40 Questions
What is the approximate percentage of the general population affected by amblyopia?
3%
What is the term used to describe the process of increasing the curvature of the lens to focus on near objects?
Accommodation
What is the shape of the lens when the ciliary muscle is relaxed?
Flattened
What is the maximum additional refractive power added to the eye in young individuals due to accommodation?
12 diopters
What is the term used to describe the condition where parallel light rays are brought to a focus on the retina?
Emmetropia
What is the purpose of the lens ligaments?
To hold the lens under tension
What happens to the lens when the ciliary muscle contracts?
It becomes more convex
What is the minimum distance from the observer at which parallel light rays are brought to a focus on the retina?
6 m
What is the unit of measurement for the refractive power of a lens?
Diopters
What is the refractive power of the human eye at rest?
60 diopters
Where does the refraction of light occur in the eye?
At the anterior and posterior surfaces of the lens and the anterior surface of the cornea
Why do we perceive an inverted image on the retina as right side up?
Because of the connections of the retinal receptors
What is the result of turning retinal images right side up by means of special lenses?
The objects viewed look upside down
What is the condition characterized by an eyeball that is too long?
Myopia
What is the term for the uncorrectable loss of visual acuity that is not directly due to organic disease of the eye?
Amblyopia ex anopsia
What percentage of children under 6 years of age are affected by Strabismus?
4%
What is the term for the condition where one eye turns inward, outward, upwards, or downward?
Strabismus
What is the condition characterized by a misalignment of the eyes?
Strabismus
At what age is it crucial to institute treatment for strabismus in children to prevent permanent loss of visual acuity?
Before age 6
What is the result of visual images not falling on corresponding retinal points in children?
Suppression scotoma
What is the consequence of suppression persisting in children with strabismus?
Permanent loss of visual acuity
What is the term for the weak eye with poor vision in a child with strabismus?
Amblyopic eye
What is the type of phenomenon that suppression scotoma is in children with strabismus?
Cortical phenomenon
What is the result of vision in one eye being blurred or distorted due to refractive error in children?
Amblyopia ex anopsia
What is the main reason for the recession of the near point with advancing age?
Steady decrease in the curvature of the lens
What is the purpose of the contraction of longitudinal muscle fibers in the ciliary body?
To pull the whole ciliary body forward and inward
What is presbyopia, and how is it corrected?
A condition of loss of accommodation, corrected by wearing glasses with convex lenses
What is the approximate distance of the near point at age 10?
9 cm
What happens to the edges of the ciliary body when the longitudinal muscle fibers contract?
They come closer together
What is the function of the circular muscle fibers in the ciliary body?
To exhibit a sphincter-like action
What happens to the visual axes when an individual looks at near objects?
They converge
What is the approximate distance of the near point at age 60?
83 cm
What is the reason why individuals who need maximum visual sensitivity and dim light can avoid waiting 20 minutes in the dark?
Because they wear red goggles in bright light
What are the three attributes of color?
Hue, intensity, and saturation
What is the sensation produced by the absence of light?
Black
What can be produced by mixing various proportions of red, green, and blue light?
The sensation of white, any spectral color, and even the extra spectral color, purple
What are the primary colors?
Red, green, and blue
What happens to the rods in the peripheral portions of the retina?
They adapt
What is the purpose of wearing red goggles in bright light?
To allow the cones to function reasonably well
What is the compensatory color that, when properly mixed with a color, produces a sensation of white?
A color with opposite hue
Learn about refractive power, how it's measured in diopters, and its relation to the curvature of a lens. Understand how the human eye refracts light at different surfaces.
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