Squint eyes over the years have been looked upon as a black spot
on the human beauty. Nevertheless, it has been posing the
prospective brides with innumerable problems in matters of
matrimony. However of a beauty she might be, one look at her
eyes the boy turns her down. Such boys do not care to probe
whether squint eyes can be set right.
Sometimes, on the other hand, people with squint are considered
lucky in the society. But the Ophthalmologists who know the
consequences of squint, do not think so. On the contrary, they
stress the disadvantages and negative aspects of squints- as
outlined below.
The two eyes normally should be in a definite visual axis.
A manifest deviation of the visual axis of either eye is known
as squint or strabismus. So one eye is deviating or squinting,
the other eye takes up the visual function mainly. So it
becomes a dominate eye. Most of the time, the deviating eye
slowly becomes impaired functionally. Later it almost becomes
blind. This hard fact will not be known to the squinting person
unless he closes the good eye and tests for the other eye vision.
When the degree of squint is gross, it is very easy to recognise
that. But when there is a small amount of squint, various tests
have to be done to diagnose correctly the type and amount and
presence of squint.
Mainly there are two types of squint -paralytic and non-paralytic.
There are seven small muscles around each eye-ball, which are
responsible for the various movements of the eye. These muscles
are supplied by 3rd,4th, and 6th cranial nerves- which are derived
from the brain.
Whenever these nerves become weak or lose their conducting
capacity, the respective eye muscles become immobile. So when
the other normal eye moves in a particular direction, if the
affected eye cannot move in the same direction, squint becomes
evident which is a paralytic squint.
Non- paralytic or concomitant deviations are for the most part,
produced by anomalies of the power of convergence and divergence
and the co-ordinated use of the two eyes to obtain binocular
single vision. In these cases the amount and character of the
deviation does not vary when the eyes are turned to the right
or left.
Before going to the causes of squint, it is necessary to know
the necessity of two eyes. It is the fact that when we observe a
single object with both the eyes we see it as a single object
instead of two. Obviously one may ask -what is the necessity of
having two eyes? Even if one becomes blind, the other one can
function normally – one may think.
One eye is always complement to the other eye. When we see
with both eyes, the extent or field of vision is definitely wider
than with one eye. Moreover, two eyes are necessary to have
what we call as ” BINOCULAR SINGLE VISION” the important
aspect of this being depth perception. There are 3 stages in this
binocular single vision.
1. Simultaneous perception.
2. Fusion.
3. Steriopsis ( the one which gives the sense of depth )
The development of reflexes concerning the binocular single
vision and the movements of eye muscles – are not complete
until the child is 5 years. Usually this will be established
when the child becomes 8 years old. So any disturbances during
this period ( below 5years ) may hamper the relation between the
movement of the two eyes and may cause a squint.
Causes of Squint :
1. Accommodation and convergence anomalies.
2. Refractive errors.
3. Weakness in the nerves supplying the eye muscles.
4. The gross difference in the vision between 2 eyes
due to any reason.
5. Patching or closing of one eye for a prolonged period.
6. Defect in the development of the nerves between retina
and the brain.
7. Hereditary and genetic or familial causes.
Clinically, there are two types of squints – Convergent Squint-
when one or both eyes are turned in, and Divergent Squint –
when one eye is turned outside the normal visual axis.
Treatment :
No case of squint can be said to be ‘cured’ unless, in addition
to normality of appearance, there is restoration of binocular
single vision in all circumstances. Although the latter cannot
be achieved in every case, a satisfactory cosmetic result can
invariably be obtained by means of operation or surgery.
In a case of squint there may be three possible defects of
function which have to be remedied:
1. The loss of normal function of the squinting eye. This
may not only concerns visual acuity but also visual
localisation.
2. The loss of normal binocular function.
3. The physical deformity caused by the deviation of the
visual axis. This is the defect which attracts the attention of
parents but is the least important from the point of view
of visual function.
To give complete treatment, child should be between 6 and
8 years. So the parents and school teachers have a very
important role to play. They should subject these squinting
children for treatment at the earliest. Because any treatment
or surgical correction done after the age of 8 years is not
complete or perfect because then we can only correct the
physical deformity but we cannot get the very important
functional part of it i.e. binocular single vision. So most of
the time in persons who are treated for squint after the age
of 8 years, one eye would be stronger, other eye would be
weaker. They will not have binocular single vision – which
can give them the exact form and depth perception.
The methods of treatment:
1. Correcting the refractive errors – by glasses whenever
refractive error is found to be the cause of squint.
2. Deliberate occlusion or patching of the fixing eye so as
to improve the vision of the squinting eye.
3. By special type of (orthoptic ) exercises in order to
improve the binocular faculties.
4. By operation or surgery – to restore parallelism of the
visual axis.
One or more of these methods or all four may be needed in any individual
case.
Finally it is the dire responsibility of the parents and the
teachers to detect this malady, which renders their children
look ugly in the eyes, during the tender age of 6 to 8 years
lest it is practically impossible to develop a squintless society.
— Dr.H.S.Mohan
Source by Mohan H.S.
