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How to choose eye lenses

There are about 2.2 billion visually impaired and blind people in the world. Many refractive errors can be treated with an ophthalmic laser. Despite the fact that surgical correction of vision has long been not uncommon, for various reasons, not everyone decides to undergo surgery. Corrective glasses and contact lenses are still the priority.

Optical means are prescribed depending on the type and degree of refractive errors. Lenses are considered more comfortable and reliable. Compared to glasses, they do not distort the image, provide peripheral vision, do not fog up, and do not interfere with physical activity. You can appreciate all the advantages of co

Why go to the doctor?

Many contact lenses are sold without a prescription, but it's best to seek advice from an ophthalmologist before purchasing. Correct eye optics takes into account the features of the organs of vision, which can only be determined by a doctor.

Comprehensive diagnostics includes:

• visometry - checking visual acuity according to the Sivtsev table;
• eye tonometry - measurement of intraocular pressure;
• objective assessment of refractive anomaly (computer refractometry, skiascopy);
• keratometry - the study of the cornea of ​​\u200b\u200bthe eye;
• testing of visual-oculomotor function;
• peripheral vision test;
• biomicroscopy - examination of the eyeball;
• one-dimensional or two-dimensional echography (ultrasound of the eyes).
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If the results of the examinations do not reveal contraindications, the doctor will write a prescription, advise a suitable model, and explain how to put on and take off the lenses correctly. An obstacle to contact correction can be ophthalmic diseases - glaucoma, lens displacement, strabismus >15°. Wearing lenses is not recommended for dry eye syndrome, ptosis of the upper eyelid, as well as for people prone to allergies, since regular use of antihistamines causes dry mucous membranes. Temporary restrictions include inflammatory diseases of the organs of vision - blepharitis, conjunctivitis, keratitis, dacryocystitis. In this case, the doctor will prescribe treatment with ophthalmic preparations , and after recovery it will be possible to wear contact corrective agents.

How are the models different?

Corrective contact optics are classified according to several parameters, each of which must be considered when buying.

Type of refractive error and diopter

Lenses are selected according to the type of disproportionate refraction:

• hypermetropia (farsightedness) - contact correction diopter range - from +1 to +15 (some models - up to +25 diopters);
• myopia (nearsightedness) - from -1 to -30 diopters;
• astigmatism.

Corrective glasses and contact lenses have different diopters. In the first case, the optics are moved about 12 mm away from the cornea, in the second, they are located directly on it. If spectacle lenses were, for example, +3 diopters, then contact lenses will be 1-1.25 diopters less. In addition, doctors prescribe corrective agents with slightly reduced diopters so that the organs of vision “do not relax”. This is especially true for presbyopia - progressive age-related farsightedness that develops after 40 years.

Kinds

To correct hypermetropia and myopia, spherical or aspherical lenses are prescribed. For models in the form of a sphere, the optical power is concentrated mainly in the center. At the periphery, it is smaller, so slight aberrations are possible - lateral distortions. With a significant decrease in visual acuity, this will cause certain inconvenience. Aspherical contact optics are elliptical, lighter and thinner. The models are characterized by a wide view, a clear picture in the center and on the periphery, a high-quality contrast image at any time of the day. Astigmatism is corrected with spherical toric lenses. In addition to the radius of curvature and diopters, they take into account the axis and the cylinder. It is impossible to choose toric optics without consulting an ophthalmologist. For presbyopia, multifocal lenses are provided that provide contrast and clarity of visible objects,ntact correction only in lenses that correspond to the characteristics of the eyes. How to choose contact lenses, what parameters should be taken into account? Read the article.

Texture

Depending on the materials used for the manufacture, vision correction products are:

• Hard. They contain silicone, so they pass oxygen well. They are suitable for patients with astigmatism, effective in the treatment of dystrophic changes in the cornea, resistant to damage. Rigid lenses are better cleaned of fat and protein deposits. The disadvantage of products is a long addiction to wearing. During the adaptation period, it is desirable to use drops to moisturize the eyes .
• Soft. They are made from hydrogel or silicone gel. Hydrogel products have low air permeability, so when worn for a long time, there is a threat of corneal hypoxia. The air permeability of silicone gel is 2-3 times higher. Additional advantages of optics include quick adaptation of the eye, the ability to wear in any weather, do not take off while sleeping, playing sports. Minus the soft texture - high care requirements.

