Cataract (Cataract) clouding of the lens is called cataract. Aging, heredity, metabolic abnormalities, trauma, radiation, poisoning and local malnutrition can cause damage to the lens capsule membrane, which increases its permeability and loses its barrier effect, or lead to disorders of lens metabolism, resulting in degeneration of lens proteins and formation of clouding. It is divided into congenital and acquired.
Classification of formation: Congenital cataracts mostly exist before and after birth, while a small proportion gradually forms after birth, and are mostly hereditary diseases with two types: endogenous and exogenous. Congenital cataracts are classified into anterior pole cataract, posterior pole cataract, round nucleus cataract and total cataract. The first two do not require treatment, while the latter two require surgery. Acquired cataracts are clouding of the lens after birth due to systemic diseases or local eye diseases, abnormal nutrient metabolism, poisoning, degeneration and trauma. There are 6 types of cataracts: ① Age-related cataracts. The most common . Most often seen above 40 years of age, and with age.
The cause is related to the slow metabolism of degenerative lesions in the elderly, and some believe it is related to long-term sunlight exposure, endocrine disorders, and metabolic disorders. According to the location of the initial clouding, it can be divided into two categories: nuclear and cortical. Visual impairment is related to the location and density of the clouding, and post-cortical and nuclear clouding affects vision earlier. (2) Complicated cataract (complicated by other eye diseases). (iii) Traumatic cataract. ④Metabolic cataract (due to endocrine insufficiency, such as diabetic cataract). ⑤ Radioactive cataract (related to X-rays, β-rays, γ-rays, etc.). ⑥ Drug and toxic cataracts. If treated in time, the cataract will become more and more severe in the lens and eventually become completely blurred and the nucleus of the lens disintegrates, resulting in complete loss of vision. The main symptom of cataract is visual impairment, which is related to the degree and location of lens clouding. Severe cataracts can lead to blindness.
Cataracts are classified by etiology as age-related (senile), traumatic, concurrent, metabolic, toxic, radiation, developmental and posterior cataracts.
Main symptoms
Blurred vision, which may include photophobia, seeing objects darker or yellow, or even diplopia (double vision) and distortion of seeing objects.
Symptom classification
Crystalline lens consists of crystal capsule, crystal epithelium and protein-rich crystal fibers. A normal crystal is transparent and non-vascular, and its nutrition comes mainly from atrial fluid. When the atrial fluid composition and crystal capsule permeability change and metabolic disorders are caused by various reasons, the crystal protein degenerates, edema, water fissures between fibers, vacuoles, and epithelial cells proliferate, and the crystal changes from transparent to cloudy. Regardless of the location and degree of clouding, and whether it affects vision, it can be called cataract. However, in epidemiological surveys, there are also cases of clouding of the lens with reduced visual acuity below 0 or 7 that are classified as cataracts.
Cataracts can be classified according to the cause, age of occurrence, speed of development, degree and location of crystal clouding
1. according to the etiology: traumatic, senile, concurrent, drug and toxic, etc.
2.According to the age of occurrence: congenital, infantile, youthful, adult, and geriatric
3.According to the degree of crystal clouding: immature stage, swelling stage, mature stage, overripe stage
4.According to the speed of development: stationary, progressive.
5.According to the site of clouding: nuclear, cortical, cystic, subcapsular
6. according to the morphology of the clouding: lamellar, coronal, punctate and other forms.
Usually, cataracts are classified into several types such as senile, concurrent, congenital, traumatic, metabolic, drug and toxic, and posterior.
Etiology
To the best of our knowledge, the development of senile cataracts may be related to the following factors.
(1) Nutrient metabolism Through animal observation, it is found that certain vitamin and trace element deficiencies are related to cataract formation, such as calcium, phosphorus, vitamin E, A, B2, etc.
(2) Sunlight and ultraviolet light Over the years, it has been noted that sunlight is involved in the formation of human cataracts. Under the influence of UV light, phosphorus ions may combine with calcium ions in the aging lens to form insoluble calcium phosphate, which leads to the hardening and calcification of the lens. Also ultraviolet light affects the redox process of the lens, prompting the denaturation of lens proteins and causing cataracts.
