A cataract is a clouding of the lens in the eye from clear to opaque, preventing light from entering the eye and thus affecting vision. Cataracts are the leading cause of blindness worldwide. According to the results of our survey, cataract is also the most important eye disease causing blindness in China. The causes of cataracts are multifaceted, except for traumatic cataracts, radioactive cataracts, congenital cataracts and diabetic cataracts which have relatively obvious causes, the cataract formation process may have multiple 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 over-exposure to ultraviolet light, genetic factors, and malnutrition. In addition, diabetes mellitus, galactosemia, and hypothyroidism, which are common in clinical practice, can also cause cataracts.
Clinical manifestations:
1, often both eyes are affected.
2. Immediate shadows and progressive painless vision loss.
3. Refractive power increases and becomes myopic.
4. Monocular diplopia or hyperopia may occur.
5.Iris vision may be present.
6. Photophobia and glare.
2.Cautions for cataract surgery
Pre-operative preparation.
Keep clean: Be sure to take a bath, wash your hair and change your clothes before surgery;
Maintain physical strength: avoid labor and travel, and avoid diseases such as cold;
Administer medication on time: eye drops should be administered 4-6 times a day for more than 3 consecutive days.
Post-operative management: post-operative medication and review must be carried out according to the physician’s medical advice. On the day of surgery, take more rest, avoid coughing with your head down, avoid dry stools and avoid lifting heavy objects. All daily life is normal, do not smoke and drink. After surgery, cooperate with the doctor’s examination and take regular eye drops as prescribed by the doctor. Post-operative blurred eyes, mild foreign body sensation, and orbital bruising are normal. If significant eye pain, nausea, vomiting, etc. occur, and if eye redness starts to increase and eye pain begins 5-7 days after surgery, do not be nervous, but check promptly and deal with it early.
Do not allow sewage or soapy water to enter the operated eye for 2 weeks after surgery, do not apply pressure (rubbing the eye, etc.) for 4 weeks, and avoid trauma. do not do heavy labor or strenuous exercise for 3 months. Vision is unstable for 3 months to 6 months after surgery. Refractive examination is usually done at 3 months, and a pair of low-degree glasses is prescribed if necessary to adjust the vision of seeing far or near to achieve the best results.
What are the causes of cataract?
Except for traumatic cataract, radioactive cataract, congenital 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 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 exposure to ultraviolet radiation can affect the oxidation and reduction process of the lens, causing degeneration and clouding of the lens proteins to form cataracts. In addition, diabetes, galactosemia, hypothyroidism and other common clinical conditions can also cause cataracts.
Cataract: timing of surgery
Due to the limitation of medical technology, in the past, cataract had to wait until it was completely “mature” and the affected eye could not see before surgery, and the patient had to endure the trouble and pain of low vision for a long time. With the application and development of cataract surgery, the safety and effectiveness of cataract surgery have been greatly improved. Patients no longer need to wait until they are completely blind before undergoing surgery, but can receive surgery when cataract medication is ineffective and affects their daily life and work.
The risk of surgery does not increase for experienced surgeons when surgery is done early. For different patients, the timing of early or late surgery can vary greatly. For a person who has a delicate job and needs more vision, surgery can be done earlier. At present, it is common in developed countries to receive surgery for eyes with visual acuity of 0.5, and the number of cases with such requirements is increasing in China; for a person who does not require higher visual acuity, it is not a bad idea to wait until the vision is poor. In any case, the timing of surgery must be determined from the patient’s actual requirements and discussed between the doctor and patient.
In addition, the degree of IOL implantation plays a decisive role in the recovery of the patient’s vision after surgery. In hospitals that have the conditions, patients must undergo eye A ultrasound and corneal curvature measurement before surgery to precisely calculate the IOL prescription, and only if the right IOL is implanted during surgery can they obtain good vision after surgery.
In principle, surgery should be done as early as possible for congenital cataracts, and the development of retinal macular function can be promoted after surgery under the stimulation of external light. Surgery should be strived for within 2 months after birth, and no later than 3 to 4 years old, and should be performed as soon as visual acuity is found to be lower than 0.2. If surgery is performed beyond 6 years of age, it often causes amblyopia that is difficult to recover. However, for incomplete cataracts that still have some vision, surgery can be postponed until after 5 to 6 years of age. The possibility of IOL implantation for congenital cataract surgery is determined on a case-by-case basis.
The purpose of IOL implantation in children is to correct visual acuity, prevent amblyopia, and restore fusion function and stereo vision. Therefore, the visual function should be carefully checked before surgery, and patients with poor visual function should be treated with surgery as early as possible. However, IOL implantation is only one method to correct aphakic eyes in children, but not the only method. Contact lenses for children under 2 to 3 years old are still the preferred method for aphakic eyes. Because the affected eye has no adjustment function after IOL implantation, although better distance vision is obtained after surgery, near vision (reading vision) is still poor. This is extremely detrimental to the developing visual system and has a greater impact on pediatric patients who attend school and study.
Traumatic cataract crystal cortex can be stimulated to cause capsular hyperplasia and clouding during absorption, the inflammatory reaction caused by cortex can spread to retina and optic nerve, and iris adhesion and neovascularization can cause secondary glaucoma and impair visual function, thus timely treatment should be provided after the injury to avoid late complications. If there is only limited clouding of the crystal after trauma, do not rush to do cataract surgery, because it is difficult to determine the degree of damage and can be further observed.
If the crystal cortex is completely clouded and the cortex is protruding or free to the anterior chamber, surgery should be performed as soon as possible and the crystal cortex should be completely removed as much as possible. For those who have total clouding of the lens after trauma and the cortex has not entered the anterior chamber, the inflammatory response should be controlled and cataract surgery should be performed after the traumatic iridocyclitis has stabilized.