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Everything You Need to Know About Keratoconus

Published by Auckland Eye on Tuesday, 19 Mar 2019
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Keratoconus is an inherited condition of the cornea (the transparent front surface of the eye), where the normally round cornea becomes thinned, distorted and coned-shaped.

The cornea is important to our eyes for a number of reasons. The cornea is the outermost layer of the eye, which contains five layers of membranes that each have different functions. All five layers help to protect the rest of the eye from dirt, bacteria, and other substances that our eyes might come into contact with throughout the day.

Our corneas also play a significant role in the refractive process of our eyes, focusing 65-75% of the images that we see. Without this refractive process that takes place in the corneas, the images that we see would become blurry. With keratoconus, this abnormal shape of the cornea prevents the light entering the eye from being focused correctly on the retina and causes distortion of vision. For this reason, patients with this condition often experience distorted vision which makes everyday tasks like driving, reading, or typing difficult.


 

Symptoms

Keratoconus symptoms range from mild to severe. Signs and symptoms of keratoconus may change as the disease progresses. They include:

  • Nearsightedness
  • Astigmatism
  • Blurred or distorted vision
  • Increased sensitivity to bright light and glare which can cause problems with night driving
  • A need for frequent changes in eyeglass prescriptions
  • Sudden worsening or clouding of vision

 

Who gets it?

Keratoconus does not discriminate, it affects people of all races and both sexes. Typically this condition develops during the individual's teenage years, progresses through the 20s and usually stops progressing after the age of 30. Since is it common for there to be a family history of the disease, about 1 out of 10 people with keratoconus have a parent who has it too.

Risk Factors

While eye care professionals do not know for sure what causes keratoconus, there are several risk factors which can increase your chances of developing this condition, which includes:

  • Having a family history of keratoconus.

Studies have provided evidence to suggest a genetic basis for keratoconus. Up to 50% of family members of patients with keratoconus have subtle signs of early keratoconus.

  • Rubbing your eyes vigorously.
  • Having certain conditions, such as retinitis pigmentosa, Down syndrome, Ehlers-Danlos syndrome, hay fever and asthma.

 

Can you Prevent Keratoconus?

While there are several different surgical and nonsurgical options to treat and stop the condition from further development, there is no way that you can prevent this condition as such. The best thing you can do to help decrease the severity and prevent it from getting worse is not to rub your eyes and seek treatment as soon as possible.

 

How is Keratoconus Treated?

Keratoconus treatment depends on the patient's symptoms and how quickly the condition is progressing. When the symptoms are mild to moderate, the patient’s vision can often be corrected with eyeglasses or soft contact lenses. For most people with keratoconus, the cornea will become stable after a few years. If you have this type, you likely won't experience severe vision problems or require further treatment.

Other non-surgical treatments option include: 

  • Hard Contact Lenses

As keratoconus gets worse, vision may no longer be correctable with glasses because of the amount of irregular astigmatism. Therefore to correct the patient's vision, he/she may need to be fitted with a special type of hard gas permeable contact lenses.

In most cases, these rigid gas permeable contact lenses are adequate but they require frequent check ups and must be carefully fitted by an optometrists. Lens changes may be needed to achieve and maintain good vision.

  • Piggyback lenses

If the patient finds rigid lenses to be uncomfortable, the ophthalmologist or optometrist may recommend "piggybacking" a hard contact lens on top of a soft one as an alternative. Although it takes more work to put on each day with an extra step, some patients find this dual lens system prevents the rigid lens surface from irritating the sensitive cornea.

  • Hybrid lenses

These speciality contact lenses incorporate a GP (gas permeable) lens and have a rigid center with a softer ring around the outside for increased comfort. People who can't tolerate hard contact lenses may prefer hybrid lenses.

  • Scleral lenses

These lenses are useful for very irregular cornea shape changes in advanced keratoconus. Scleral lenses are larger than regular contact lenses and are designed to vault over the entire cornea and rest on the sclera (the white part of the eye). Because of the size, the lens bowl must be filled with non-preserved saline before being placed on the eye. 

Instead of resting on the cornea as traditional contact lenses do, scleral lenses sit on the sclera and vault over the cornea without touching it. While many patients initially find applying and removing scleral lenses challenging, the majority achieve exceptional vision and comfort.

Surgery:

  • Corneal Crosslinking

Corneal crosslinking is the newest treatment for keratoconus. Although corneal crosslinking has only been around for 10 years, this innovative and highly effective treatment which is now available at Auckland Eye, provides a less invasive alternative to other more traditional treatment options.

The corneal crosslinking process involves dropping Vitamin B2 into the patient’s eye and exposing the cornea to UV rays. Before the procedure the patient will be given local anaesthetic drops, so the procedure will be painless. The combination of B2 and UV rays forms a chemical reaction that hardens the cornea. To prevent the keratoconus from progressing, the UV light encourages bonds between collagen fibrils to form which strengthens the cornea. To help with the healing process and to make the eye more comfortable, a contact lens will be placed on the patient's eye after the treatment.

Although this treatment will not restore the cornea back to its original rounded shape, this process has been proven to halt the progression of keratoconus in 94% of patients.

  • Intacs

Intacs are very small clear plastic arcs that are designed to be inserted into the substance of the cornea. When they are inserted into the eye, intacs reshape the cornea by flattening it closer to its original dome shape. By flattening the steep part of the cornea or cone to reduce distortions helps to refocus light rays and improve vision. Although the procedure usually improves uncorrected vision, most patient who have had this procedure will still need glasses or contact lenses after the intacs are inserted.

 

For some patients the cornea can become scarred, making if difficult to wear contact lenses. In this instance, surgery may be necessary. Surgical procedures designed to treat more severe cases of keratoconus include:

  • Corneal Transplants

When keratoconus continues to progress and contact lenses or intacs are no longer a solution, eye care professionals may recommend a corneal transplant. A corneal transplant operation involves replacing the damaged cornea with healthy donor tissue (human tissue provided by the National Eye Bank after careful quality screening). Depending on the severity of keratoconus, a corneal transplant may involve replacing one or more layers of the cornea. The entire cornea may be replaced if the keratoconus is severe.

 

Book an Appointment

If you are having difficulty with your vision and suspect you or your loved one may have keratoconus, we recommend you book an appointment at Auckland Eye. Here at Auckland Eye, we have most advanced technology and equipment to treat keretoconus and accurately determine the topography (shape and thickness) of the cornea, which allows us to screen for potential keratoconic changes to the eye. We offer the highest quality of care as each ophthalmologist has international and specialist training in specific eye diseases and surgery techniques to provide the best possible visual outcomes for all of our patients.

Auckland Eye - New Zealand Centre of Excellence for Eye Care