(3) External temperature The incidence of cataract in workers over 60 years old who work under high temperature is significantly higher in a survey conducted by foreign scholars.
(4) Hypoxia Under the condition of hypoxia, it can increase sodium and calcium in the crystal, reduce potassium and vitamin C accordingly, and increase lactic acid, prompting the formation of cataracts.
(5) Endocrine endocrine disorders can contribute to cataracts, as illustrated by the higher occurrence of cataracts in diabetic patients compared to the general population.
(6) Sclerotic dehydration When dehydration occurs in human body, the fluid metabolism in the body is disturbed, and some abnormal substances are produced to damage the crystal. Animal experiments have proved that after giving hypertonic dehydration, the crystal appears empty.
What tests are required for cataract.
Before cataract surgery, we should know whether the vitreoretinal retinal macula area is normal and whether there are lesions in the choroid, and we will have a correct estimation of the recovery of vision after cataract surgery. It is possible to understand whether there is vitreous lesion retinal detachment or intraocular swelling with the help of A and B type ultrasound. It is also possible to understand the length of the eye axis and the position of dislocated crystals Electroretinography (ERG) is of great value in evaluating the retinal function. In order to rule out visual impairment due to macular degeneration in monocular cataract patients, preoperative evoked potential (VEP) examination can be performed, and visual interferometry can also be used to examine the macular function of immature cataracts.
With modern microsurgery becoming more sophisticated, cataract and IOL implantation is possible as an outpatient procedure. At present, postoperative astigmatism is controlled as much as possible, while preoperative astigmatism is corrected during surgery and viscoelastic substances are used to minimize endothelial and other tissue damage. The expansion of surgical indications, such as one-eyed diabetic cataract can be implanted IOL capsule technology, the development of the nucleus and cortical treatment technology new IOL design size and surface treatment have been developed. Yellow IOLs were introduced in an attempt to improve the symptoms of glare and visual color field after general IOL implantation. With the increasing popularity of cataract extraction by ultrasound and IOL implantation, laser emulsification will also be used in clinical practice. The research and development of injectable IOLs will certainly bring cataract surgery to a new level.
Cataract and which diseases are easily confused
Congenital and acquired.
(1) Congenital cataracts are mostly present before and after birth, and some of them are formed gradually after birth. The first two require no treatment and the second two require surgery.
(2) Acquired cataract is a clouding of the lens after birth due to systemic diseases or local eye diseases such as abnormal nutrient metabolism, toxic degeneration and trauma, etc. There are six types of cataracts.
(1) Age-related cataracts are the most common, most often seen in people over 40 years of age and increase with age. The cause is related to slow metabolism and degenerative lesions in the elderly, and some believe it is related to long-term sunlight exposure, endocrine disorders, metabolic disorders and other factors. Postoperative contact lenses can be used as well as surgical IOL implantation.
(ii) Complicated cataract (complicated by other eye diseases).
(iii) traumatic cataracts.
④Metabolic cataract (due to endocrine insufficiency such as diabetic cataract).
(5) Radioactive cataracts (related to X-rays, β-rays, γ-rays, etc.).
⑥ If drug and toxic cataracts are not treated in time, the bleaching in the lens will become more and more serious and eventually become completely blurred and the nucleus of the lens will disintegrate, resulting in complete loss of vision.
Treatment
Cataracts can usually only be treated with surgery. Cataract surgery has made significant progress in the past 30 years due to the application of surgical microscopes, microsurgical instruments and artificial lenses, and improvements in suture materials and local anesthesia methods. Currently, most cataracts are treated by cataract extraction, and after surgery, an artificial lens is implanted in the eye or glasses or corneal contact lenses are worn to correct vision.
Because light entering the eye must pass through the lens, vision can be affected if the lens blocks the incoming light, or if the incoming light is deflected or diffused. The extent to which vision is affected depends on the location and density of the lens clouding (cataract maturation).
