Child and spectacles

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During first year of life general reasons for correction are aphakia and myopia of high grade. Leading reason for correction in children under 3 years is hypermetropia while cross-eye



Children of certain age periods pass medical check-ups at ophthalmologist`s.
  
During first year of
life general reasons for correction are aphakia and myopia of high
grade. Leading reason for correction in children under 3 years is
hypermetropia while cross-eye. Early acquired myopia and astigmatism
join correction of aphakia, inborn myopia and hypermetropia for
children preschool age. In school age, leading reason for correction is
acquired myopia.
  
Material for eyeglass lenses
  
Polycarbonate is the
first choice for children eyeglass lenses material, as it is
characterized by the highest impulse load resistance, and spectacles
with polycarbonate eyeglass lenses are the safest.
  
Firstly, plastic
eyeglass lenses are 2-3 times lighter mineral. Spectacles, made on the
basis of heavy mineral eyeglass lenses can cause tic in a child, break
normal growth of internasal septum, lead to irritation and infection of
skin integument, slipping down of spectacles and, as a result, unequal
correction, and also sense of discomfort and lowering of a child`s
motivation for wearing spectacles.
  
Secondly, advantage of
plastic eyeglass lenses - is high safety. Children lead more movable
way of life, go in for active kinds of sport and games with usage of
objects, potentially dangerous for eyes, so spectacles on the basis of
mineral eyeglass lenses can be a source of additional danger by
themselves. After-effects of eye traumas with splinters of broken
eyeglass lenses can be very sad, so many ophthalmologists insist on
prohibition of usage of mineral eyeglass lenses while production of
children spectacles, considering them an additional risk factor. Usage
of plastic eyeglass lenses contributes to keeping of a child`s health,
in particular his visual organ.
  
For eyeglass lenses of
high refringences plastic eyeglass lenses with high index of refraction
are preferrable. This allows reduce thickness and weight of lenses on
30% and makes spectacles on their basis aesthetically attractive.
  
UV protection
  
A child`s visual organ requires more UV protection, as:
  
- children spend more time on open air, than aduls;
  
- a child`s lens absorbs more UV rays and short-wave visible rays to retina;
  
- damages, caused by
UV radiation in retina, are cumulative. With age it may lead to
development of cataract and a number of other diseases and, as a
result, to loss of vision.
  
Timely protection of
organ of vision in young age contributes to prevention of development
of diseases. Most eyeglass lenses on the basis of polymeric materials
have special UV-absorbers in the structure of initial composition,
which provide absorption of UV component up to 350-380 bicrons.
  
One should pay a
special attention to quality of children sunglasses. As a rule, parents
don`t want spending much money on children sunglasses and, not thinking
about quality, buy them from casual sellers.
  
Special coverings
  
A person, who doesn`t
wear eyeglasses, can sense negative sensations because of light
reflection from external and internal surfaces of an eyeglass lens.
These sensations are redoubled in a child, while work in a class-rooms,
illuminated by fluorescent lighting, which light has a certain
periodicity of blinking. Anti-reflex coverings on surface of eyeglass
lenses help to reduce sensitiveness to interfering reflections and make
eyeglasses more aesthetically attractive.
  
Anti-reflex coverings,
applied by vacuum evaporation method, reduce light reflectance from
eyeglass lens surface and increase its light transmission. Some
companies recommend application of eyeglass lenses with antireflection
coating while work at PC, as these coverings reduce sensitiveness to
twinkling of luminescent symbols and display itself.
 

Plastic eyeglass lenses
with hardsurfacing overlay, which increase their resistance to
appearance of casual scratches and working lifespan, are also
recommended. Nowadays most leading international manufacturers produce
plastic eyeglass lenses with multi-coverings (quantity of layers can
reach 10).

Eyeglass lenses design

Choice of potimal desing of eyeglass lenses allows making spectacles
light to the maximum. Most often experts recommend aspheric eyeglass
lenses for production of spectacles with lenses of high refringences.
In combination with high-index material, aspheric eyeglass lenses can
reduce thickness of lenses on 40% - and, as a result, their weight too.

According to a number of indications, doctors prescribe bifocal
eyeglass lenses for small patients. Most often this happens in cases,
when a child suffers from myopia and he needs spectacles to see a
blackboard well, however, there`s no necessity in correction for
proximity (or vice versa). Of course, bifocal lenses are a good
alternative.  
 



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