Week 1 Notes Flashcards
Child presents with retinal hemorrhage or detachment without history of trauma =
Child Abuse
Vision Loss Scheme - Keratitis
- Acute or Chronic, Def. + Location, Physical Exam
- Acute
- Def: Inflammation of Cornea (Pre-retinal) due to trauma, infection, etc.
- Visualized under cobalt blue light with aid of fluorescein dye
Vision Loss Scheme - Corneal Edema
- Acute or Chronic, Causes, Details
-Acute
- Cause #1 - Blunt Trauma
- Cause #2 - Acute Angle-Closure Glaucoma (EMERGENCY)
Hx: sudden, unilateral eye pain. Seeing HALOS. Nausea and Vomiting.
Px: Red eye, corneal cloudiness, tearing, pupil fixed in mid dilated position.
Vision Loss Scheme: Vitreous Humor
- Acute or Chronic, Hx Risk Factor, Physical
- Acute
- Risk factor to be aware of: Poorly controlled Diabetes = retinal neovascularization = hemorrhage.
- Monocular vision loss, diminished red reflex.
Vision Loss Scheme: Retinal Occlusion = Artery vs Vein
- More detail in 1.12
- Acute
Retinal Artery Occlusion - Def: a form of stroke (via thrombosis, embolism, arteritis, etc.)
- Hx: Sudden, severe, PAINLESS, CENTRAL vision loss
- Px: Vascular narrowing, ischemic retina, cherry red spots
Retinal Vein Occlusion
- DEF: Thrombosis (via venous stasis which I suppose can technically cause a stroke.)
- Hx: Monocular, vision deficit corresponds with area of occlusion.
- Px: “Blood and thunder” fundus = hemorrhages, cotton wool spots, disc swelling.
Vision Loss Scheme: Retinal Detachment
- Hx + Px
- Acute
Hx: Sudden onset of floaters or black dots, PHOTOPSIAS (flashes of light) + NOT PAINFUL
Px: Dulling red reflex, elevated retina with folds
Vision Loss Scheme: Papilledema
- Hx + Px
- Acute or Chornic
Hx: More of Headache, nausea, and vomiting due to elevated intracranial pressure than visual sx.
Px: Bilateral optic disc swelling
Vision Loss Scheme: Optic Neuritis
- Risk Factor + Hx.
- Acute or Chornic
Risk Factor: MULTIPLE SCLEROSIS - Hx: Washed out vision, pain with eye movement, reduced visual acuity.
Vision Loss Scheme: Stroke/Tumor
- Important Px trait
Visual acuity NOT Affected
Vision Loss Scheme: Macular Degeneration
- Dry vs Wet Type
- Chronic
- Def: Degenerative disease of CENTRAL portion of retina + loss of vision in CENTER of visual field (scotomas.
Dry Type
- DRUSEN: Deposition of yellowish extracellular material
- Slowly progressive vision loss
Wet Type
- NEOVASCULAR: Growth of abnormal blood vessels into subretinal space. Blood vessels leak.
- Rapid loss of central vision over weeks/months + metamorphopsia (distortion of straight lines)
Vision Loss Scheme: Diabetic Retinopathy
- Nonproliferative vs Proliferative
Nonproliferative
- Absence of neovascularization
- Vision loss is primarily due tot macular edema
- Intraretinal hemorrhages, nerve fiber infarcts (cotton wool), and hard exudates.
Proliferative
- Neovascularization of both retina and optic disc.
- leads to vitreous hemorrhage, tractional retinal detachment, fibrosis.
Superior Oblique Eye Muscle:
Action vs Testing.
Action of Superior Oblique
- Downward, Abduction + Internal rotation
Testing of Superior Oblique
- Ask the patient to look medially in order to limit lateral rectus
- Then ask the patient to look downwards to test Superior Oblique
- Note: downward motion is not as affected by inferior rectus because the muscle doesn’t align with the orbital axis while the is looking medially.
Eye muscles of adduction.
Main adductor = medial rectus
- Superior/inferior rectus also have some component of adduction.
Fovea
- Distinctive fact
- Area of most visual acuity
- Purely Cones (no rods or ganglion cells)
Retinal Blood Supply
- Inner and Outer
Inner Retina: Ophthalmic artery branch of internal carotid
Outer Retina: Diffusely perfused by arteries from choroid
Visual Image
Inverted + Reversed
Lateral Geniculate Nucleus (in thalamus)
- Organization
- Types of cells
- area of termination
Organization
- Topographically organized according to specialization
- First 3 layers are magnocellular, the last 3 layers are parvocellular
Types of Cells
- M Cells (Magnocellular) = ROD related: Visual perception
- P Cells (Parvocellular) = CONE related: Color and Detail
Area of Termination
- Superior Colliculus but information does continue along the GeniculoCalcarine Tract
Note: Sensory info from the right SIDE of each retina goes to the right LGN via the P and M cells
Superior Colliculus (Mid Brain)
- Ending point of Lateral Geniculate Nucleus
- Function
Function
- Orients and Coordinates eyes and head to specific stimuli via several separate sensory stimuli = almost reflexive?
