Traditional colours for highly tinted sunglass lenses are brown, grey and green. Spectacle lenses with a light tint can be worn all day. People experiencing asthenopia may find relief by using slightly tinted lenses (10-20%) that are also often worn for cosmetic reasons. Ophthalmic lenses are available in different colours and tint densities. An overview of the tint and filter options available is presented in the following. Selecting the appropriate lens depends, for instance, on the degree of latitude or where the wearer wants to use the spectacles, whether the correction eyewear is used only indoors or also outdoors, or whether the wearer wants to avoid irritating water reflections when fishing. Light protection lensesĭifferent types of light protection lenses are available to accommodate individual requirements. The deviation from the required correction is usually so pronounced in the peripheral areas that the wearer cannot use them for direct vision. The peripheral areas on the right and left-hand side of the progression channel limit the useable zones of the progressive lens. The width of the progression channel depends on the design of the progressive lens and the power of the addition. The transition between these zones is smooth and invisible on the outside. Progressive lenses are roughly divided into three vision zones: distance zone, progression channel (intermediate zone) and near zone. They allow smooth vision at any distance. Unlike bifocals or trifocals, progressive lenses offer the right dioptric power for every distance. The intermediate zone usually provides 50% of the added magnifying power of the near zone. Most have one zone for distance vision, one for intermediate vision and one for near vision. Trifocal lenses are multi-power lenses with three points of focus. Bifocal lenses eliminate the need to swap between different pairs of glasses for different visual tasks. The upper part is designed for distance use and the lower part for reading. Multifocal lenses are lenses designed to provide two or more visibly divided portions of different focal powers.īifocal lenses enable clear vision at two different distances, usually for near and distance vision. Prismatic deviation refers to the change in direction imposed on a ray of light as a result of refraction. Prismatic lenses use the prismatic effect which results from the prismatic deviation and base position. Astigmatic lenses feature two meridians perpendicular to each other that have different refractive powers. This results in a thinner lens design, less weight and significantly better image quality.

Aspherical lenses have different refractive powers in every point of the lens regardless of the meridian. Spherical lenses have the same refractive power in all meridians. They are classified in spherical, aspherical, astigmatic and prismatic lenses. Single-vision lenses usually offer visual correction for just one distance, be it for general distance vision, for a specific distance or for near vision. Types of ophthalmic lenses Single-vision lensĪccording to DIN EN 13666: 2013:10, a single-vision lens “is designed to provide a single dioptric power”. Special visual aids for dry eye syndrome.Scanning and reading devices - turning text to speech.