Astigmatism
Once pictured
ASTIGMATISM
Astigmatism affects 23.9% of the European population today. This visual impairment results in blurred vision and distortion along the periphery of sight both in near and distance vision. People with astigmatism have difficulty perceiving contrast and differences between vertical and horizontal lines. For instance, it can be difficult for them to distinguish between an “O” and a “Q” and read street signs from afar. Astigmatism rarely occurs on its own and tends to be diagnosed alongside other visual impairments such as myopia and hyperopia.
Astigmatism: Definition
The cornea of an astigmatic eye is shaped like a torus, sort of like a rugby ball, while a spherical form like a tennis ball is normal. This deformation diverts beams of light headed towards the retina, which in turn distorts image interpretation in the brain. Astigmatism is considered to be weak between 0.25 and 1.50 dpt, medium between 1.50 and 3.00 dpt, and strong above 3.00 dpt.
If the toric shape of the cornea is the only cause of astigmatism, this is referred to as corneal astigmatism, If the cause is an irregularly shaped lens, this is called lenticular astigmatism. Total astigmatism is when both of these phenomena occur together.
Astigmatism: Causes and symptoms
Astigmatism can occur from birth and is in some cases significant. It can also be caused by a strong tone of the eyelids, or excessive strain on the lens or affect people who overexert their near vision. Possible symptoms of astigmatism include headaches or pain in the eye musculature.
Coating and surface treatment
Astigmatism can be corrected with toric single vision lenses, which are thicker along the edges and thus focus beams of light back on the retina for clearer sight. The stronger the astigmatism, the thicker the lenses are along the edges. Thinner aspherical single vision lenses offer a more attractive and aesthetical option.
The corresponding lens
A lens tailored to your specific visual impairment
THE MONOVID FREE-FORM SINGLE VISION LENS
A combination of precision and lightness