CK Flashcards
Refractive errors - types / explain
- Hyperopia –> Eye too short
- Myopia –> eye too long
- Astigmatism –> abnormal curvature of cornea
- Presbyopia –> Age - related impaired accommodation (focusing on near objects), 1ry due to decreased lens elasticity
uveitis is divided to (according the place) (AKA)
- anterior uveitis (iritis)
- intermediate uveitis: pars planitis
- posterior uveitis (choroiditis and/or retinitis)
Uveitis may have - symptoms/findings
- hypopyon (accumulation of pus in anterior chamber)
2. conjuctival redness
Uveitis is associated with
systemic inflammatory disorders:
- Sarcoidosis 2. Rheumatoid arthritis 3. juvenile arthritis
- Bechet disease 5 . HLA-B27
optic disc is
the point of exit for ganglion cell axons leaving the eye.
optic nerve head
The optic disc is shaped like a (and why)
doughnut with a pink neuroretinal rim and a central white depression called the physiologic cup.
Glaucoma - characteristic cupping
thinning of outer rim of the optic nerve head versus normal
open angle glaucoma is associated with
- increased age
- African american race
- family history
open angle glaucoma is divided to
- primary
2. secondary
causes of primary open glaucoma
unclear
causes of secondary open glaucoma
blocked trabecular meshwork from
a. WBC (eg uveitis)
b. RBCs (eg vitreous hemorrhage)
c. retinal elements (eg retinal detachment)
primary closed/closed narrow angle - mechanism
enlargement or forward movement of lens against central iris (pupil margin) –> obstruction of normal aqueous flow through pupil –> fluid builds up behind iris, pushing peripheral iris against cornea and impeding flow through trabecular meshwork
secondary closed/narrow angle - mechanism
hypoxia from retina disease (diabetes mellitus, vein occlusion) –> vasoproliferation in iris that contracts the angle
chronic closed/narrow angle - symptoms and findings
- often asymptomatic
- damage to optic nerve
- damage to peripheral vision
acute closed/narrow angle - mechanism
elevated intraocular pressure pushes iris forward –> angle closes abruptly
acute closed/narrow angle - do not give (and why)
epinephrine because of its mydriatic effect
acute closed/narrow angle - symptoms and signs
- very painful
- red eye
- sudden vision loss
- halos around halos
- rock hard eye
- frontal headache
Conjunctivitis - types and presentation (and MC)
- Allergic –> itchy eyes
- Bacterial –> pus
- Viral (MC)–> sparse mucous discharge, swollen preauricular node
Viral vs bacterial conjunctivitis - transmissible
Virus easy
Bacterial poorly
Viral vs bacterial conjunctivitis - adenopathy
Only virus (preauricular)
characteristics of Viral conjunctivitis
bilateral, Watery discharge, easily transmissible, normal vision. itchy, preauricular adenopathy, no specific therapy
characteristics of Bacterial conjunctivitis
unilateral, purulent + thick discharge, poorly transmissible, normal vision, not itchy, no adenopathy, topical antibiotics
red eye (opthalmologic emergencies) - types and presentation
- conjunctivitis: itchy eyes with discharge
- uveitis autoimmune disease
- glaucoma: pain
- abrasion: trauma
red eye (opthalmologic emergencies) - types and eye findings
- conjunctivitis: normal pupil
- uveitis: photophobia
- glaucoma: fixed dilated pupil
- abrasion: like sand in the eye
red eye (opthalmologic emergencies) - types and most accurate test
- conjunctivitis: clinical diagnosis
- uveitis: slit lamp examination
- glaucoma: tonometry
- abrasion: fluorescein stain
red eye (opthalmologic emergencies) - types and best initial therapy
- conjunctivitis: topical antibiotics
- uveitis: topical steroids
- glaucoma: acetazolamide, mannitol, pilocarpine, laser trabeculoplasty
- abrasion: no specific therapy, patch not clearly beneficial
glaucoma treatment if medical treatment fails
laser trabeuloplasty
it can precipitate closed angle glaucoma
walking into a dark rook can precipitate pain because of pupillary dialation (SOS)
acute angle-closure glaucoma - the diagnosis is confirmed by
tonometry
keratitis - definition / presentation
infection of cornea
the eye may be very red, swollen and painful, but do not use steroids (make it worse)
hepres keratitis - diagnosis
Fluorecein staining of the eye helps confirm the dendritic pattern seen on examination
hepres keratitis - treatment
oral acyclovir, famciclovir or valacyclovir
topical anthepretic treatment is trifluridine and
Cataracts - diagnosis
early Cataracts: ophthalmoscope or slit lamp exam
advanced: visible on examination
- Hypertropia is corrected by
2. myopia is corrected by
- convex lens
2. biconcave lens
- astigmatism is corrected by
2. presbyopia is corrected by
- cylindric lens
2. convex lens
tunics of the eye?
