Definition of cataract
Cataract is defined as a partial or total opacification of the crystalline lens, the natural transparent lens inside the eye that allows to correctly display an object, a figure or any other image.
Cataract is a serious disease that, if left untreated from the earliest symptoms, can cause permanent blindness.
Curiosity
The term cataract seems to have very ancient origins: the word derives from the Greek "katarraktês" which literally means "something that falls from top to bottom". The definition can only be more indicated: the ancient meaning of the term cataract is also used in medicine to highlight the sort of "fog" that "descends" before the eye when the lens becomes opaque.
Causes and risk factors
Most cataracts manifest as a result of crystalline lens injuries. To avoid misunderstandings, it is good to specify that the "lesion" we are talking about should not be understood only as a physical or mechanical trauma at the level of the natural lens of the eye: advanced age, for example, involves physiological changes to crystalline charge, such as to make it less flexible, less transparent and thicker. As a result, age-related changes can also negatively affect the eye, making it difficult to focus on the image.
To understand...
The crystalline lens is placed behind the iris, the colored part of the eye. This natural lens, thanks to the peculiar flexibility that allows it to vary its shape, focuses the light that passes through the cornea, thus producing clear and clear images on the retina.
In the presence of cataracts, the crystalline lens gradually tends to become opaque: in other words, the light that passes through the crystalline lens is dispersed, preventing the retina from "translating" light into clear images.
In addition to senescence, other risk factors for cataract development have been identified, listed below:
- Intake of corticosteroids during pregnancy (congenital cataract)
- Iodine deficiency (presumed and not proven cataract risk factor)
- Diabetes mellitus
- Exposure to ionizing radiation
- Exposure to UV rays and X-rays
- Severe dehydration and chronic diarrheal crisis
- galactosemia
- Infections of the mother during pregnancy (possible cause of congenital cataract)
- Physical injuries to the eye
- Genetic predisposition
- Female sex
- Uveitis
- smoking / alcoholism (possible aggravating factors)
Senile cataract
The category of people most at risk of cataracts is undoubtedly that of the elderly: for this reason, in the absence of metabolic pathologies or pre-existing traumas, one speaks of senile cataract to indicate a form of opacification of the crystalline lens linked exclusively to old age.
Data in hand ...
Cataract is a rather common disorder among the elderly: just think that 30% of patients over 65 are affected by cataract in one or both eyes. Still, it seems that 71% of people aged 85 or over suffer from the same disorder.
- Analysis of these data shows that advanced age is a concrete risk factor for the development of cataracts.
When the cataract occurs in a healthy subject between the ages of 40 and 60, we speak of presenile cataract to indicate a form of opacification of the crystalline lens that anticipates the actual cataract.
Medication cataract
A cortisone therapy that lasts for long periods (at least two years) could, in some subjects, cause cataracts. Similarly, even myotic drugs (which cause the pupil to shrink), used in the form of eye drops or ophthalmic ointments for the treatment of glaucoma, can cause the same disorder.
Traumatic cataract
As the same term predicts, traumatic cataract is closely related to traumatic events of a physical or mechanical type to the eye. Generally, it is the perforating wounds and the blunt traumas that constitute the main causes; precisely because of the aetiology (research into the causes) of the disorder, traumatic cataract is often monocular, meaning that it occurs only in the eye involved in the accident.
Congenital cataract
Although it is now a fact that the elderly are clearly more exposed to the risk of cataracts than young people, it is nevertheless true that the disease can appear from birth or appear in the following months. In such situations, the causes can be multiple:
- Metabolic alterations in the mother: dietary deficiencies, diabetes, hypothyroidism
- Metabolic alterations of the fetus
- Taking medicines during pregnancy (in particular, corticosteroids and sulfonamides)
- Unknown causes
- Inheritance
- Infections contracted by the mother during pregnancy: rubella (above all), systemic herpes, toxoplasmosis, mumps (mumps), varicella, rubella infection, Epstein-Barr virus and cytomegalovirus
- Pre-term birth
- Marfan syndrome (complex inherited disorder affecting connective tissue, which mainly affects eyes, cardiovascular system and skeletal muscle system)
Cataract from diseases
DIABETES
The cataract can also appear in the young subject in the presence of some diseases, first of all diabetes. It is estimated that the risk of a diabetic patient developing cataracts is four times higher than for a healthy patient.
In most cases, young diabetic patients undergo bilateral cataracts, which means that it affects both eyes. Furthermore, this category of patients is often destined for an acute course of the disease, which means that complete opacification of the lens tends to be much faster than normal.
SKIN DISORDERS
In addition to diabetes, some skin disorders can also cause or promote cataracts. These include:
- Scleroderma
- Atopic dermatitis
- Poichilodermia (skin disorder that consists of alteration of the chromatic tone of the skin and the formation of telangiectasias)
EYE DISEASES
Some diseases that affect the eye can be the fuse that triggers the cataract. In particular, the posterior uveitis, acute angle glaucoma, iridocyclitis (infection of the iris and ciliary bodies) and myopia have all the potential to predispose the victim to cataract. Sometimes even eye tumors and retinal detachment can cause cataracts.
