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Biomedical subjects

G Fonda

Publications and source records attributed to G Fonda.

31 records · Page 2Linked to original sources
PubMedDate not supplied

Spectacle correction for aphakia. The prismatic effect.

Because spectacle lenses are fixed in position relative to the eyes, the visual axes during convergence pass nasal to the optical centers, and create a prismatic effect. The eye rotates less than 25 degrees before the head is turned; therefore for central vision, only an area of the lens about 13 mm wide is used. A reading addition of +6.00 D is probably the maximal power bifocal addition that can be prescribed for comfortable binocular vision in a high plus correction. The distance correction produces a base-out effect of at least 4 delta for each eye at the reading distance, even though the bifocal segments are adequately decentered.

Aphakia, Postcataract↗
PubMedDate not supplied

Low vision correction for high myopia.

High myopia is favorable for low vision corrections because the vision has usually been poor since childhood and the person has been able to read at close range, producing magnification. For near vision, in addition to bringing objects close, magnification is produced by high-add bifocals, trifocals, strong near vision spectacles and nonspectacle magnifiers. Hand magnifiers held at a distance from the eye are used with the spectacle correction. This paper describes the Visolett, used without correction or near vision correction, as the preferred non-spectacle magnifier because the reading area is self-illuminated, it doubles the approach magnification, rests on the paper, is simple to use, produces binocular vision, and attracts the least attention. Combination method of magnification consists in the use of the Visolett in addition to a spectacle magnifier, which doubles the magnification.

Contact Lenses↗