Radius of curvature of lens
What is the radius of curvature of the lens? How correctly to calculate it? This question is asked by each person who decides to wear contact lenses for vision correction and is sent to them to optics. The exact answer to this question can be given only by a professional ophthalmologist. If the radius of curvature of the lens will be picked up incorrectly, you risk not only not to improve your vision, but also to worsen it. Your eyes will be uncomfortable, they will experience stress, and you are a constant inconvenience.
The radius of curvature of the lens that fitsspecific person, depends on the structure of his eyeball. The lens is put on the cornea of the eye, and therefore it should accurately repeat its shape. The standard sizes of the eyeball are roughly the following:
the length of the optical axis is 24 mm,
the length of the eye equator is 23.6 mm,
and the vertical diameter is 23.4 mm.
For a person with such standard indicatorsThe desired radius of curvature of the lens is 8.6. Lenses with rates from 8.3 to 8.8 are easy to find on a free sale. If there is a significant deviation from the average statistical rate, one must look for a manufacturer who produces contact lenses on order. At the same time, it is necessary to draw a sketch of the desired lens in a full-time consultation with an ophthalmologist.
How the doctor determines the appropriate radius of curvaturelenses? For this, there is a special method called autorefractometry. The oculist conducts corneal examinations using computer diagnostic methods. The procedure takes only a few minutes. At the heart of the method of autorefractometry lies the principle of radiation by the device of infrared light. The sensors fix the image of the light beam before it is reflected from the retina and after it. The results of the study of the retina carry a lot of useful information for a person who is going to buy lenses. The radius of curvature is only one of the indicators, the procedure also gives an idea of the difference in refraction observed between the eyes, and determines the magnitude of astigmatism. As the fixing point, an infinitely distant image is used.
What to do if the lens has already been purchased, andthe radius of curvature of the lens you do not like? If the difference does not exceed 0.2, doctors advise to try on lenses and wear them if discomfort is not noticeable. Often, lenses of the same manufacturer with a radius of curvature of 8.5 match the lenses of another manufacturer with a radius of 8.6. If the deviations exceed 0.2, then such contact lenses can not be worn in any case!
What symptoms and discomforts are observed in people,wearing lenses that do not suit them? If a person wears a more convex lens than required by the structure of his eye, then the mobility of such a lens will be difficult. The eyeball will be in constant tension, the blood vessels will be squeezed, which will inevitably cause redness of the entire eye. There may be a disturbance in the lacrimal exchange, since tears can not pass through the lens, which is closely adjacent to the cornea. The threat of inflammatory diseases will increase, and vision will become unstable. If, on the contrary, the radius of curvature of the lens is greater than the desired index, the lens will be too mobile. It can easily fall out of the eye or cause tear, damage the cornea. A flat lens will easily move away from the cornea, and you will see practically nothing. You will be painfully blinking, as the lens will touch the upper muscles of the eye, and every time you hit the eye with a fine grain of sand or mote the eyes will itch and blush.
Choose together with an ophthalmologist suitablethe radius of curvature of the lens and look at the world with wide eyes! Myopia and hyperopia are not grounds for refusing to enjoy all the colors and colors of life. Get contact lenses, which will be convenient for you.
