Concerning visual sharpness, no differences were found when placing a yellow, brown or orange filter or a neutral filter of the same density in front of the eye.
Recently studies were made on the sensitivity to contrast, measuring the reaction time presenting reticula of a spatial frequency of less than 10 cycles per degree (angular vision) and a contrast of less than 50%. The conclusion was that reaction times are shorter when brown or yellow lenses are used instead of a neutral filter of the same density. But this difference does not exist with a contrast of more than 50% or frequencies greater than 10 cycles per degree. This agrees with the fact that visual sharpness is independent of the colour, given that in the tests the visual sharpness is very high.
In any case, in literature we will find, as always, different opinions on the advantages of yellow glasses.
There is an analogous controversy regarding stereo-sharpness but, under certain aspects, the same considerations can be repeated. But the problem remains open except in the cases where brown or orange lenses reduce the luminosity to such a level that the stereo-sharpness is altered.
To clear-up the above a research was made using lenses that cut the blue with an optical density of of 0.76 (and therefore a transmittance of 17,4%).
The stereo-sharpness has been determined by Howard Dolman’s device. Colour vision has been examined using the Test of the 100 tonalities of Farnsworth-Munsell. The results in part confirm and in part contradict the above conclusions.
Articolo Correlati: Lenses that cut the “Blue”, part 1/4
by Prof. Sergio Villani
Instead of the traditional surgical thread, a laser that bonds, in 2-3 minutes, minuscule cornea borders with intraocular tissues. The new technique has been developed by a research group of the Istituto di fisica applicata (Ifac) of the Consiglio nazionale delle ricerche (Cnr) of Florence in cooperation with the Unità Oculistica of the Hospital of Prato and with the Bascom Palmer Eye Institute of Miami (the most important US clinic in this branch). The innovation allows the substitution of the traditional suture, used in cornea transplants, in cataract surgery, in the future techniques of lens refilling (replenishment of the crystal) as the definitive solution of the problem of senile nearsightedness.
The splendid venezuelan model and show-girl Aida Yespica is the new face of the Oxydo campaign, the line of sunglasses and eyeglasses frames dedicated to trend-setters. Two unique personalities met: Aida Yespica, show-star, and Oxydo at the set of the video of “Dip it”, the new hit of the american rapper Coolio… and fell in love at first sight!
They render eyes more brilliant, bring relief to reddened eyes and are used to cure congiuntivitis, cateratta and glaucoma and to fight-off allergic symptoms. Many are sold without recipe and their use is very simple but use may also become an abuse. Let’s see how to avoid their use with the help of artificail tears. We will discuss this with Dr. Fabrizio Camesasca.