Disorders Of Ocular Fundus Flashcards
What constitutes the ocular fundus
Retina - neuro sensory retina and RPE
Optic disc
Choroid - includes tapetum
Spatial relationship of posterior eye structures
Neurosensory retina - clear and first structure
potential space between
RPE - retinal pigmented epithelium, can be non pigmented
Choriocapillaries
Tapetum -
Choroid
Sclera
Tapetal features
Age/coat color can influence color
Size vary within species
Tapetal reflectivity
Function of thickness of neurosensory retina /fluid underneath retina
Hyperreflectivity / hyporeflectivity
blood vessels of fundus
Retinal vessel patterns vary in species
Choroidal vessels - vary in visibility, dependent on RPE pigmentation
Holaniotic retinas
All of speices have this, vessels extend in all directs from disc to periphery of retina
Optic disc
Normal appearance varies by species, degree of intraocular myelination
Developmental disorders
Retinal dysplasia
Collie eye anomaly
Micropapilla
Optic nerve hypoplasia
Optic disc coloboma
Retinal dysplasia
Anamolous retinal differentiation
Multi focal dysplasia - no clin sig
Geographic dysplaisa - can lead to retinal detachment
Total dysplasia - results in retinal detachment/non attachment
Collie eye anomaly
Involves defects of posterior vascular (choroid) & fibrous tunics of eye
Highly pleiomorphic manifestations within litters
Lesions of collie eye anomaly
Chorodial hypoplasia - sparse but enlarged choroidal vessels lateral to optic disc
Optic nerve & peripapillary coloboma - 2nd retinal detachment, 2nd hyphema
Congenital small optic nerves
Micropapilla - small than normal optic nerve in visual eye, PLR normal
Optic nerve hypoplasia - smaller than normal optic nerve in BLIND eye, direct PLR in affected eye diminished to absent
Optic nerve coloboma
Focal to extensive developmental defect of optic nerve - non progressive
Typical colobomas occur at 6 o clock position but may occur elsewhere
Vision impact is relative to coloboma size
Optic neuritis findings
Ophthalmoscopic findings -
Intraocular optic neuritis - optic disc swollen, raised, hyperemia, papillary hemorrhage
Retrobulbar optic neuritis - fundus appears normal
Retinal degenerative disorders
Progressive retinal atrophy (PRA)
Canine sudden acquired retinal degeneration syndrome (SARDS)
Feline central retinal degeneration (taurine deficiency retinopathy)
Progressive retinal atrophy
Heritable, develops normally THEN degenerates
Rods degen first, then cones - dim light vision(NIGHT) impacted first
Age of onset/rate of disease progression variable - most progress to blindness
DX of PRA
Signs can involve - diminished menace/PLR
Ophthalmoscopic abnormalities - tapetal hyperreflectivity, vascular attenuation, optic atrophy
*maze test, eleectroretinography
Managing PRA
No effective treatment
Counsel owners regarding maintenance of safety
quality of life
Canine sudden acquired retinal degeneration syndrome (SARDS)
Idiopathic disorder
sudden onset blindness, normal fundus
Small breeds, middle age, FS dogs
Concomitant polyphagia, weight gain, PU/PD
- Biochem panel abnormal: low urine SG, ^ SAP/ALT
Feline central retinal degeneration (taurine deficiency retinopathy)
Taurine deficient diets causes retinal degeneration & dilated cardiomyopathy
Stages: start in area centralis —>extends in band dorsal to optic disc —>generalized disorder
TX for FCRD
Normalize taurine intake to stop progression but will not reverse damage
Mechanisms of retinal detachment
Exudative detachment - most common form, fluid build up under neurosensory retina
Rhegmatogenous detachment - due to tear in retina (periphery), vitreous fluid enters subretinal space & propagates tear
Traction detachment - rare in dom species
Exudative detachment
Common cause: systemic hypertension, chorioretinitis due to infectious or immune mediated inflammation
Fix the cause = reattachment
Rhegmatogenous detachment
Require surgical repair
Chorioretinitis manifestations of systemic disease
Hypertensive retinopathy
Chorioretinitis
Optic neuritis
Hypertensive retinopathy
Systemic hypertension - most common a secondary condition
- kidney disease
- hyperthyroidism
- hyperadrenocoritcism
- diabetes mellitus
Complaints and findings with hypertensive retinopathy
Vision loss due to retinal detachment & hyphema
Retinal arteriolar tortusity
Retinal edema
Retinal hemorrhage
Retinal detachment
Managing hypertensive retinopathy
Treat hypertension/disease
Prognosis is generally good
Chorioretinitis
Inflammation of choroid and retina
Causes:
Infectious, immune mediated, neoplastic, idiopathic
Ophthalmoscopic findings for chorioretinitis
Inflammatory lesions are HYPOreflective
Lesions may be focal, multi focal to coalescing or generalized
Severe chorioretinitis leads to exudative retinal detachment
DX chorioretinitis
Find underlying disease - work up
TX /PX vary WIDELY
