Astigmatism usually occurs when the front surface of your eye, the cornea, has an irregular curvature. Astigmatism is one of a group of eye conditions known as refractive errors and these errors cause a disturbance in the way that light rays are focused within your eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors. It is not a disease nor does it mean that the eyes are “bad”. It simply means that you have a variation or disturbance in the shape of your cornea.
Symptoms
- Distortion or blurring of images at all distances
- Headache and fatigue
- Squinting and eye discomfort or irritation
The symptoms described above may not necessarily mean that the astigmatism is present. However, if someone experiences one or more of these symptoms, it is important to undergo a complete exam.
Causes
Normally, the cornea is smooth and equally curved in all directions and light entering the cornea is focused equally on all planes or in all directions. In astigmatism, the front surface of the cornea is curved more in one direction than in the other. This abnormality may result in vision that is much like looking into a distorted, wavy mirror. The distortion results because of an inability of the eye to focus light rays to a single point.
If the corneal surface has a high degree of variation in its curvature, light refraction may be impaired to the degree that corrective lenses are needed to help focus light rays better. At any time, only a small proportion of the rays are focused and the remainder are not, so that the image formed is always blurred. Usually, astigmatism causes blurred vision at all distances.
Risk Factors
A small amount of astigmatism is very common and the tendency to develop astigmatism is inherited. A larger amount of astigmatism can be associated with diseases such as keratoconus.
Tests and Diagnosis
The amount of astigmatism in the eye can be measured in various ways. The autorefraction or the subjective refraction—based on the patient’s response—that are done at the beginning of an eye exam is one way to measure astigmatism. The amount of astigmatism caused by the cornea is measured in the clinic by a diagnostic instrument called a keratometer.
Treatment and Drugs
If the degree of astigmatism is slight and there are no other problems of refraction, such as nearsightedness or farsightedness, corrective lenses may not be needed. If the degree of astigmatism is great enough to cause eye strain, headache, or distortion of vision, corrective lenses will be needed for clear and comfortable vision.
The corrective lenses needed for astigmatism are called Toric lenses and they have an additional power element called a cylinder. They have greater light-bending power in one axis than in others. Ophthalmologist will perform precise tests during the eye exam to determine the ideal lens prescription. Refractive surgery also may be an option for correcting some forms of astigmatism.
Astigmatism may increase slowly. Regular eye care can help to insure that proper vision is maintained.
Bojan Kozomara (Banjaluka, 30. decembra 1978) je doktor medicine, specijalista oftamologije i direktor specijalne oftalmološke bolnice Svjetlost Banja Luka.
U svom rodnom gradu završio je Gimnaziju i Medicinski fakultet, a 2009. godine specijalizovao se za oblast oftamologije. 2016. godine postao je magistar medicinskih nauka iz oblasti oftamologije, a svoju profesiju usavršio je na Klinici za očne bolesti, VMA Beograd, Srbija, te na Klinici Oculistica Universita „Careggi“, u Firenci, Italija. Nakon završene specijalizacije u Italiji, odlučio se vratiti u rodnu Banjaluku i tu pokrenuti privatnu kliniku, koja će za vrlo kratko vrijeme postati popularna i prepoznatljiva u regionu, ali i svijetu.
