WHAT IS KERATOCONUS?

 

The name comes from: Kerato-cornea, conus-cone;

 

The cornea represents the window that lies in front of the eye. The light enters through it, crosses the crystalline lens to the retina, and then the information is transmitted to the brain to create the visual image.

 

Keratoconus is a degenerative eye condition classified in the ectasia group, with keratoglobus and pellucid marginal degeneration.

 

It is characterized by change in the shape of the cornea which becomes cone-shaped from round-shaped and in corneal thickness which becomes increasingly thinner.

 

It is typically diagnosed in adolescent patients, sometimes reaching severe forms in 20 to 30 years old patients. It affects both eyes with a slight gap in evolution, leading even to the inability of patients to drive a car and to read a text.

 

It affects both sexes.


WHAT CAUSES KERATOCONUS?

 

Study demonstrate that an enzyme deficiency in the cornea may lead to the development of keratoconus. The prevalence in the general population is 1/1000.

Some studies also have provided evidence of the fact that there are some genetic mutations in chromosomes 16q and 20q. Others suggest that it is transmitted in an autosomal dominant matter. It is particularly encountered in patients with Down syndrome. It relates to atopic diseases such as asthma and allergies.


WHAT ARE THE SYMPTOMS OF KERATOCONUS?

 

The patient frequently complains of:

 

  • Blurred vision;
  • distorted image;
  • Increased sensitivity to light;
  • Eye irritation;


HOW TO DIAGNOSE KERATOCONUS?

 

There are some characteristic signs of keratoconus that are seen by doctors at the slit-lamp. But there are frequent situations where there are no signs at the onset of the disease.

We may suspect this diagnosis when we have a young patient who frequently changes his glasses, who shows a progressive and irregular astigmatism.

As a modern diagnostic method there is the corneal topography, which determines many corneal parameters including:

 

  • radius of curvature of the anterior and posterior surface;
  • dioptric power of the cornea both anteriorly and posteriorly;
  • corneal thickness, the thinnest corneal area;
  • corneal indices

 

Another investigation that must be considered is OCT with the anterior segment program that gives valuable information about the thickness of the cornea.

Ultrasound pachymetry is another procedure that should be considered before determining a therapeutic attitude.


HOW TO TREAT KERATOCONUS?

 

In incipient cases patients’ vision can be corrected with glasses and soft contact lenses.

Another method is the use of rigid gas permeable contact lenses but they have a disadvantage, and that is patient’s discomfort. The patient may not tolerate them, may have a foreign body sensation in the eye and is not a method of stopping the disease.

As a modern method we have the implantation of rings of a particular PMMA biocompatible material at the cornea level.

These rings are called INTRACORNEAL RINGS and are customized, meaning they are specific for each patient. They are calculated in a very well established manner according to the visual and anatomical parameters of the eye and aim the flattening of the cornea. This flattening leads to a very important improvement of vision.

In WEST EYE HOSPITAL this implantation is performed using an INTRALASE technology laser, a femtosecond laser. It is the one which makes the tunnel through which this ring is inserted, leading to a final accurate and easy to quantify result compared to the manual method.

Corneal CROSSLINKING is also a modern method of treatment. It is a photo-polymerisation reaction between a special substance riboflavin and corneal stoma collagen under a special UV-A lamp. The Rib is applied every 5 minutes at the corneal level, and then the patient should sit under the UV lamp for 30 minutes. The Riboflavin strengthens the collagen structure at the corneal level preventing cornea from deforming.

The technique is performed using the femtosecond laser, and the patient experiences minimal discomfort.

 

The patient starts to experience the refraction stabilization and vision improvement in approximately two months.

In most times, these two techniques can be associated either in the same session or in successive steps.

The corneal transplantation are difficultly performed in Romania, and there are very long waiting lists due to legislative problems.

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