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Neuro 2 > Eye Stuff (Gianani / Heck) > Flashcards

Eye Stuff (Gianani / Heck) Flashcards

1
Q

Two compartments divided by the lens, suspensory ligaments and ciliary body

A

Anterior compartment

  • Filled with aqueous humor
  • Contains anterior and posterior chambers separated by the iris

Posterior compartment
- Filled with vitreous humor

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2
Q

Three tissues

A

Corneo-scleral layer (fibrous tunic)
- Makes up the sclera in the posterior (5/6) wall of the eye

Uveal layer (vascular tunic)
- Makes up the choroid in the posterior (5/6) wall of the eye

Retinal layer (neural tunic)

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3
Q

Accessory Structures

A

Conjunctiva
Lacrimal Gland
Eyelid

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4
Q

Corneo-scleral layer

A

The Sclera
Opaque white posterior 5/6 of the eye
Nearly avascular
Composed of collagen and elastin

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5
Q

The Cornea

A

Transparent in the anterior 1/6 of the eye

Avascular but highly innervated

5 layers

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6
Q

Refractive Error (not on the test)

A 
Myopia
Nearsightedness
Light rays are focused in front of the retina
Cornea is too curved or 
lens is too powerful for length of globe

Hyperopia
Farsightedness
Light rays are focused behind the retina
Lens and cornea too weak for length of globe

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7
Q

LASIK

A

Laser assisted in-situ keratomileusis
For both myopia and hyperopia

Procedure:

  • A corneal flap is raised using a microkeratome
  • — About 160 microns thick
  • An ultraviolet or “cool laser” is used to ablate a precise amount of the exposed corneal stroma
  • The flap is irrigated and replaced
  • NO sutures are applied
  • — The flap remains in place due to the dehydration pump action of the corneal endothelium
  • Corneal epithelial cells are replaced by mitotic cells found in the periphery, which migrate into the wound
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8
Q

Uveal layer

A

The Choroid

Posterior pigmented portion of the vascular layer

Components:

  • Loose connective tissue
  • Fibroblasts
  • Melanocytes
  • Bruch’s Membrane
    Separates it from the retina

Choriocapillaris
- Area next to the retina, rich in capillaries

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9
Q

The Ciliary Body

A

Forward continuation of the Uveal (vascular) layer
- Making up the Choroid in the posterior 5/6

Wedge shaped
- Between the iris and vitreous body
- Contains:
Loose connective tissue
Pigmented epithelium
Nonpigmented epithelium
*** Filtrate plasma to create aqueous humor
Smooth Muscle 
Zonule Fibers
- Radiate from ciliary processes to lens
- Form suspensory ligaments of lens
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10
Q

Accommodation

A

Ciliary Muscle:

  • Three bundles
    • Opens the canal of Schlemm
    • Two stretch the ciliary body
  • —- Occulomotor innervation

Altering the shape of the lens

  • Via suspensory ligaments
  • – As ciliary muscles contract, ciliary body stretches in length, thereby releasing tension on the suspensory ligaments
  • – Lens gets thicker and more convex
  • – Permits focus on nearby objects
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11
Q

Circulation of Aqueous Humor

A

Ciliary Processes

  • On medial surface radiating from core
  • Epithelial folds with a core rich in fenestrated capillaries
  • Continuous production of aqueous humor
  • Flow:
  • – Enters the posterior chamber, passes through the papillary aperture between the iris and lens and enters the anterior chamber.
  • – Drains through the trabecular meshwork into the Canal of Schlemm and directly into venous circulation.
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12
Q

Corneal-irideal angle

A

The area between Descemet’s membrane of the cornea and the anterior surface of the iris
Canal of Schlemm forms a complete circle here
Clinical correlation

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13
Q

Glaucoma***

A

Refers to a group of diseases characterized by optic neuropathy resulting in loss of vision due to retinal ganglion cell death

The number one risk factor for glaucoma is increased intraocular pressure, however, not only does high IOP not occur in all patients but management may not slow progression

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14
Q

Open-Angle Glaucoma

A

The most common form

Corneal-irideal angle is open

Usually presents with increased IOP
- May be due to increased production or decreased outflow

Slow neurodegenerative process with characteristic optic nerve cupping

Treatment:

  • Prostaglandins
  • Beta-blockers
  • Alpha adrenergic agonists
  • Trabeculectomy or trabeculoplasty
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15
Q

Angle-Closure Glaucoma*

A

Corneal-irideal angle is obstructed
Aqueous outflow is impeded
Primary: Unknown anatomical cause

Secondary: Inflammation
Hemorrhage, neovascularization or tumor growth
Patient may show characteristic conjunctival redness

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16
Q

Cataract

A

Leading cause of blindness in the world

Mechanism yet unknown, but we do know:

  • Lens does not shed nonviable cells
  • Lens fibers do not have intracellular mechanism to deal with accumulation of substances
17
Q

cataract risk factors**

A
  • Advanced age
  • Smoking
  • Sun exposure
  • Alcohol consumption

(Metabolic syndrome
Diabetes mellitus
Malnutrition
Inactivity)

This leads us to believe the cause is photo/oxidative injury

18
Q

cataract treatment

A

Currently no pharmaceuticals available

Changes in lifestyle may slow progression but damage is irreversible

Surgical replacement with synthetic intraocular lens
- Lens nucleus removed leaving lens capsule to support prosthetic

19
Q

The Retina

Histology

A 
Cell types:
Neurons
- Photoreceptor cells
----- Rods and cones
- Retinal ganglion cells
- Interneurons (integrating neurons)
---- Bipolar cells, horizontal cells and amacrine cells

Retinal pigment epithelial cells (RPE)
— Outermost layer separating the retina from the choroid
Neuron support cells

20
Q

structures of the retina

A 
Fovea:
Visual axis of the cornea
- Depression in the retina
---- Flattening of the inner layers to let more light in
- Greatest visual discretion
---- The most neuronal interconnections for the most representation in the visual cortex
- Almost exclusively cones
---- Poor in low light
Optic nerve:
Convergence of the axons of retinal ganglion cells
- Unmyelinated afferent fibers 
- Myelination begins at optic disc
Absence of photoreceptor
- Blind spot
21
Q

Blood supply

of the retina

A

Choroid:
Maintenance of the outer retina

Central retinal artery:
Rises from the optic nerve head
Maintenance of inner retina
- Has branches that supply three layers of capillary networks
Branches run posterior to the inner limiting membrane, within the nerve fiber layer
- Capillaries can be found running through the retina but generally no deeper than the outer plexiform or nuclear layer

22
Q

Retinal Detachment

A

Detachment of the photoreceptor cell layer from the pigment epithelial layer can result in blindness

RPE needed to maintain support of visual function

Choroid needed to nourish and maintain cells

23
Q

Diabetic Retinopathy

A

an ocular complication of diabetes.
Prevalence
60-80% of all diabetics develop some sort of retinopathy
15-20 years after diagnosis
Nearly all type 1 diabetics after 20 years
50% of which will have proliferative

24
Q

Preproliferative (Nonproliferative)

diabetic retinopathy

A

Increased size and number of intraretinal hemorrhages
Most vision loss occurs from macular edema
- Would not treat unless clinically significant

25
Q

Proliferative

diabetic retinopathy

A 
Includes the formation of new blood vessels
Neovascularization
- Can protrude into vitreous
--- Hemorrhage here and cloud vision
--- Detach retina

Can eventually extend into and grow from other structures in the eye
- Causing secondary forms of blindness

Neuro 2 (15 decks)

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