Eye Flashcards
What are refractive errors?
Impaired vision that improves w/ glasses
What is Hyperopia?
Eye too short for refractive power of cornea & lens→ light focused behind retina
What is Myopia?
Eye too long for refractive power of cornea & lens→ light focused in front of retina
What is Astigmatism?
ABN curvature of cornea resutling in different refractive power at different axes
What is Accomodation?
Focusing on near objects→ ciliary muscles tighten→ zonular fibers relax→ lens becomes more convex
What does Accommodation occur with?
Convergenc & miosis
What is Presbyopia?
Dec change in focusing ability during accomadation d/t sclerosis & dec elasticity
What is Uveitis?
Inflam of uveal coat (iris, ciliary body & choroid)
What is Uveitis assoc w/?
- Systemic inflam disorders
- Sarcoid
- RA
- Juvenile idiopathic arthritis
- TB
- HLA-B27 assoc cond
What is Retinitis?
Retinal edema & necrosis leading to scar
What causes Retinitis?
Often viral (CMV, HSV, HZV)
What is Retinitis assoc w/?
Immunosuppression
What is Central retinal artery occlusion?
Acute, painful monocular vision loss
Retina whitening w/ cherry-red spot
What is Glaucoma?
Optic neuropathy, usually w/ inc intraocular pressure (IOP)
What is Open/wide angle Glaucoma char by?
Peripheral then central vision loss usually assoc w/ inc IOP
What is Open/wide angle Glaucoma?
Optic disc atrophy w/ cupping
What is Open/wide angle glaucoma assoc w/?
- Inc age
- African American race
- FHx
- Inc IOP
- MC in US
What is the primary cause of open/wide angle glaucoma?
Unclear
What is the secondary cause of open/wide angle glaucoma?
- Uveitis
- Trauma
- Corticosteroids
- Vasoproliferative retinopathy that can block or dec outflow at the trabecular meshwork
What is Closed/narrow angle glaucoma?
Enlargement or forward movement of lens against central iris l/t obstruction of normal aqueous flow through pupil→ fluid build up behing iris, pushing peripheral iris against cornea & impeding flow through the trabecular network
What is Chronic closure closed/narrow angle glaucoma?
Often asx w/ damage to optic nerve & peripheral vision
What is Acute closure closed/narrow angle glaucoma?
Ture ophthalmic emergency
Inc IOP iris forward→ angle closes abruptly
What are the clinical features of Closed/narrow angle glaucoma?
- Very painful
- Sudden vision loss
- Halos around lights
- Rock-hard eye
- Frontal HA
Why can’t you give Epi in closed/narrow angle glaucoma?
Mydiratic effect
What is a Catarct?
Painless, often bilateral, opacification of lens→ dec in vision
What are the risk factors of Cataracts?
- Age
- Smoking
- Alcohol
- Excessive sunlight
- Prolonged corticosteroid use
- Classic galactosemia
- Galactokinase def
- DM (sorbitol)
- Trauma
- Infection
What is Pailledema?
Optic disc swelling (usually bilateral) d/t inc intracranial pressure
What will be found on fundascopic exam in papilledema?
Enlarged blind spot & elevated opotic disc w/ blurred marigins
What happens in CN III damage?
- Eye looks down & out
- Ptosis
- Pupillary dilation
- Loss of accommodation
What happens in CN IV damage?
- Eye moves upward particularly w/ contralateral gaze & ipsilateral head tilt
What happens in CN VI damage?
Medially directed eye that cannot abduct
What is Miosis?
Constriction controlled by PNS
What is the 1st neuron involved in miosis?
Edinger-Westphal nucleus to ciliary ganglion via CN III
What is the 2nd neuron involved in miosis?
Short ciliary nerves to pupillary sphincter muscles
What is Mydriasis?
Pupil dilation controlled by SNS
What is the 1st neuron involved w/ Mydriasis?
Hypothalamus to ciliospinal center of Budge (C8-T2)
What is the 2nd neuron involved w/ Mydriasis?
Exit at T1 to superior cervical ganglion (travels along cervical SNS chain near lung apex, subclavian vessels)
What is the 3rd neuron involved w/ Mydriasis?
Plexus along internal carotid, through cavernous sinus; enters orbit as long ciliary nerve to pupillary dilator muscles
What is the Pupillary light reflex?
Light in either retina sends a signla via CN II to pretectal nuclei in midbrain that activate bilateral Edinger-westphal nuclei; pupils contract bilaterally
What is Marcus Gunn pupil?
Afferent pupillary defect d/t to damage or retinal detachment . Dec bilateral pupillary constriction when light is shone in affected eye relative to uneffected eye
What is CN III motor output to ocular muscles affected by?
Vascular dz d/t dec diffusion of oxygen & nutrients to the interior fibers from compromised vasculature that resides on outside of nerve
What are the signs of CN III moto damage?
Ptosis, “down & out gaze”
What is 1st affected in the PNS fibers of CN III?
Peripheral fibers 1st affected by compression
What are the signs of damage to PNS fibers of CN III?
Diminished or absent pupillary ligh reflex
“blown pupil”
What is Retinal detachment?
Separation of neurosensory layer of retina from outermost pigment epithelium→ degen of photoreceptors→ vision loss
What can retinal dettachment be secondary to?
- Retinal breaks
- Diabetic traction
- Inflam effusions
Who are retinal breaks MC in?
Pt w/ high myopia & often preceded by posterior detachment & eventual monocular loss of vision like a “curtain drawn down”
Which area of the retina affected in Age-related macular degeneration?
Central area of retina
What does Age-related macular degeneration cause?
Distortion (metamorphopsia) & eventual loss of central vison (scotomas)
What is Dry age-related macular degeneration?
Nonexudative >80%
What is seen on PE in Dry age-related macular degeneration?
Deposition of yellowish extracellular material beneath retinal pigment epi w/ gradual dec in vision
What can prevent the progression of Dry age-related macular degeneration?
Multivitamin & antioxidant supplements
What is Wet age-related macular degeneration?
Exudative, 10-15%
What causes Wet age-related macular degeneration?
Rapid loss of vision d/t bleeding secondary to choroidal neovasculaization
What is the tx for Wet age-related macular degeneration?
Anti-vascular endothelial growth factor injections (anti-VEGF) or laser
What is Meyer’s loop?
Ineferior retina
Loops around inferior horn of lateral ventricle
What is Dorsal optic radiation?
Superior retina
Takes shortest path via internal capsule
What is the Medial longitudinal fasiculus (MLF)?
Pair of tracts that allows for crosstalk b/w CN VI & CN III nuclei. Cooridnates both eyes to move in same horizontal direction
Who get MLF lesions?
Pts w/ demyelination since the MLF is highly myelinated
What is Internuclear ophthalmoplegia?
MLF syndrome
What happens in a MLF lesion?
When CN VI nucleus activates ipsi lateral nucleus, contra CN III nucleus doesn’t stim medial rectus to fire. Abductin eye gets nystagmus
