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Vision Disorders


When the eye's axial length is shorter than normal, close objects appear blurry. This is called hyperopia or presbyopia, commonly termed long-sightedness. It may be latent—meaning the eye can compensate through accommodation, the ability to adjust; or it may be absolute—in which case correction requires convex or positive lenses. Around middle-age, the eye's ability to accommodate deteriorates, which is why almost all people over 45 or 50 years of age require glasses for close-up vision. Irregular curvature of the cornea or lens will produce the same deficit.

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Science EncyclopediaScience & Philosophy: Verbena Family (Verbenaceae) - Tropical Hardwoods In The Verbena Family to WelfarismVision Disorders - Refractive Errors, Hyperopia/presbyopia, Other Refractive Errors, Strabismus, Nonparalytic Strabismus, Paralytic Strabismus - Myopia, Astigmatism, Glaucoma, Secondary glaucomas, Degeneration of the macula, Retinal dystrophies