Заказ мягких контактных линз через интернет-магазин(аукцион). Можно купить acuvue для коррекции близорукости и soflens для зрения при астигматизме, цветные, однодневные, непрерывного ношения и растворы для линз. Доставка по Москве, Петербургу... и другим странам. Офтальмологические тесты и советы окулиста.


Self-test for visual acuity
 
    There some ways of checking different eye functions that help to diagnose various eye diseases and to determine whether someone is fit for this or that job or not.

    The most important and the most frequently checked eye function is visual acuity, which is measured separately for each eye without spectacles (contact lenses) or with them both for near and distance vision.


    To check your visual acuity using your PC monitor (taking into account the characteristics of your monitor and the size of your room) you need to do the following:
 - measure the distance from which you will do the test (in metres) and input these figures into the table below (to get the accurate result you need take into account the size of your room and, preferably, choose the distance of 3 to 5 metres); Examples of figures: 3, 4.2, 5.0
 - measure the real size of the table itself (using a ruler, for instance): how to do it is shown below with the help of arrows from point A to point B) Input the figures into the table. Examples of figures: 185, 215, 225

The distance from which eyesight is tested in metres metres
The length of the table (actual) in mm millimetres

    After you click:

    Move away from your monitor to the distance decided above and determine which line of letters or rings of the smallest size you can read. This will be your distant visual acuity with all the modifications taken into account.

    The normal visual acuity is considered to be 1.0. However, it happens that it is 1.5 or even 2.0. The reasons for decrement in visual acuity can be eye diseases, which are to be treated, or the so-called ocular refraction anomalies when wearing spectacles (contact lenses) is sufficient. There three main groups of ocular refraction anomalies: shortsightedness (or myopia), when wearing distance spectacles is prescribed; longsightedness (hypermetropia), when wearing reading spectacles is prescribed; and astigmatism which can only be improved by wearing astigmatic spectacles.

    To check whether you have shortsightedness or longsightedness, click here:

    If you distinguish letters on the red background better, you are likely to have shortsightedness. If you distinguish letters on the green background better, you are more likely to have longsightedness.

    To do a pre-check for astigmatism click:

    If some lines on this page seem to be clearer to you than the others, you may have astigmatism.

    One of the diseases that alarm much anxiety both in patients and doctors, is pathology of the central part of retina (macula lutea), which may be either a separate disease or complication of some other diseases, like pancreatic diabetes, for instance. To diagnose this pathology you may use our

    If the results of this test are positive, you need to consult your ophthalmologist.

    You can test your chromatic sensitivity on the web-page called Rabkin’s tables. Click here to do this test. You can find the correct answers below (in the same order as the tables themselves are located).
    The more wrong answers you have, the more your chromatic sensitivity is impaired. The results of this test should be evaluated critically, taking into consideration the fact that colour rendering on different monitors can vary, depending on basic characteristics of the monitor.


 
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    Please, take into consideration that the results of all the above described tests should evaluated very cautiously. If they point out to any deviation, it’s advisable to consult an ophthalmologist. And even if their results are just perfect it doesn’t give 100 % guarantee that you don’t have any eye diseases or that you are well-suited for this or that profession.

The main terms used for ocular tests description

In ophthalmology the measure for visual acuity is defined as the value reciprocal of the permissive visual angle, at which the smallest interval between two points is visible. To test visual acuity special tables with certain symbols (rings or letters) of various sizes are used.

It is customary to measure the value of visual acuity in percentage terms or with the help of decimal fractions. If you can see one line in the table, then your visual acuity is 10% or 0.1, if you can see 3 lines then it is 30% or 0.3. In the USA visual acuity is measured with the help of common fractions: 6/6 is analogous to 100%.

The number of lines one can read in the ophthalmologic table for visual acuity self-testing will depend both on visual acuity itself and on the distance from which they are read (in former USSR countries the norm is a 5-metre distance, in other countries it is a 6-metre distance). The visual acuity self-testing table with variable size of the symbols is used here to exclude the influence of this factor.

Visual acuity is not to be mixed with optical power of spectacles or contact lenses (measured in diopters), which are prescribed by an ophthalmologist and used for vision correction.

Contrast sensation is very close by its meaning to visual acuity. There tests for achromatic contrast sensation (roughly speaking, it is the difference between white, various shades of grey and black colours) and chromatic (colour) contrast sensation (it is, for instance, the difference between white, light blue and dark blue colours). Achromatic contrast sensation is used in ophthalmology for diagnosing cornea edema, which may occur due to excessively long contact lens wear (see the test for a possibility of contact lens continuous wear).

Ocular refraction anomalies (shortsightedness and astigmatism) are described in details in the corresponding articles. Worth's four-dot self-test allows you to reveal chromatic aberration.

Chromatic sensitivity (color sensing) anomalies are fully covered in the article containing a special table for color sensing self-testing. It’s important to note that these ocular anomalies are inborn and thus, unlike shortsightedness and astigmatism, they cannot be corrected with the help of spectacles or contact lenses or treated.

    A trichromat is a person who distinguishes all the colours. An achromate (or a daltonian) does not distinguish colours. Someone who does not distinguish one of the colours is a dichromat. Protanopes do not distinguish a red colour, while deuteranopes cannot distinguish a green one.