With strong refractive errors, concomitant ophthalmic disorders, doctors recommend hard optics. To correct the initial changes in vision, it is better to choose soft contact lenses.

Mode

The duration of continuous wearing of contact correction means should be agreed with the doctor. Manufacturers produce models:

• Daily. Can be worn up to 12 noon. At night, it must be placed in a special solution.
• Night. Put on before going to bed to correct the shape of the cornea.
• One-day (disposable). Suitable for continuous wear up to 24 hours, then subject to disposal.
• Prolonged (weekly, two-weekly, monthly). Can be worn for the specified period, periodically disinfecting.

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  Using optical aids for longer than the recommended time means exposing the mucous membrane of the eye to the risk of developing infectious and inflammatory diseases, allergic reactions.

  Purpose

  Contact optics can be medical (for correcting refractive errors) and color, which does not correct vision.

  Multi-colored models are used:

  • to reduce sensitivity to sunlight;
  • to hide defects (thorn, congenital or acquired absence of a fragment of the iris;
  • as a way to change the image.

  Creative models imitate the eyes of animals, mystical creatures. They are bought for theme parties, carnivals.

  Notation

  Before buying contact optics, you need to carefully inspect the packaging. The basic features include:

  • diopter indicator - D;
  • corneal curvature required for comfortable application - BC;
  • diameter - DIA;
  • oxygen permeability level (the more, the better) — Dk/t.

  additional characteristics

  batch number

  wearing time

  prescription sale

  thickness

  sterility

  UV protection

  LOT

  numbers + hourglass

  RXOnly

  CT

  Steril

  sun image

  The countdown of the service life begins from the moment the sterile package is opened.

  Selection rules

  The right lenses meet the refractive characteristics and personal needs of the patient. Parameters to consider:

  • The degree of reduction in visual acuity and curvature. For strong deviations, rigid spherical models are needed. With changes in refraction within 3 diopters, soft aspherical ones are suitable.
  • Oxygen permeability. Optics with low Dk/t should not be worn permanently. The lack of oxygen leads to drying of the mucosa, the development of xerophthalmia (dry eye syndrome). Daily lenses have the highest Dk/t, but they are not suitable for correcting severe cases of farsightedness and nearsightedness.
  • type of refractive error. If you have astigmatism, it is better to buy toric lenses. Due to the spherical shape, they do not move relative to the cornea, they have double optical power (vertical, horizontal). For presbyopia, multifocal devices are recommended. In most people aged 40+, the ciliary muscle that holds the lens weakens, so visual acuity and accommodation decrease. For a clear visualization of objects, glasses "for distance" and "for near" are required. Multifocal lenses replace two pairs of glasses, the need for their constant change.
  • Lifestyle. For intensive sports activities, soft one-day correction products are recommended. They are held on the cornea, do not damage the mucosa in case of injury. With daily work with paper documents, a computer, it is better to buy daytime optics. At night, the eyes will rest, and the lenses will be restored (cleaned in solution).

  Unpleasant sensations after the first "acquaintance" with the lenses is normal. The organs of vision will get used to the correct optics in 2-3 days. Having decided to wear lenses, you need to remember three important rules - regularly clean the products, visit an ophthalmologist every six months, take vitamins for the eyes (the doctor will advise a specific drug).

  How to understand that the choice was made incorrectly?

  If the rules for choosing optics are ignored, neither after 2 nor after 5 days will the eyes get used to the lenses. To understand that the model does not fit, you can by the following signs:

  • sensation of a foreign body in the eye;
  • painful tingling of the cornea;
  • frequent headaches;
  • irritation of mucous membranes (redness, itching);
  • fatigue from reading, working at a computer;
  • increased sensitivity to sunlight.

  The visible image will also be fuzzy.