Progressive-vision contact lenses have a similar benefit for contact lens wearers as progressive-vision glasses do for eyeglass wearers: they enable sharp vision at near and far distances using the same medium. Today, these continuously technically advanced vision aids offer the same level of comfort as other contact lenses.
What are varifocal contact lenses?
Progressive contact lenses are also called multifocal contact lenses or multifocal contact lenses. Progressive contact lenses are also called multifocal contact lenses or multifocal contact lenses. They help to correct age-related refractive error and another refractive error (nearsightedness or farsightedness). The special contact lenses are similar to bifocal glasses, with the difference that they have two types of manufacture. With multifocal contact lenses, the patient with age-related vision defects can replace not only varifocals, but also glasses for distance vision and those for near vision (reading glasses). The special contact lenses – if they are optimally adapted to the specific needs of their user – have the same advantages as other contact lenses. They can be worn for a long time, have a good fit and are more practical than glasses because, unlike the latter, they do not restrict the user’s field of vision. They float invisibly on the tear film of the cornea, do not restrict movement during sports, and do not alter the face. With high-quality multifocal contact lenses, the quality of vision is almost equal to that of natural vision. Like other contact lenses, presbyopia correcting contact lenses adapt perfectly to the curvature of the cornea. In addition, they follow every eye movement, so they are usually not perceived as annoying.
Shapes, types and types
There are two manufacturing types of multifocal contact lenses: alternating (segmental) and simultaneous (bivisual or concentric) progressive contact lenses. The alternating ones are similar in principle to varifocals. The upper vision area is suitable for distance vision, the lower for near vision. The distinction between the two visual acuities, which is clearly noticeable at the beginning, is not perceived later after a longer period of acclimatization. In bivisual progressive contact lenses, the two visual powers are located on different concentric rings. They ensure that the two visual areas on the retina are displayed simultaneously (hence the term simultaneous multifocal contact lenses). These contact lenses have the advantage over the alternating ones that their wearer has a slightly shorter period of acclimatization. The brain adjusts to the altered way of seeing: it selects the appropriate near or distance image while suppressing the undesirable other. Multifocal contact lenses are available as soft or hard contact lenses, daily, weekly or monthly contact lenses and for special requirements. Alternating multifocal contact lenses are hard contact lenses, simultaneous are made as soft contact lenses. As hard contact lenses, they are more permeable to oxygen and can be worn longer every day. They provide sharper vision than soft contact lenses and are not as prone to inflammatory reactions in the eye. In the form of soft contact lenses, they offer a more comfortable wearing experience because they conform to the cornea better than hard multifocal contact lenses. They are therefore particularly suitable for patients with sensitive eyes. Users with insufficient tear fluid and people whose eyes are not sufficiently supplied with oxygen use them as silicone hydrogel contact lenses. For people with astigmatism, progressive contact lenses are custom-made in the form of hard and soft contact lenses.
Structure and function
Multifocal contact lenses each have two visual zones with two different visual powers: one for near vision and one for distance vision. There is also an intermediate zone for seeing objects that are at intermediate distances. Where each zone is located on the contact lens depends on whether it is alternating or bivisual. In alternating multifocal contact lenses, the near and far areas are clearly delineated: With the upper part of the contact lens, which is located exactly on the pupil, the user can clearly see objects in the distance, and with the lower near objects.Eye movement when looking down aligns the contact lens so that the user looks through the lower part (near vision area). In the bivisual progressive contact lens, the near zone is located in the center of the contact lens and lies on the pupil. Around it, on a larger concentric circle, is the intermediate distance zone (intermediate zone) and around it is the distance zone. When the patient sees a near object, the pupils contract and the entire outer area of the contact lens is blanked out due to the limited incidence of light (due to the pupillary reflex). Although bivisual multifocal lenses are more comfortable for the user to wear as soft contact lenses, they cannot compensate for all refractive errors: Under no circumstances should the user wear them while driving at night. Prolonged reading and working on the computer are often so exhausting for the brain that he gets a headache or tires more quickly.
Medical and health benefits
Multifocal contact lenses restore normal vision in patients who are presbyopic due to age. Since presbyopia, which occurs in most people after the age of 45, cannot be corrected by laser surgery, unlike other refractive errors, the patient would only be left with the purchase of varifocals or the supplemental use of reading glasses. In the case of presbyopia, degenerative changes cause the eye to lose its natural ability to adapt to near vision (accommodation). For example, objects that the patient used to see clearly at a distance of 10 cm can now only be seen accurately at a distance of 38.5 cm. Multifocal contact lenses offer their users many advantages beyond the restoration of vision, which are essentially the same as those of normal contact lenses. The advantages are clearly noticeable, for example, during busy work, sports, or swimming.
