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Why do you need reading glasses?
With age, many people face the problem of deteriorating eyesight – presbyopia – and although they can see print and distant objects, reading becomes difficult. The lens in a young person’s eye is elastic and changes shape easily to focus on different objects. When looking at near objects, the lens becomes convex, refracting light rays and fixing the image on the retina.
As we age, the lens loses its flexibility, making it harder to focus on distant objects. The lens thickens, becomes fixed in one position and loses its refractive power. This makes it difficult to see up close, thread a needle or use a mobile phone. People who are not ready for laser correction should choose glasses that allow them to focus on near objects.
Types of reading glasses
Depending on the type of lens used, reading glasses can be divided into three types.
Monofocal – standard lenses that work in one optical zone, usually at a distance of up to 40 cm. Spectacles with these lenses are designed for reading only and do not allow you to focus your vision throughout the day.
Bifocal lenses are lenses with two zones of vision correction. The upper zone is designed to focus vision on distant objects, and the lower zone is designed to focus vision on close objects, such as when reading or sewing. Bifocal lenses act as the primary optical component for the wearer.
Progressive lenses are lenses whose optical power changes gradually. As with bifocal lenses, there is no visible boundary between the zones of vision correction. Due to the special structure, the optical power depends on the foreshortening of the object being viewed.
There are glasses for reading while lying down, which are characterized not by the special properties of the lenses, but by a special design resembling a periscope. This type of lens allows the wearer to hold a book close to their chest and at the same time see the pages of the book without having to bend their neck at an uncomfortable angle. With these glasses, the wearer only needs to look over the top of the glasses when looking into the distance.
Important! The best way to choose the right reading glasses is to be examined and advised by a specialist.
How to choose reading glasses
At the appointment, the optician will examine the patient using a table at a distance of 30-35 cm from the patient’s eyes. The smallest letter (top) corresponds to a visual acuity of up to 1 diopter, the largest letter (bottom) corresponds to a visual acuity of up to 0.1 diopter. Your optician will test each eye individually and gradually increase the lens power to a comfortable level.
If you want to wear the same glasses and work at the computer at the same time, this should be taken into account when choosing optics. If farsightedness is combined with presbyopia, the age standard deviation should be added to the optical power. Conversely, if you have myopia, subtract the age standard deviation for myopia from the optical power.
Reading glasses can be selected and purchased by trying on ready-to-wear reading glasses without visiting an optician. If you don’t have any complex vision problems or conditions, you can buy inexpensive glasses with simple lenses for single vision.
Important! Ready-made glasses are made according to an average value, such as the average interpupillary distance (about 63 mm). If you are far from the average, too big or too small, reading glasses are uncomfortable and can cause dizziness and migraines.
The disadvantages of buying ready-to-wear reading glasses
Although both lenses have the same optical power, most people’s left and right eyes have different visual characteristics, so different lenses need to be fitted. Wearing unsuitable glasses means that one eye has to work harder than the other, increasing fatigue, and does not take into account astigmatism – one in two people have some degree of astigmatism, however slight, due to changes in the shape of the cornea.
There are products on the market with the same interpupillary distance (62-64mm). However, even a slight asymmetry can be uncomfortable to wear. Unlike bespoke glasses, which protect against dust, glare and scratches, they do not have a protective coating. The advantages of off-the-shelf glasses are that they are relatively inexpensive and there is no need to wait for your glasses to be made.
Customized reading glasses
With made-to-measure glasses, the wearer chooses the frame, which is then checked and adjusted in the optician’s shop. The appropriate lenses are then recommended. Individual parameters such as the optical power of the eye, the presence or absence of astigmatism, the distance between the pupils and the optimum diameter of the lenses are taken into account. During the fitting process, the optician may recommend progressive lenses, which provide optimal vision at all distances – from far to near.
If the wearer’s job or lifestyle involves prolonged use of a computer, special computer glasses may be recommended. As well as providing clear vision, these glasses have a special coating to protect against radiation and vibrations from the screen. Photochromic filters can be added to individual lenses to protect the eyes from bright light and glare, increase visual contrast and reduce symptoms of eye fatigue and strain. Such lenses prevent the negative effects of radiation on the conjunctiva, cornea and retina.