Infancy

Babies are able to see at birth, but vision is not fully developed. Newborns can distinguish bright colors, masses, and bold, contrasting patterns. Babies can focus on objects 8 to 12 inches away - about the distance between the baby's and mother's face during breastfeeding. Beyond this distance, babies cannot see clearly, but can distinguish patches of light, larges shapes and movement. The ability to recognize what we see lies in the brain's occipital lobe, near the back of the head. In babies, the pathways that relay the information from the eye to the brain are not fully developed yet. So, at first, babies don't understand what they are seeing. Birth to 4 Months In the first few months of life, focusing ability, color distinction, depth perception and hand/body coordination develop rapidly. During the first month, babies prefer contrasting dark and light patterns to solid colors. They are unable to tell the difference between similar shades (red and orange) or distinguish pastels. From age 2 to 4 months, colors become distinct and babies begin to recognize primary shades. In the first few weeks, eyes may wander in different directions. By 1 to 2 months of age, eyes focus equally and babies can track moving objects. Babies will follow faces and objects from side-to-side, which will help develop the ability to focus on close objects. If you talk while moving around the room, the baby will look in the direction of your voice. This action may help the baby focus the eyes equally on distant objects. Stationary crib mobiles in bright, primary colors-red, green, blue and yellow, or high contrast patterns help develop focus. At about 2 months of age, babies lose interest in stationary objects and prefer to track moving objects. Brightly colored toys and wall hangings will capture their attention and develop the ability to distinguish colors and shapes. At about 2 months, when babies' fists begin to uncurl, they will begin reaching for bright objects, developing eye-hand coordination. When a baby holds a noisy toy, the sound attracts his or her attention, making it easier to learn the connection between what the eyes see and what the hands do. In the third month, babies swipe at objects strung across the crib or stroller. Reaching like this refines hand-eye coordination. Age 4 to 8 Months Beginning at about 4 months, depth perception, focus, and object tracking skills are refined. By this time, the eyes should work together and focus equally on objects. This ability is important for binocular and three-dimensional vision. Babies begin to be able to track moving objects near-to-far. At this time, babies also learn to recognize people and remember things. Hide and seek or "peekaboo" games improve this skill. Toys with things to touch and see will hold babies' attention. Big colored pictures or complex designs will attract their interest and exercise binocular vision. Reaching, touching, and tracking noises are still important for developing hand-eye coordination. Babies will grab objects, instead of swiping at them. They begin moving objects from hand to mouth. Hair and jewelry are easy targets at this age. By 5 months of age, babies can spot small objects and track movements. Because of depth perception, they will turn objects over to get different perspectives. They begin to recognize pastels and similar color shades. By 8 months, babies often begin to crawl. This helps babies develop eye-hand-body-foot coordination that is important for walking. Age 8 to 12 Months By 8 months, babies begin to see like an adult. Color vision is fully developed. Near vision is better than far vision, but babies can see an object across a room and may be able to crawl to it. They will look around when they hear a noise. Eight-month-olds can track objects in all directions, including up-and-down. Because of their new awareness of vertical space, babies of this age may fear heights. Hand-eye coordination improves dramatically. Babies can grasp and throw with much greater accuracy. Fine motor skills begin to develop. As they move into the toddler stage, babies can hold toys between the thumb and forefinger, poke or point at objects with an index finger, or reach behind their back without looking to grab a toy. Building blocks, stacking toys, or very simple puzzles are good for hand-eye coordination at this stage. Eye color (iris) will have changed by now, although subtle variations may occur. By 10 months, parents may be able to tell whether their baby is right- or left-handed. At this age, books attract interest. Babies may try to turn pages or grab at pictures. Ability to judge distances improves continually. By 12 months, babies can grasp and throw things with much greater accuracy and steer a wheel in a car seat or stroller.

