Whether an individual is far-sighted (only distant objects are seen sharply), near-sighted (only near objects are sharply reproduced on the retina), astigmatic (vision is blurred or distorted due to a warped cornea) or presbyopic (cumulative short-range ametropia) – the right eyeglass lenses are out there for every visual defect.
Our eyes work like a precision camera. The cornea and lens of the eye represent the camera lens. They concentrate the light rays and project them accurately onto the retina. Accommodation is a sort of focusing system of the lens. It is comparable to a camera in that it makes it possible for us to accurately see objects both at a distance and up-close. However, only a small minority of people can rely on eyes that work that well.
For this reason, starting at the age of 40 at the latest, everyone should have an annual eye and vision test. An eye care professional can check your visual acuity. The good news: The right lenses are out there for virtually every visual defect, regardless of the form of ametropia.
An eye test should be also conducted regularly to check for further abnormalities and organic changes to the eye.
The shortfall in the eye’s refractive power is balanced by a corrective concave lens so that the image is once again sharply reproduced on the retina.
The excessive refractive power of the eye is balanced by a corrective convex lens so that the image is once again sharply reproduced on the retina.
The uneven refractive power of the eye is balanced by a corrective cylindrical lens so that the image is once again reproduced sharply and undistorted on the retina.
The failing refractive power of the eye in the near range is re-balanced with a corrective convex lens (reading glasses). As a result, near objects are once again sharply reproduced on the retina.
As the name suggests, these lenses contain two (the prefix “bi”) optical effects – for near and far vision.
For glass bifocal lenses, the dioptric value required for the near range is achieved through a fused additional lens in the bottom part of the lens. With plastic bifocal lenses, the near range effect is achieved by a molded additional surface with a small front face radius. Bifocal lenses are now being overtaken by progressive lenses.
In addition to enabling the wearer to see far and near, they also have an additional, third intermediate zone for medium-range vision (50 cm to 1.50 m). Trifocal lenses are also increasingly losing market share due to progressive lenses.
Innovative stars modern progressive lenses offer key advantages over bifocal and trifocal lenses: Progressive lenses make sharp vision possible at all distances. There are no image jumps in the visual field, nor is there a separating edge.
As early as 1983, ZEISS was setting new standards for progressive lenses with its Gradal HS solution. The acronym HS stands for Horizontal Symmetry. It ensures homogenous visual impressions for the right and left eye in eye movements.
Thanks to Gradal Top E, the ranges of vision, and especially the intermediate range, could be widened substantially and were further adapted to the physiological requirements of the user. The first customized progressive lens by Carl Zeiss was used in 2000 and has been continually enhanced to this day. The latest generation is called ZEISS Progressive Individual2. The functional surface can now be optimized for each individual effect. In addition, the individual features, such as inter-pupillary distances, tilt, distance between the vertex of the cornea, frame size and the near-range primary working distance were all taken into consideration.
They changed the world with their ideas
The ZEISS Vision Science Lab at the University of Tübingen in Germany carries out fundamental research into vision
What makes our eyes so special
What are the key points to remember when choosing single-vision lenses?
How our brain compensates for perplexing design flaws in the human eye.