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Can lenses be worn with astigmatism?
Astigmatism is a specific ophthalmic disease in which there is no single point of focusing rays on the retina. This is due to the irregular shape of the cornea, and much less often – the shape of the lens.
The normal cornea has a smooth convex spherical surface. But with astigmatism, the surface of the cornea has anatomical features – it is irregular, not spherical in shape. It has a toric shape in the center, so the standard methods of vision correction with contact lenses will not work for the patient.
Contact lenses have been used in ophthalmology for a long time, but until recently they were not recommended for patients with astigmatism. This is due to the fact that due to severe or severe visual impairments, a full fit on the cornea of standard lenses for correcting visual acuity in patients with astigmatism was difficult. Standard lenses for these patients did not give the desired effect, brought discomfort during use and could worsen the condition of the visual analyzer.
Today, ophthalmologists use special lenses, toric lenses, to correct moderate and high degree visual impairment in this pathology. The outer or inner surface of such lenses has a special shape. Toric lenses correct corneal astigmatism up to 6 diopters or lens astigmatism up to 4 diopters.
Which lenses are best for astigmatism
Correcting visual impairment in the presence of astigmatism is helped by correction glasses or the use of contact lenses. When choosing the type of correction, it is necessary to take into account several criteria – this is the type of astigmatism, as well as its stage, features of visual impairment. With a mild degree, correction is possible due to the use of cylindrical lenses or contact correction with products with an aspherical shape.
With a complex form of astigmatism, for example, with its mixed type, cylindrical lenses will not solve the problem, since the pathology of refraction may be accompanied by hypermetropia or myopia. If there is astigmatism with myopia, the picture is focused in two points, not reaching the retina. With astigmatism, which is accompanied by farsightedness, two points of focus of the image are formed behind the retina. Lenses having a toric shape can help in correcting this defect.
What is the difference between astigmatism lenses and regular lenses?
For contact correction, spherical, toric, aspherical or multifocal lenses can be used. Conventional product options will not cope with myopia or hyperopia, a person will notice a distortion of the picture on the periphery of the image.
Aspherical lenses correct vision much more effectively, widening viewing angles due to a snug fit to the cornea and repeating its abnormal shape. Such lenses compensate for astigmatism within 2 diopters, but they cannot correct more severe degrees. To solve this problem, already spherical types of lenses are used.
How do lenses with this pathology differ from ordinary ones? They can be imagined as an ordinary ball, which was squeezed from both sides by hands. Where the surface of the ball is compressed, its curvature is more pronounced than from the side surfaces, but on the outside there remains a surface in the form of a hemisphere. It is the same with lenses, due to a similar shape, they form two optical centers at once. With the passage of light rays, not only the main problem of vision is corrected, but also the accompanying nearsightedness or farsightedness.
Lens Fitting Tips
In the presence of astigmatism, the selection of lenses should be carried out only by an ophthalmologist. It measures a number of standard indicators – lens diameter, radius of curvature, as well as optical power and cylinder axis for contact lenses. In addition, it is necessary to correctly select the method of stabilizing the product in the eye so that the toric lens is clearly fixed on the surface of the cornea. Any slight displacement provokes a sharp deterioration in the image.
Modern toric lenses are produced using various stabilization techniques:
- the presence of ballast – the lens has a small area of compaction in the area of the lower edge: if a person keeps his head in a straight position, the lens will stand correctly, but when the head is tilted or the position of the body changes, the lenses will shift, the image will begin to blur (today such lenses are no longer produced );
- cutting off a certain edge of the lenses so that they stabilize with the natural pressure of the eyelids – such products can move when blinking, but then restore the correct position again;
- the presence of periballast – these lenses have thin edges, they have four seal points that help to keep the lens in the desired position without restricting motor activity.
What lens options are acceptable for astigmatism
There are many types of contact lenses available today. These can be daily toric lenses with a high level of comfort. They correct astigmatism in parallel with farsightedness and nearsightedness.
Monthly lenses are also used – they are cheaper than daily ones and have high optical parameters.
Reviews of doctors about lenses for astigmatism
– The choice of a method for correcting astigmatism remains with the patient, depends on his lifestyle, age, work performed, – says ophthalmologist Olga Gladkova. – Toric lenses allow you to get clearer vision compared to spectacle correction of astigmatism. Do not forget about contraindications for wearing contact lenses, such as inflammatory diseases of the anterior segment of the eye, dry eye syndrome, when the use of contact lenses is excluded.
Popular questions and answers
We asked questions ophthalmologist Olga Gladkova regarding wearing lenses in the presence of astigmatism in combination with other vision problems.