Babies' VisionBabies have poor vision at birth but can see faces at close range, even in the newborn nursery. At about six weeks a baby's eyes should follow objects and by four months should work together. Over the first year or two, vision develops rapidly. A two-year-old usually sees around 20/30, nearly the same as an adult.
Parents should be aware of signals of poor vision. If one eye turns or crosses, that eye may not see as well as the other eye. If the child is uninterested in faces or age-appropriate toys, or if the eyes rove around or jiggle (nystagmus), poor vision should be suspected. Other signs to watch for are tilting the head and squinting. Babies and toddlers compensate for poor vision rather than complain about it.
Should a baby need glasses, the prescription can be determined fairly accurately by dilating the pupil and analyzing the light reflected through the pupil from the back of the eye.
A baby's vision can also be tested in a research laboratory where brain waves are recorded as the child looks at stripes or checks on a TV screen. The test is called Visual Evoked Potential (VEP). Another test called preferential looking or Teller Acuity Cards uses simple striped cards to attract the child's attention. In both tests, as the stripes grow smaller, the child eventually does not respond (with brain waves or by looking at the stripes).
Childhood Reading ProblemsWhen children have difficulty reading, parents often think poor vision is the problem. If a visit to an ophthalmologist rules out any medical or vision problems, it may be a learning disability.
A learning disability is a disparity between a person's ability and performance in a certain area. It has nothing to do with intelligence or IQ. A learning disability can make it difficult to succeed in school and, if untreated, gets worse, causing a child to lose self-confidence and interest in school.
Identifying the learning disability is the first step in treating it. Dyslexia, a reading disability that may involve reversing letters and words, is one of the many learning disorders that can affect reading.
Exercises have been used to improve the coordination or focusing of the eyes. Since poor reading is not usually an eye problem, these exercises rarely prove helpful. Colored lenses, special diets or vitamins, jumping on trampolines, or walking on balance beams have also been prescribed without much success. Over time, these methods have tended to fall out of favor.
Children with learning disabilities benefit from various educational programs, in or out of school. Parents also play a vital role. They can support their children by reading with them at home. Children with learning disabilities need to be encouraged to develop strengths and interests so they can fully develop their unique talents and abilities.
Children and VisionPeople are often confused about the importance of glasses for children. Some believe that if children wear glasses when they are young, they won't need them later. Others think wearing glasses as a child makes one dependent on them later. Neither is true. Children need glasses because they are genetically nearsighted, farsighted, or astigmatic. These conditions do not go away nor do they get worse because they are not corrected. Glasses or contacts are necessary throughout life for good vision.
Nearsightedness (distant objects appear blurry) typically begins between the ages of eight and fifteen but can start earlier. Farsightedness is actually normal in young children and not a problem as long as it is mild. If a child is too farsighted, vision is blurry or the eyes cross when looking closely at things. This is usually apparent around the age of two. Almost everyone has some amount of astigmatism (oval instead of round cornea). Glasses are required only if the astigmatism is strong.
Unlike adults, children who need glasses may develop a second problem, called amblyopia or lazy eye. Amblyopia means even with the right prescription, one eye (or sometimes both eyes) does not see normally. Amblyopia is more likely to occur if the prescription needed to correct one eye is stronger than the other. Wearing glasses can prevent amblyopia from developing in the more out-of-focus eye.
Children (and adults) who do not see well with one eye because of amblyopia, or because of any other medical problem that cannot be corrected, should wear safety glasses to protect the normal eye.
Color VisionColor 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 LensesOver 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.
StrabismusStrabismus refers to misaligned eyes. If the eyes turn inward (crossed), it is called esotropia. If the eyes turn outward (wall-eyed), it is called exotropia. Or, one eye can be higher than the other which is called hypertropia (for the higher eye) or hypotropia (for the lower eye). Strabismus can be subtle or obvious, intermittent (occurring occasionally), or constant. It can affect one eye only or shift between the eyes.
Strabismus usually begins in infancy or childhood. Some toddlers have accommodative esotropia. Their eyes cross because they need glasses for farsightedness. But most cases of strabismus do not have a well-understood cause. It seems to develop because the eye muscles are uncoordinated and do not move the eyes together. Acquired strabismus can occasionally occur because of a problem in the brain, an injury to the eye socket, or thyroid eye disease.
When young children develop strabismus, they typically have mild symptoms. They may hold their heads to one side if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates, especially at first. Adults, on the other hand, have more symptoms when they develop strabismus. They have double vision (see a second image) and may lose depth perception. At all ages, strabismus is disturbing. Studies show school children with significant strabismus have self-image problems.
Amblyopia, or lazy eye, is closely related to strabismus. Children learn to suppress double vision so effectively that the deviating eye gradually loses vision. It may be necessary to patch the good eye and wear glasses before treating the strabismus. Amblyopia does not occur when alternate eyes deviate, and adults do not develop amblyopia.
Strabismus is often treated by surgically adjusting the tension on the eye muscles. The goal of surgery is to get the eyes close enough to perfectly straight that it is hard to see any residual deviation. Surgery usually improves the conditions though the results are rarely perfect. Results are usuallybetter in young children. Surgery can be done with local anesthesia in some adults, but requires general anesthesia in children, usually as an outpatient. Prisms and Botox injections of the eye muscles are alternatives to surgery in some cases. Eye exercises are rarely effective.
