What you need to remember when choosing a frame for glasses?

 

Participation points is a fairly serious procedure. Many people, especially women, are choosing to purchase the frames as a costume or decorations. The frame should be modern, "trendy" and yet have to face, color and styling your hair, and jewelry.

 

In this most commonly thought that the setting was comfortable and not think about the functional purpose of points - to improve vision and facilitate the work. Meanwhile, precisely this purpose are any points, and this should serve as the main criterion in selecting frames.

 

So the first requirement - setting should be strong, light, not to push to any part of the face (ears, nose, cheeks, under the eyes). The frame must provide the correct position of lenses in front of his eyes. This means that the average line of light apertures must pass approximately through the center of pupils, or slightly below, and the rear surface of the lens should be located at 12 millimeters from the apex of the cornea.

 

The exception is the so-called glasses "halves" that serve to quickly switch views from a distance (over the glasses) to the neighbors (through glasses): skylights these points are below the pupil and the distance from the eye lens is slightly larger than usual.

 

The position on the lens barrel must be borne in mind that eyeglasses lenses, particularly high-refraction glass, greatly aggravate weight points, and they can slide on the tip of the nose. If the glasses ready yet slip from his nose, optics, a well-known method - slightly bends temples. In this case, however, need to check do not drag it on the curved part of the ear hook the ears, and nasal stops points - on the bridge.

 

Of great importance is the form of skylights. At one time in fashion glasses were huge and the most bizarre forms of configuration. Points with large skylights require very large and, consequently, thick and heavy workpieces lenses. But the quality of spectacle lenses is determined by the minimum thickness, minimum weight and minimum convexity. In addition, at the periphery of such a lens must arise aberration - the distortion of the visible image.

 

In recent years fashion trends have shifted in the points with small skylights. The lenses in these glasses look like horizontal ovals, elegantly framing the eye slit. This form from the functional point of view much better score, "giants", but it is not without drawbacks. The fact is that for a variety of activities a man needs a very small angle of rotation of the eyes horizontally (30 degrees) in both directions. It is easy to show that with a clear vision should provide a section of ophthalmic lenses, having a width of 25 millimeters.

 

But unfortunately, this part should be at different heights: for orientation in space, while using the computer it must be in a horizontal plane passing through the center of the eye, while reading or other such work - at an angle of 45-50 degrees down from the horizontal plane. The only area that is almost never used in everyday life, this is the upper part of the field of view: if the person needs to look up, he raises his eyes and throws back her head.

 

If you drag all these "ideas" on the lenses, the zone of optimal correction should take the form of a trapezium of height about 30 millimeters wide, the top platform and 25 millimeters lower - about 30 millimeters. In this case it is best to support elements rims (Temples and nose) is attached directly to the lens, that is, setting a so-called "bezobodkovoy", with mounting screws on the lens or on the fishing line. In this case, races gaze beyond the lens man will not come on look at the rim of the frame.

 

Of course, such "trapezoid" glasses are unlikely to materialize any time soon, but the conclusions we could make: skylights should be small, round spectacles more oval, and barrel with screw mount lenses on or fishing line - better than conventional frames.

 

All of the above applies strictly to medical recommendations. But the choice of frame should discuss the technical side of things. Namely, whether the selected frame is suitable for designated points. It is known that the astigmatic lens "capricious" ordinary spherical. Very few frames are suitable for high-refraction lenses (± 6,0 D and above).

 

Considerable importance is the interpupillary distance. The frame is selected by the person who may be broad (ie, the distance between the ears of many), and the distance between the eyes may be small. In these cases, the lens center should shift that is not always desirable: necessary to take a large diameter workpiece, and such lenses in the spectacles are thick and ugly.

 

A well-known mischief to insert lenses are nasal stops, especially in the "folding" frame. There are times when, after inserting lenses glasses are no longer to emerge, and this is a legitimate customer dissatisfaction.

 

So, choose glasses frames - just a responsible process, which has not only aesthetic, but also medical and technical aspects. Therefore, it is desirable that participated in it and a qualified optometrist, and ophthalmologist.