In a normal eye, images are focused directly on the retina. Conversely, astigmatism causes images to be focused on different points near the retina. As a result, blur vision can occur at both near and distant distances.
In most cases, it is due to irregular curvature of the cornea. Normal eyeballs are spherical. Conversely, astigmatic corneas are shaped like a rugby ball. That is to say, one surface is more curved than the other. Hence, light rays enter the eye and are focused on two different points. This causes blur and multiple vision.
In addition, curvature of the lens causes astigmatic eyes.
An astigmatic eye sees blur at distant and occasionally at near. In severe cases, the eye may see double or triple vision.
Astigmatism can occur on its own, or together with myopia or hyperopia.
Singapore has a high occurrence of astigmatism as compared to other countries. According to the Health Promotion Board, ‘over the last five years, the proportion of students with vision problems, including myopia and astigmatism, has been stable at about 28% among Primary 1 students, 65% among Primary 6 students, and 70% in secondary 4 students.’
Glasses & Contact Lenses
These optical aids are readily available at any optical shop. People with astigmatic eyes have to wear toric contact lenses. However, optical aids only grant temporary correction. Upon removal, vision errors are still present.
LASIK is the gold standard in vision correction. During a 15 to 20 minute surgery, high-tech lasers correct the cornea shape. As a result, LASIK corrects myopia, astigmatism, hyperopia, and presbyopia at the same time.
Implantable Contact Lenses (ICL)
The ICL is an FDA-approved device.They are a long-term treatment – ICLs can in the eye for up to a lifetime. It is an attractive althernative to LASIK as it can treat higher degrees of myopia.
Cataract Surgery with Intraocular Lens Implantation
Patients with cataracts must remove them in order to have clear vision. Having a LASIK or ICL procedure alone is insufficient. A cataract surgery removes the clouded lens. At the same time, an intraocular lens (IOL) in implanted. IOLs come in various types. IOLs can help to correct astigmatism, myopia, hyperopia and presbyopia (lao hua)
There is no “best” option. Consult an eye specialist. A good doctor will be able to recommend options based on your eye condition and lifestyle.