is extensive |
|
|
Term
| How do we treat retinal degeration in general? |
|
Definition
-we can't, it can't be fixed
-sometimes give Ocu-GLO a non=proven nutriceutical but it doesn't hurt |
|
|
Term
| Definition: Rhegmatogenous |
|
Definition
| -retinal detachment due to a tear or hole in the retina |
|
|
Term
| Definition: Non-rhegmatogenous |
|
Definition
| -detachment due to chorioretinitis or hypertension |
|
|
Term
| What is the physiology behind rhegmatogenous retinal detachment? |
|
Definition
| -tear ro hole develops in the retina => vitreous leaks under the tear/hole => the retina detaches |
|
|
Term
| What are the possible etiologies behind rhegmatogenous retinal detachment? |
|
Definition
-secondary to hypermature cataract
-complication following cataract surgery
-Breed: Shih Tzu and Boston Terriers
-Severe globe Trauma |
|
|
Term
| How do we treat rhegmatogenous retinal detahcment? |
|
Definition
-laser retinopexy to "seal edges" and prevent further detachment
-retinal reattachment surgery |
|
|
Term
| What is the physiology behind non-rhegmatogenous retinal detachment? |
|
Definition
| -chorioretinitis inflammation => leaky choroidal +/- retinal vessels => fluid leakds under retina |
|
|
Term
| What are the three major etiologic categories responsible for non-rhegmatogenous retinal detachment? Give an example or two of each. |
|
Definition
-Systemic dz: infectious or neoplastic
-Immunde-mediates: VKH or Equine Recurrent Uveitis
-Trauma |
|
|
Term
| What are the clinical signs of optic neuritis see on optho exam? |
|
Definition
-optic disc appears hyperemic, blurry and protruding
-dilated pupil with no direct PLR or consensual PLR to other eye (afferent deficit)
-blind in affected eye(s) |
|
|
Term
| What are the three possible etiology categories responsible for optic neuritis? |
|
Definition
-Immune-mediated: granulomatous meningoencephalitis
-Infectious: cryptococcosis, canine distemper
-Neoplasie: lymphoma |
|
|
Term
| What are the two most common types of optic nerve neoplasia? |
|
Definition
|
|
Term
| Describe the presentation of optic nerve disease. |
|
Definition
-exophthalmia without globe deviation laterally
-optic disc may/may not appear abnormal
-blind |
|
|
Term
| How do we treat optic nerve neoplasia? |
|
Definition
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