Many
people who wear spectacles or contact
lenses go through life knowing that
they are short or long sighted, or have
astigmatism, without ever understanding
exactly what this means. The aim of
this page is to introduce you to the
basic concepts of vision correction
and show you some of the equipment we
have at our disposal to aid us in our
diagnosis
MYOPIA
Myopia is the term used
to indicate short sight. In this situation
the light rays from a distant object
come to a focus in front of the retina
causing the image we see to be blurred.
Myopia is corrected with 'minus' lenses,
which are thicker at the edge than they
are at the center. Myopic people can
usually see clearly for close vision
without their correction in place but
their distance vision is very blurred.
HYPERMETROPIA
If you are long sighted
then you suffer from hypermetropia,
or hypermetropia for short. In this
case the light from a distant object
is focused behind the retina, or at
least it would be if the retina was
not there, so the image on the back
of the eye is again blurred. Hypermetropia
is corrected with 'plus' lenses, which
are thicker in the center than they
are at the edge. Young people with
low to medium errors of long sight
can often focus quite clearly for
distance, but near vision will be
difficult - this problem increases
with age.
ASTIGMATISM
Astigmatism is always
difficult to explain or describe. The
easiest answer is that instead of being
spherical, like the surface of a football,
the front surface
of the
eye, called the cornea, is unequally
curved like a rugby ball. The effect
this has on the vision is that for a
given object two images are formed in
the eye produced by the two different
curvatures. This obviously leads to
blurred vision, and needs to be corrected
with a 'toric' or 'astigmatic' lens
to bring the two focuses together. Astigmatism
can exist on its own or be combined
with either long or short sight.
Frames
Contact
Lenses
Spec
Lenses
Errors
of
vision explained
Our Vision is Your Vision
Our Vision is to introduce our patients to the freedom and pleasures of life
without glasses. Specialists for over 35 years we have the expertise to
fit those others consider unfittable.
Opening Times at our Birmingham
Practice
Monday-Friday 9:00am-5:30pm :: Saturday
9:00am-5:00pm
Times may vary around Bank Holidays.
24 hour answerphone service. Full access for disabled patients.
