What is Keratoconus?

 

Keratoconus is a condition that affects the cornea, the clear outer layer of the eye that covers the pupil and iris. In keratoconus, the cornea becomes thin and gradually bulges outward into a cone shape. This irregular shape can cause vision problems, including blurred vision, sensitivity to light, and difficulty seeing at night.

 

Causes of Keratoconus:

 

The exact cause of keratoconus is not fully understood, but it is believed to involve a combination of genetic, environmental, and biochemical factors. Some potential causes and risk factors include:

 

1. Genetics: Keratoconus often runs in families, suggesting a genetic predisposition. If someone in your family has keratoconus, you may be at a higher risk of developing it.

 

2. Eye Rubbing: Excessive rubbing of the eyes, particularly during the teenage years when the cornea is still developing, may contribute to the development or progression of keratoconus.

 

3. Thin Corneas: People with naturally thin corneas may be more susceptible to developing keratoconus, especially if they undergo any laser refractive surgery.

 

4. Eye Conditions: Certain conditions such as retinitis pigmentosa, Down syndrome, and Ehlers-Danlos syndrome are associated with an increased risk of keratoconus.

 

5. Environmental Factors: Environmental factors such as allergies and chronic eye rubbing may exacerbate the progression of keratoconus in susceptible individuals.

 

Symptoms of Keratoconus:

 

The symptoms of keratoconus can vary from person to person and may include:

 

- Blurred or distorted vision

- Increased sensitivity to light (photophobia)

- Difficulty seeing at night (night vision problems)

- Frequent changes in eyeglass or contact lens prescription

- Double vision or ghosting of images

- Eye strain or discomfort

 

Diagnosis and Treatment:

 

Keratoconus is typically diagnosed through a comprehensive eye examination, which may include tests such as corneal topography / tomography and corneal pachymetry to assess the shape and thickness of the cornea.

 

 

Treatment options for keratoconus depend on the severity of the condition and may include:

 

1. Glasses:

   - Glasses can provide initial correction for mild keratoconus, especially in the early stages when the irregularity of the cornea is not severe.

   - However, as keratoconus progresses, glasses may become less effective in providing satisfactory vision correction due to the irregular shape of the cornea.

 

2. Contact Lenses:

   - Soft Contact Lenses: Suitable for early stages of keratoconus or mild irregular astigmatism. They provide good initial correction and comfort but may not be effective as the condition progresses.

   - Rigid Gas Permeable (RGP) Contact Lenses: Often the primary choice for moderate to severe keratoconus. RGP lenses provide better visual acuity by vaulting over the irregular cornea, creating a smooth optical surface.

   - Hybrid Contact Lenses: Combines a rigid center with a soft skirt, aiming to provide both visual clarity and comfort. They may be a good option for patients who find RGP lenses uncomfortable.

 

3. Scleral Contact Lenses:

   - Scleral lenses vault over the cornea and rest on the sclera, providing stable visual correction and comfort.

   - They are particularly beneficial for patients with advanced keratoconus or irregular corneas who have difficulty tolerating other types of contact lenses.

 

4. Corneal Cross-Linking (CXL):

   - Considered a standard treatment for progressive keratoconus.

   - CXL involves applying riboflavin drops to the cornea, followed by exposure to ultraviolet light. This strengthens the corneal collagen fibers, halting or slowing the progression of the disease.

   - CXL may be combined with other treatments such as contact lenses or ICRS or topography guided laser treatment for optimal outcomes.

 

5. Intra-corneal Ring Segments (ICRS):

   - ICRS, such as INTACS, are small, arc-shaped plastic implants inserted into the cornea assisted by femtosecond laser, to reshape and flatten it, improving visual acuity.

   - They are primarily indicated for patients with progressive keratoconus who have poor tolerance to contact lenses or are not suitable candidates for corneal transplant.

  - Newer techniques have evolved which use donor corneal tissue instead of plastic implants to reshape the cornea. This is more biocompatible, and reduces the risk of complications associated with plastic implants.

 

6. Corneal Transplantation:

   - Reserved for patients with advanced keratoconus who do not respond to other treatments.

   - Techniques include Deep Anterior Lamellar Keratoplasty (DALK) ie partial corneal transplantation, wherein the inner layer of cornea is preserved thereby reducing the risk of rejection, or Penetrating Keratoplasty (PKP) ie full thickness corneal transplantation which replaces all the layers of cornea, usually performed if there is a corneal scar in the central cornea.

   - Advances in transplantation techniques, such as DALK, have led to improved outcomes and reduced risks of rejection.

 

Conclusion:

 

Keratoconus is a progressive eye condition that causes the cornea to thin and bulge, resulting in vision problems. While the exact cause is not fully understood, genetics, eye rubbing, and environmental factors may play a role. Early detection and treatment are essential for managing keratoconus and preserving vision. If you experience symptoms such as blurred vision or sensitivity to light, it's important to see an eye care professional for a comprehensive eye examination.

Patients with keratoconus should undergo regular monitoring by an ophthalmologist or corneal specialist to assess disease progression and determine the most appropriate management strategy tailored to their individual needs and stage of the condition.

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