Transcript VISUAL DEVELOPMENT

The Human Eye
Intra uterine
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The eyelids are not have fully separated;
The pupil is not constrict or dilate; the aqueous
drainage system may not be fully functional.
The iris lacks pigment.
The choroid lacks pigment.
Retinal blood vessels are immature.
Optic nerve fibers may not be myelinized;
There is still a pupillary membrane and/or a hyaloid
system.
Lack of ability to control light entering the eye;
visual system is not ready to function.
At birth
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Infants are born with a complete visual system, but not
fully developed.
From birth to maturity
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The size eye increases to three times of that at birth,
Most of this growth is complete by age 3 years
One third of the eye's diameter growth is in the first year
of life.
At birth:
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The irises of infants:
The iris lacks pigment and may have a gray or bluish
appearance; natural color develops as pigment forms.
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The eyes' pupils: are not able to dilate fully yet.
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The curvature of the lens: is nearly spherical not oval.
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The retina: (especially the macula) is not fully developed.
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The infant: is moderately farsighted and has some degree of
astigmatism.
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The newborn has poor fixation ability, a very limited ability to
discriminate color, limited visual fields,
By 1 month:
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The infant can follow a slowly moving black and white
target intermittently to midline
May also intermittently follow faces (usually with the
eyes and head both moving together).
He/She will blink at a light flash,
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There is a preference for black and white designs.
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By 2 months:
 Brief fixation occurs sporadically, ocular movements are still
uncoordinated
 The infant follows vertical movements better than horizontal
 Begins to be aware of colors (primarily red and yellow).
 There is probably still a preference for black and white
designs.
By 3 months:
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Ocular movements are coordinated most of the time;
attraction is to both black and white and colored (yellow
and red) targets.
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The infant is capable of glancing at smaller targets and
is interested in faces; visual attention and visual
searching begins.
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The infant begins to associate visual stimuli and an event
(e.g., the bottle and feeding).
By 4 months:
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"Hand regard" occurs; there is marked interest in the
infant's own hands.
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He/she is beginning to shift gaze, and reacts (usually
smiles) to familiar faces.
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He/she is able to follow a visual target past midline, and
can track horizontally, vertically, and in a circle.
By 5 months:
 Eye-hand coordination (reach) is usually achieved by now.
 The infant is able to look at an object in his/her own hands;
 The infant is visually aware of the environment ("explores"
visually), and can shift gaze from near to far easily;
By 6 months:
 Eye movements are coordinated and smooth; vision can be
used efficiently at both near point and distance.
 The child recognizes and differentiates faces , and can reach
for and grasp a visual target.
 Hand movements are monitored visually; has visually
directed reach.“
 May be interested in watching falling objects, and usually
fixates on where the object disappears.
Between 6 and 9 months:
 Acuity improves rapidly (to near normal);
 "explores" visually (examines objects in hands visually, and
watches what is going on around him/her).
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Can transfer objects from hand to hand, and may be
interested in geometric patterns.
Between 9 months and a year
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The child can visually spot a small (2-3mm) object
nearby;
Watches faces and tries to imitate expressions;
Searches for hidden objects.
Visually alert to new people, objects,
surroundings.
Can differentiate between known and unfamiliar
people.
By 1 year
 Mild farsightedness,
 Ability to focus, accommodate (shift between far and
near vision tasks),
 He/She can discriminate between simple geometric
forms (circle, triangle, square), scribbles with a
crayon, and is visually interested in pictures.
By 2 years:
• Myelinization of the optic nerve is completed.
• All optical skills are smooth and well coordinated.
• The child can imitate movements, can match
same objects by single properties (color, shape),
and can point to specific pictures in a book.
By 3 years:
 Retinal tissue is mature.
 The child can complete a simple form board correctly
(based on visual memory),
 Can do simple puzzles, can draw a crude circle, and
can put 1" things into holes.
Top 5 Milestones in Vision Development
1. Focusing ability
 Most infants can focus accurately by two to
three months of age. The ability to focus
requires special eye muscles to change
the shape of the lens in order to form
clear images. Before two months of age, an
infant is capable of focusing objects both
near and far, but not very well.
2. Eye Coordination and Tracking
 A baby usually develops the ability to track and follow
a slow-moving object by three months of age. Before
this time, an infant will follow large, slow-moving
objects with jerky motions.
 A three-month-old can usually track an object quite
smoothly. A baby should begin to follow moving
objects with the eyes and reach for things at around four
months of age.
3. Depth Perception
 Depth perception is the ability to judge objects that are nearer or
farther than other objects. Depth perception is not present at
birth. It is not until the third to fifth month that the eyes are
capable of working together to form a three-dimensional view
of the world.
4. Seeing color
 An infant's color vision is not as sensitive as an adult's. It is hard
to tell if babies can distinguish colors because their eyes might be
attracted by the brightness, the darkness, or the contrast of
an object against its surroundings, and not by the color alone.
By two to six weeks of age, however, a baby can distinguish two
highly contrasted colors, such as black and white.
5. Object and face recognition
 An infant is born with the ability to see facial features at arm's
length, but is attracted instead to high-contrast borders of
objects. For example, a baby will gaze at the edge of a face or
the hairline when looking at a human face. By two to three
months of age, a baby will begin to notice facial features, such as
the nose and mouth. By three to five months, most babies can
differentiate between mother's face and a stranger's face.