Keratoconus

1. What is keratoconus ?

The cornea is the transparent front wall of the eye which acts as a natural lens.
Keratoconus is a disease that alters the normal shape of the cornea, causing a
progressive deformation which in the final phases takes on a cone shape. This gradually alters the visual quality of the affected eye.

2. What causes keratoconus ?

It is clearly a hereditary disease but with ‘variable penetrance’, that is it can
affect minimally or even to a severely advanced extent, ranging in intensity not only
between patients but between the pair of eyes (it occurs bilaterally and
asymmetrically).

This process depends on the age of the patient and when the symptoms start to appear. Usually the younger the patient and the earlier the onset of keratoconus, the faster the
progression, and its early diagnosis strongly influences the success of treatment.

3. How is keratoconus detected ?

In more advanced cases detection is simple. Unfortunately most initial keratoconi are difficult to diagnose without special equipment and experience in early diagnosis.


Therefore, the Amigó Eye Institute uses not just one but several different corneal topographs (Pentacam, Keratograph), wavefront aberrometers (Ladar Wave) and specialised equipment to detect subtle degrees of corneal weakness (ORA). Together with our extensive experience in the early diagnosis of keratoconus, these aids not only permit us to diagnose keratoconus in the early stages but also the less obvious «forme fruste», almost undetectable by other methods. Their timely identification often positively influences the final visual outcome.

4. How is keratoconus operated on?

When the disease is not too advanced, patients can wear glasses. But when it
progresses, it cannot be adequately corrected with glasses and they complain that they never
manage to see well with them. In these cases, rigid contact lenses are used that, although they improve vision, do not stop the progression of the conical malformation.


Keratoconus surgery is the only way to stop the progressive deformation of the
cornea and in many cases successfully improve vision.

How is keratoconus operated on?

Keratoconus is thus a malformation of the cornea which affects vision. It can be progressive or halt at a certain age, with greater or lesser impact on vision. Consequently, the treatment also varies whether the degree of visual impairment is advancing or not.

• Corneal cross-linking:
  When the disease is seen to be advancing, this method of corneal hardening is today the preferred technique with proven efficacy in stopping progressive deterioration of vision.
• Intracorneal rings::
  This technique is used when the person’s visual quality
is poor and cannot effectively be improved with glasses or contact lenses. It may be
combined with cross-linking or not. Since it is a relatively simple low-risk technique, it has led to a breakthrough in the modern treatment of keratoconus. Together with cross-linking it has greatly lowered the need for corneal transplants, which until now was the only and rather dramatic possibility to improve vision in advanced cases of keratoconus.
• Corneal transplant::
  When the disease has been allowed to progress too far, neither
cross-linking nor intracorneal rings are effective any longer and the only solution is a
corneal graft, definitely a riskier, more complex process.

CROSS LINKING

What is it and how is it achieved?

Cross-linking involves the application of a hardening substance (Riboflavin – vitamin B2) onto the
cornea while illuminated with ultraviolet light, to achieve increased cross-linking of the
collagen fibrils that make up the corneal tissue. This holds corneal deformation at bay and can improve visual quality.

It is a painless technique only requiring anaesthetic drops to numb the eye surface. The patient lies down looking towards a
light source while Riboflavin is dripped on the affected eye.
Treatment is not short, in total it lasts just over an hour.

CROSS LINKING treatment with special UV lamp in a case of
advanced keratoconus, I.O.A. May 2010

INTRACORNEAL RINGS

How is it done and what are they made of? (Keraring, Intacs)

It is a surgical treatment that respects the cornea, without penetrating inside the eye
like a corneal transplant does. One or two rigid semicircular segments are
implanted within the cornea, which act to tighten and regularize the centre of it, thus improving quality of vision.


The rings are made of Perspex, an acrylic material used for
over 25 years in the manufacture of intraocular lenses. It has proved to be perfectly
 tolerated by the body, without the risk of rejection. Such surgical treatment with
intracorneal rings is far safer and less traumatic for the correction of keratoconus
than corneal grafts, provided deformation is not overly advanced.


Intracorneal rings implant surgery

What is the surgical technique like?

At the Amigó eye clinic the entire procedure is performed under a surgical microscope
with topical anaesthesic to avoid any pain, i.e. drops only, without any injection. The procedure lasts between 10 and 15 minutes and the next day the patient may perform basic activity while treatment with eye drops is maintained for a few weeks.

Intracorneal ring

What are the visual results?

The degree of improvement depends on the extent of progression of the keratoconus, since patients operated on in the early stages benefit most from surgery, with an exceedingly high success rate (85-90 %).


Visual recovery is rapid and usually already noted from the first few days on, but it should be remembered that the use of glasses or contact lenses may be necessary to complete the visual improvement.


Today surgery with cross-linking and/or intracorneal rings is our
technique of choice for the surgical treatment of keratoconus, given the rapid recovery and
scarce complications.


A case of keratoconus treated with intracorneal rings