C3R (corneal collagen cross-linking) for keratoconus in Ahmedabad

Sanjivani Eye Hospital was one of the first laser centres in Gujarat to treat keratoconus with the C3R method, also known as corneal collagen cross-linking (CXL). Hundreds of patients with keratoconus have been treated this way at the hospital in Ahmedabad. The treatment stabilises keratoconus and stops it progressing, and the hospital reports a success rate of 92–95%.

This guide explains what keratoconus is, how C3R works and what to expect.

What is keratoconus?

Keratoconus is a condition of the cornea, the clear front window of the eye. The cornea's normal curve becomes misshapen and, in fact, turns cone-shaped.

The cornea is built from collagen fibres. In keratoconus, the chemical links between these collagen strands, which keep the cornea's regular shape, are defective, so the cornea becomes elastic.

When the cross-links between the layers are weak, the cornea tends to thin, bulge and deform. This distorts the images you see and changes your vision. Left untreated, the fibres keep weakening and breaking down, damaging the corneal surface further and making vision worse.

Advanced keratoconus may need a corneal transplant. C3R aims to avoid reaching that stage.

Early symptoms of keratoconus

• The first sign is often a change in spectacle power.
• As the disease progresses, vision gets worse and may not improve with glasses.
• Vision can be distorted, with multiple images, streaking and sensitivity to light.
• Redness, watering and pain in the eye may also occur.

Treatment options for keratoconus

C3R: corneal collagen cross-linking with riboflavin

Collagen cross-linking uses riboflavin (vitamin B2), a light-sensitising agent, and ultraviolet A light (UVA, 365 nm) to increase the cross-links between the collagen fibres of the cornea. This stabilises the shape of the cornea and can increase its strength by up to 300%.

Detected early enough, C3R can arrest the progression of keratoconus. The patient can then keep good sight with glasses or contact lenses, and may later be suitable for PRK laser treatment (see laser vision correction) or INTACS (corneal ring) implantation. In the Dresden clinical study, 3- and 5-year results in human eyes showed that keratoconus stopped progressing in all treated eyes (Wollensak G. Crosslinking treatment of progressive keratoconus: new hope. Current Opinion in Ophthalmology 2006;17:356–360).

How C3R is done

C3R is a quick procedure done on an outpatient basis; the whole visit takes about an hour and a half. It is performed under topical anaesthesia (numbing eye drops).

1. The surface layer of the cornea (the epithelium) is partially removed.
2. Riboflavin eye drops are applied for about 30 minutes so that they soak into the cornea.
3. The eye is exposed to UVA light of a specific wavelength for about 30 minutes.
4. The light combines with the riboflavin to create chemical bonds within the cornea, making it more rigid and stable.
5. Antibiotic ointment is applied and the eye is protected with a soft bandage contact lens, worn for a couple of days until the surface heals.

After the procedure

• Expect some discomfort; minor irritation may be felt for the next 24 hours, and pain-relief tablets may be needed for the first one to two days.
• Eye drops are prescribed: four times a day for five days, then twice a day for the next four weeks.
• The effect of the treatment is long-lasting, which makes C3R a good option for people with keratoconus.

What C3R does and does not do

• C3R arrests the progression of keratoconus.
• It does not undo damage to the cornea that happened before treatment, although partial flattening of a steep cornea has been reported in some eyes.
• It does not reduce the refractive error (your spectacle power).

Corneal transplantation

A corneal transplant is surgery reserved for advanced keratoconus, when vision can no longer be improved with glasses or contact lenses. The central part of the cornea is removed and replaced with a donor cornea of similar size. Because there is a high possibility of complications and graft rejection, it is kept for the most advanced cases.

Contact lenses

Hard contact lenses were used for keratoconus in the past. Early keratoconus can still be managed with rigid contact lenses, which correct the irregular cornea and give better quality of vision. Their drawbacks are that a good fit is hard to achieve in severe cases, and rigid lenses are more difficult to wear.

Frequently asked questions

Is the ultraviolet light harmful?

No. The ultraviolet A light used in C3R is not harmful to the eye in measured doses, and the wavelength used is chosen to be safe. The light output is carefully measured and calibrated before each treatment.

How often will I need follow-up visits?

You will be seen soon after the procedure to remove the bandage contact lens, and you will stay on eye drops for a few weeks. Follow-up visits are at 1 month, 3 months, 6 months and one year, and then once a year.

When can I wear contact lenses again?

You can usually return to contact lenses after one month. Your lenses may need to be changed if the shape of your cornea changes.

How long does C3R take to work?

The cornea becomes more rigid soon after the procedure, and cross-linking continues for a few days afterwards. Changes in the shape of the cornea take longer, and flattening does not happen in every treated eye. A satisfactory result is one where keratoconus stops progressing.

How is cross-linking different from other treatments?

Strengthening the cornea by cross-linking its collagen building blocks treats the cause of keratoconus: it can arrest the disease and has been reported to partly reverse the steepening that has already occurred. Other options, such as glasses, contact lenses or a transplant, address vision rather than the underlying disease.