Mixed astigmatism is a complex visual defect, in which both hyperopia and myopia are observed simultaneously in one eye, i.e. two types of violation of refraction are combined. In this regard, there is no single focus of the rays on the retina, and the image in the eye is focused twice: in front of the retina and behind the retina. Therefore, vision is significantly distorted. In people suffering from this pathology, the cornea of the eye is slightly arched or, conversely, concave. Mixed astigmatism can be in both eyes, and only on one of them.
Causes of mixed astigmatism
The vast majority of cases of mixed astigmatism is associated with heredity. Also, the pathology can occur due to eye surgery or after a traumatic eye injury, resulting in scarring of the cornea. Other causes of such a visual defect may be various changes in the cornea caused by diseases (for example, keratonus).
Symptoms of mixed astigmatism
With hereditary form of the disease, its manifestations are already revealed in childhood. Visual acuity with mixed astigmatism is low, all observed objects are distorted: they lose their clarity, they warp, and their real dimensions and distance to them are more complicated. In addition, patients with mixed astigmatism experience rapid eye fatigue, especially when working, which requires constant attention and strain of vision. Often they have headaches of a paroxysmal nature.
How to treat mixed astigmatism?
For the diagnosis, an ophthalmologic examination using tables and cylindrical lenses is required to determine the difference in the curvature of the cornea. Computer diagnostics is also carried out. After that, the tactics of treatment are chosen.
Fortunately, even mixed astigmatism today is highly susceptible to effective correction and treatment. Timely appeal to the doctor with symptoms of the pathology allows avoiding complications ( strabismus , sharp decrease in vision).
Conservative methods of treatment of mixed astigmatism consist in the selection of vision correction means: astigmatic glasses or contact lenses, which will allow to correct the difference in the optical strength of the two main meridians of the eye. In glasses with mixed astigmatism, a combination of cylindrical and spherical glasses is used. Contact lenses, which can be either hard or soft, have a toric shape. Modern soft lenses allow you to wear them for a long time without experiencing any discomfort.
However, lenses or glasses do not allow you to completely get rid of the problem, but only allows you to improve your eyesight while wearing them. To correct a situation it is possible only by means of a surgical operation. It can be prescribed in cases where the patient does not have retinal pathologies, there are no scars on the surface of the eyeball or other ophthalmic diseases.
Currently, there are two main radical treatments for mixed astigmatism:
- Astigmatic keratotomy - this method involves microscopic incisions on the cornea of the eye in certain places. This makes it possible to change the curvature of the cornea in the desired plane (along the axis of the incisions). But such an operation has many
deficiencies, the main of which - a long and painful post-operation period, low efficiency. - Laser treatment (laser keratomileus) is a modern and effective method. It involves the impact of a laser beam on certain areas of tissue in the middle layer of the cornea after a special cut previously performed by a special device. Thus, the cornea is given a regular smooth shape with certain parameters, which allows one to increase the optical power of the eye in one meridian and reduce it in another.