Cataracts are a very common ocular pathology. They occur due to a loss of the transparency of the lens, the structure of the eye that allows us to focus on objects correctly. In light of this, it is difficult to perform various daily activities such as reading, driving, etc.
Types of cataracts
Depending on how they are formed, cataracts can be divided into:
- Congenital: These appear during early childhood.
- Secondary: These appear as a consequence of another process and can be:
- Derived from another ocular pathology (such as uveitis).
- Systemic diseases derived from certain illnesses (such as diabetes mellitus and hypoparathyroidism).
- Seniles: These are due to aging and are the most common. They constitute 90% of the cases of cataracts.
Their prevalence increases with age. Thus, 60% of the population between 65 and 74 years of age has cataracts and the percentage increases to 70% among those over 75 years. This is because, with aging, the transparency of the lens is progressively lost due to several factors:
- Environmental factors:
- Solar radiation.
- Metabolic factors:
- Genetic factors.
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Congenital cataracts appear from birth or in early childhood. They can be unilateral or bilateral. They appear due to multiple factors during pregnancy. Congenital cataracts can be caused by certain maternal metabolic diseases, such as diabetes mellitus, hypocalcemia or certain nutritional deficiencies, such as vitamin A deficiency or folic acid.
Intrauterine infections are also an important cause, the most common being rubella, which accounts for between 30 and 60% of cases. It presents with a case of microphthalmos, retinitis pigmentosa, deafness and congenital heart disease associated with the cataract. Other infections are mumps, hepatitis and toxoplasmosis.
Another cause of cataracts, although less frequent, is the administration during pregnancy of certain drugs, such as thalidomide, or diagnostic tests such as X-rays. It should be noted that certain diseases in the fetus may increase the risk of cataracts. This is the case of some chromosomal diseases, such as Down syndrome, or hereditary infantile metabolic diseases (these include galactosemia, hypoparathyroidism or Lowe’s syndrome).
Cases of cataracts due to chromosomal abnormalities or hereditary infantile metabolic diseases account for 1% of the population.
What do cataracts produce?
Cataracts cause a decrease in visual acuity. Depending on which part of the crystalline lens they affect, they will present in one way or another:
- Nuclear cataracts, representing 30% of cases, affect the nucleus.
- Cortical cataracts represent 50% and with a slit lamp appear as triangular and radial opacities.
- Subsequent subcapsular cataracts, 20%, in which visual acuity decreases with intense light. They can occur due to corticosteroid treatments or diabetes mellitus.
The loss of visual acuity is gradual. Thus, we can distinguish different stages of evolution for cataracts:
- Incipient: Visual acuity between 0.8 and 1.0. It is called phacosclerosis. There is a hardening and stiffness in the lens due to age.
- Developed: Visual acuity between 0.1 and 0.5. The cataract has a dense core.
- Mature: Visual acuity less than 0.1. One can perceive movements and variations of light. The lens is white, which is called leukocoria and is swollen. It is not possible to see the back of the eye with a slit lamp.
- Hypermature: One can only perceive light variations. The nucleus is brown. This is very unusual in our environment.
A patient with cataracts will have blurred vision, as if seeing through a dense fog, with a decrease in progressive visual acuity (faster in posterior capsular cataracts, which also produce a glare).
It is important to ask the patient about the rate of progression of the vision loss. On the other hand, it must be evaluated if lighting conditions influence the patient’s vision, which usually makes night vision difficult. These patients will also report a decrease in contrast sensitivity and alteration in their perception of colors.
Cataracts may also present with other ocular symptoms, such as myopia or monocular diplopia (commonly known as double vision).
When it is suspected that a patient may have cataracts, it is necessary to perform a complete ophthalmological examination. When the presence of cataracts is confirmed, other tests are made in the face of corrective surgery:
- Biometric studies, such as type A ultrasounds and studies to determine the measurements of the intraocular lens that will be used to replace the lens.
- Study of the corneal endothelium with a specular microscope. This is important because the cells of the corneal endothelium do not reproduce. In reaction to trauma such as cataract surgery, many of these cells are detached, which can result in long-term eye problems. It is interesting to check the status of these cells before surgery to foresee possible complications.
The treatment is fundamentally surgical. This consists of a simple and minimally invasive procedure that, in fact, is done without hospital admission. In addition, there are other research techniques that will offer other alternatives in the future.
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