The lens plays the role of a lens in the eye. He is able to focus light in the retina. Before the appearance of the artificial lens, patients after cataract removal wore glasses with very massive plus glasses or contact lenses.
Today, the choice of artificial lenses is very wide. Not even any surgeon understands the variety of models. The main types of the lens will be described in this review article.
In what cases is implantation of an artificial lens required?
An intraocular lens is implanted in the area of the natural lens, provided that it has lost its natural functions. For example, during surgical intervention to remove cataracts, when the natural crystalline lens loses its transparency, the IOL makes it possible to correct myopia, hyperopia and astigmatism of a high degree.
A lens placed inside the eye can act as a natural lens and provide all the necessary functions of vision.
The invention of a phakic intraocular lens was a true solution to the problem for patients with a high degree of myopia, hyperopia and astigmatism. Also, such models are installed for patients who, for various reasons, are contraindicated in conducting vision correction using a laser.
An alternative to laser vision correction is the method of refractive lens replacement with an artificial IOL model. The visual apparatus thus loses the ability to accommodate (vision of objects located at different distances). After such surgical intervention, the patient is prescribed to wear glasses for reading and seeing objects close by. This method is indicated if natural accommodation is lost, which usually applies to patients over the age of 45-50
The implantation of a phakic intraocular lens has proved to be the best in the event that natural accommodation has not yet been lost and it is possible to implant a lens without removing the natural lens. Phakic lenses enable the patient to see objects both close and at a distance.
IOL device
Typically, an intraocular lens includes two elements: optical and reference.
The optical component is a lens made of a transparent material. It is combined with living tissues of the eye. On the surface of the optical part there is a diffraction zone, which makes it possible to obtain a clear vision. The supporting part is responsible for the reliable fixation of the lens in the capsule of the eye.
An implanted artificial intraocular lens does not have an expiration date. It provides a person with full vision for many years.
Key benefits of phakic models
- Do not touch the iris and cornea, which prevents the development of dystrophic changes.
- Combined biologically with the human eye.
- They have special retina protection from the negative effects of ultraviolet radiation.
- Provide speedy recovery of vision.
- Preserve the structure of the cornea.
Hard and soft modifications
The lenses are divided into two main types: hard and soft. In the practice of oculists around the world, the golden rule has been the operation without seams - phacoemulsification.
Phacoemulsification of cataracts by implantation of an intraocular lens implies an incision of 2.5 mm in length. The lens should be soft. This allows you to roll it into a tube through an injector specially designed for these purposes. Inside the eye, he straightens and acts as the lens.
An outdated technique involved making a 12 mm long incision and suturing for six months. So a rigid model was implanted.
Spherical and Aspherical IOL Type
Aspheric intraocular lens provides minimal glare from light sources day and night. This means that no matter where its point hits the light, it will everywhere undergo refraction, both in the center and along its edges. This is a very important indicator for the dark, when the pupil of the eye is as wide as possible.
For example, there is no blinding from headlights of cars. This property is very important for drivers. Optical color reproduction and a high level of contrast are also characteristic of the aspherical type of lens.
The spherical type involves the refraction of different intensities in different areas of the lens. This contributes to the scattering of light, which adversely affects the quality of the visual function. This type of lens can cause glare and glare.
Multifocal and monofocal model
Monofocal lens is designed to provide high-quality visual perception of objects located far away. For reading after surgery, plus points are required.
The intraocular lens device (IOL) of the multifocal type is the most advanced. This determines its high cost. It allows the patient to see objects at all distances. Such a function is provided by the complex configuration of its optics. For vision near, in the middle and in the distance, three different zones are responsible. In this case, the patient does not need to wear glasses. That is why the cost of such devices is extremely high.
Toric models
Toric models are designed to solve the problem of astigmatism. Astigmatism refers to the irregular shape of the cornea that distorts the image. If such a patient undergoes cataract removal and a standard lens is placed, the pathology will not disappear. So, after the operation, he will again be shown wearing cylindrical glasses.
