Eye & Contact Lens Factsheets
KERATOCONUS
Keratoconus is a relatively rare
pathological condition, which causes the corneal
surface (the front of the eye), to begin to grow
forward and take up a conical shape (a bit like
an ice cream cone) rather than normal spherical
curve. This leads to distorted vision and, if
the progression of this shape change is not physically
halted, it can ultimately lead to the rupture
of the cornea and subsequent blindness. If the
problem gets to such a position a corneal graft
may be necessary but the visual results may not
be good.
Correction of keratoconus with
spectacles is not effective since we are technically
unable to create the curves on the spectacle lens
that will focus light correctly upon the retina
at the back of the eye - at best the vision may
be better but still very distorted! Furthermore
if glasses are prescribed then, bearing in mind
this condition is continually changing, frequent
alterations to the spectacle prescription will
be needed making for increased costs.
The universally accepted method
therefore of controlling keratoconus is the use
of Contact Lenses to exert a positive pressure
over the apex of the cornea to hold the cornea
in a pre-determined shape of the Contact Lens.
The lenses used to correct this are generally
Flexible Oxygen Permeable designs because of their
hardness but recently specialist Soft Lenses have
become available which also have a good controlling
effect on the eye shape.
Although we can never effectively
make the cornea totally spherical by using Contact
Lenses the tear lens created between the back
of the Contact Lens and the front of the cornea
helps considerably in reducing the distortion
which would be apparent with a spectacle correction.
Correction of Keratoconus requires
the skill of an expert Contact Lens Practitioner
but our results are such that many Keratoconic
patients fitted with Contact Lenses are able to
achieve vision up to and above that required to
read a number plate at 25 yards. In other words
making the difference between being able to drive
or not. Keratoconic patients with well
fitted Contact Lenses, if regularly monitored
by an experienced Contact Lens Practitioner, should
expect to enjoy good stable vision. As a specialist
practice we regularly receive referrals from colleagues
of the more complex patient such as keratoconics.
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