A prism has the same cross-section across the entire length of its shape. When used in eyeglasses, they often correct abnormalities associated with nearsightedness, farsightedness and double vision. Eyeglasses, or corrective lenses, reduce or increase the size of the image based on the eyes’ ability

Optical filters carefully transfer light in a specific range of wavelengths or colors while obstructing what remains. These dyed plastic or glass devices are placed in the optical path. They are described by their frequency response, and this identifies how the scale and stage of each frequency component

Rotation trainers consist of a disk – with various designs – that is attached to a rod-like base. As the disk rotates, the patient is asked to perform tasks that are designed to test and enhance eye-hand coordination, space awareness, perceptual awareness and visual acuity.

This entails a wall-mounted square board with a starburst design. Along the various striations of the starburst are lighted buttons. As the buttons light up, the patient works quickly to see how many of these lit buttons they can push before they go out. The key is to keep the head still. Peripheral

This device integrates all of the senses used for learning. It is one of the basic instruments used for visual-motor training, and helps with direction, rhythm, eye-hand coordination, and work and shape recognition. It consists of an aluminum case with illuminated membrane switches organized along a

Here, a ball with letters, numbers, colors, pictures, or a combination is hung from the ceiling. In activities used to help focus visual attention, the individual may be asked to concentrate on a figure while bunting the ball with a rod, or hitting or catching it with their thumbs, palms or fists.

Known also as optometric phototherapy, syntonics deal with the application of selected visible-light frequencies and are used to treat lazy eye and problems with peripheral vision and depth perception. By applying particular visible-light frequencies through the eyes, syntonics can improve vision. This

Amblyopia, commonly called lazy eye, refers to the improper development or significant loss of vision in an eye. It occurs when the brain does not acknowledge the images seen by the amblyopic eye. Amblyopia Causes Amblyopia occurs when an individual cannot use binocular vision (both eyes working together)

There are many potential causes for blurry eyes. The answer to why you have blurry vision is best answered by your eye care professional, who can offer diagnosis and prompt treatment so that your vision does not get worse. Some conditions that cause blurry vision are easy to treat, but others require

Double vision, also known as “seeing double” or the medical term diplopia, is the perception of two images of a single object. This occurs when two nonmatching images are sent to the part of the brain that processes visual input. Over time, the brain eventually begins to compensate for this misinformation

An eye condition affecting roughly 50 percent of individuals who need glasses, hyperopia (commonly called farsightedness) is characterized by difficulty focusing on nearby objects while being able to see objects at a distance properly. Hyperopia occurs when your eyeball is too short or when your cornea

In an ideal world, everyone would have perfectly-shaped eyes. The reality, however, is that practically every eye has some form of aberration somewhere in it. These aberrations may or may not cause vision problems, but don't be too surprised if your eye doctor informs you that you are having difficulties

The name conjures up pain, but ocular migraines are less about headaches and more about a vision problem. Ocular migraines are temporary visual disturbances that can last up to 30 minutes. This condition can affect one eye or both eyes simultaneously. An ocular migraine does not typically cause pain

Myopia, commonly called nearsightedness, is a refractive error of the eye, meaning that the shape of the eye or its cornea improperly bends light as it enters the eye. This hinders your ability to focus. Myopia is the most common refractive error of the eyes, and is caused by several factors including

Simply put, accommodative dysfunction means that the eyes have difficulty focusing properly. Studies suggest that between 2 and 17% of children may suffer from accommodative dysfunction. The nature of this disorder means that it sometimes goes unnoticed in standard vision screenings conducted at school.

Convergence insufficiency is a relatively common eye condition that is typically diagnosed in childhood. A study of two large optometry clinics found that 17.6% of children who received vision exams had convergence insufficiency. As this disorder may cause difficulty focusing on written pages, some children

Parents are often aware of the need to screen children for nearsightedness or farsightedness, but fewer know about other pediatric vision problems. Ocular motor dysfunction is a condition that often manifests in childhood, although adults may also have this disorder. Because ocular motor dysfunction

If you find yourself struggling to see both at far distances and nearby reading materials, then it may be time to consider bifocals. Your eye care provider and the trained optometry staff will work with you to determine the best way to meet your needs while helping you to look and feel your best. What

