What is cataract? Cataract is a common and major blindness-causing eye disease. Under normal conditions, it is transparent and light passes through it and some refractive interstitium to reach the retina so that people can see objects clearly. Once the lens becomes cloudy for some reason, it will affect the light entering the eye and reaching the retina, making it difficult for people to see, which is the occurrence of cataract. In other words, a cloudy lens that causes vision loss is a cataract.
Cataracts are the leading cause of blindness and vision impairment worldwide and are most commonly seen in people over the age of 50. As the population grows and ages, cataracts will cause more and more vision impairment. Approximately 20 million people worldwide are blind due to cataracts, and another 100 million cataract patients need surgery to restore their vision. In most African and Asian countries, cataracts account for at least half of all blind people. According to the results of our survey, cataract is also the most important eye disease causing blindness in China.
II. Causes of cataracts The causes of cataracts are many, except for traumatic cataracts, radioactive cataracts, congenital cataracts and diabetic cataracts which have relatively obvious causes, the cataract formation process may have many factors and the situation is quite complicated. The pathogenesis of common senile cataracts 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 cataracts is relatively higher in highland areas and areas with more sunlight radiation. This is because long-term ultraviolet radiation can affect the oxidation-reduction process of the lens, causing degeneration and clouding of lens proteins to form cataracts. In addition, diabetes, galactosemia and hypothyroidism, which are common in clinical practice, can also cause cataract.
What are the symptoms of cataract? Generally, the symptoms of cataract are gradual loss of vision and finally blindness, without eye pain during the whole process. The onset of cataract can be sequential in both eyes. In addition to vision loss, some patients can see a fixed black spot against a bright background, and some may have monocular diplopia and increased myopia. If patients suddenly feel a significant loss of vision without pain, they should consider whether there is a lesion in the fundus, such as fundus hemorrhage, optic nerve papillopathy or retinal detachment, etc. They must see an ophthalmologist immediately and not be mistaken for the cause of cataract.
Clinically, geriatric cataracts are classified into three types: cortical, nuclear and subcapsular. During the development of cortical cataracts, there is a period called the “swelling phase”. During this period, more water accumulates in the lens, causing the lens to increase in size and the anterior chamber to become shallow. In some patients, this can even lead to secondary glaucoma, where the patient can experience eye redness, eye pain with headache, nausea, vomiting, and a dramatic loss of vision or even light perception. If this kind of glaucoma is not treated in time, it will cause permanent blindness, and even if cataract surgery is performed again, vision cannot be saved.
How to treat cataract Although people have never stopped exploring cataract treatment since ancient times, until today, there is no real effective drug to stop the development of cataract, and surgery is still the only effective way to treat cataract. Early cataracts with only a mild loss of vision that does not affect daily life can be checked regularly at the hospital and do not require immediate surgery. When the disease deepens, patients can discuss with their doctors to decide when to undergo surgery according to their daily work and life needs for vision. It is not necessary for a cataract to be fully mature before receiving surgery. For mature or near-mature cataracts, surgery is needed as soon as possible.
Some people think that there is no harm in not having surgery when the cataract is mature, because they just can’t see. This is actually a very wrong and dangerous view. If cataracts are not treated in time, many serious complications will occur, such as glaucoma and uveitis, which occur in the middle and late stages of cataracts, such as the expansion stage and the overripe stage. Sometimes it can cause serious inflammation in the eye, which can cause blindness and even lead to atrophy of the eye. Some patients have long-term eye pain due to cataract secondary to glaucoma, which is unbearable, and finally they have to have their eyes removed as a last resort. Therefore, we are reminded that cataracts must be treated surgically when they reach a certain level, and the concept of “cataracts can be operated only when they are ripe” should be abandoned.
The common surgical methods for cataract extraction are divided into two categories: intracapsular and extracapsular extraction, according to the integrity of the crystal capsule during extraction. Intracapsular cataract extraction and traditional extracapsular cataract extraction have become a thing of the past. With the improvement of microsurgical techniques, modern extracapsular cataract extraction combined with human lens implantation has gained wide popularity. The requirements of this surgical operation are relatively easier and safer. In recent years, cataract ultrasound emulsion aspiration combined with human lens implantation has been carried out. This surgery is performed through a corneal incision of about 3 mm to crush out the nucleus and cortex of the lens and preserve the posterior capsule of the lens so that a posterior chamber IOL can be implanted, which has the significant advantages of small surgical incision, quick healing of the incision after surgery, small corneal astigmatism, and satisfactory vision at an early stage.