Jenisha
Bhattarai
Children as
young as 6 months old or less may require an optical aid for good vision. It
may sound strange, but it is true. Refractive error in children may be
hypermetropia, myopia or astigmatism. All of these refractive errors cause
blurred vision in children. If not corrected, their consequences can be harmful
for children, since vision mostly develops within the first six years of life.
Cornea and
crystalline lens contribute the most to the converging power of the eye.
Therefore, changes in curvature or refractive index will affect the refractive
status of the eye. The distance between anterior and posterior poles of the
eyeball (axial length) governs the need for greater or lesser convergence of
light. The refractive error depends on whether the eyeball is longer (myopia)
or shorter (hypermetropia).
Refractive
error has also been associated with prolonged near work. Today, the increasing
demand of virtual educational classes has further increased the risk of
developing short sightedness in the school going children. Many studies have
estimated that half of the world’s population will go myopic by the year 2050.
Besides, the hindrance in overall development of children in conditions such as
premature birth and congenital syndrome is found to be associated with the
development of refractive error.
Infants and
pre-school children with vision problems may consistently sit too close to the
object of interest. Besides, squinting, tilting head, frequent rubbing and
excessive watering of eyes, closing one eye to see better, avoiding activities
at near, complaining of headache and frequent tripping and bumping into things
should arouse suspicion.
Young
patients with vision problems cannot follow the class normally, as they have
difficulty seeing words from a distance. This can cause a child to be
distracted and lose concentration and interest in continuing with his/her
studies. It is therefore very important for all children who are underachieving
at school to have an eye examination to rule out this possibility.
Children
with uncorrected refractive error adjust to the poor eyesight by sitting nearer
to the blackboard, squeezing their eyes and even avoiding work requiring visual
functioning. This may sometimes evade early detection. Visual blur at the level
of the retina later, leads to disuse of visual cortex, resulting in amblyopia
or lazy eye. Although ocular structures in amblyopic children are usually
normal, conditions such as unequal refractive error between the two eyes and
strabismus (misaligned eyes) are highly associated with it. Bilateral amblyopia
can also occur, particularly in patients with high refractive errors in both
eyes. Uncorrected refractive error is also associated with decreased
vision-related quality of life and increasing difficulty in performing
vision-related tasks.
Normally, a
new born full term child has+2D of refractive error, on an average. Stability
in refractive error is evident between the age of 2 to 6 with a trend toward
hypermetropic regression. This process of development of the eye towards
emmetropia (no refractive error) is called emmetropization. Any significant
refractive error during this phase or onward may cause amblyopia. Timely
detection of vision problems and their correction can tremendously improve a
child's potential during this formative year. The American Optometric
Association (AOA) recommends children to have their first eye examination at
six months of age, three years and every one year thereafter.
Refractive
error may require spectacles, contact lens or intraocular lens depending on its
type and degree. Treatment of amblyopia requires eyeglasses, contact lens, eye
patch, eye drops or vision therapy. The choice of treatment depends on severity
of amblyopia, age of the patient, presence of deviation and the compliance of
children. If amblyopia goes untreated, temporary or permanent loss of vision
can occur. This can include loss of depth perception and 3D vision.
[The author is an optometrist at Reiyukai Eye Hospital, Banepa]
0 Comments