There are several varieties 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 who needs them? What features distinguish them from others? All these questions need answers, but first you need to understand the pathologies that such lenses compensate.
What is presbyopia
Age-related changes occur in the human body. Some of them (closing of fontanelles, changing milk teeth to permanent ones) are progressive. Others (decrease in the 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 farsightedness. Inadequate focus results in the inability to see small details up close (letters, numbers, graphics).
If such phenomena are associated with age and occur after 35-40 years, such farsightedness will be natural. It's called presbyopia, and to correct it,multifocal contact lenses. At the moment, this is the most modern way to correct age-related farsightedness.
Multifocal Contact Lenses Benefits
Contact correction methods are actively gaining popularity in patients with presbyopia. There are several reasons for this.
Firstly, the lenses do not introduce additional restrictions on life. This is an opportunity to actively move in any conditions. Whether you're at the gym, at work, or out with your baby, you need to feel free.
Secondly, they do not change the appearance of a person. On the one hand, one does not always want to tell the world about the deterioration of vision. On the other hand, the selected points may not be suitable for a particular moment. The lenses are neutral.
Third, they are safe. The glasses break, injure the face in collisions. Modern contact materials are not only soft and elastic, which prevents damage to the eye, but also have a protective effect against UV, allergens and irritants. Daily disposable multifocal lenses must be disposed of with any material that has come into contact with them.
Fourth, they are always clearly visible. They don't sweat, they don't get dirty. And if their integrity is broken (scratched or torn), then multifocal disposable contact lenses can simply be thrown away and another pair taken.
Multifocal lenses - what is it
Possibility to correct presbyopicchanges with the help of glasses delivers significant inconvenience. The patient needs to carry and change 2 pairs of glasses. One is used to focus on close objects. The second is designed to achieve visual acuity when looking into the distance.
For the correction of presbyopia, the optical pair has a bulge both outside and inside. Two optical centers make multifocal lenses unique. What it is? This structure of the optical system allows you to choose at what distance to view the object at the moment. One center is designed to render nearby objects, the second - to detail distant objects.
Types of contact lenses for presbyopia
Multifocal contact lenses are selected by an ophthalmologist. On the sites you can clarify specific features, but you can not go through the primary diagnosis. If the selection of multifocal lenses is made correctly, then their use will bring a lot of pleasure. They will comfortably and completely correct focus violations. Selection of multifocal contact lenses is carried out taking into account their type. Not all presbyopia contact devices are multicenter. According to the location of the refraction points, 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 obtain a clear picture both near and far. The optical center for work in the near sector is locatedfrom below. The center of distance vision is located on top. The lens must be in a constant position on the surface of the eye in order to obtain a consistently clear image. 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 in a circle, alternating. Belts are changed 4-5 times. In the middle of the lens is often the center of refraction of rays from distant objects. This is the standard arrangement for rigid lenses. In soft versions, it is possible to use the same arrangement on the leading eye, and the opposite one on the second. Thus, 2 images are simultaneously formed on the retina, refracting rays from near and far objects. The central nervous system independently chooses the projection it needs at the moment.
Aspherical
The refractive power of such lenses changes smoothly from the center to the periphery. From the middle with a section for small distances, it gradually passes to the edge, where there are zones for distance vision along the entire radius. This is the most physiological model, because when working near the pupil is narrowed, and when looking at distant objects, it expands and then the ability of refraction by the peripheral regions 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 multi-center. When using a distance sample on one eye and a near sample on the otherdistance, this method will be the most inferior of those listed. When using it, 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 lifespan
Like spherical lenses, lenses for the treatment of presbyopia are divided by the period of use:
- Traditional. Models of this type can be used for 30 or more days. During this period, they need disinfection and enzymatic treatment.
- Scheduled replacement. Such optical pairs are used 2-3 weeks before disposal. Safer and do not require additional processing. Stored in special containers. Each lens requires a separate container.
- Multifocal daily replacement lenses. Such optical pairs are applied within 24 hours. They do not require containers and disinfectant solutions. Discarded after one use.
The contact of the surfaces of the lens and the eye takes a long time. The optical pair is subject to increased requirements. 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 disposable contact lenses are more commonly recommended for presbyopia correction.
Patient feedback on presbyopia correction methods
Patients with agechange in vision, various methods of its correction are used. With the surgical method, they note the time spent on the operation, invasiveness and different tolerability of the rehabilitation period. Refractive methods, according to not only patients, but also doctors, can reduce the level of distance visual acuity. They affect stereo vision, the contrast of the perceived picture and the sense of quality of vision. An increase in photosensitivity, dizziness, double vision may also disturb.
When using glasses, along with ease of use, patients note the lack of aesthetics of bifocal models. Also a significant disadvantage is the limitation of peripheral vision, spatial perception. It is 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 glasses with you.
Combined methods often combine the shortcomings of all applied correction methods. For example, when contact lenses and glasses are used together, patients cannot engage in mobile activities, have limited fields of vision, and spend time fitting and caring for lenses.
Why do patients choose multifocal lenses
Multifocal lenses patient reviews are positive. Especially important for most is high visual acuity in the full range.
Smooth change of near and far viewing modes makesperception of the picture is softer. They allow you to live in an active motor mode and do not interfere with either driving or playing sports. Multifocal lenses: what is it? Ability to see well at any age.
