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There are many possible defects or diseases of the visual system , but,
fortunately, many of them appear after the first few years
of life. There are still many defects, diseases, infections, disorders and malformations that can affect the visual system in infants and toddlers. Only a few of the
many visual disorders found in young children is described below:
Cataracts: defined as a clouding of the lens of the eye;
can be congenital, caused by trauma, or associated with disease; when caused
by maternal rubella, cataracts are not removed early, and
acuity never develops well; if not caused by rubella,
cataracts are surgically removed soon after birth (usually within the first
two months), to allow the retina to be stimulated by light within the first
6-8 weeks of life; good acuity is possible if cataracts are removed early
enough.
Glaucoma- (infantile): (also known as
"buphthalmos") intraocular pressure build-up caused by an imbalance
between the rate of production of the aqueous fluid and the rate of normal
drainage; must be treated medically (often surgically).
Cortical Visual Impairment (CVI): apparent lack of or
reduction in vision when eyes appear to be normal; cause of the visual
reduction is in the visual cortex of the brain; there is no nystagmus;
special intervention techniques are indicated (contact VI teacher).
Infections: many types, with a variety of symptoms; most
common involve the conjunctiva (thin layer of tissue lining the eyelids and
connected to top layer of sclera); require medical treatment (usually
medication); other systemic infections (toxoplasmosis, herpes,
cytomegalovirus) can also involve the visual system.
Malformations: many types; most common are clefts in the
iris, dislocated lens, and syndrome-related abnormalities; may have prenatal
causes
Ocular-muscle problems: most common is strabismus
(one or both eyes out of alignment); can be outward, inward, upward, or
downward, depending on which muscle(s) are affected; must be evaluated
medically, for possible surgical treatment; if noticed after 6 months of age,
child should be seen by an eye specialist; treatment can be before the child
is a year old; every year of delay past age two lessens the chances for good
prognosis in acuity; can cause loss of or diminished acuity in one eye
(amblyopia) if not treated.
Nystagmus is another ocular-muscle anomaly; manifested by
involuntary eye movements, usually noted as "jerky" or
"jumpy" eye movement; occasionally occurs alone but most often
accompanies other eye conditions; there is no cure; acuity may be reduced,
but visual function may improve with age.
Ocular trauma: occurs when the eyeball is hit, lacerated,
or punctured; always requires medical evaluation and treatment.
Optic nerve defects: Optic atrophy
occurs when, for a number of possible reasons, the optic nerve does not
function properly; may result in inconsistent visual functioning; often
causes reduced acuity; there are usually no outward indicators - the eyes
appear normal ; glasses will not improve acuity; must be medically diagnosed;
the phrase pale optic disk(s) suggests the possibility of optic atrophy. Optic
nerve hypoplasia (ONH) differs from optic atrophy; in ONH, the optic
nerve has regressed in development (usually during the prenatal period, and
usually caused by a prenatal insult to the neurological system); must be
medically diagnose; may have accompanying brain malformation and/or endocrine
problems; there is no treatment, and glasses will not help. Septo-optic
dysplasia seem to be an extreme form of ONH.
Refractive errors: (nearsightedness, farsightedness,
astigmatism) These are the only defects glasses will help, but, since the
infant eye is still developing (and clear acuity is still poor), they are
usually not identified as problems in the early months. If present to a
marked degree after about 12 months, they may require a
prescription for glasses but most toddlers will not need corrective lenses.
If acuity seems to be reduced (not within normal ranges) after about age 2,
medical evaluation is recommended. In the case of premature infants, an eye
specialist should monitor vision periodically from birth.
Retinoblastoma: a tumor behind the eye which, if left
untreated, can be both blinding and life-threatening; medical treatment
(chemotherapy and/or enucleation) is essential, usually before age 2.
Retinopathy of Prematurity (ROP) : (formerly called
retrolental fibroplasia, or RLF) a condition found primarily (but not
exclusively) among premature infants; despite the suspected role of oxygen in
this disease, prematurity seems to be the major factor; identified medically;
cryotherapy appears to halt the progression of the disease; visual function
can range from near normal acuity to total blindness, depending on the stage
of the disease; about a fourth of children with ROP have severe visual
impairment; many of these children are also myopic (nearsighted).
NORMAL DEVELOPMENT
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