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HD 2 > Eyes > Flashcards

Eyes Flashcards

0
Q

Myopia

A

Near sightedness, where the image forms before the retina because the eyeball is too long or the refractory power is too high

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1
Q

Emmetropia

A

Correct eyeball size and refractory power such that the image forms appropriately on the retina

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2
Q

Hyperopia

A

far-sightedness, where the image forms past the retina because the length of the eye is too short or the refractory power is weak

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3
Q

Cornea (content and function)

A

Avascular w/ highly ordered collagen –> transparent.
* thickness varies across –> best vision @ central, where thinnest.
F(x): main focusing mech. (2/3 of total (60 diopter) converging power); also protective w/ selective permeability.

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4
Q

Corneal layers (3)

A
  1. endothelium
  2. stroma
  3. epithelium **innervated w/ sensory afferents –> corneal scratch hurts!
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5
Q

Bowman’s Layer

A

very thin, acellular layer just below the corneal epithelium;
(part of cornea).
* does NOT regernerate, so injury => corneal opacity (vision deficit)

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6
Q

corneal stroma

A

thickest layer of cornea, contains highly ordered collagen type I
(uniform spacing and thickness).
** collagen & proteoglycan IS regrown after injury, but less orderly => opaque scar & vision deficit.

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7
Q

Corneal endothelium

A

innermost layer of cornea, transports Na, K, & H ions + removes water from stroma (“deturgescence”) –> to maintain clarity of vision.

    • limited regeneration w/ injury.
  • ** water removal decreases w/ age –> increased cloudiness.
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8
Q

sclera

A

most (80%) of eye surface; ~avascular, made of less organized collagen + higher water content than cornea (–> not clear).
w/ sensory & autonomic innervation, extraocular m insertions, & holes for optic nerve, etc.
** slow to heal, but will w/o affecting vision.

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9
Q

anterior & posterior chambers

A

Both filled w/ aqueous humor to provide O2 & nutrients to cornea, lens, & trabecular meshwork.
Anterior: btwn cornea & iris/lens
Posterior: btwn iris & vitreous chamber

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10
Q

Aqueous humor (flow, content, etc)

A

Made by ciliary body, flows into anterior chamber, then drains via Schlemm’s canal (trabecular meshwork – main resistance to flow).

  • maintains clarity bc NO plasma cells or proteins.
  • ** if builds up –> glaucoma! (high intraocular pressure)
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11
Q

3 responsibilities of Ciliary Body

A
  1. produce aqueous humor
  2. regulate aqueous humor outflow
  3. accommodation (adjust vision using ciliary muscles)
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12
Q

Trabecular meshwork

A

thin channels of connective tissue, lined w/ epithelium & gap junctions;
= main source of resistance to aqueous humor outflow/drainage.

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13
Q

path of aqueous humor flow

A
  1. ciliary body (produced) –> anterior chamber
  2. –> Schlemm’s canals (trabecular meshwork)
  3. –> collector canals
  4. –> episcleral veins
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14
Q

Glaucoma

A

painless, often unnoticed/”symptomless” disease resulting in blindness.
due to increased intraocular pressures (from reduced aqueous humor outflow) +/- other unknown mechs.

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15
Q

Uvea (contents, function)

A

Uvea = iris, ciliary body & choroid;
= highly vascular, pigmented cells.
F(x): provide nutrients to lens, cornea & trabecular meshwork

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16
Q

Iris

A

highly vascular colored segment around pupil, contains:

  • iris sphincter muscle: circular fibers, w/ parasymp. innervation.
  • iris dilator muscle: radial fibers, w/ sympathetic innervation.
  • help w/ visual accomodation
17
Q

Ciliary muscle

A

contracts w/ parasympathetic stimulation, ==> lens thickens (for visual accomodation) by releasing pressure.

18
Q

Presbyopia

A

loss of visual acuity w/ age due to decreased elasticity of the lens

19
Q

Lens

A

Asymmetric, biconcave, avascular & NOT innervated;
Mostly water w/ some protein (crystallin).
– adjusts thickness in order to keep light focused on retina for any object distance.

20
Q

Cataracts

A

protein aggregations that decrease visual acuity, caused by conversion of a-crystallin to albuminoid in aging lens.
* preventable & treatable!*

21
Q

Vitreous body

A

clear substance filling most of eye past lens,
– 99% water + hyaluronic acid-collagen gel.
lets light pass through eye to retina.
** attached everywhere except anteriorly –> posterior detachment appears like retinal detachment! **

22
Q

macula & fovea

A

Macula = central region of retina, w/ high clarity.
Fovea = center of macula, w/ highest density of cones & no blood vessels.
* macular degeneration happens w/ age, not preventable. :(

23
Q

Oculomotor nerve f(x)

A

Motor: to levator m. + all Extraocular mm except superior oblique and lateral rectus mm.
Parasympathetic: to ciliary body & iris sphincter m.

