1. What is a cataract?
Cataract is a clouding of the normal transparent lens that affects vision. In common parlance, the human eye is like a camera, the lens of the camera is the lens, and the retina of the fundus is equivalent to the film. Cataract is like a clouded camera lens, and it is difficult for light to reach the film —– fundus retina, so it is difficult to get a good image. The patient’s vision is related to the degree of clouding of the lens. Initial clouding has little effect on vision, while it gradually worsens and significantly affects vision or even blindness.
Cataracts are the leading cause of blindness worldwide, with approximately 20 million people worldwide now blind due to cataracts, and in most African and Asian countries, cataracts account for at least half of all blind people. According to the results of our survey, cataracts affect more than 11 million people nationwide and are the leading eye disease causing blindness in China.
As the life expectancy in the world increases, the number of cataract patients will continue to increase.
The most effective method of cataract treatment is surgery. The majority of patients can successfully recover their vision through surgery.
2. What is the function of the lens?
The lens is one of the important refractive interstitium of the eye, a biconvex, flat, transparent structure. It relies on the elasticity of the lens, the contraction and relaxation of the ciliary body, and the relaxation and tension of the lens suspensory ligament to enable our eyes to adjust to see at various distances, which we call the adjustment function.
As we age, the elasticity of the lens capsule decreases, the nucleus of the lens increases and hardens, the ciliary muscle becomes weaker, and the adjusting power decreases, resulting in presbyopia.
3. The common cataracts are as follows: (1) Age-related cataract is the most common. This term has been replaced by age-related cataract because some patients develop cataract in middle age instead of old age, and it is more accurate to use age-related cataract to describe the change of the lens in relation to age. It is mostly seen in people over 50 years of age, and almost 100% of older people over 80 years of age have cataracts, only to varying degrees.
(2) Some are congenital cataracts (mostly seen in children), present at birth or occurring at an early age.
(3) Eye trauma can also cause cataracts, called traumatic cataracts.
(4) Complicated cataracts caused by diseases such as intraocular inflammation and hemorrhage.
(5) There are also metabolic cataracts caused by diabetes, nephropathy and other medical diseases, and drug cataracts caused by the use of hormones and other drugs, or radioactive cataracts caused by exposure to infrared light and microwaves, etc.
4.What are the causes of cataract?
Apart from congenital cataract, traumatic cataract, radioactive cataract and diabetic cataract, which have obvious causes, the formation process of cataract may have various factors and the situation is quite complicated. The pathogenesis of the common senile cataract (age-related cataract) has not been fully revealed so far, and may be related to ageing, long-term excessive exposure to ultraviolet light, genetic factors and malnutrition. In China, it has been confirmed by investigation that the incidence of cataract is relatively higher in highland areas and areas with more sunlight radiation, with the highest incidence in Tibetan areas of China. This is because long-term exposure of the lens to ultraviolet radiation affects the oxidation-reduction process of the lens, causing degeneration and clouding of the lens proteins to form cataracts. In addition, diabetes, galactosemia, hypothyroidism, etc. can also cause cataract.
5. What are the symptoms of cataract?
Cataracts often develop in both eyes, but the onset may be sequential and the severity may vary. The main symptoms are: shadow in front of the eyes and gradual and painless vision loss. The clinical manifestations vary depending on the location of the clouding.
(1) Cortical cataract, early —, does not affect vision; after development, check vision is good 0.6, to read books and newspapers in bright light. Some people read books in dark light clear, central clouding. Some develop slowly (fissure) and develop quickly (fissure clouding).
(2) nuclear cataract such as highly myopic eyes, in the process of vision loss may appear refractive power enhancement, both the original myopia increased or the original presbyopia reduced, some people who usually need to wear presbyopic glasses can even remove glasses to read newspapers and books, the second vision.
(3) Overlap of what is seen. Contrast sensitivity decreases in strong light, and glare occurs at night under headlights. French Monet is a famous impressionist painter, it is said that his fame is related to cataracts. The early painting Bridge over a Pool of Water Lilies, which did not become famous, was painted in a delicate style with realistic colors. Later, after getting a cataract due to an eye disease, the bold use of bright colors became a master of impressionism, due to a decrease in contrast sensitivity.
(4) Symptoms such as monocular diplopia or hyperopia, iridopsia, photophobia and glare may also occur.
Generally speaking, symptoms develop slowly, but patients with systemic diseases such as diabetes or with localized eye diseases such as high myopia, post-operative glaucoma, retinitis pigmentosa, uveitis, etc., cataracts will occur earlier and progress faster.
6.Will cataracts also cause sudden vision loss?
In general, the symptoms of cataract are gradual loss of vision and finally blindness, without eye pain and other symptoms during the whole process. If patients suddenly feel a significant loss of vision without pain, they should consider that there may be lesions in the fundus of the eye, such as fundus hemorrhage, optic nerve papillopathy or retinal detachment, etc. They must go to an ophthalmologist immediately not to mistake it for cataract.
During the development of senile cortical cataract, there is a process called expansion period. During this period, there is more water accumulation in the crystal, which makes it swell sharply, increase the volume and make the anterior chamber shallow, and patients can feel the speed of vision loss at this time. If this kind of glaucoma is not treated in time, it will cause permanent blindness, and even cataract surgery cannot save the vision.
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