Glasses or contact lenses: what to choose
In our days people suffering from myopia or hyperopia, have the opportunity to correct their eyesight with glasses or contact lenses. Which of these methods of correction better? What is better: glasses or contact lenses? Together with the Country councils will try to find answers to these questions.
In the human eye, the image of objects focuses on the retina using the lens of biological lenticular lenses. The lens can shrink and expand by changing its curvature, as a result, we can see equally well close and far objects. Such a property of the lens called accommodation.
For the accommodation of the lens meet, special eye muscle – the ciliary muscle. In cases of abnormalities in the work of these muscles, short-sightedness or hyperopia usually occurs.
Nearsightedness, known in official medicine myopia. Is a visual defect in which the image in the distance perceived by the eye is formed not in the retina of the eye, but in front of it. As a result, a person suffering from myopia, sees well near, but does not see well in the distance - the outlines of objects seem to him vague, indistinct.
Myopia can develop due to the weakening of the ciliary muscles - they can not sufficiently compress the lens to properly focus the image. Often you can see how short-sighted people screw up their eyes, looking afar - so they try to compensate for the missing tension of these muscles and "sharpen".
Myopia can be congenital and acquired. With congenital myopia, problems with vision are caused by either an elongated shape of the eye (axial myopia), or features of the structure of the lens (refractive myopia). Acquired myopia develops as a result of weakening of the eye muscles.
Hyperopia – hyperopia - this is a violation of the refraction of vision, in which the image of objects in the distance is focused behind the retina of the eye. Hyperopia can be caused by a reduced size of the eyeball on the anteroposterior axis or by a decrease in the ability of the lens to change the curvature (age-long farsightedness).
Contrary to popular belief sighted people often sees poorly and far and near. Well seen in the distance people with age-long farsightedness, presbyopia, because the lens of them is always in a relaxed state. When doing work near (reading, writing), long-sighted people often experience headaches.
Violation of the uniform curvature of a lens leads to another violation of the refraction of the eye astigmatism. With astigmatism, the light rays can not be focused at one point, so that a person sees objects as fuzzy, "doubled". Often, astigmatism develops at an early age and is accompanied by myopia or hyperopia. Congenital astigmatism up to 0.5 diopters does not bring discomfort and does not require correction.
Correction of myopia, hyperopia and astigmatism is with glasses, contact lenses, surgical or laser correction. Glasses and contact lenses are the most common and available methods. To correct farsightedness, we need spherical collective lenses (convex, "+"), myopia - spherical scattering (biconcave, ""). Correction of astigmatism requires cylindrical lenses.
Optical power of glasses and contact lenses is selected in accordance with the degree of development of myopia or hyperopia:
- weak - up to 3 diopters (dptr);
- medium – 3 to 6 diopters
- strong – more than 6 diopters.
And glasses and contact lenses have their pros and cons. So, spectacle correction has several advantages. First, it's cheap – once buying glasses, you can forget about a re-purchase. Secondly, the modern eyeglass frames not only spoil the appearance, but, on the contrary, decorate it as a stylish accessory. And finally, thirdly, to remove and wear the glasses much more comfortable than lenses.
However, sunglasses have many drawbacks. They mist over in the cold, scratching, often slipping from the nose. Glasses with glass lenses are very traumatic - if they break glass shards fall into the eyes. In addition, glasses violate the stereoscopic effect and spatial perception (in "short-sighted" glasses objects seem farther than in fact, in the "farsighted" - closer), limit lateral vision. Glasses do not give 100% correction of vision, and increasing the optical power of eyeglasses can lead to eye strain.
Contact lenses, in turn, completely deprived of all the aforementioned shortcomings. So, due to the fact that the lens "sits" directly on the surface of the eyeball, the "effect" of the correction is higher and a lens of lesser optical power is needed in comparison with the spectacle lens.
When contact lenses are used, the side vision and stereoscopic effect are not impaired, no distortion of spatial perception occurs. Lenses can not be smashed, they do not fog up and, contrary to the popular among the "glasses" opinion, do not fall out of sight. In contact lenses it is convenient to do sports and even swimming, provided that the head does not sink into the water.
The disadvantages of contact lenses include the need for their frequent replacement and scrupulous care. Contact lenses for long-term use are covered with protein deposits, micro-scratches and microcracks, and therefore lose their effectiveness. In addition, in some cases, there is an individual lens intolerance and then in this case, contact correction is impossible.
Keep the lens should be in a special solution, and the lens, intended for wearing for 3 or more months, should be regularly cleaned with special means. Wear and remove contact lenses only with clean hands to avoid infection. Sleep in contact lenses can not, you can not also rub eyes - this can lead to irritation of the mucosa.
People who use contact lenses often complain of dry eyes. Discomfort arises from the fact that the lens, while in the eye, prevents the natural wetting of the eye with tear fluid. Special eye drops help maintain the necessary level of moisturizing.
Women who wear contact lenses should be particularly careful approach to the selection of cosmetics – it is best to use a special line for contact lenses. It should be remembered that in the morning you need to apply makeup after putting on contact lenses, and in the evening to remove - before removing the lenses.
What to choose glasses or contact lenses, as a rule, everyone decides for himself. However, in some cases only contact correction can bring the required result.
In particular, contact lenses need to be people with a large difference in the optical power of the lens for each eye because when using glasses, the difference should not be more than 3 diopters. Otherwise, anisometropic amblyopia may develop - a "lazy" eye syndrome. Contact lenses make it possible to achieve a uniform load on the eyes, even with a large difference in the optical power of the eyes.
I have glasses 3.5 D read and 1.2 D for driving and not only. 1,2 glasses well see the road but can't see the readings on the display of the dashboard of the car. Question: if I change my glasses for contacts – I can equally see both distance and near?
Yours faithfully and hope Valentine.
Contact lenses forever!)))
Here's just a question: where can I buy acuvue in St. Petersburg? I used to take in ochkov.net, but now I really want to find another service with delivery.
Here's an article about the dryness is written, but it means that you need lenses with a very good moistening system. I wear in the last six months somewhere Air Optix Aqua, the eyes moisten with blinking, very naturally occurs, dryness does not appear throughout the day. Now I use drops only for the night. Simply lenses need to be selected correctly and then they bring only benefit and comfort.