24
Q

Arteritic Ischemic Neuropathy (Temporal Arteritis)

A

Sx: monocular decreased vision, temporal pain & scalp sensitivity, jaw claudication, fatigue, Aff. pupillary defect;
*age > 60
Tx: Emergency! High dose steroids, biopsy

25
Q

Non-Arteritic Ischemic Optic Neuropathy

A

= microvascular insult to optic n.,
Risk factors: HTN, diabetes
Sx: sudden decrease in vision, aff. pupillary defect
Tx: none, assess for risk of temporal arteritis

26
Q

Central Retinal Artery Occlusion

A

Sx: very acute monocular vision loss (= embolic occlusion of retinal a.)
Dx: pale retina w/ “cherry red spot,” *rule out temporal arteritis
Tx: if <2 hrs reduce eye P, occular massage, etc. (to improve occular circulation)

27
Q

Central Retinal Vein Occlusion

A

= obstruction of venous outflow
Risk factors: HTN, DM, glaucoma, hypercoagulability
Dx: “Blood & Thunder” retina, decreased vision
Tx: laser or injections to prevent neovascularization

28
Q

Vitreous Hemorrhage

A

= blood in vitreous cavity
Causes: diabetes, trauma, retinal tear
Tx: observe, laser surgery if diabetic

29
Q

Ruptured Globe (trauma)

A

Sx; Subconjunctival hemorrhage, hyphema, peaked pupil

Tx: eye shield, systemic antibiotics, CT to rule out foreign body, surgical repair

30
Q

Traumatic Hyphema

A

= blood in anterior chamber,
Complications: risk rebleed @ 3-5 days, risk glaucoma
Tx: NO aspirin, surgical evacuation only if 100% + increased ICP

31
Q

Endopthalmitis

A

*often complication of corneal ulcer
= internal infection of eye
Tx: intravitreal antibiotics +/- vitrectomy

32
Q

Acute Angle Closure Glaucoma

A

Sx: acute pain & vision loss w/ halos, frontal headache, nausea, cloudy cornea, & Elevated IOP
Pathophys: iris bows to block drainage of aqueous humor
Tx: eye drops to reduce IOP + systemic P lowering meds; laser iridotomy
*IRReversible if not treated in 1st 24 hrs!

33
Q

Retinal Detachment

A

Sx: sudden flashes of light & floaters, “curtain over vision,” may have normal acuity
Risk factors: prior surgery, myopia
Tx: surgical repair

34
Q

Non-proliferative vs. Proliferative Diabetic Retinopathy

A

General Retinopathy: loss of pericytes -> dot-blot hemorrhage -> microaneurysms, hard exudates, nerve fiber layer infactions, venous beading.
(ischemia => retinal damage)
Proliferative = w/ new blood vessels growing on retina & iris -> vitreous hemorrhage, retinal detachment (w/ scarring).

35
Q

Treatment for (Proliferative) Diabetic Retinopathy

A

Laser reduction of peripheral retina to decrease O2 need. (aka: photocoagulation)

36
Q

Primary Open Angle Glaucoma

A

= asymtomatic optic n damage due to high IOP,
=> slow, chronic loss of peripheral vision
Dx: increased cup/disk ratio, high IOP, periph.VF loss
Tx: #1 eye drops to suppress aqueous fluid (timolol, a-adrenergics, carbonic anhydrase inhibitors); 2. surgery to increase aqueous outflow

37
Q

Macular Degeneration: non-exudative vs. exudative

A

*Macular Degen = loss of deep vascular supply to retina
Non-exudative (“dry”): gradual loss of central vision, (“drussen”/geographic atrophy)
Tx: vitamin supplementation

38
Q

Cataracts - pathophysiology & etiology

A

*leading cause of blindness in world (but not in USA bc treatable)
= yellow/clouding of crystalline lens (bc grows inward for entire life);
Causes: #1 Senile, congenital (Emergency!), drug induced, systemic illness

39
Q

Clinical characterization of Cataracts

A

may be nuclear sclerotic, cortical or posterior subcapsular of lens.
Sx: decreased visual acuity, monocular diplopia
Tx: surgical extraction & replace w/ new lens

40
Q

Exudative Macular Degeneration

A

*Macular Degen = loss of deep vascular supply to retina
Exudative (“wet”): rapid central vision loss, bc of neovascular subretinal membrane (subretinal hemorrhage)
Tx: ant-VEGF meds

HD 2 (14 decks)

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