- retina (inner)
- uvea or vascular (middle)
- fibrous tunic (outer)
fibrous tunic is divided to
sclera and cornea
uvea tonic is divided to
iris - ciliary body - choroid
retina is divided to
pigmented layer and neural layer
vascular arcades of retina
retinal artery
retinal vein
vessels that perforate into eye with optic nerve
central retinal vein
central retinal artery
The central retinal artery branches off the
ophthalmic artery (from internal carotid artery)
ciliary muscle contraction - receptors
M3
ciliary epithelium - function (and control by)
nonpigmented epithelium of ciliary –> body produces aqueous humor (decreases by β-blocker, α2-agonists and carbonic anhydrase inhibitors)
- dilator muscle of iris - receptor
2. splinter muscle of iris- receptor
- a1
2. M3 (accommodation)
splinter muscle of iris- receptor
M3 (accommodation)
vision accommodation (adaptaing to short range focus) mechanism
ciliary muscle contraction –> releases the tension (relaxation) on the lens caused by the zonular fibers –> lens becomes more spherical –> adapts to short range focus.
aqueous humor outflow
- Trabecular flow (90%) –> drainage through trabecular meshwork –> Canal of Schlemm –> episcleral vasculature
- Uveoscleral outflow (10%) –> drainage into uvea and sclera
α1 - agonists effect on aqueous humor
decrease aqueous humor synthesis via vasoconstriction
prostagladin effect on aqueous humor
increase uveoscleral outflow
Ophthalmoscopy (funduscopy) - how to identify left and right eye
the macula is in the center of the image, and the optic disk is located towards the nose
glaucoma drugs - classes
- α-agonists 2. β-blockers 3. diuretics
4. cholinomimetics 5. Prostagladin
glaucoma drugs - α agonists - drugs (and receptors)
epinephrine (α1)
Brimonidine (α2)
glaucoma drugs - α1-agonists - do not use in (and why)
in closed - angle glaucoma
Mydriasis
glaucoma drugs - α-agonists - side effects
- Mydriasis (α1 epinephrine) 2. Blurry vision 3. ocular hyperemia
- foreign body sensation 5. ocular pruritus
- ocular allergic reaction
glaucoma drugs - α-agonists - action on glaucoma
α2 –> decrease aqueous humor synthesis via inhibition of nonpigmented epithelium on ciliary body
α1 –> vasoconstriction –> decrease aqueous humor synthesis
glaucoma drugs - β-blockers - action on glaucoma
decrease aqueous humor synthesis via inhibition of nonpigmented epithelium on ciliary body
glaucoma drugs - β-blockers - side effects and drugs
no papillary or vision changes
- timolol
- betaxolol
- carteolol
glaucoma drugs - acetazolamide mechanism of action
carbonic anhydrase inhibitor –> decreases aqueous humor synthesis via inhibition of nonpigmented epithelium on ciliary body
glaucoma drugs - prostagladin (PGF2a) - drugs and mechanism of action
- Bimatoprost
- latanoprost
increases outflow of aqueous humor through the Uveoscleral outflow
glaucoma drugs - PGF2a - side effect
- Darkness of color of iris (browning)
2. eyelash growth
glaucoma drugs - cholinomimetics are divided to (and which drugs)
direct –> a. pilocarpine b. carbachol
indirect –> a. physostigmine c. echothiophate
glaucoma drugs - cholinomimetics side effects
- Miosis
2. cyclospasm (contraction of cilliary muscle)
glaucoma - in emergencies - drug? (and why)
pilocarpine
very effective at opening meshwork into canal Schlemm
glaucoma - drugs that decrease aqueous humor synthesis
- α - agonists
- β - blockers
- acetazolamide
glaucoma - drugs that increase aqueous humor outflow
- cholomimetics
2. Prostagladins
miosis mechanism - 1st neuron / 2nd neuron
1st. Edinger-Westphal nucleous to ciliary ganglion via CN III
2nd: short ciliary nerves to pupillary sphincter muscles (M3)
Pupillary light reflex - mechanim
Light in EITHER retina sends signals via CN II (and chiasm and tract) to pretectal nuclei in midbrain that activates bilateral Edinger-Westphal nucleous –> Pupils contract bilaterally (consensual reflex)
mydriasis vs miosis - number of neurons
miosis: 2
mydriasis: 3
mydriasis - 1st neuron (beginning and end)
hypothalamus to ciliospinal center of Budge (C8-T2)
Synapse in the lateral horn
mydriasis - 2nd neuron - direction
exit T1 - travels along cervical sympathetic chain near lung apex, sublavian vessels - superior cervical ganglion
mydriasis - 3rd neuron - direction
