Cataract is what?

Written by Peng Xi Feng
Ophthalmology
Updated on September 03, 2024
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All sorts of reasons, such as aging, genetics, local nutritional disorders, immune and metabolic abnormalities, trauma, poisoning, radiation, etc., can cause metabolic disorders in the lens, leading to the denaturation of the lens proteins and resulting in opacity known as cataract. At this point, the light is obstructed by the opaque lens and cannot be projected onto the retina, causing blurred vision. It is commonly seen in people over the age of forty, and the incidence increases with age. This disease can be divided into congenital cataracts and acquired cataracts. Congenital cataracts are also known as developmental cataracts, and there are six types of acquired cataracts.

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Written by Zhou Qing
Ophthalmology
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Early symptoms of cataracts

The early symptoms of cataracts can manifest as day blindness or night blindness. When the cloudiness of the lens originates from the middle of the eye, the strong daylight and illumination can cause the pupil to contract, which then blocks the light from entering the eye, resulting in day blindness. When the cloudiness of the lens is located around the periphery of the eye, the dim light at night cannot reach the peripheral retina, thus causing night blindness. Other early symptoms of cataracts include the following: when the cloudiness of the lens is located at the pupil, patients may see fixed dots or patches of shadow in front of their eyes. However, since cataracts share similar characteristics with floaters, they should be distinguished; the shadows in floaters can move, while the shadows in cataracts are fixed. Varying degrees of blurry vision are also early symptoms of cataracts. Patients may experience gradually increasing blurriness of vision, often perceiving halos around lights or seeing colors of objects as dull and unclear. The early development of cataracts is quite slow and can be determined by the deepest and most obvious part of the lens cloudiness and its development condition.

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Written by Peng Xi Feng
Ophthalmology
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Cataract is what?

All sorts of reasons, such as aging, genetics, local nutritional disorders, immune and metabolic abnormalities, trauma, poisoning, radiation, etc., can cause metabolic disorders in the lens, leading to the denaturation of the lens proteins and resulting in opacity known as cataract. At this point, the light is obstructed by the opaque lens and cannot be projected onto the retina, causing blurred vision. It is commonly seen in people over the age of forty, and the incidence increases with age. This disease can be divided into congenital cataracts and acquired cataracts. Congenital cataracts are also known as developmental cataracts, and there are six types of acquired cataracts.

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Written by Peng Xi Feng
Ophthalmology
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Causes of cataracts

Various causes, such as aging, genetics, local nutritional disorders, immune and metabolic abnormalities, trauma, poisoning, radiation, etc., can lead to metabolic disorders of the lens, causing the denaturation of lens proteins and resulting in cloudiness; this is called cataract. Cataracts can be divided into congenital and acquired. Congenital cataracts, also known as developmental cataracts, are divided into anterior polar cataracts, posterior polar cataracts, nuclear cataracts, and total cataracts. Acquired cataracts are divided into senile cataracts, complicated cataracts, traumatic cataracts, metabolic cataracts, radiation cataracts, and those related to medications and poisoning.

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Written by Peng Xi Feng
Ophthalmology
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How is a cataract formed?

Inside the eyeball, there is a relatively important transparent tissue called the lens. Clinically, clouding of the lens is referred to as cataracts. Many factors, such as aging, genetics, metabolic abnormalities like diabetes, trauma, radiation, poisoning, and local nutritional disorders, can lead to damage to the capsule of the lens, increasing its permeability and losing its barrier function, or causing metabolic disturbances in the lens. This can cause the proteins in the lens to denature, leading to cloudiness of the lens, which is known as cataracts. Under a slit lamp microscope, varying degrees of cloudiness in the lens can be observed.

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Written by Peng Xi Feng
Ophthalmology
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The main symptoms of cataracts

The main symptoms of cataracts include: First, a decline in vision, which is the most obvious and significant symptom of cataracts. Second, a decrease in contrast sensitivity, particularly noticeable at high spatial frequencies in cataract patients. Third, changes in refractive power. Nuclear cataracts lead to increased lens power due to an increase in the lens and refractive index, causing nuclear myopia. Fourth, monocular diplopia or polyopia due to uneven refractive power across different parts of the lens, similar to the effect of a prism, resulting in monocular diplopia or polyopia. Fifth, glare. Sixth, changes in color perception. Seventh, varying degrees of visual field defects.