There are several types of contact optical materials. One-day, toric, traditional. The purpose of most optical pairs is clear to everyone. Multifocal lenses: what is it? Why and for whom are they needed? What features distinguish them from others? All these questions need answers, but first you need to deal with pathologies that compensate for such lenses.
What is presbyopia?
In the human body, age-related changes occur. Some of them (closing fontanelles, changing milk teeth for permanent teeth) are progressive. Others (decreased intensity of metabolic reactions) are signs of regression. Such processes include a decrease in the elasticity and curvature of the lens, weakening of the eye muscles, leading to age-related hyperopia. Inadequate focusing leads to the inability to see small details near (letters, numbers, graphics).
If such phenomena are associated with age and occur after 35-40 years, such farsightedness will be natural. It is called presbyopia, and multifocal contact lenses are used to correct it. At the moment, this is the most modern way to correct age-related farsightedness.
Multifocal contact lenses: benefits
Contact methods of correction are actively gaining popularity in patients with presbyopia. There are several reasons for this.
Firstly, lenses do not introduce additional restrictions. This is an opportunity to actively move in any conditions. Wherever you are, in the gym, at work or on the street with a child, you need to feel freedom everywhere.
Secondly, they do not change the appearance of a person. On the one hand, one does not always want to tell the world about visual impairment. On the other hand, the selected points may not be suitable for a particular moment. The lenses are neutral.
Thirdly, they are safe. Glasses break, injure your face in a collision. Modern contact materials are not only soft and elastic, which eliminates eye damage, but also have a protective effect against UV, allergens and irritating substances. Multifocal daily replacement lenses are disposed of with substances that have fallen on them during use.
Fourth, they are always clearly visible. They do not fog, do not get dirty. And if their integrity is broken (scratched or torn), then multifocal one-day contact lenses can simply be thrown away and take another pair.
Multifocal lenses - what is it
The ability to correct presbyopic changes with glasses is a significant inconvenience. The patient must carry and change 2 pairs of glasses. One is for focusing on close subjects. The second is designed to achieve visual acuity when looking into the distance.
To correct presbyopia, the optical pair has a bulge both externally and internally. Two optical centers make multifocal lenses unique. What it is? This structure of the optical system allows you to choose at what distance the object is currently viewed. One center is designed to visualize nearby objects, the second - to detail distant ones.
Types of contact lenses for presbyopia
The selection of multifocal contact lenses is carried out by an ophthalmologist. On the sites you can clarify specific features, but you can not go through the initial diagnosis. If the selection of multifocal lenses is done competently, then using them will bring a lot of pleasure. They will comfortably and completely correct focus violations. The selection of multifocal contact lenses is carried out taking into account their type. Not all contact devices for presbyopia correction are multicenter. According to the location of the points of refraction, they are divided into bifocal, multifocal and monocentric.
Bifocal
Their second name is variables. They are the simplest kind. Contain 2 optical zones. Their different refractive power provides the ability to get a clear picture both near and far. The optical center for working in the near sector is located below. The center of far vision is located above. To obtain a constant clear picture, the lens must be in a constant position on the surface of the eye. Such optical pairs are a complete replacement for glasses.
Circular
Also called concentric. A more modern modification of the bifocal model. With this option, the centers of near and far refraction are arranged circularly, alternating. Belts are replaced 4-5 times. In the middle of the lens, the center of refraction of rays from distant objects is more often located. This is the standard arrangement for hard lenses. In soft versions, it is possible to use the same arrangement on the leading eye, and on the opposite one. Thus, 2 images are simultaneously formed on the retina, which refract the rays from near and far objects. The central nervous system independently chooses the projection that is currently needed.
Aspherical
The refractive power of such lenses varies from the center to the periphery smoothly. From the middle with a site for small distances, it gradually moves to the edge, where zones for distance vision are located throughout the radius. This is the most physiological model, because when working close to the pupil is narrowed, and when looking at distant objects, it expands and then the ability to refract by the peripheral areas of the lens becomes relevant.
Correction of presbyopia with spherical lenses
This method is called monovision. In fact, these are ordinary lenses, they are not multicenter. When using a sample for distance at one eye and for close range on the other, this method will be the most inferior of those listed. When applied, there is no true binocular vision. They are categorically contraindicated for motorists, because they do not give a complete picture of the volume, depth and distance in space.
Lens Life
Like spherical, lenses for the treatment of presbyopia are divided by the period of use:
- Traditional. Models of this type can be used for 30 days or more. During this period, they need disinfection and enzymatic treatment.
- Planned replacement. Such optical pairs are used 2-3 weeks before disposal. They are safer and do not require additional processing. They are stored in special containers. Each lens needs a separate capacity.
- Multifocal daily replacement lenses. Such optical pairs are used within 24 hours. They do not need containers and disinfectant solutions. After single use thrown away.
Touching the surfaces of the lens and eye takes a long time. Increased demands are made on the optical pair. Numerous studies have established a direct relationship between the duration of lens use and the number of complications received. The more days an optical pair is used, the higher the risk of adverse events. Therefore, multifocal one-day contact lenses are more often recommended for the correction of presbyopia.
Patient reviews on presbyopia correction methods
Patients with age-related changes in vision use various methods for its correction. With the surgical method, they note the time spent on surgery, invasiveness and various tolerance of the rehabilitation period. Refractive methods, according to not only patients, but also doctors, can reduce the level of visual acuity in the distance. They affect stereo vision, the contrast of the perceived image and the sense of quality of vision. They may also be bothered by an increase in photosensitivity, dizziness, double vision.
When using glasses, along with ease of use, patients note a lack of aesthetics of bifocal models. Also a significant minus is the limitation of
peripheral vision, spatial perception. It’s impossible to play sports with them. And when using different pairs for near and far vision, there are inconveniences with changing clothes and constantly carrying extra points with you.
Combined methods often combine the disadvantages of all applied correction methods. So, when using contact lenses and glasses together, patients cannot engage in mobile activities, have limited visual fields, spend time installing lenses and caring for them.
Why do patients choose multifocal lenses?
Multifocal lenses patient reviews are positive. Especially important for most is the high visual acuity in the full range.
Smooth change of near and far viewing modes makes the perception of the picture softer. They allow you to live in an active motor mode and do not interfere with driving or sports. Multifocal lenses: what is it? The ability to see well at any age.