Astigmatism correction for clear and comfortable vision
Astigmatism causes different amounts of blur in different directions.
This causes images to appear distorted, or sometimes doubled due to curvature of the cornea and the lens.
Certain letters may be more difficult to read than others, depending on the orientation of the lines within them.
This is equal to the power of the “cyl” which is measured by moving the red and green lines so they cross over at the same point.
Exactly halfway (measured in Dioptres) is where there is equal blur in both meridians. If the astigmatism is corrected the cross over point or focus can be on the retina not in front of it (myopia or short sightedness) or behind it (hyperopia or long sightedness)
This is equal to the spherical equivalent, or best vision sphere
Blurred vision by refractive errors is due to the lens inside the eye and the cornea not transmitting light rays from the front surface and rear surfaces focused to a point on the retina.
The types of astigmatism are evaluated by an eye doctor Ophthalmologist or Optometrist during an eye examination for most eye conditions as well as signs of eye disease and eye injury in addition to the irregularly shaped astigmatic eye with its power meridians analysed.
How common is astigmatism ?
Astigmatism will effect how light enters the eyes and is focused. Whilst it is extremely common it ideally should be corrected depending upon the magnitude so as not to cause blurred,distorted vision or uncomfortable vision which can impact your visual acuity.
To focus light glasses or contacts have to correct in all directions.
How is astigmatism corrected ?
Astigmatism is common together with short-sightedness (myopia) or long-sightedness (hyperopia) in an eye exam.
Vision correction often utilises contact lenses to reshape the cornea. Astigmatism can also be corrected by glasses, or laser eye surgery techniques (assuming healthy corneal profile and eye care) LASIK, ASLA and SMILE to rectify the curvature of the front of the eye.
Sometimes optical errors can be overcome when the eye’s natural lens is removed and replaced with an artificial lens including people with astigmatism. Residual errors can be overcome by glasses or a contact lens.