1. Different materials:
Intraocular lenses are divided into foldable crystals and non-foldable crystals, colorless crystals and yellow crystals. They can be divided into similar and different material combinations. It is single-chip and three-chip; in terms of the materials that make up the crystal, it can be divided into: polymethyl methacrylate (PMMA), hydrogel, silicone gel and other crystals.
2. Different functions:
Functionally divided into single focus and multi-focus; UV-resistant and non-UV-resistant (now rarely used) crystals; the crystal surface is treated with heparin Sodium-treated versus non-heparin sodium-treated crystals.
3. Prices are different:
In terms of crystal prices: imported, folded crystals; crystals surface-treated with sodium heparin (Pharmacia crystals) are more expensive; others The price is in the middle, and the domestic ones are cheaper.
4. Different user groups
Normal people can see distant objects clearly because light passes through the refractive system, including the lens, to form a clear image on the retina. When looking at something close, This is accomplished by ciliary muscle contraction pulling the lens ligament to change the convexity of the lens, so that a clear image can be formed on the retina when looking near or far.
The intraocular lens is a lens made of artificial materials with a fixed diopter. When looking far, a clear image can be obtained. When looking close, a 300-degree spectacle lens is needed to see clearly. In recent years, with the continuous development of science and technology, the lens has been developed into a bifocal or multifocal intraocular lens that is closer to a physiological lens, but is more expensive.
Extended information:
1. Yellow intraocular lens
1. Intraocular lenses add UV absorbers to block ultraviolet light, but ordinary intraocular lenses cannot block blue light. The yellow intraocular lens is designed to block blue light and reduce light damage to the macula.
2. Introduction to the groups suitable for yellow light intraocular lens and white light intraocular lens:
1. The previous intraocular lenses have only one focus and no adjustment power. They can see far clearly but cannot see near. To see clearly (presbyopia), on the contrary, to see clearly at near distance and to see distance requires myopia glasses. In order to overcome this defect, over the past 30 years, people have developed and applied multifocal intraocular lenses.
2. It is mainly divided into two types: A, multi-zone multifocal type, including two zones, three zones, four zones, five zones, etc., that is, the intraocular lens is divided into a central zone and a surrounding ring. The refractive power of each part is different, generally 2.5D, forming two focus points, one for near vision and one for distance vision. The disadvantage of this type of lens is that distance and near vision are affected by pupil size and ambient light intensity.
3. B, diffraction multifocal type. This type of crystal is based on the wave theory of Huygens light. 30 small grooves with a depth of 2 μm are carved on the back surface of the artificial lens to overcome the problem of Zonal multifocal lenses are affected by changes in pupil size.
4. The same disadvantage is that the energy of the light entering the eye must be divided into two parts. Half is used to see near and the other half is used to see far. The distance is not very clear, and the visual acuity is affected to a certain extent. It is used by a few doctors and patients and has not become mainstream.
3. Aspheric intraocular lens:
1. Reduce aberrations, effectively improve imaging quality, significantly improve night vision, close to normal eyes, especially suitable for elderly people with difficulty moving at night or driver patient.
Baidu Encyclopedia-Intraocular Lens