In bright light, the pupil narrows and the light pathways in the eye become narrower, making cataracts more likely to block incoming light. As a result, many cataract patients have worse vision in bright light. And halos, glare and scattered light appear around the light. Blurred vision is especially noticeable when cataract patients enter a bright environment from a dark place, or when reading under a bright light. Patients who have both glaucoma and cataract also experience a significant loss of vision after pupil-diminishing drops due to pupil narrowing.
Cloudiness located at the posterior aspect of the lens (posterior subcapsular cataract) also has a heavier effect on vision in bright light. Because the posterior pole of the lens is where light must pass, this type of cataract is more likely to impair vision.
There is a type of nuclear cataract (clouding from the center of the lens), which can show improved near vision in the early stages. The reason for this is that nuclear cataract increases the focusing ability of the lens and makes objects at close range appear clearer. Most older adults who have difficulty seeing close objects because of their old eyesight are surprised to find, in the early stages after developing a cataract, that they can read without presbyopic glasses, a phenomenon often referred to as second sight. Although cataracts are generally painless, a few patients may experience eye pain due to increased eye pressure (glaucoma) caused by swelling of the lens.
Corneal contact lenses for cataract correction, also known as medical cosmetic contact lenses
1.Medical blind lenses effectively cover up the defects of cataract patients, so that your eyes can reach perfect alignment.
2, play the role of artificial pupil, commonly used in patients with iris trauma, atrophy or albinism.
It can cover up corneal defects with realistic wearing effect.
Types of cataract surgery
(1) Modern cataract extracapsular cataract extraction (extracapsluar cataract extraction) means microsurgery under coaxial light illumination. The basic procedure is to puncture and tear away the central part of the anterior capsule, deliver the nucleus, and aspirate the cortex in the peripheral capsule with a cataract simultaneous aspiration needle, leaving the posterior capsule and the peripheral anterior capsule intact.
The main advantage of extracapsular cataract extraction is that the posterior capsule is preserved, which facilitates the implantation and fixation of IOLs and is suitable for adults with nuclear cataract. Currently, extracapsular extraction and IOL implantation are the main surgical procedures in developed regions. The disadvantage is that some patients need to undergo posterior capsulotomy again due to clouding of the posterior capsule affecting vision within 1 to 5 years after surgery.
(2) Intracapsular cataract extraction is an operation that removes the lens after disconnecting the suspensory ligament of the lens. It is suitable for elderly cataracts with sclerotic or dislocated crystals. The lens is removed outside the incision by clamping the anterior capsule of the lens with special capsular forceps or by freezing the adhesion to the anterior capsule of the lens with a frozen tip.
Due to the loss of crystal support after surgery, the vitreous motility increases, and there are more complications after surgery, and it is not easy to implant a posterior chamber IOL. This procedure is less frequently done now. However, in underdeveloped areas, most hospitals do not have the conditions for microsurgery yet, and intracapsular surgery is still the main cataract surgery. For aphakic eyes with better conditions after intracapsular extraction, suture fixation of IOLs through the sclera is feasible.
(3) aspiration of cataract is an extracapsular procedure in which the anterior capsule is punctured and the cloudy nucleus and cortex are aspirated. It is mainly used for congenital cataracts with hard nuclei and soft cataracts. In recent years this procedure has evolved into cystectomy.
(4) Cataract phacoemulsification is an extracapsular extraction procedure. The basic method is to make a small incision of 3mm at the corneoscleral rim, insert an ultrasonic crusher to crush the nucleus of the lens and then aspirate it.
(5) Crystalline capsulotomy or excision is to cut the cloudy posterior capsule and the attached cortex centrally for the purpose of light transmission. It is mainly applied to congenital cataract or posterior cataract. The YAG laser can be used to perform posterior capsule dissection or membrane dissection.
(6) Optical iridotomy In the past, segmental iridotomy below the nose was used for congenital nuclear cataracts. It uses the peripheral part of the clear crystal to transmit light and improve vision. Since the light comes from the outer region of the visual axis, the imaging quality is poor. The corrected visual acuity after surgery is mostly unsatisfactory. The surgery also destroys the barrier of the iris, making future surgery and optical correction difficult. This surgery is no longer advocated.
