The aphakic eye represents an optical system of the simplest form, that is, a single curved surface, the cornea, separating air from the aqueous and the vitreous, both of which may be regarded as a single medium, since they have nearly the same index of refraction. It has the same length as the normal eye, but without the crystalline lens it has lost a considerable amount of dioptric power and, therefore, represents a high type of curvature hyperopia. It is devoid of accommodation.
In the exact schematic eye of Gullstrand the crystalline lens system at rest is given a power of 19.11 diopters, reduced for air. This is lower than the power assumed for the lens by most other authorities. The reduced power of Helmholtz' lens for air is about 26.39 diopters and of Tscherning's lens, 21.39 diopters.
While the actual power of Gullstrand's crystalline lens is 19.11 diopters, because
COWAN A. SOME FACTORS CONCERNED IN THE CORRECTION OF APHAKIA. Arch Ophthalmol. 1934;12(4):571–579. doi:10.1001/archopht.1934.00830170109013
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