Let’s also remember that there exists a compensation for aberrational effects on the cornea and the chrystal (one corrects too much, the other too little) but the individual difference is such that it makes no sense to establish an average value. Anyway, the influence of the spherical aberration on the chrystal has been asserted by experiments that have demonstrated how, with varying accomodations, one passes from undercorrection to overcorrection of the retinal image. There exists also another phenomenum caused by the prismatic effect of a lens. That effect increases with the angle of thge prism, i.e., the power of the lens.
The phenomenum is called “Jack in the box” or also “Roving Ring scotoma”.
The dimensions of this “ring” around the visual field depends on several factors: the lens’s power, its dimensions, size of the pupil, distance to the corneal apex, the configuration and the thickness of the lens.
One of the inconveniences of the above described scotoma is that it tends to move independently from the rotation of the eye. If the eyebulb rotates laterally 30 degrees, the scotoma turns to the inside by 20 degrees. When the individual sees an object, in order to bring the image on the fovea, he sees a dark spot. He then moves the eye, more or less disorderly, to focus better on the image. Aspheric lenses have been made (panorama lenses) but their success has been modest.
A partial solution can be found correcting the aphakia with contact lenses.
From Optometria e Oftalmologia by Prof. Sergio Villani
Realted article: Afakia (4/5)
I
A new generation of monofocal lenses to reduce eyesight fatigue.
This year Gucci Eyewear collection is 85 years old. According to this a new collection is shown: the “Britt” Collection. The new models in acetate are personalized by the new logo with the double crossed G, which creates an oval form inside a plate in metal and crystal or which is directly put on the temples or which is coated with Swarovski Strass. We are sure that everybody will appreciate this fascinating logo “GG Britt” . What are you waiting for? Let’s come and discover this new Glamour. And than let us know how do you feel about this fascinating Charm.