When a toric lens model is implanted, the patient can be compensated for astigmatism and obtain a contrast vision of objects. The required cylinders are already integrated into the toric lens. By installing such a lens inside the eye through special marks on the lens, the patient can achieve a clear image.
The installation of such models involves conducting clear calculations before surgery. For each patient they are carried out individually.
Testimonials from patients with astigmatism indicate that the implantation of toric models brings the best result. Many patients after surgery note that their vision has become so clear that it was not even in young years.
Multifocal toric lens
A series of IOLs completes the multifocal toric model. If the patient suffers from astigmatism and wants to see equally well both close and at a distance, then he is shown implantation of this particular type. Such a lens allows you to restore vision. In this case, the patient will never need glasses. This is the most expensive type of lens.
Yellow and Blue IOL UV Filters
The natural eye lens has a unique protective ability that blocks the harmful radiation of the sun. This prevents damage to the retina. Modern ophthalmology involves the release of all types of IOLs with a UV filter.
Special lens models are painted with yellow pigments to achieve maximum resemblance to the natural lens. These filters filter out harmful blue light that is in the invisible part of the spectrum.
AcrySof IQ
The AcrySof IQ smart lens is used to correct spherical aberrations (glare, ghosting, and glare) in bright light. This model is able to give excellent vision in any lighting conditions. This is an ultra-thin lens (two times thinner than usual).
In the central part, the ordinary lens is thinner than on the sides. It is because of this that the light rays that pass through its peripheral region are focused to the retina, and the central rays are focused on it. So the rays of light are focused at more than one point. As a result, the image on the retina is not clear.
The intraocular lens AcrySof IQ fixes this problem. Its rear surface is created in such a way that makes it possible for all light rays to gather at a single point. The image provided by this model is characterized by a high level of quality, contrast and clarity at any time of the day.
Surgical replacement of the cataract lens
Today, implantation of an intraocular lens by ultrasound phacoemulsification is a low-risk manipulation for patients. It has a high level of efficiency. In almost 95% of cases of cataracts in Europe, the USA and our country, this method is removed.
The World Health Organization recognized the operation as the only surgical intervention among all that is distinguished by complete rehabilitation.
What is the essence of surgical intervention?
The basis of cataract surgery is the removal of a clouded lens, which prevents the full flow of light to the retina. An artificial intraocular lens replaces a damaged natural lens.
The main stages of implantation
The vast majority of phacoemulsification operations are performed in private clinics on an outpatient basis. The stages of preparation for an operation are almost the same everywhere:
- An hour before the start of the operation, the patient should be at the clinic.
- In order to expand the pupil, drops containing an anesthetic are instilled into it.
- The patient is placed on the operating table. Anesthetist does anesthesia.
- The cataract is removed by the surgeon and the lens is implanted.
- The operation does not require suturing.
- After surgery, the patient is redirected to the ward.
- An hour after the operation, the patient is sent home.
- The next day, the patient should come for a visit to the doctor.
How is the operation
To access the cornea, a microscopic incision of 1.8 mm is performed. A clouded lens is softened by ultrasound and transformed into an emulsion, which is removed from the eye. An intraocular flexible lens is inserted into the capsule by means of an injector. It enters the eye in the form of a tube, where it itself unfolds and is securely fixed.
The microscopic incision is subsequently sealed without outside intervention. Therefore, suturing in this case is not necessary. Vision for the patient returns, as a rule, already in the operating room.
The duration of the operation is 10-15 minutes. In this case, drip anesthesia is used, which is easily tolerated by the body and does not exert pressure on the heart and blood vessels. After surgery, the patient quickly joins the normal rhythm of life. Limitations are minimal. They mainly relate to hygiene.
Rehabilitation period
After the operation, the doctor prescribes special drops for the eyes to the patient and determines the frequency of their use. Dates for additional preventive examinations are also set. The patient is allowed to lead his usual lifestyle: read, write, work at the computer, watch television, take baths, sit and lie in a comfortable position. There are no dietary restrictions either.
What is the complexity of the operation?
