Eye Flashcards
(74 cards)
1
Q
Tunica Fibrosa
A
Cornea + Sclera
2
Q
Tunica Vasculosa
A
Ciliary Body + Choroid + Iris
3
Q
Tunica Nervosa
A
Retina
4
Q
Layers of the Cornea
A
- Anterior Corneal Epithelium
- Bowmans Membrane
- Corneal Stroma
- Descemet Membrane
- Posterior Corneal Endothelium
5
Q
Anterior Corneal Epithelium
A
➢Stratified squamous epithelium (~5 layers)
➢Microvilli on most superficial cells (vermiform ridges)
➢Basal cells mitotic activity
➢Regeneration -7 days
➢Free nerve endings
6
Q
Bowmans Membrane
A
➢Homogenous collagen fibers
➢Provides stability and strength
➢Does not regenerate
7
Q
Corneal Stroma
A
➢ 60 lamellae, each made of collagen fibrils
➢ Oriented at right angles to each other
➢ Fibroblasts - Keratocytes – flattened end to end: between the lamellae
➢ Keratan and chondroitin sulphates
➢ Regular arrangement accounts for transparency
8
Q
Descemet Membrane
A
➢Homogenous collagen filaments
➢Meshwork of collagen
➢Fenestrations +
9
Q
Posterior Corneal Endothelium
A
➢Simple squamous cells
➢Abundant sodium pumps
➢Maintains optimum hydration of corneal stroma
10
Q
Tenson’s Space
A
between episcleral layer and substantia propria
Site of attachment of the ocular muscles
11
Q
Choroid Function
A
Absorption of stray light
Blood Retinal Barrier
12
Q
Ciliary Process
A
Provides attachment to the capsule of lens by means of zonule fibers
13
Q
Accomodation, Distant Object
A
Ciliary muscles relax
Zonular fibers tighten
Lens flattens
14
Q
Accomodation, Near Object
A
Ciliary muscles contract
Zonular fibers relax
Lens becomes more spherical (more convex)
Greater convergence of light rays
15
Q
What deliniates from anterior & posterior chamger
A
Iris
16
Q
Layers of the Retina
A
- Pigment epithelial layer
- Outer segments of rods & cones
- Outer limiting membrane (outer limit of Muller cells)
- Outer nuclear layer (inner segments of rods & cones)
- Outer plexiform layer (synapses of photoreceptors &
bipolar cells) - Inner nuclear layer (cell bodies of bipolar, horizontal,
amacrine & Muller’s cells) - Inner plexiform layer (synapses of bipolar cells &
ganglion cells) - Ganglion cell layer
9.Optic nerve fiber layer (axons of ganglion cells) - Inner limiting membrane (inner limit of Muller cells)
17
Q
Blood Supply to Retina
A
Chorio Capillaries- Layers 1-5
Central Retinal- Layers 6-10
18
Q
Layers of the Lens
A
- Lens Capsule
- Subcapsular Epithelium
- Lens Fibers
19
Q
Sebaceous within tarsal plate
Lubricates –delays drying of tears
A
Meibomian glands
20
Q
Sebaceous glands within the eyelids
A
Glands of Zeiss
21
Q
Sweat glands at the lid margins
A
Glands of Moll
22
Q
Protect eye from dust and dirt, spread tear moisture
A
Eyelids
23
Q
white of eye, Protect the eye from injury and serves as attachment for extra-ocular muscles
A
Sclera
24
Q
Controls the size of the pupil, defines eye color
A
Iris
25
Size regulates the amount of light entering the eye and reaching the retina
Pupil
26
Clear, gel-like liquid inside the eye ball
Vitreous Humor
27
Releases vitreous humor, ciliary muscles change shape of lens when focusing
Ciliary Body
28
Changes its shape to optimize focal distance of the eye to project a sharp image onto the retina
Lens
29
Contains photoreceptors that transduce
| light into neural signals
Retina
30
Transmits neural impulses from retina to the brain
Optic Nerve
31
Macula
* Area of retina dedicated to central vision
* No large blood vessels
* Roughly circular
* Appears darker
32
Fovea
* Area of the retina with highest cone density
| * Area of highest visual acuity
33
Optic Disc
* Area where retinal ganglion cells leave the eye
* No rods or cones
* Area of no visual receptors -> blind spot
* Located nasally
34
– Light rays bounce off a surface
Reflection
35
– Transfer of light energy to a surface
| – Basis for color vision
Absorption
36
Change in direction of light when passing from one medium
| – Basis for visual focusing and corrective vision (glasses)
Refraction
37
The variability of the refractive power of the lens between far vision (13 D) and near vision (26 D) is called
refractive plasticity
38
the lens looses its elasticity during aging, thereby reducing the ability to focus on near objects, a condition called
presbyopia
39
the ability to distinguish between two nearby points
visual acuity
40
Emmetropia
Focuses parallel rays onto retina without need for accommodation
-> no vision problem
41
Myopia
Nearsightedness
eyeball is too long, lens cannot accommodate enough, image focused before retina
-> blurry vision
Correction: Concave lens is placed in front of eye
42
Hyperopia
Farsightedness
eyeball is too short, lens cannot accommodate enough, image focused behind retina
-> blurry vision
Correction: Convex glass lens in front of eye
43
Papilledema
Indicates increased intracranial pressure.