Cataracts and their modern surgical outcomes
There are no drugs that have a definite effect on the treatment of cataracts, and surgery is the main treatment. Surgical treatment of cataracts by ophthalmologists means that the clouded lens is surgically removed. So, what is the effect of removing one’s own lens on the eye? In addition to transmitting light, the lens of the human eye also serves as a convex lens, or magnifying glass. After the lens is removed, an artificial lens must be implanted, which is often referred to as an IOL implant. The purpose of IOL implantation is to correct the high degree of hyperopia caused by the surgical removal of the lens.
Since the introduction of cataract microsurgery, the method of cataract removal has continued to improve. From the traditional surgical method of cataract extracapsular extraction to the more advanced cataract ultrasonic phacoemulsification, there has been a transition from large incisions to small incisions. The former has a large incision, but this method will not be eliminated at this time. This is because some patients who are not suitable for cataract ultrasound emulsification still need to use this surgical method. The latter is characterized by small incision, small postoperative astigmatism, fast recovery of vision after surgery, low incidence of intraoperative and postoperative complications, and no rupture of the original wound in case of accidental injury after surgery.
Nowadays, the domestic advanced ultrasonic emulsification combined with IOL implantation is also used to treat cataract. It is the application of advanced ultrasonic emulsification device with the smallest incision of only 2, 0mm to crush and suck out the cloudy crystal, which can well preserve the crystal capsule membrane and can put the artificial crystal into the capsule bag, thus effectively preventing the postoperative crystal deviation and dislocation, etc.
The advantages of this procedure are.
(1) It can be operated at the immature stage (as soon as the patient feels that the cataract affects the vision), instead of having to wait until the surgery is mature, so that cataract patients can regain their sight as soon as possible.
(2) Small incision, no suture, good closure of the incision, and the patient can go home after surgery.
(3) Short operation time (6-7 minutes to complete); only local anesthesia is needed.
(4) Small postoperative astigmatism and fast recovery of visual function.
(5) Light postoperative reaction and low complication rate.
(6) For people with fundus lesions, the presence of cataract directly affects the examination, diagnosis and treatment of fundus diseases. This surgery can make the fundus disease become timely examined and treated.
(7) The blindfold can be removed the day after the surgery and the patient can resume normal life.
Cataract Ultrasound Emulsification Technology
Since 1967, Dr. KELMAN in the United States invented the first ultrasonic emulsification instrument and used it in clinical practice. After more than 30 years of continuous improvement and perfection by many ophthalmologists, cataract ultrasonic emulsification technology has become a world-renowned, advanced and mature surgical method. Ultrasound emulsification is now popular in developed countries and has been introduced and promoted in China since 1992. During the surgery, an ultrasound probe is inserted into a small incision in the cornea or sclera to break the cloudy lens and cortex into celiac disease, and then the celiac disease is sucked out with the help of a suction and perfusion system, while keeping the anterior chamber full. The ultrasonic emulsification technology truly achieves the surgical ideal of small incision, no pain, short operation time, no hospitalization, and rapid recovery of vision.
What are the features of cataract ultrasonic phacoemulsification IOL implantation.
Compared with traditional surgery, cataract ultrasonic emulsification IOL implantation has the following advantages.
1. Small surgical incision, 12MM for traditional surgery, but less than 3MM for this surgery.
2. Light postoperative reaction, quick healing of the incision, faster and better recovery of vision.
3.Smaller post-operative astigmatism, and easier to correct or control.
4, better control of surgery, safe and stable.
5.Surgery time is short, generally only about 15-30 minutes.
6.No need for hospitalization, you can go home 1 hour after surgery.
7. No need to wait for the cataract to mature before performing the surgery.
Why is it necessary to install IOL after cataract extraction?
After cataract removal, the eye loses the essential structure of the lens, so the vision is still unclear. Under normal circumstances, IOL implantation can be used for a lifetime.