Vision that is 20/20 describes a normal level of clarity and sharpness in your vision. This is called visual acuity. This measurement offers a way to compare the quality of your vision to a professional standard. Using this tool helps your eye care provider to accurately gauge whether you need corrective

When you’re picking out a new pair of glasses, choosing the frames that best fit your face is just the beginning. After selecting your frames, you’ll need to choose the type of lens, lens material, and lens coating. With advances in eyeglass technology, there are several lens coating options to choose

Sometimes your eyes don’t make enough tears or the tears evaporate too fast because they don’t have the right amount of compounds in them. This is called dry eye. Up to 5% of Americans complain of some form of dry eye. Individuals who wear contact lenses or have undergone LASIK or other types of

During the normal aging process, components of your eyes change in shape and flexibility. This frequently corresponds to vision changes that may make it difficult to see close objects. Although not all adults experience these changes, many find that they need reading glasses as they get older. Visiting

Eye pain is not normal and should always be checked by your eye care professional. It is especially urgent if the pain comes with any of the following symptoms: The pain is intense and sudden. Your eye is injured or is being irritated by a foreign object. The pain comes with sensitivity to light

Do you find yourself squinting or closing your eyes in bright light? It could be photophobia or acute light sensitivity. Eyes are designed to respond to light, but certain conditions can create light sensitivity. Exposure to sunlight, fluorescent light, incandescent light and other bright light sources

Few eye issues are as simultaneously subtle and annoying as a twitch that comes on suddenly and/or recurs frequently. A twitching eyelid may not appear visible to the people around you at all, but it can make you feel highly self-conscious and drive you to search for the cause and the cure. Unfortunately,

Many people experience small, dark, cobwebby shapes drifting across their field of vision. These floaters are especially common as people age. Flashes, a similar phenomenon, are quick flickers of light. Both are usually harmless, but, occasionally, can be a sign of serious eye troubles. Causes Vitreous

The redness associated with “red eye” is usually caused by dilated or swollen blood vessels. As a result, the surface of the eye looks bloodshot. In contrast to vision problems or pain in the eye, red eye is often less of a concern. However, there are times when red eye may be a sign of a more serious

Ptosis (TOE-sis) refers to an upper eyelid that droops and can occur in children or adults. The droop may be hardly visible, or it could cover the entire pupil. Depending on the severity of the droop, it could interfere with vision. People with ptosis may try to lift the eyelids or tilt their heads back

Sometimes referred to as "sleep" or eye matter, eye discharge that appears in normal consistency upon waking is a typical part of your body's defense mechanisms, protecting your eyes from bacteria or other irritants. Eye discharge that appears in abnormal consistency, color, or quantities might be a

Swollen eyelids are a fairly common eye condition caused by inflammation or excess fluid in the connective tissues surrounding the eye. Depending on the cause, swollen eyelids can be painful or not painful and affect the upper eyelid, the lower eyelid, or both. Swollen eyes can be caused by many different

Cytomegalovirus (CMV) retinitis is a serious disease causing compromised vision and ultimately a total loss of vision. CMV retinitis is typically associated with Acquired Immunodeficiency Syndrome (AIDS). In the early days of the AIDS epidemic, nearly one-quarter of all individuals diagnosed with late-stage

Suffering from watery eyes, also known as tearing, or epiphora, is a condition that happens when the eyes make too many tears or produce them constantly. There are many causes of excessive tearing, but only a few are signs of more serious conditions. Causes of Excessive Tearing One of two things often

If you find yourself experiencing blurred or distorted vision that seems to get worse year after year, you may suffer from an irregularity of the cornea known as keratoconus. This condition is infamous for causing astigmatism and nearsightedness that can progress rapidly, calling for constant updates

Bifocal contact lenses are a type of contact lens that combine two different prescriptions in the same lens. One component corrects nearsightedness and the other prescription addresses farsightedness or farsightedness. Several types of bifocal contacts are available; your eye care provider can help you

You may have heard of macular degeneration, an age-related condition in which people suffer permanent vision loss due to damage in a part of the retina called macula. But you may not be so familiar with a similar macular condition that also causes vision loss -- even in young people. This condition,