Astigmatism occurs when the cornea, the front surface of the eye, is curved slightly in one direction and causes blurred vision. The cornea refracts (bends) light so it focuses on the retina in the back of the eye. With astigmatism some of that light focuses in front of or behind the retina, so your vision may be blurry for nearby (hyperopia), far-away (myopia) or all objects.
Indications of astigmatism can include headaches, eye strain, fatigue, and blurred or distorted vision. The severity of symptoms depends on the degree of astigmatism in your eyes.
Routine eye exams include testing for astigmatism, which affects many people. Once diagnosed, astigmatism can usually be corrected with prescription eyeglasses or contact lenses. Corneal modification techniques such as LASIK (laser vision correction) are also useful treatment options.
Farsightedness, or hyperopia, is the condition in which the eye focuses on distant objects better than on objects closer to the eye, so nearby objects appear blurry. This happens when light rays refract, or bend, incorrectly in the eye. The eye is designed to focus images directly on the surface of the retina; when the cornea is incorrectly curved, light rays focus behind the surface of the retina, producing a blurry image.
Hyperopia can be treated in a variety of ways. The most common is a pair of reading glasses or contact lenses. Hyperopia can also be treated with invasive or non-invasive medical procedures, including the laser surgeries PRK (photorefractive keratectomy) and LASIK (laser-assisted in situ keratomileusis).
Nearsightedness, or myopia, is a vision condition in which nearby objects are clear and distant objects appear blurry. This may be caused by excess corneal curvature or an oblong rather than a spherical shape to the eye, both of which affect the way light is bent upon entering the eye and whether it focuses properly on the retina.
Almost a third of people in the U.S. experience some degree of nearsightedness, which normally emerges by age 20. Symptoms include difficulty focusing on objects in the distance, such as a chalkboard or TV. There is some evidence that it is caused or worsened by sustained focus on nearby objects. Nearsightedness may also be hereditary.
Eyeglasses and contact lenses are common methods of correcting nearsightedness. Eyewear may be used for certain activities, like watching television or driving, or for all activities. Alternatively, vision correction procedures such as refractive and laser surgery and orthokeratology (a non-invasive procedure involving rigid contact lenses) may rectify the problem.
You may have noticed that you need to hold reading materials further away than usual, or that your vision is blurry at a distance that never used to be a problem. Or maybe you’ve been suffering from eye fatigue and headaches when working with materials at a close range. These are classic symptoms of presbyopia.
Presbyopia is a natural change in our eyes’ ability to focus. It occurs when the crystalline lens of the eye loses its flexibility, causing objects to appear blurry. Symptoms take years to develop and typically begin to show in the early- to mid-40s.
The effects of presbyopia can be corrected with glasses or contact lenses, including multifocal and progressive lenses; monovision; and conventional or laser surgery, such as CK, PRK, monovision LASIK, and intraocular lenses (IOLs).
FLASHES AND FLOATERS
Although most flashes and floaters occur in people with healthy or merely nearsighted eyes, they can be symptoms of serious problems including injury and retinal and posterior vitreous detachments. Flashes in vision are caused by pressure on the retina, the bundle of nerves in the back of the eye where images are detected and transmitted to the brain. Patients complain of flashing lights or lightning streaks.
Floaters are often seen when fibers move within the vitreous humor, the gelatinous substance made of water and protein fibers that fills the eye. Patients complain of small specks or dots that can be seen against clear backgrounds. Serious vision loss can occur if the retina or vitreous detach from the eye wall. Patients experiencing flashes and floaters should contact their doctor immediately so an examination can be performed.