The lens and the cornea normally have a regular spherical shape. Violation of its curvature is called astigmatism. This disease is the main cause of visual defects, usually combined with myopia and hyperopia .
Diagnosis of the pathology is helped by the test for astigmatism. To conduct it very simply, for this purpose it is not even necessary to visit an ophthalmologist.
Symptoms for an astigmatism test
Characteristic signs of pathological curvature of the cornea or lens:
- deterioration of vision clarity;
- headache;
- blurring, distortion or bifurcation of objects;
- rapid fatigue when working, requiring eye strain;
- myopia;
- hypermetropia.
It is worth noting that these symptoms do not always indicate the presence of astigmatism. The diagnosis needs to be carefully checked.
Vision tests for the diagnosis of astigmatism
The most popular image, which allows to identify pathology - the star of Siemens.
Test number 1:
- Arrange so that the pattern is at eye level.
- Between the head and the screen should be a distance of about 35-50 cm.
- Carefully review the image.
With visual impairments, the rays, not reaching the middle, begin to blur, overlap or merge with the background. It may seem that the picture becomes its negative - the white rays turn black and vice versa. Also, people with astigmatism see the boundaries of the clear visibility of lines in the shape of an ellipse or more complex figures, rather than a circle.
Test number 2:
- Do not change the position taken in the previous case.
- Close one eye with a palm or a paper sheet, consider the picture.
- Repeat the same for the other eye.
All lines in the image are the same color and width, and the segments in each group are strictly parallel. If it seems that this is not the case, there may be an astigmatism.
Test number 3:
- To sit so that the star was at the level of the head, at a distance of 25-30 cm.
- Alternately closing one and the other eye, carefully look at the rays.
As in the previous test, all the lines in the star are equally black and long. In the center they converge in the right circle. When it seems that some segments are lighter or darker, thicker, longer, and in the middle instead of a circle, an ellipse, figure eight or other figure, you should consult an ophthalmologist.
Do you need an Amsler test for astigmatism?
This image is sometimes used in the diagnosis of astigmatism as a way to identify additional visual impairment, in particular - macular degeneration .
Performance:
- When wearing contact lenses or glasses constantly wear them.
- Arrange the picture at the level of the bridge of the nose, at a distance of 25-30 cm.
- To cover one eye, to look at the point in the center, remembering how the grid looks like this.
- Repeat for the other eye.
With normal vision, the lines of the grid remain flat, without stains, distortions or distortions. Otherwise, you need to visit a specialist.