Vision & Hearing Exam Questions
and Answers 100% Correct
6 Steps of Physiology of Vision - ANSWER - 1. Initial Refraction
2. Light passes thru aqueous humor and thru pupil
3. Accommodation
4. Projection
5. Conversion
6. Transmission & Interpretation
Initial Refraction - ANSWER - - light enters the cornea
- refracts scattered light to begin focus
- 70% of total refraction in eye
Light passes through aqueous humor and on thru pupil - ANSWER - - Iris (muscle)
moves - pupil changes size
- Regulates the amount of light passing through the lens and on the retina
Accommodation - ANSWER - - Crystalline lens = remainder of refraction (30%)
- light should now be a single beam/100% focused
- Muscles in ciliary body bend the lens to focus on specific object/distances
Projection - ANSWER - - Refracted light converges at a single point in vitreous humor
- Then diverges to protect an (upside down) image on retina
- brain fixes this
Conversion - ANSWER - - Changing light waves into action potentials
- Retina
- contains many photoreceptors (convert light to AP signal)
, - Rods
- Cones
Photoreceptors - ANSWER - Convert light to AP signal
Transmission & Interpretation - ANSWER - - AP travels down optic nerve to occipital
lobe of brain
- Brain reads, interprets, and responds to visual stimuli
Common Vision Problems (3) - ANSWER - Myopia, Hyperopia, Astigmatism
Myopia - ANSWER - - "Near-sightedness" = see clearly up close, not far
- Light does NOT REACH the retina
- Eyeball is longer than normal or steeply curved cornea = image is focus in front of
the retina, image blurry
Hyperopia - ANSWER - - "Far-sightedness" = see clearly far, not close
- Eyeball is shorter than normal or cornea too flat = image (attempts to) focus
behind retina, image blurry
Astigmatism - ANSWER - - Uneven curvature of cornea (like back of spoon)
- Unable to focus at any distance
- Objects are focused on several places on retina
= distortion in brain = blurry
Presbyopia - ANSWER - Ability to focus up close decreases with age, flexibility of
lens decreases
Goal of Corrective Lenses - ANSWER - To change the angle of the refraction to focus
image (correcting for mishapen cornea)
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