Implantation of an intraocular lens has a certain complexity, which lies in the high requirements for the accuracy of calculation and selection of a lens model, as well as the professional work of an ophthalmologist. That is why the most important condition before the operation is a complete diagnosis. Only a detailed examination carried out by means of a whole complex of modern equipment makes it possible to obtain an objective state of vision of the patient.
Benefits
Ultrasonic phacoemulsification of cataracts is distinguished by the perfection of the technology developed over many years. The operation is carried out in a short time. The patient feels comfortable and safe. However, behind such an idea of manipulation is the high skill of the operator and the utmost clarity of the organization of the process.
The main advantages of such a surgical intervention include:
- absolute cataract relief;
- achievement of high visual characteristics;
- quick recovery of the patient;
- lack of restrictions during physical and visual stresses thanks to a seamless method;
- lack of pain, as the lens does not have nerve endings;
- passing a quick rehabilitation, after a week you can go to work;
- compliance with restrictions for a month;
- excellent transmission of color and contrast with lenses.
Indications for surgery
Indications for surgical intervention may be cataracts at any stage. The best option is to perform surgery with an immature form of cataract, allowing surgery without risk.
For the patient, this is also a big plus: do not wait for the moment of complete blindness of the eye, as it was before. Removing clouding at the initial stages of the development of the disease minimizes complications both during and after surgery.
Possible complications after surgery
The vast majority of phacoemulsification by implantation of an intraocular lens, which is carried out by professional surgeons, has a successful outcome. If the surgeon is a novice specialist, then complications are noted in 10-15% of cases.
They can be caused by:
- weakness of the ligaments of the lens;
- a combination of cataract with diabetes, glaucoma or myopia;
- the presence of common eye diseases.
Complications after surgery include:
- corneal damage through ultrasound;
- violation of the integrity of the ligaments of the lens;
- rupture of the lens capsule, causing prolapse of the vitreous body;
- displacement of the artificial lens, etc.
It should be noted that all the complications that arose after surgery can lead to serious problems. The treatment in this case will be continuous, and the result may not be very positive.
Lens removal
Sometimes, with an inflammatory process or pathological processes in the retina, removal of an intraocular lens is required. In such cases, a total vitrectomy of the IOL is performed. The lens is grabbed with tweezers and moves forward. The sclerosome for the introduction of the endoplaster is closed with a stub. The surgeon performs an incision in the cornea using diamond-coated scissors. An IOL can be intercepted by a doctor from 25G tweezers with another, for example, 20G diamond-coated tweezers.
After removing the lens, the incision is sutured with a solid or X-shaped seam with nylon thread No. 10-0. The use of thin material for the seam causes a lesser manifestation of astigmatism, but requires extreme caution, since there is a high risk of leakage through the seam during manipulation.
Sometimes the intraocular lens is removed in the presence of a fibrovascular membrane, which is the result of fibrovascular proliferation on the anterior base of the vitreous due to trauma or uveitis. This process can also be caused by diabetes.
In this case, the haptic components intersect with scissors, and in order to maintain the depth of the anterior chamber, viscoelastic is used.
Haptic elements can be left in the ocular cavity if they are surrounded by a fibrous capsule and cannot be removed with tweezers. To increase the level of tightness, several X-shaped sutures are applied to the wounds. Monoflamen thread No. 9-0 or 10-0 is used.
Which IOL manufacturers are preferred?
How to choose an intraocular lens? Manufacturers present a wide range of models with various specifications. To date, modifications of phakic ICL lenses (STAAR, CIBA Vision) with a rear camera have become widespread.
These models are implanted behind the iris in front of the lens and provide high optical characteristics. If desired, such lenses can be removed from the eye without violating its anatomy.
Reviews
Intraocular lenses, the reviews of which are the most positive, have become for many people the only and sure way to regain lost vision.
According to patients, ultrasound cataract phacoemulsification with IOL implantation is a highly effective, reliable and painless method that can permanently eliminate cataracts and provide excellent vision. The intraocular lens has become a real breakthrough in the field of cataract treatment.