All about Keratoconus and C3R - Symptoms, Causes, Diagnosis, Treatment (RGP contact lenses, corneoscleral or miniscleral or scleral contact lenses, Corneal Collagen Cross-linking with Riboflavin C3R procedure)

What is Keratoconus?


Keratoconus is a disease of the Cornea which is the clear, transparent dome shaped front layer of the eye. In Keratoconus, the cornea thins out and bulges like a cone. As the cornea thins out, it brings light rays out of focus. Due to this, the patient’s vision becomes blurry and distorted, which make daily tasks like reading or driving difficult.

What are the symptoms of Keratoconus?

In the early stages of Keratoconus, a patient will generally notice a minor blurring of vision. At this stage the condition is often confused with that of an issue which require corrective lenses (w.r.t nearsightedness and farsightedness). However, as Keratoconus progresses to next stage, patients will find that their vision has deteriorated further. It results in distorted or blurred vision at all distances and poor night vision.

Generally, patients with Keratoconus will have very little or no pain. However, some patients develop sensitivity to bright light, have eye strain while trying hard to read objects. Also, patients with Keratoconus will find luminous object appear like a cylinder in shape with the same intensity at all points.

What causes Keratoconus?

The causes for Keratoconus can be attributed to a number of reasons such as the following:

  • Genetics

  • Allergies of the eye

  • Too much rubbing of eyes

  • Connected tissue disorders (such as Marfan syndrome and Ehlers-Danlos syndrome)

  • Over exposure to Sun’s ultraviolet rays

  • Improper use of contact lenses (i.e. contact lenses which are not properly fitted)

New research suggests that imbalance of enzymes within the cornea leads to weakening of corneal tissues leading to Keratoconus. The imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, which cause the cornea to weaken and then the cornea bulges forward

How is Keratoconus treated?

In the early stages of Keratoconus, a patient is prescribed eyeglasses or soft contact lenses, which shall help to correct the mild nearsightedness, blurring or distortion of vision.

In later stages of Keratoconus, when the cornea thins out and changes shape, rigid gas permeable (RGP) contact lenses and corneoscleral or miniscleral or scleral contact lenses are generally prescribed. These specialised contact lenses must be carefully fitted. Also, in order to maintain good vision, patient is required to undertake frequent checkups and lens changes. Other surgeries like Intracorneal ring segments (eg. Intacs) may sometimes be indicated to improve vision.

In progressive Keratoconus, Corneal Collagen Crosslinking with Riboflavin (C3R or CXL) is a treatment option to halt the spread of Keratoconus. C3R strengthens the weak corneal structure of Keratoconus patients. It is a non-invasive procedure (doesn’t require medical equipment to be introduced into the body).

In severe case of Keratoconus where vision cannot be improved using glasses or contact lenses, a Corneal Transplant may be needed. This is a surgical procedure that replaces the keratoconus cornea with healthy donor cornea tissue. Depending on the severity of condition either a full thickness Corneal transplant (Penetrating Keratoplasty) or a partial thickness Corneal transplant (Lamellar keratoplasty) may be indicated.

How is the Corneal Collagen Cross-linking with Riboflavin (C3R) procedure done?

C3R is based on cross-linking of collagen fibers within cornea with ultra-violet light and Riboflavin (vitamin B2, a photo sensitizing agent). This changes the intrinsic bio-mechanical property of the cornea, increasing its strength by almost 300%. This increase in corneal strength has been shown to stop the progression of Keratoconus.

C3R is performed under topical anaesthesia with the patient in a lying down posture in the sterile environment of the operating room. The patient's corneal epithelium is gently removed, then Riboflavin solution is applied every 5 minutes for the first half an hour. After that the patient's cornea is exposed to ultraviolet light for half an hour. After the C3R treatment, a patient will be given a soft bandage contact lens and administered antibiotic drops.

The treatment is painless and lasts for an hour, at the end of which the eye is patched.

How will C3R affect my vision post treatment?

It is important to understand that the aim of C3R procedure is to try and stop the progress of Keratoconus and thereby stop further deterioration of vision. While C3R treatment generally does not lead to significant improvement in the inherent vision of the eye, however, as the corneal curvature flattens and the surface stabilizes, the best corrected visual acuity with spectacles and contact lenses improves. The overall fit of the contact lens also improves so that patient can experience much better quality of vision.

What to expect post the C3R procedure?

Immediately after C3R procedure the vision will be somewhat hazy or blurry. This is because after the collagen is cross linked its rigidity increases and the corneal transparency is affected. The vision will continue to fluctuate over the next 3 months as the process of cross-linking continues.

The patient will have to take prescribed eye drops for a few weeks. The patient is expected to see the doctor in the intervals of one week, one month and three months post-procedure. Once the vision stabilizes which is typically after a period of around 3 months, further treatment for visual improvement in the form of specialized contact lenses like RGP lenses or Scleral contact lenses can be prescribed.

What are the major risk associated with C3R procedure?

C3R is a non-invasive procedure. There are no major risks associated.  There may be a rare risk of corneal infection, which can be treated by the use of antibiotic eyedrops. In some cases there is a possibility of vision deterioration due to the occurrence of corneal scarring after C3R.

Have more questions about Keratoconus or C3R? Schedule a consultation with our Cornea Specialist Dr. Aditi Agarwal

Disclaimer: All information, provided above is for informational purposes only and is not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider.

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