Cataract: Definition, Etiology, Patophysiology
Cataract affects Left Eye


What is Cataract?

Cataract comes from Greek (Katarrhakies), and Latin (Cataracta) which means waterfall, because it was initially thought that cerebral liquor leakage that flowed into the lens surface causes cataracts.

The cataract is an opaque or cloudy area in the eye lens that varies from mild to complete. It causes refraction or blockade of the incoming ray so that it is not precisely focused on the photoreceptor system on the retina.

The small opacity on the periphery of the lens have little or no effect on vision. However, if cloudiness occurs in the center of the lens, the transfer of incoming light can be disrupted and produce visual disturbances to blindness.

In addition, there is a change in the color of the lens to yellow, which reduces the ability to perceive blue due to interference with light dispersion.

Etiology and predisposing factors

What are the causes of cataracts?

The cause of cataracts is still unknown with certainty but generally associated with lens protein denaturation. Here are various factors that influence the progression of cataracts:
1. Old age
Old age is a major risk factor associated with the lens degeneration process.
2. genetic
If one of the identical twins has cataracts, the sibling has 48 times more chances. Genetic factors have correlated with congenital cataracts, family history of cataracts acts as a predisposition to cataracts development at an early age.
3. Long-term radiation exposure, for example, UVB, infrared light, etc.
4. Eye inflammation and local trauma.
5. Systemic Diseases
Secondary effects of systemic diseases, such as diabetes mellitus, hypertension, chronic dehydration, diarrhea, and malnutrition, increase the risk of cataracts in the empire at times.
6. Malnutritions
Deficiencies of vitamins C and E, selenium, beta carotene, and lycopene. The nutritions play a role in protecting body cells from damage, which is caused by free radicals.
7. Smoking and alcohol 
Smoking and consuming alcohol also increase the incidence of cataracts.
8. Atopic or allergic
Atopic or allergic status accelerates the cataract's progressivity, especially in the incidence of Juvenile cataracts.
9. Drug-induced cataracts
Corticosteroids, amiodarone, phenytoin, chlorpromazine, and statins, also accelerate cataracts' development.


How can Cataract occur?

Lens Protein
Physical and chemical changes result in changes in multiple fine fibers (zonula) that extend from the ciliary body to around the area outside the lens. Thus, the zonular changes cause a loss of transparency, resulting in distorted vision.

The eye lens structure contains two types of proteins: water-soluble protein (cytoplasmic protein) and water-insoluble protein (cytoskeletal protein). Under normal circumstances, soluble protein levels are higher than those that are insoluble. Chemical changes in lens protein can cause lens proteins to become water-insoluble and form larger particles (coagulation) so that the lens becomes cloudy. The cloudiness blocks the passage of light to the retina.

Most components in the lens are water and protein. With the aging of a person, the eye lens will lack water and become denser. The lens becomes solid in the middle or central, so the ability to focus on seeing objects near is reduced. In old age, the formation of a new cortical layer on the lens that causes the lens nucleus to push and harden (nuclear sclerosis).

At that time, there is a change in lens protein, namely the formation of proteins with high molecular weight and cause changes in the lens refraction index so that it reflects incoming light and reduces lens transparency. This chemical change is also followed by the formation of pigments in the lens nucleus.

One theory states that the process of water influx into the lens breaks the strained lens fibers and interferes with the transmission of light.

Another theory says that an enzyme has a role in protecting the lens from degeneration. These enzyme levels decrease with age and are absent in most patients who suffer from cataracts.