Cataract surgery is a lens replacement surgery, in which a round opening is made in the anterior capsule of the clouded lens, the contents of the capsule are removed, and then an artificial lens is inserted. Therefore, cataract surgery cannot remove the cataract alone, but an artificial lens must also be installed to restore vision. If no crystal is installed, just like the cataract pinning surgery done by the ancients, one needs to wear glasses with more than 1,000 degrees of farsightedness to see, or a patient with high myopia who originally suffered from 2,000 degrees of myopia, just to offset the degree of myopia, simply removing the lens can improve vision, but after all, it is very few.
IOLs come in different styles, functions and colors, and their prices vary greatly, from a few hundred to ten or twenty thousand. It is worth considering how to choose a suitable crystal, because IOLs should not be replaced after installation, and a one-time choice is a matter of long-lasting visual experience in the future.
From the position of the crystal installation, there are two types: one is the anterior chamber IOL, which is fixed on the iris, so this type of crystal is prone to complications such as iridocyclitis and corneal endothelial loss, and is rarely used now; the other is the posterior chamber IOL, which is usually placed in the capsular bag and is most in line with the original eye structure and has no effect on the eye, so this type of crystal is basically used now. The following are all posterior chamber IOLs.
There are two types of IOLs in terms of their structure: one is the three-piece IOL, which consists of three basic units, including two loops and an optical surface. The other is the one-piece IOL, in which the two loops and the optical surface are integrated. There is no difference in the use of these two types of crystals, and they can be put into secondary consideration. If you really want to choose, the one-piece type does not need to take into account the problem of whether the three-piece interface is strong or not.
From the foldability of the IOL, there are two types: one is hard crystal, which cannot be folded and is an early type of crystal, which can be chosen for the old type of large incision surgery. If the mainstream small incision surgery is to be fitted with this type of crystal nowadays, the incision needs to be enlarged, because the surgical incision nowadays is done below 3mm and the optical surface of the crystal is at least 6mm. incision; the other type is soft crystal, which can be folded and can pass through a smaller surgical incision, and is now the mainstream choice for crystals.
Artificial crystals are divided into two types according to color: one is transparent crystal, which is completely light-transmitting, but ultraviolet light and part of blue light will lose the macula, which is the most important and sensitive part of the light-sensitive area and has great impact on vision after damage; thus, another type of crystal, yellow crystal, is produced, and this type of crystal can filter the blue light with shorter wavelength and the This crystal can filter the shorter wavelength of blue light and shorter wavelength of invisible light (such as ultraviolet), and play a certain protective effect on the macula.
However, yellow crystals can reduce the brightness, so for patients with poor visual function (such as glaucoma patients), you can consider bringing sunglasses to block harmful light when you go out, and clear crystals will have better visual effect when you return to the room without harmful light.
There are two types of crystals according to whether they can correct astigmatism: one is a non-astigmatism-correcting crystal, for patients who have astigmatism before surgery, after implanting this crystal, those who have astigmatism after surgery can wear glasses to correct it; the other is an astigmatism-correcting crystal, for patients who have corneal astigmatism before surgery, the crystal can offset the degree of corneal astigmatism accordingly, and basically achieve a state of no obvious astigmatism after surgery, with more natural visual effect.
There are two types of crystals according to whether there is aberration: one is spherical crystal, early crystals belong to this type, because there is aberration, in bright places with small pupils, it does not affect much, but in dark places, when the pupils are dilated, it is not clear enough, especially when there is glare, which affects driving at night, etc.; thus another type of crystal is produced – Aspheric crystal, this kind of crystal eliminates the spherical aberration through aspheric design, and is not affected by the size of the pupil, so there is no obvious glare when looking at lights at night.
In order to overcome this shortcoming, another type of crystal was created, the multifocal crystal, which can divide the light into several parts to see different distances, usually divided into Theoretically, this can restore the vision to that of a young person.
However, since multifocal crystals divide the light into several parts, the objects seen in each part will be darker, and the visual sensitivity will be lower than that of monofocal crystals; moreover, since the images of far, middle and near are focused at the same time, the brain has to differentiate the images of different distances. It is not suitable for elderly patients with poor visual function.