Glasses and lenses to correct astigmatism
Glasses with special cylindrical lenses are the most common ways to correct astigmatism. According to the statistics released by leading ophthalmological companies, up to 80% of astigmatic patients prefer eye glasses for vision correction.
Glasses may be positive (plus) or negative (minus), and those are selected depending on a type of astigmatism. In case of high astigmatism, glasses cause discomfort – giddiness, pain, fatigue. Very often the cylindrical lenses for correcting astigmatism are combined with lenses used to correct myopia (shortsightedness) or hyperopia (fargsightedness) that may accompany astigmatism.
It is pretty difficult to select a pair of intricate glasses – something which only a highly qualified specialist can do. It is important to remember that incorrectly selected glasses may cause overstrain of eyes and vision deterioration.
In spite of the fact that glasses remain the simplest method of vision correction, they have plenty of drawbacks. Glasses not only alter the appearance of the person wearing them, they may break and get fogged up at the most inappropriate moment. But there are also medical aspects of this problem. Above all, glasses restrict the side vision and often distort the size and shape of objects.
Besides eyeglasses, contact lenses are also used to correct astigmatism. In the near past, people suffering from astigmatism could not use soft contact lenses. At that time, correction of astigmatism could be done only with help of hard contact lenses. Astigmatism correction today is based on the use of special toric contact lenses. These lenses may have toric surface either on the front or the back side of the lens. Contact lenses with a toric front surface are capable of correcting corneal and lenticular astigmatism of up to 4.5 D. Contact lenses with a toric back surface may correct corneal astigmatism of up to 6.0 D.
Contact lenses display several undisputable advantages:
- Contact lenses can correct high corneal astigmatism;
- Contact lenses produce minimum change in the vision field and distortion of images on the retina;
- Contact lenses allow optimum conditions for binocular vision, that is vision with both eyes;
- Contact lenses reduce to a minimum any optical aberration and prism effect which is typical to eye glasses.
Otherwise, contact lenses also have their own drawbacks
- Specialists register frequent cases when contact lenses wearing results in various complications in the form of inflammatory processes. In view of the greater thickness of most of the toric contact lenses, they bring discomfort to a patient and extend the period of adaptation. Eyes are highly sensitive to these lenses and get tired faster in comparison with standard soft lenses. Besides, there have been cases of such complications as growing myopia and distortion of the shape of the cornea surface.
- This growth of myopia is due to chronic oxygen deficiency in the cornea. Besides, the different indexes of thickness of toric contact lens in its different points may cause various optical aberrations (distortions).
- Ophthalmologists draw attention to the fact that many patients wearing soft toric contact lenses suffer from changing shape of cornea. Although discontinued use of contact lenses removes the problem (the cornea restores its shape). In some cases, the changes may be unnoticed and this could lead to errors in next selection of toric contact lenses or correcting glasses and, what is more important, estimation of excimer laser correction of astigmatism.
- Long-term use of toric soft contact lenses may change the topography of the cornea in such a way that the results of keratotopography resemble an early keratoconus with the result that the patient is denied laser correction surgery.
Glasses and contact lenses are the most widely used ways for astigmatism correction. However, they compensate vision defects only temporarily, when being used and do not eliminate astigmatism.
The Excimer Eye Clinics select glasses and contact lenses only following a comprehensive diagnostic testing. The Excimer Eye Clinics have up-to-date computer-based equipment meeting all the world standards which makes it possible to measure all parameters with micron precision and identify eye ailments at an early stage. Modern techniques of examination may detect even the slightest astigmatism.
Both glasses and contact lenses are effective only when properly selected on the basis of individual features of the patient. Otherwise, they may impose a negative effect on a patient’s health. It is essential to pay a regular visit to your ophthalmologist and undergo a regular medical examination to check glasses or contact lenses.
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