The normal lens is transparent, which, in addition to its regular, clear fiber arrangement and avascularity, relies on its specific, complex metabolism – maintaining transparency through diffusion and permeation of the capsule membrane to draw nutrients from the atrial fluid and excrete metabolic products from the lens. There are many clinical causes such as trauma, genetics, and severe malnutrition that can cause a cataract to develop from one of these factors, but the most common cause is age-related cataracts that occur in the elderly. In fact, cataracts generally mean senile cataracts if not specifically stated.
Geriatric cataracts are one of the most common blindness-causing eye diseases and are the main cause of blindness in the elderly. 60% to 70% of people between the ages of 50 and 60 years old and up to 80% of people over 70 years old have this disease, often in both eyes. However, the degree of lens clouding varies greatly between individuals and even between the two eyes. Why do cataracts occur in the elderly? Why is there a difference in speed of development? Although several theories have tried to explain it, it remains a medical mystery. The more common theory is that cataracts, which cause blurred vision, are an “aging” phenomenon in the human body, along with graying hair and loose teeth.
The lens is subtly composed of protein and is the most protein-rich tissue in the body. In everyday life, you know that transparent proteins immediately turn milky white when heated. Chemically treated proteins also become mixed, as exemplified by skinned eggs and vinegar eggs. These facts make us understand the truth: transparent proteins will “change” and become cloudy after being affected by external adverse effects. Since the lens is a protein, of course, will not be an exception. Once the chemical composition of the eye changes in the elderly, the lens is bound to become cloudy gradually. The real cause of senile cataract is not yet clear, but it is obviously related to the disorder of certain amino acid metabolism in the body; to the photo-oxidation of the lens; and to the lens receiving more ultraviolet radiation.
Although cataracts are mostly seen in the elderly, they can be acquired at any stage of life: whether it is a newborn baby dreaming of life, a toddler, or a young and middle-aged person who is vibrant and young.
A pregnant mother who has a fever, viral infection or malnutrition during the first 3 months of pregnancy can give birth to a doll with cataracts. For example, the incidence of cataracts in children of mothers infected with rubella in the second trimester can be as high as 100% and up to 50% in those infected in the third trimester.
Cataracts can be complicated by inflammation or other pathological reactions in the periocular lens tissue that affect the normal nutrition and metabolism of the lens. Common eye diseases that cause cataracts are: severe keratitis, uveitis, high myopia and diseases of the fundus.
Sharp objects pierce the lens; external forces act on the lens through the conduction of atrial water, causing lens rupture and degeneration; lightning strikes and electrocution; infrared, microwave and ionizing radiation are all culprits of cataracts.
Diabetes, kidney disease, low blood calcium and other disorders can occur with certain characteristics of cataract. Long-term application of steroids, or “hormones”, is also a cause of cataracts.