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What retinal layer are the rods and cones found in?
Outer nuclear layer
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What retinal layer are the horizontal cells, bipolar cells, and amacrine cells found?
Inner nuclear layer
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What layer of the retina are the ganglia found?
inner plexiform layer
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What are the three symptoms of vitamin A deficency in the eye?
- Nycatopia (night blindness)
- Xerosis (Drying of eye, Cornea)
- Xerophthalmia (faliure to produce tears)
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What is the medical term for night blindness?
nycatopia
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what is the medical term for drying of the eye or cornea?
Xerosis
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What is the medical term for the failure to produce tears?
Xerophthalmia
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What is the main blood supply of the retina?
Central retinal artery
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What is the main purpose of vitamin A in vision?
Converts 11-trans retinal back to 11-cis retinal
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What is protanope ?
Loss of red cones
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What is deuteranope?
loss of green cones
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What are the most common types of color blindness?
Protanope (loss of red cones)
Deuteranope (Loss of green cones)
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What causes the Na+ channels to close during visual stimulation?
Decrese in cGMP as it is converted to 5GMP by phosphodiesterase?
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During phototropic conditions what are most photochemicals reduced to?
Retinal and opsins
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During scotopic conditions what does retinal convert back to?
Rhodopsin
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What is the visual pathway?
- 1. optic nerve
- 2. optic chiasm
- 3. optic tract
- 4. dorsal lateral geniculate body
- 5. optic radiation
- 6. Visual cortex
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What are the four parts of the old visual system?
- 1.Suprochiasmatic nucleus of hypothalamus
- 2. Pretectal nuclei
- 3. Superior Colliculus
- 4. Ventral lateral genicuate body
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What is the main function of the suprachiasmatic nucleus of the hypothalamus?
Regulate circadian rhythms
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What is the function of the pretectal nuclie?
- Pupillary light reflex
- Accommodation of lens
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How many layers are in the dorsal lateral geniculate body?
6 layers
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What is the function of layers II, III, and V of the LGB?
Receive info from lateral half of ipsilateral eye
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What is the function of layers I, IV, VI of the LGB?
Receive info from medial half of contralateral eye
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What are the magnocellular layers of the LGB?
Layers I, II
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What are the main features of the magnocellular layers (I, II) of the LGB?
- Rapid conduction to V1
- Comprised of large Y ganglion cells
- Black and white only
- Poor, point-to-point
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What LGB layers contain small to medium X retinal cells, have a moderate conduction, and Good color / point-to-point.
III-VI
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In what layer of the visual cortex do geniculocalcarine signals enter first?
IV
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What is a blind spot in the field of vision called?
Scotoma
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What is Retinitis pigmentosa?
Melanin deposits of retina
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What is strabismic Amblyopia?
Lazy Eye
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What disease has lens accommodation, no pupil reaction, associated with neurosyphilis?
Argyll-Robinson
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What are the three parts of the uveal tract?
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What eye muscle is responsible for miosis?
Sphincter pupalae m.
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What nerve is responsible for miosis and what type of innervation does it have?
CN 3 (Parasympathetic)
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What tract in the eye has the following order Retina-->optic nerve--> pretectal neurons--> edinger-westphal neuron--> Ciliary ganglia-->sphincter pupalae muscles (Via Acetylcholine)?
Light Reflex
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What function of the eye is the following derived? Superior thoracic spinal chord--> preganglionic neurons--> superior cervical ganglion--> Dilator pupalae muscles?
Mydriasis (sympathetic)
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what reflex utilizes increased optic power, pupillary constriction, activation of medial rectus muscles ?
Accommodation Reflex
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How much of the refractory power is derived from the cornea?
2/3
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What is the total refractory power of the eye?
59
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what cranial nerve controlls accommodation? and is it sympathetic or parasympathetic?
Oculomotor CNIII
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What ligament and muscle are used to adjust the length of the lens?
- Suspensory ligament
- Ciliary musccle
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What is the inability to accommodate which may be caused by denaturing of proteins of the lens?
Presbyopia
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What is the normal papillary diameter?
1.5 to 8mm
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What type of correction is needed for astigmatism?
Spherical lens
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What is caused by short eye or weak lens which causes the focal point to be behind the retina?
Hyperopia (far sighted)
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What type of lens is used to correct hyperopia?
Convex
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What is myopia and what type of lens is used to fix it?
- Near sighted
- focal point anterior to retina
Concave lens
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What is caused by O2 toxicity in premature babies?
Retrolental fibroplasia
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What is the normal ocular pressure?
12-20 mm hg
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What is a malignant retinal tumor in children?
Retinoblastoma
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What retinopathy is seen as microaneurysm, exudate, and hemorrage?
Diabetic
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What retinopathy is seen as flame hemorrhage, papilloedema, cotton wool spots, and hard exudate?
Hypertension
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