Childhood

From the time we are born to about 8 years of age, our eyeballs undergo remarkable changes. Normally, as the front of the eye grows, it flattens, which sends images deeper inside the eye. If the eye grows as it should, light will converge on the retina. But if the convergence is off by even a hair's breadth, vision will be blurred. Most preschool and elementary school children are slightly farsighted. This lessens as children grow, usually stabilizing by adolescence. During these years of growth, the eye senses where images are focusing and compensates accordingly. If light is converging in front of the retina, the eye will stop growing longer until images catch up to the retina. If the focus is behind the eye, it will grow longer at a remarkable rate, pushing the retina further from the source of light until images can be focused. The eyes are generally able to maintain clear focus throughout childhood even though the size of the eyeballs is continually changing. The ability to see in three dimensions, stereoscopic vision, is usually fully developed by the age of 6 or 7.

Adolescence

Changes in the length of the eye occur mostly during youth, while the eye is still growing in the socket. However, the front of the eye may continue to grow well into the 20s. The longer the eye gets, the more likely you are to become nearsighted. Nearsightedness most often develops during the rapid growth years. It may progress until growth has ceased, in early adulthood. Some experts claim that some activities, such as prolonged reading at close distances, may actually lengthen our eyes during these years. It is recommended that reading materials be held 12-16 inches away, computer screens be at least 20 inches from the face, and televisions be viewed from at least 3 feet away.

Adulthood

The human eye reaches peak strength in the young adult, around the mid- to late-20s. This strength involves many abilities not measured by eye charts. Night vision, eye-hand coordination, motion and depth perception, and color discrimination may all improve during this time. During the years of increasing visual abilities, nutrition is essential for optimum vision development. By the time we reach our mid- to late-30s, it may begin to be difficult to focus on close objects. The ciliary muscles that adjust the thickness of the lens start to weaken. Meanwhile, the lens itself loses its elasticity. Consequently, the ability of lens to focus at close range decreases. Most people notice signs of "aging eyes," or presbyopia, around the age of 40 to 45, when they begin holding reading material at arms' length. You will probably need to wear reading glasses, bifocals, or multifocal glasses or contact lenses to correct your vision at this stage. The condition will usually stabilize by the age of 65 or 70 but may progress indefinitely. During our mid-40s, the iris muscles tend to slow. The reflex response decreases, increasing the amount of light entering the eye. For many people, sensitivity to glare starts at this age. Their eyes may be overexposed to the sun and other UV light, potentially causing permanent damage. Eyewear with ultraviolet radiation protection can shield the eyes from the harmful rays.

Pregnancy

During pregnancy, women's bodies change dramatically. Hormone levels rise, which may affect eye health and vision. Eye-related changes that may occur during pregnancy include: a change in refraction; requiring a different prescription for corrective eyewear, blurry vision, dry eye, less tolerance of contact lenses, worsening of existing eye conditions. Eyesight usually returns to normal after delivery. Vision problems during pregnancy may signal other health problems. Blurred vision or seeing spots may indicate gestational diabetes or pregnancy-induced hypertension, an increase in blood pressure that usually occurs after the twentieth week of pregnancy. Eclampsia and pre-eclampsia, caused by extremely high blood pressure, can cause eye hemorrhages and retinal detachment. Not all pregnant women develop eye problems, but experts recommend routine examinations by an eye doctor each trimester. Early treatment is vital to the health of the mother and baby.

Maturity

Some vision changes are a normal part of aging. Others may be warning signs of other diseases such as high blood pressure or diabetes, both common in older adults. Common occurrences during the elder years include: stabilization of presbyopia, development of cataracts, increase in spots; floaters and flashes, onset of glaucoma, incidence of dry eye, disease; infection or injury of the cornea, retinal disorders Retinal disorders are a leading cause of vision loss in elderly people. When damaged, the light-sensitive cells lining the retina cannot pass images to the brain. If detected and treated early, vision loss may be slowed or halted. Some of the more common retinal conditions include: macular degeneration, diabetic retinopathy, retinal detachment

Sources

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