Nearest Point Of The Eye
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
The nearest point of the eye is the closest point at which an object can be clearly seen when brought toward the eye. This distance decreases with age as the eye's accommodative power weakens.
Encyclopedia article (1928–1936)
Nearest Point Of The Eye, N. p. of clear vision (punctum proximum), the limiting point of approach of an object to the eye, from which this object can be perceived distinctly. The distance of the punctum proximum from the cornea, expressed in centimeters or in diopters (D), determines the refraction of the eye, strengthened to the extreme limits of accommodation. With age, the power of accommodation weakens, and the distance of the N. p. of the eye from the cornea decreases. In a normal emmetropic eye it is equal: at 10 years of age - 7 cm, or 14.5 D, 20 years - 10 cm, or 10 D, 30 years - 14.3 cm, or 6.5 D, 40 years - 22.5 cm, or 3 D, 50 years - 40 cm, or 2.5 D, 60 years - 200 cm, or 0.5 D. To determine the position of the N. p. of the eye, small objects (usually small print) are brought closer to the eye until they are clearly visible. The distance of still possible clear vision determines the N. p. of the eye. More precise measurements of it are made with an optometer.
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Cite this page
“Nearest Point Of The Eye.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/nearest-point-of-the-eye/