- Dorsal Layers: processing of incoming visual info
- Ventral Layers: Somatic sensory, auditory, etc.
GeniculoCalcarine Tract
- Pathway of Optic Tract
- Characteristic of GC Tract + Lesion
Pathway of Optic Tract
- LGN of Thalamus => GeniculoCalcarine Tract/Cortex => Occipital Cortex (Primary Visual Cortex)
Characteristic + Lesion
- Fans out in temporal and parietal areas
- has an INVERSION. Therefore inferior tract lesion = superior deficit and vice versa
Primary Visual Cortex
- Function
- Characteristic of Lesion along efferent pathway to higher order cortical areas.
Function
- Receives a lot of the visual information (via optic radiations from LGB) and retinotopic organization continues here. Projects to higher order visual areas of occipital, temporal, and parietal lobes.
Lesion along the efferent tracts from the PVC
- Inf. Temporal lobe lesion: Loss of Object recognition
- Post. Parietal lobe lesion: Loss of Object localization
Pathway of Pupillo-Constriction
- What Nerve
- Pathology of Lesion along this tract
Tract:
- Pretectal nucleus [Midbrain] (receives retinal input from CN2 and projects to CN3 efferently for pupilloconstrction)
- EDINGER WESTPHAL NUCLEUS, “hitches” With CN3 =>
- Ciliary Ganglion, the cell body, controls amount of light reaching Retina.
Pathology:
- Lesion in CN3 =Pupillo-Dilatation = Pupils Blown
Macular Sparing
- When does it often present
- Reason for Sparing
Presentation
- hemianopic stroke in the occipital territory.
Reason for Sparking
- Dual Blood Supply
- Mostly from the posterior cerebral artery but some people have some supply from middle cerebral artery.
Retina
- Layers of the Retina
- (cell bodies photoreceptors in outer nuclear layer)
- cones: high resolution and color
- rods: night vision - retinal interneurons (inner nuclear layer)
- Ganglion cells in ganglion cell layer (form optic nerves).
Aniscoria
- Def
- Location of Lesion: which fibers, etc.
Definition
- Asymmetric Pupils
Location of Lesion
- EFFERENT fibers supplying the pupillary sphincter muscles therefore swinging flashlight test doesn’t work.
- Don’t think CN2, think sympathetic or parasympathetic.
Note: Sympathetic lesion (SNS, outside of brainstem/SC such as tumor at apex of lung)
- Horner’s Syndrome: ptosis + constriction of pupil of eye
Note: Parasympathetic lesion (CN3, Ex. aneurysm)
- Dilated pupil of eye.
Pupillary Light Reflex
- Function of the Test
- Determination of results
Function
- Checks for AFFERENT Pupillary defect (CN II + CN III)
- NO anisocoria with CN II Defect
Determination of Results
- The eye that shows paradoxical dilation = side of lesion.
MS Relationship? Optic Neuritis is MS until proven otherwise (look it up)
Internuclear Ophthalmoplegia
- Area of lesion
- Results
- Bilateral vs Unilateral
Area of Lesion
- Medial Longitudinal Fasciculus Lesion (BRAIN STEM)
- f(x) of MLF = connects CN VI nucleus on one side with CN III nucleus on other. Allows for conjugate horizontal gaze.
Results of Lesion
- Lesion manifests by impaired adduction on affected side w/ nystagmus in the other abducting eye.
Note: Bilateral = MS, Unilateral = Stroke.
Transient Monocular Visual Loss (aka Amaurosis fugax)
- Differential Dx
Vasospasm
- Tx: Calcium channel blockers such as nifedipine or verapamil
Emboli
- “shower” of Hollenhorst plaques from aortic valve
- Could be via artificial valve, a fib, or MI
Hypercoagulopathy
Note: Migraine does not belong in the differential dx of TMVL. Visual change/aura in migraine is CORTICALLY mediated not retinal.
Giant Cell Arteritis
- When to consider it as a dx
- Tests to confirm
- Tx
SX:
- Any AION, PION, or CRAO or diplopia with headache, > 50 years of age = get STAT ESR + Start steroids!
Note: acute ischemic optic neuropathy, progressive ischemic optic neuropathy, central retinal artery occlusion.
Tests
- ESR and CRP: Inflammatory markers
TX:
- Steroids.
Cranial Nerve III Palsy
- Sx
- What to look out for + Imaging test to confirm
SX:
- Down and out gaze with dilated unreactive pupil (CN III Palsy/complete)
- Compressive lesion (tumor/aneurysm) must be excluded IMMEDIATELY. Especially if there is headache symptoms.
Note: pupil sparing complete III in vasculopath, ok to watch pupil.
Imaging to confirm/rule out:
- MRI/MRA of the brain. Perhaps CTA and LP
if > 60 yo, check ESR for Giant Cell Arteritis
Wernicke’s Encephalopathy
- Relevant HX and labs to consider
Symptom Triad
- Acute mental confusion, ataxia, and ophthalmoplegia
Cause
- Thiamine Deficiency
- Hx: Gastric Bypass surgery: potential for malabsorption of B1 or severe alcoholism.
Labs
- Will show as increased Vitamin B labs.
