The age of onset of cataracts is very variable: 21% of people between 50 and 64 years of age have them. As we get older this percentage increases so that 53% of people between 65 and 74 years old have them, and 80% of individuals between 75 and 85 years old have them (Source: Monograph “Cirugía del cristalino” Drs Lorente and Mendicute).
It is usually bilateral but asymmetric.
Types of cataracts
- Congenital or infantile cataracts: in children under 1 year of age. Usually the cause is unknown, sometimes it is associated with metabolic diseases, such as Down Syndrome, infectious diseases during pregnancy, among others.
- Nuclear cataract: it is the most frequent form of cataract. It is caused by a progressive hardening and opacification of the lens nucleus. It is usually accompanied by progressive myopization due to an increase in the refractive index of the crystalline lens.
- Cortical cataracts: the second most frequent. Opacification of the lens cortex occurs, causing patients to report blurred vision, loss of contrast sensitivity and glare.
- Posterior subcapsular cataract: this is a type of cataract that appears in young people after prolonged intake of corticosteroids, in myopia magna or after inflammatory processes. It causes loss of vision and a lot of glare in a few months.
- Traumatic cataract: it is usually unilateral and associated with other ocular alterations such as rupture of the iris sphincter, zonular weakness or rupture of the posterior capsule.
How to prevent cataracts
The main risk factor for the appearance of cataracts is age. Therefore, we cannot delay the onset of cataracts. However, there are exogenous factors that we can control to prevent cataracts from progressing rapidly or appearing at an early age:
- Exposure to sunlight: cataracts are more prevalent in populations near the equator, therefore a good protection with sunglasses is recommended to protect our crystalline lens.
- Diabetes: poorly controlled and prolonged hyperglycemia produces oxidative stress of the crystalline lens proteins.
- Tobacco and alcohol: increase the risk of posterior nuclear and subcapsular cataracts. Smoking cessation decreases this risk.
- Taking medications such as corticosteroids for long periods of time and at high doses also favor the appearance of cataracts.
Cataract surgery
Cataract surgery consists of replacing the opaque crystalline lens with a transparent lens made of a biocompatible material and with the prescription that the patient needs. It is a surgery that, in general, is performed with topical anesthesia (drops), through a 2.2 mm incision; a circular hole is opened in the lens with a diameter of 5 to 5.5 mm (capsulorexis) and the lens is fractured with ultrasound to subsequently aspirate these fragments and leave the sac where the lens was contained clean. The intraocular lens is implanted inside this sac.
Types of intraocular lenses
PHAKIC: they are added to the optical system keeping the crystalline lens, so they are indicated for young patients or those who cannot undergo corneal surgery to correct their prescription defect. It allows to see at all distances with a high image quality. It is a reversible technique.
Pseudophakic: they replace the crystalline lens, which in all cases eliminates the cataract if it exists. The surgery is performed with a microincision in the cornea through which the previously fractured crystalline lens is extracted with ultrasound.
Nowadays, cataracts can also be operated with Femtosecond laser, which allows greater precision when performing the capsulorhexis and less manipulation since the fragmentation is performed by the laser.
PSEUDOPHAKIC lenses are divided into:
- Monofocal: they allow very good distance vision without correction, but require the use of glasses for intermediate distance and near vision.
- Extended range: they are a type of lenses that allow good distance and intermediate vision with less dysphotopic phenomena than multifocal lenses. The patient usually needs a near spectacle to be able to read comfortably.
- Multifocal: they allow an independence of near glasses for common things so the patient will not have presbyopia. Multifocal lenses are subdivided into: bifocal, good distance and near vision (may need glasses for intermediate vision); trifocal, good distance, intermediate and near vision.
- Toric lenses: allow correction of astigmatism greater than 1 D. There are both monofocal (correcting distance refractive defects and astigmatism, requiring glasses for near vision) and multifocal toric lenses (correcting all prescription defects).