What are refractive errors?
The following are the most common refractive errors, all of which affect vision and may require corrective lenses or surgery for correction or improvement: • astigmatism Astigmatism is a condition in which an abnormal curvature of the cornea can cause two focal points to fall in two different locations – making objects up close and at a distance appear blurry. Astigmatisms may cause eye strain and may be combined with nearsightedness or farsightedness. Eyeglasses, contact lenses, or corrective surgery may help to correct or improve the condition.
The eye functions like a camera. Light rays entering the eye are focused by the cornea and the lens of the eye onto the light sensitive retina (which is like the film of a camera) at the back of the eye. The retina then transmits a clear image, or photo, to the brain. In people with refractive errors (or poor vision, such as nearsightedness or farsightedness), the light rays do not get focused on to the retina and blurred images are formed. These can be measured as aberration patterns.