superior cervical ganglion - plexus along internal carotid through cavernous sinus - enters orbit as LONG CILIARY NERVE - sypathetic fibers also innervate smooth muscle of eyelids (minor retractors) and sweat glands of forehead and face
Marcus Gunn pupil - clinical finding
decreased bilateral pupillary constriction when light is shone in affected eye relative to unaffected eye
Marcus Gunn pupil - mechanism
Afferent pupillary defect due to optic nerve damage or severe retinal injury
Some causes of Horner syndrome
- spinal cord above T1: Brown-Sequard syndrome (cord hemisection), Late stage syringomegalia
- Pancoast tumor
- Lateral medullary (Wallenberg) syndrome
- Infernal carotid dissection
- Carvenous sinus syndrome
Ocular motility - muscles and innervation
- Superior rectus (CN III)
- Lateral rectus (CN VI)
- Inferior oblique (CN III)
- Inferior rectus (CN III)
- Medial rectus (CN III)
- Superior oblique (CN IV)
Superior rectus action
Elevate the abducted eye
superior oblique action
Depress the adducted eye
MC affected CN by tuberculosis
CN VI is the most commonly affected VI in immunocompetent people with tuberculosis
Abducens nerve (CN VI) damage/palsy - physical finding
Medially directed eye that cannot abduct
- adducted at rest
- cannot be abducted
- diplopia occurs on lateral gaze to the side of the affected eye
Trochlear nerve (CN IV) damage/pulsy - eye at rest
Eye moves upward (hypertropia)
Trochlear nerve (CN IV) damage/pulsy - increased elevation with
- adduction (contralateral gaze)
2. head tilting to the affected side
Trochlear nerve (CN IV) damage/pulsy - solution
may present with compensatory head tilt in the opposite direction
Oculomotor nerve (CN III) has both ……. components (and area)
- motor (central of the nerve)
2. parasympathetic (peripheral of the nerve)
Motor output of CN III to ocular muscles is affected primarily by ….. due to …..
vascular disease (diabetes mellitus: glucose –> sorbitol) due to decreased diffusion of oxygen and nutrients to the interior fibers from compromises vasculature that resides on outside of nerve
Motor output of CN III to ocular muscles - signs of damage
- ptosis
2. down and out gaze
Parasympathetic output of CN III - examples of compression
- uncal herniation (an anterior extremity of the Parahippocampal gyrus)
- Posterior communicating artery aneurysm
Parasympathetic output of CN III - signs of damage
- diminished or absent papillary light reflex
- Blown pupil (mydriasis)
- often with down and out gaze
visual field defects - types
- (right/left) anopia (total blindness of left or right eye)
- Bitemporal hemianopia (vision is missing in the outer half of both the right and left visual field)
- (left/right) homonymous hemianopia (visual field loss on the left or right side of the vertical midline)
- (left/right) upper quadrantic anopia
- (left/right) lower quadrantic anopia
- (left/right) hemianopia with macular sparing
- Central scotoma
Central scotoma is caused by
macular degeneration
(right or left) anopia - mechanism
complete lesion of the right or left optic nerve
(left or right) homonymous hemianopia is caused by
- a lesion in (left or right) of the left optic tract
2. a complete lesion in (left or right) of the left optic radiation
left upper quadrantic anopia is caused by
- partial involvement of the optic radiation (Meyer loop) by a lesion in the right temporal lobe
- Middle cerebral artery stroke
Mayer loop contains fibers from the
inferior retina (superior part of the visual field)
left lower quadrantic anopia is caused by
- partial involvement of the optic radiation (dorsal optic radiation) by a lesion in the left parietal lobe
- Middle cerebral artery stroke
Calcarine sulcus function
primary visual cortex (V1) is concentrated
medial longitudinal fasciculus (MLF) is a
pair of tracts that allows for crosstalk between CN VI and the contralateral CN III nuclei
- it coordinates both eyes to move in same horizontal direction
medial longitudinal fasciculus (MLF) - it coordinates both eyes to move in same horizontal direction - mechanism
when looking left, the left nucleus of CN VI fires, which contracts the left lateral rectus and stimulates the contralateral (right) nucleous of CN III (via the MLF) to contract the right medial rectus
directional term for internuclear ophthalmoplegia (e.g. right INO, left INO)
refers to which eye is paralysed
