Keratoconus: symptoms, causes and treatment


The eye is a complex organ made up of several layers. The first is the conjunctiva that covers the sclera, also called the white of the eye. Next is the cornea, a transparent layer of dome-shaped tissue that covers the iris and pupil. Its main function is to help focus light in the lens and pupil.

Keratoconus is a progressive condition characterized by thinning of the cornea which causes it to lose its symmetrical dome shape. Corneal imbalance can cause blurry or distorted vision.

Read on as we dig deeper into Keratoconus, including its causes, symptoms, and treatment options.

The name keratoconus comes from the Greek “keras” (horn) and “konos” (cone).

Keratoconus is an eye disorder characterized by the transformation of the cornea from a symmetrical dome into an asymmetric or unbalanced cone. The main function of your cornea is to refract light into your pupil. When light passes through your asymmetric cornea, it can cause distortion and blurring in your vision.

Keratoconus was first described in the medical literature in 1854. It most often develops during your teenage years or early adulthood. It tends to get progressively worse for 10 to 20 years before stabilizing and tends to be more aggressive in children than adults.

Symptoms can start in one eye, but around 96 percent cases of keratoconus affect both eyes.

Researchers estimate that the prevalence of keratoconus is around 1 in 2,000 people, but some studies report that it’s as common as 1 in 500 people.

The characteristic sign of keratoconus is a thinning of your cornea which disrupts its natural dome shape. In the early stages of keratoconus, it is common to have no symptoms. As the disease progresses, the asymmetry of your cornea can cause blurred vision and slight to severe distortion of your vision.

Some of the early signs of keratoconus include:

  • Rizzuti sign. A sharply curved reflection seen by casting a light on the side of your cornea closest to your temple.
  • Fleischer ring. A brown ring of iron is deposited around your cornea which is more visible with a cobalt blue filter.
  • Vogt’s streaks. Vertical lines seen on your cornea which usually disappear when firm pressure is applied to your eye.

You can also experiment:

In rare cases, you can develop corneal blisters which can cause scarring and swelling.

Acute hydrops of the cornea is a rare complication of keratoconus that involves sudden swelling due to a rupture of the Descemet membrane found deep in your cornea.

Researchers still don’t fully understand why some people develop keratoconus. In most cases, it develops for no apparent reason. It is generally believed that environmental and genetic factors play a role in its development.

  • Family story. It is believed that some people with keratoconus can carry genes which make them predisposed to its development if they are exposed to certain environmental factors.
  • Underlying disorders. Keratoconus sometimes occurs in the presence of certain underlying disorders, but a direct cause and effect has not been established. These disorders include Down syndrome, sleep apnea, asthma, certain connective tissue disorders including Marfan syndrome and brittle cornea syndrome, and congenital Leber’s amaurosis.
  • Environmental risk factors. Certain environmental risk factors can contribute to the development of keratoconus, including excessive rubbing of the eyes and wearing contact lenses.

To make a diagnosis of keratoconus, your eye doctor will do a thorough eye exam and review your medical and family history.

During the eye exam, your eye doctor may examine:

  • the general appearance of your eyes
  • your visual acuity
  • your visual field
  • your eye movements

You may also have a slit lamp exam where your doctor examines your eye with special light under high magnification.

Diagnosing keratoconus may also involve a specific imaging test called a corneal topography to allow your doctor to look for changes in your eye that might not be visible otherwise. Corneal topography creates a three-dimensional image of the surface of your cornea.

Treatment for keratoconus focuses on maintaining your visual acuity and stopping changes in the shape of your cornea. Treatment options vary depending on the severity of the disease and how quickly it progresses.

Prescription contacts or glasses

Prescription glasses or soft contact lenses can be used to improve visual acuity in mild cases of keratoconus. Due to the gradual changes in your cornea, you may need to change your prescriptions frequently.

Other types of contact lenses

Gas permeable rigid contact lenses

Many people with keratoconus need these hard contact lenses. They allow oxygen to pass through the contact lens and help reshape your cornea to help minimize distortion of vision.

Some people find rigid gas permeable contact lenses uncomfortable. In these cases, piggyback lenses can be used. Piggyback lenses are when a hard contact lens is placed over a softer lens.

Hybrid lenses

These lenses have a hard center and a soft ring along the outer edge to increase comfort.

Scleral lenses

Another alternative to rigid gas permeable contact lenses, scleral lenses work similarly to a rigid gas permeable lens in that they provide a liquid layer between the contact lens and the front of the eye. This liquid layer masks the distortion caused by the corneal irregularity.

However, these lenses are often more comfortable because they rest on the white part of your eye, which is less sensitive than the cornea.

Surgery

Some people with keratoconus do not tolerate contact lenses well due to discomfort, severe thinning of the cornea, or scarring. If your vision cannot be corrected with lenses, you may need surgery.

  • Intracorneal annular segments. Food and Drug Administration (FDA) -approved to treat keratoconus in 2004This surgery involves inserting two crescent-shaped pieces of plastic called INTACS into the cornea to help support your cornea. Often times, you will still need contact lenses or glasses even after surgery to correct your vision.
  • Corneal transplant or keratoplasty. This surgery involves replacing your corneal tissue with tissue from a donor. It is generally only used in severe cases.

Collagen crosslinking device (CXL)

The FDA approved the first collagen crosslinking device to treat keratoconus in 2016. CXL is a minimally invasive procedure in which your doctor places special eye drops containing riboflavin in your eye and then uses ultraviolet light to strengthen the collagen fibers in your cornea.

This treatment limits the progression of keratoconus. CXL is an effective treatment for keratoconus for many and can actually stop the progression of the disease. However, according to the American Academy of Ophthalmology, more randomized controlled trials are needed.

Risk factors to develop keratoconus include:

  • Family story. On 10 to 20 percent of people with keratoconus have a family history.
  • Rubbing of childhood eyes. It is believed that excessive rubbing of the eyes during childhood Iincrease your risk by 25 times.
  • Close genetic relationship between the parents. It is believed that having a close genetic relationship between the parents increases the risk of developing keratoconus by approximately 3 times.
  • Race. Studies suggest that keratoconus levels are higher in Asians than in Caucasians.
  • Atopy. It has been suggested that atopy may be associated with the development of keratoconus, possibly due to increased eye rubbing due to eye irritation. Atopy is the genetic tendency to develop allergic diseases such as eczema, asthma, or allergic rhinitis.

Keratoconus is a progressive disorder that tends to worsen over a period of about 10 to 20 years. The speed at which the disorder progresses usually slows down in your 40 or 50 years old. He can stop progressing at any time.

According to American Academy of Ophthalmology, with early diagnosis and treatment with corneal crosslinking, many people with keratoconus maintain adequate vision with glasses or contact lenses.

If the keratoconus progresses to the point of drastically changing your vision, you may need to have a cornea transplant. Progression of keratoconus after corneal surgery has been reported, but it is not known how common this is.

Keratoconus is a disorder that causes thinning of the cornea. This thinning causes your cornea to lose its typical dome shape and can cause vision distortion. It develops most often in adolescents and young adults and usually progresses for about 10 to 20 years before stabilizing.

In many cases, it is not known why keratoconus develops. Some people with keratoconus have a family history of the disease. If any of your close family members have keratoconus, or if you have any potential symptoms, it is important to see your eye doctor for a proper exam.

Diagnosing and treating keratoconus at an early stage gives you the best chance of minimizing permanent changes in your vision.


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