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Biomedical subjects

G E Fonda

Publications and source records attributed to G E Fonda.

7 recordsLinked to original sources
PubMed1994

Optical treatment of residual vision in diabetic retinopathy.

PURPOSE: The purposes of this study of diabetic retinopathy are to classify degree of vision impairment, determine the percentage of patients for whom vision can be improved by an accurate refraction, identify the most useful magnifying devices, and arrive at the success rate for the magnifiers. METHODS: Study of 101 consecutive subjects. RESULTS: Visual acuity was 20/200 (6/60) or better in 71% of subjects. Spectacle correction improved vision for 29%. High-add bifocal magnifiers improved vision for 30% of patients; half-eye spectacle magnifiers improved vision for 45%; and hand-held magnifiers improved vision for 11% of patients. Visolett magnifiers improved vision for 44%, and combination spectacle magnifiers and Visolett improved vision for 24% of patients. Multiple optical aids for 63% of patients resulted in a success rate of 68%. CONCLUSIONS: The ophthalmologist is obligated to ensure that eyes are refracted and appropriate magnifying devices are provided as part of treatment for diabetic retinopathy.

Diabetic Retinopathy↗
PubMed1992

New high-index visolett magnifier.

The high-index Visolett magnifier (index, 1.806) is an optically designed glass paperweight magnifier. It magnifies 2.49x, is 32mm in diameter, nonfocusable, and rests on paper. All Visoletts commercially available are made of crown glass (index, 1.523). The 32mm high-index Visolett has become commercially available recently. The use of high-index material increases the image size by 39%.

Humans↗
PubMed1989

Visolett magnifier without and with bifocal.

Visolett nonfocusable magnifiers are optically designed paperweights. The general magnification is 1.8X, and 4X through the bifocal. Using glass index 1.806, the general magnification is 2.47X. A Visolett is one of the most useful nonspectacle magnifiers because it diffusely concentrates the illumination on the field of vision, complementing the magnification. The optics differ from hand-held and stand magnifiers, in that the magnification does not increase with the dioptric power. However, the magnification of the bifocal does increase with the dioptric power and by decreasing the distance of the object from the focal point. The advantages are that they are simple to use, allow binocular vision, and almost double the magnification when used with a spectacle magnifier. Visoletts are preferred to stand magnifiers.

Equipment Design↗
PubMedDate not supplied

Designing half-eye binocular spectacle magnifiers.

The process of designing half-eye frames with a smaller than usual eye size and narrower distance between lenses (DBL) in order to produce additional base-in prism effect is described. This method enhances binocular function while the spectacle magnifier is used. The design also provides a lighter, thinner, and cosmetically more acceptable optical aid. Binocular half-eye spectacle magnifiers are useful optical aids, especially for patients with binocular vision, because they are produced in strong powers with strong prism effects incorporated in the lenses. The magnifiers range in power from +6.00 D [symbol: see text] 8 delta base-in to +14.00 D [symbol: see text] 18 delta base-in for vision ranging from 20/60 (6/18) to 20/320 (6/96). Binocular half-eye spectacle magnifiers are recommended for prolonged reading because the strong base-in prism effect relieves the convergence effort, also providing a large field of vision with both hands free.

Equipment Design↗