If the eyeball is too short too too long

If the eyeball is too short too too long - o If the eyeball...

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o If the eyeball is too short too too long, corrective lenses can alter the angle of refraction – VIEWING DISTANT OBJECTS Emmetropia – everything works the way it should Myopia – eyeball too long relative to refractive power, focal point is in front of the retina, rays are no longer converged as a single point when they reach the retina=blurry vision Myopia with correction – need to push the focal point back, concave lenses diverge rays do this Hyperopia- eyeball is too short, focal pt behind retina, need concave Viewing near objects: accommodation o Increase refractive power, lens need to be more curved which ciliary muscles cans do pulling focal point – called accommodation o In a relaxed eye parallel rays from a distant object fall into focus on the retina o Diverging rays from a nearer object will fall into focus behind the retina o In this case, muscles in the eye change the shape of the lens to increase its optical power and produce a sharply focused image
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This note was uploaded on 11/27/2011 for the course PSYC 225 taught by Professor Staff during the Fall '10 term at UNC.

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If the eyeball is too short too too long - o If the eyeball...

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