Information on Common Eye Disorders
 
Optics And Refraction

Children's Eye Safety
 
Accidents resulting in serious eye injuries can happen to anyone, but are particularly common in children and young adults. More than 90% of all eye injuries can be prevented with appropriate supervision and protective eyewear.

Goggles and face protection can prevent injuries in sports like baseball, basketball, racket sports, and hockey. It is more difficult to protect against injuries in boxing, though thumbless gloves help.

People who must rely on only one good eye should wear polycarbonate safety glasses all the time and should wear safety goggles for sports and other dangerous activities. Choose frames and lenses that meet the American National Standards Institute standard for safety (Z87.1).

Appropriate adult supervision is key in preventing all eye injuries. Children should never be allowed to play with fireworks or BB guns. Sharp and fast-moving objects, such as darts, arrows, scissors, knives, and even pencils or pens can be dangerous. Special care should be taken when working around lawn mowers, which can throw rocks and debris, and when banging two pieces of metal together, which can dislodge small shards of metal. Chemicals such as toilet cleaners and drain openers are especially hazardous.

A primary care physician or an emergency room can treat minor injuries, such as a foreign body or an abrasion (scratch) on the cornea. Any foreign material must be removed from the eye. An antibiotic drop or ointment may be applied, perhaps with an eye patch for comfort.

More serious injuries, like blood inside the eye (hyphema), a laceration (cut), or rupture of the eye, require examination by an ophthalmologist. Both surgery and hospitalization may be necessary.

Chemicals that burn should be rinsed from the eye immediately. The ultimate outcome depends on the severity of the injury, which cannot always be identified in the initial examination.
Color Vision
Color blindness (color vision deficiency) is a condition in which certain colors cannot be detected. There are two types of color vision difficulties: inherited (congenital) problems that you have at birth, and problems that develop later in life.

People born with color vision problems are unaware what they see is different from what others see unless it is pointed out to them. People with acquired color vision problems are aware that something has gone wrong with their color perception.

Congenital color vision defects usually pass from mother to son. These defects are due to partial or complete lack of the light-sensitive photoreceptors (cones) in the retina, the layer of light-sensitive nerve cells lining the back of the eye. Cones distinguish the colors red, green and blue through visual pigment present in the normal human eye. Problems with color vision occur when the amount of pigment per cone is reduced or one or more of the three cone systems are absent. This limits the ability to distinguish between greens and reds, and occasionally blues. It involves both eyes equally and remains stable throughout life.

There are different degrees of color blindness. Some people with mild color deficiencies can see colors normally in good light but have difficulty in dim light. Others can't distinguish certain colors in any light. In the most severe form of color blindness everything is seen in shades of gray.

Except in the most severe form, color blindness does not affect the sharpness of vision at all. It does not correlate with low intelligence or learning disabilities.

Most color vision problems that occur later in life are a result of disease, trauma, toxic effects from drugs, metabolic disease, or vascular disease. Color vision defects from disease are less understood than congenital color vision problems. There is often uneven involvement of the eyes and the color vision defect will usually be progressive. Acquired color vision loss can be the result of damage to the retina or optic nerve.

There is no treatment for color blindness. It usually does not cause any significant disability. It can, however, prevent employment in an increasing number of occupations.

Change in color vision can signify a more serious condition. Anyone who experiences a significant change in color perception should see an ophthalmologist.
Contact Lenses

Over 24 million people choose contact lenses to correct vision. When used with care and proper supervision, contacts are a safe and effective alternative to eyeglasses. And with today's new lens technology, many people who wear eyeglasses can also successfully wear contacts.

Contacts are thin, clear discs that float on the tear film that coats the cornea, the curved front surface of the eye. Contacts correct the same refractive conditions eyeglasses correct: myopia (nearsightedness), hyperopia (farsightedness) and astigmatism (an oval- rather than round-shaped cornea).

Contact lenses can be made from a number of different plastics. The main distinction among them is whether they are hard or soft. Most contact lens wearers in the United States wear soft lenses. These may be daily wear soft lenses, extended wear lenses or disposable lenses. Toric soft lenses provide a soft lens alternative for people with slight to moderate astigmatism.

Hard lenses are usually not as comfortable as soft lenses and are not as widely used. However, rigid gas permeable lenses provide sharper vision for people with higher refractive errors or larger degrees of astigmatism.

The majority of people can tolerate contact lenses, but there are some exceptions. Conditions that might prevent an individual from successfully wearing contact lenses include dry eye, severe allergies, frequent eye infections, or a dusty and dirty work environment.

Individuals who wear any type of contact lens overnight have a greater chance of developing infections in the cornea. These infections are often due to poor cleaning and lens care.