Eye Disease
Ferrara
Ring Surgery
Keratoconus is a degenerative non-inflammatory disorder
of the eye in which structural changes within the cornea
cause it to thin and change to a more conical shape
than its normal gradual curve. Keratoconus can cause
substantial distortion of vision, with multiple images,
streaking and sensitivity to light all often reported
by the patient. It is typically diagnosed in the patient's
adolescent years and attains its most severe state in
the twenties and thirties.
Keratoconus is a little-understood
disease with an uncertain cause, and its progression
following diagnosis is unpredictable. In most cases,
corrective lenses are effective enough to allow the
patient to continue to drive legally and likewise function
normally. Further progression of the disease may lead
to a need for surgery including corneal transplants.
Despite its uncertainties, keratoconus can be successfully
managed with a variety of clinical and surgical techniques,
and often with little or no impairment to the patient's
quality of life.
People
with early keratoconus typically notice a minor blurring
of their vision and come to their clinician seeking
corrective lenses for reading or driving. At early stages,
the symptoms of keratoconus may be no different from
those of any other refractive defect of the eye. As
the disease progresses, vision deteriorates, sometimes
rapidly. Visual acuity becomes impaired at all distances,
and night vision is often quite poor. Some individuals
have vision in one eye that is markedly worse than that
in the other eye. Some develop photophobia (sensitivity
to bright light), eye strain from squinting in order
to read, or itching in the eye. There is usually little
or no sensation of pain.
The classic symptom of keratoconus
is the perception of multiple ‘ghost’ images,
known as monocular polyopia. This effect is most clearly
seen with a high contrast field, such as a point of
light on a dark background. Instead of seeing just one
point, a person with keratoconus sees many images of
the point, spread out in a chaotic pattern. This pattern
does not typically change from day to day, but over
time it often takes on new forms. Patients also commonly
notice streaking and flaring distortion around light
sources. Some even notice the images moving relative
to one another in time with their heart beat.
Discomfort and patient preference
may limit the use of rigid contact lens wear and in
advanced cases fitting may be problematic. Severe ectasia
and central corneal scarring in advanced keratoconus
can significantly limit the amount of visual rehabilitation
achieved by rigid lenses. In addition, there is a body
of evidence to suggest that repeated trauma caused by
the wearing of rigid lenses may in some cases be responsible
for the acceleration of the condition. For these reasons,
between 10-25% of patients with Keratoconus progress
to a point where surgical intervention is required.
Surgical options include:
• INTRA-CORNEAL RING SEGMENT
INSERT (Ferrara Rings)
• KERATOPLASTY
• ULTRAVIOLET-A/RIBOFLAVIN CORNEAL CROSS LINKAGE
• LENTICULAR (LENS) REFRACTIVE SURGERY etc.
