Keratoconus

The Cornea

The cornea is one of the most important parts of our eyes. It is through the cornea that we see. It is the clear outer lens and sometimes called the "windshield" of the eye. If you will try to look at the human eye, the cornea is the dome shape that looks like a ball. But there are some situations that the structure of the cornea is not sturdy enough to hold that round shape. Sometimes it bulges outward that shapes like a cone. This situation or condition is named keratoconus.

(Souce: www.wehelpchicagosee.com/blog/2016/05/19/how-intacs-can-successfuly-treat-170335)

According to William Trattler, MD (n.d.), keratoconus is a progressive disease of the eye. This disease causes the thinning and bulging of the usually round cornea and turns into a cone-like shape. The cone-shape deflects the light that enters the eye going to the retina thus causing distorted vision. According to him, this disease can occur in one or both eyes and normally starts during adolescence to early '20s. KC is more common in people with Down syndrome. (Yeung, 2019)

What are the signs and symptoms of keratoconus?

Since this disease distorts the shape of the cornea, it causes progressive nearsightedness and develops irregular astigmatism. It further creates additional sight-challenges like distorted and blurred vision and the possibility of glare and light sensitivity.

Keratoconic patients usually undergo changes in prescription for their eyeglass every time they visit an eye doctor.

(a) Normal Vision and (b) Distorted Vision

Thus, the following are the early symptoms of keratoconus:

• Slight blurring of vision.

• A distorted vision that's difficult to correct with glasses.

• Increased sensitivity to light.

What are the causes of keratoconus?

Based on different studies, keratoconus is a result of the weakening of the corneal tissue and may have been caused by the imbalance of enzymes within the cornea. (Trattler, n.d.) This imbalance makes the cornea more vulnerable to oxidative injury from compounds called free radicals. Thus causing it to weaken and bulge frontward. According to Dr. Trattler, the risk factors for this damage and the weakening of the cornea may include a genetic predisposition. This result is the answer to the question of why this disease often affects not only one, but several members of the same family.

Keratoconus also is related with too exposure to direct ultraviolet rays from the sun, too much eye rubbing, a history of ill-fitted contact lenses and prolonged eye irritation.

What are the different methods of treating keratoconus?

At the early stage and in the mildest form of the disease keratoconus, the use of eyeglasses or soft contact lenses may be of help. However, since the disease is progressive and the cornea continuously thins and becomes more distorted in shape, the soft contact lenses and regular eyeglasses may no longer give enough vision correction. Thus further and more complex treatment method is needed.

Dr. William Trattel suggests some of the treatments for progressive keratoconus:

• Corneal crosslinking

Also called corneal collagen cross-linking or CXL, reinforces corneal tissue to stop bulging of the eye's surface in keratoconus. Its aim is to strengthen the cornea by growing the number of the so-called "anchors" that bond collagen fibers together. It may reduce the need for corneal transplants. There are two known types: the epithelium-off and the epithelium-on types of corneal crosslinking.

• Custom soft contact lenses

These are made-to-order lenses based on specific measurements of the patient’s keratoconic eye or eyes and may be more at ease to use than gas permeable lenses or hybrid contact lenses for some wearers.

• Gas permeable contact lenses

An RGP or Rigid Gas Permeable Contact Lens

Special eyeglasses and soft contact lenses sometimes cannot offer enough visual sharpness in cases of keratoconus, the gas permeable contact lenses are usually the ideal cure. GP lenses cover the cornea, substituting its uneven shape with a smooth, uniform refracting surface to develop a vision.

• "Piggybacking" contact lenses

Contact lens over a cone-shaped cornea may sometimes be uncomfortable for a person, some eye doctors advocate "piggybacking" two types of contact lenses on the same eye. This method involves putting a soft contact lens, over the eye and then a GP lens over the soft lens. This method increases wearer ease because the soft lens performs like a cushioning pad under the inelastic GP lens.

• Hybrid contact lenses

These lenses were intended specifically for keratoconus patients. Its central GP zone vaults over the cone-shaped cornea for better comfort. Hybrid contact lenses offer the crisp optics of a gas permeable contact lens and wearing ease like the soft lenses. Different brands are available in a wide-ranging variation to offer a fit that adapts well to the irregular shape of a keratoconic eye.

• Scleral and semi-scleral lenses

These are types of gas permeable contacts that are larger in diameter. They are large enough that the outside edges rest on the white part of the eye. Since it covers a larger portion of the sclera, these lenses don't put on much pressure to the eye's cone-shaped surface for a more relaxed fit.

• Prosthetic lenses

This is needed for those eyes with advanced keratoconus. It uses proprietary Elevation Specific Technology to precisely cover the unique irregularities of each keratoconic eye. Treatment begins with an EyePrint Impression, then followed by an EyePrint lab for 3-D scanning. The scanned data then undergoes a numerically controlled machining system that produces a lens that fits exactly the impression and therefore fits keratoconic eye(s).

• Intacs

Intacs are FDA-approved and exhibits clear, arc-shaped inserts that are positioned surgically within the exterior cornea to change the front part of the eye for a clearer vision. It is needed if patients can no longer obtain useful vision with the use of other treatments. It is important to that that this treatment might delay but it can't stop a transplant.

• Topography-guided conductive keratoplasty

Study shows that this procedure is a possible help to smoothen those irregularities in the corneal surface. It uses energy from radio waves, to reshape the eye's front part.

• Corneal transplant

This procedure is needed if contact lenses or other therapies can no longer provide satisfactory vision. It is the last remedy to be considered and also named a penetrating keratoplasty.

To know more about Contact Lenses for Keratoconus, or if you are looking for a Doctor who fits Keratoconus Contact Lenses you may email info@solimanparolioptical.com or call (045)4990122

Dr. Mark Paroli is a Licensed Doctor of Optometry in the Philippines who has a special interest in Prosthetic Eye fitting, Low Vision Rehabilitation, Hard and Soft Contact Lenses. He has been fitting custom made Artificial eyes in the Philippines for more than ten years.

markparoli@artificialeye.ph