Increased pressure compromises the venous drainage of the eye, leading to a dilation of the retinal veins.
As a consequence, the optic disc is pushed forward and the disk appears white, rather than pink.
44
Photoreceptor for poor spatial (convergence high) & temporal resolution
Rods
45
Photoreceptor for good spatial (convergence low) & temporal resolution
Cones
46
a chromophore, is the light absorbing compound or the visual pigment. It is derived from Vitamin A and is the chromophore of the visual pigment in rods and cones.
Retinal
47
Dyschromatopsia
* Red-green Colorblindness
* Most common color blindness--> Occurs in 6% of male population
* X-linked recessive
48
Protanopia
Insensitive to RED light
• defective long-wavelength cones (L-cones)
• Results in varying degree of colorblindness
• Or no L-cones--> dichromats
• Difficulties to distinguish between blue and green and between red and green colors.
49
Deuteranopia
insensitive to GREEN light
• Most common color blindness
• 6% of male population
• red and green are the most difficult to detect
• gray, purple and greenish blue-green hues
• Medium-wavelength (green) cones are missing
-Dichromats (no green cones at all)
-Anomalous trichromats (defective green cones)
50
Retinal Detachment
* Part of the retina pulls away from retinal pigment epithelium that provides oxygen and nutrients
* Can lead to tears
* Can lead to vision loss in area of detachment (scotoma)
* Early symptoms include sudden appearance of floaters and flashes and reduced vision
* Laser surgery can stop detachment process
51
Diabetic Retinopathy
• Chronically high blood sugar from diabetes is associated with damage to the small retinal blood vessels (leaking fluid or hemorrhaging)
• Early stage
-Micro- aneurisms
-Weaknesses in walls of vessels, leak fluid into retina
• Later stage
-Proliferation of new vessels
-Scar tissue
52
Age Related Maculardegeneration
* Leading cause of vision loss in people > 50 years
* Blurred vision in central visual field
* Affects one or both eyes
* Develops gradually
* Currently no effective treatment
53
Risk factors for AMD
• Risk factors include age, smoking, stroke or coronary heart disease, obesity, family history
54
What can cause AMD
• Likely candidates: oxidative stress, mitochondrial dysfunction, inflammatory processes
55
Retinitis Pigmentosa
A group of serious, mostly genetically determined (autosomal dominant, autosomal recessive, and X linked recessive) degenerative diseases, in which rods preferentially degenerate.
One of the earliest symptoms is night blindness followed by loss of peripheral vision, leading to “tunnel vision”.
56
Night Blindness (Nyctalopia)
Night blindness is encountered in individuals with vitamin A deficiency. Remember, vitamin A is the precursor of retinal (vitamin A aldehyde), which, together with the opsin protein, forms the photoreceptor pigment.
57
Monocular Visual Field Extends Horizontally
60 degrees nasally & 90-100 degrees temporally
58
Monocular Visual Field Extends Vertically
60 degrees superiorly & 75 degrees inferiorly
59
Meyer's Loop
projection through temporal lobe (represents upper visual field quadrants)
60
Baum's Loop
projection through parietal lobe (represents lower visual field quadrants)
61
Primary visual cortex receives its major blood supply from
Calcarine branches originating from the posterior cerebral artery
62
Cortical Color Blindness
Achromatopsia
• Inability to distinguish colors or color hues may be due to cortical lesions in Brodmann’s Areas 18 or 37 ("cortical color blindness").
• Inferior temporal cortical lesions can cause color blindness
63
Visual loss in one half of the visual field
Hemianopia
64
Visual loss in one quadrant (1/4) of the visual field
Quadrantic anopia
65
Same visual field defect for both eyes
Homonymous anopia
66
Different visual field defect for both eyes. For example visual loss affecting the temporal visual field in either eye (bitemporal hemianopia) is a heteronymous anopia
Heteronymous anopia
67
Depth & motion; Motion Pathways start in
Magnocellular Neurons (M Ganglion Cells)
68
Form & color ; Color Pathways start in
Parvocellular Neuron (P Ganglion Cells)
69
Optic nerve lesion
monocular blindness
| possible origin: optic neuritis
70
Optic Chiasm lesion
Bitemporal Hemianopsia
| possible origin: pituitary tumor
71
Optic Tract lesion
Homonymous Hemianopia
| possible origin: temporal lobe tumor
72
Temporal Optic Radiation lesion
Homonymous superior quadrantic anopia
| possible origin: temporal lobe tumor
73
Parietal Optic Radiation lesion
Homonymous inferior quadrantic anopia
| possible origin: parietal lobe tumor
74
Primary Visual Cortex lesion
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Homonymous hemianopia (with macular sparing)
possible origin: Posterior cerebral artery infarction
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