Keratoconus Treatment with Collagen Crosslinking Procedure
What is Keratoconus?
A type of corneal dystrophy in which the cornea gets progressively thinner. Between five and 14 percent of those who have the condition have a family history of Keratoconus. It starts with the thinning of the middle of the cornea, then slowly bulges outward to form a rounded cone shape. This produces moderate to severe distortion (astigmatism) and blurriness (nearsightedness) of vision.
What is the Treatment of Keratoconus?
Keratoconus usually affects both eyes. At first, people can correct their vision with eyeglasses. But as astigmatism worsens, they must rely on specially fitted contact lenses to improve vision. Several treatment options are available for persons with keratoconus, including:
Collagen cross-linkage (CXL) is the top of the list for treatments offered to patients with progressive keratoconus.
Spectacle correction/ rigid contact lenses, which can give high-quality vision for many patients for many years with little risk.
INTACS® prescription lenses, which are implanted in the eye.
Corneal transplants, which is the best option for patients who have got central corneal bulge with hydrops. Because the cornea is avascular, this procedure is highly successful (96 to 98 percent success rate) in keratoconus.
What is cross-linking?
Cross-linking is a medical procedure that combines the use of ultra-violet light and riboflavin eye drops.
What is the purpose of cross-linking?
The last two of years has seen a marked increase in the prominence of corneal collagen cross-linking as a treatment strategy for progressive Keratoconus. This interest has arisen from a body of evidence documenting the biomechanical and cellular changes induced by cross-linking. The findings of this research provide a rationale for its use in Keratoconus to retard the progression of this common disease. A rapidly growing number of clinical reports suggest a consistent stabilizing effect of cross-linking along with a variable improvement in corneal shape and visual function in some patients. As a first-line treatment, the greatest aim of cross-linking is to reduce and stop Keratoconus in the early phase of the condition and to treat the progressive vision loss that occurs which can lead to corneal transplantation.
How does cross-linking work?
Riboflavin (vitamin B2) is dripped onto the cornea and then exposed to ultraviolet light. The light causes the riboflavin to fluoresce, which leads to the formation of bonds between collagen molecules or simply stated, collagen cross-linking.
What is the safety profile regarding the use of ultra-violet light and of riboflavin in the eye?
The ultraviolet light exposure during a crosslinking procedure is comparable to, or even less than, the exposure of the eye to the ultraviolet radiation in the skylight for a full day outdoors in summer. The riboflavin drops are simply vitamin B2, commonly used in foods such as your breakfast cereal.
How long ago was the first one done?
The first human eyes were treated in 1998.
How safe is it in treating Keratoconus?
It is considered to be very safe. There are no cuts in the body of the cornea. It is much safer than a corneal graft which has been very successful in the past, and even than a gas permeable contact lens, and also there is no chance of rejection (some grafts tend to last around 10 -15 years). The transplant carries risks such as infection, rejection, cataracts, glaucoma, astigmatism and failure. At 15 years, there is no difference in the survival rate between penetrating corneal transplants performed for Keratoconus and those carried out for all other indications. Young Keratoconus patients are likely to need one or more repeated grafts during their lifetime. Crosslinking avoids the removal of any corneal structural tissue (only the surface epithelial cells are removed, and these grow back mostly within two days).
Who is suitable and who is not?
With today’s improved technology, the vast majority of people suffering from Keratoconus and other corneal ectasias may safely undergo cross-linking. However, there are exclusion criteria, so consult your ophthalmologist to determine if you are a candidate.
Are there any age limits?
Not usually but consult your ophthalmologist.
How is cross-linking performed?
Anesthetic eye drops are applied, and the surface cells of the cornea (the epithelium) are gently removed so the riboflavin eye drops can penetrate into the cornea. The riboflavin eye drops are applied and allowed to soak into the cornea. The cornea is then irradiated with ultra-violet light. The amount of time the riboflavin soaks into the eye and the amount of time the cornea is irradiated with ultra-violet light vary significantly depending on the ultraviolet light source used by the ophthalmologist. Advances in ultraviolet light sources have reduced total procedure time from one hour to as little as 12 minutes. At the completion of the procedure, a bandage contact lens is inserted, and the eye is patched overnight.
Are there newer riboflavin formulations that do not require the epithelium to be removed?
Studies are ongoing with riboflavin formulations that may allow the epithelium to remain intact during cross-linking. Check with your ophthalmologist regarding this option.
What are the possible complications and side effects of cross-linking?
Often transient and treatable and a part of the healing process: Pain in the first 1-2 days, sensitivity to light for several days, haze within the cornea that may cause blurring for up to a few weeks. There are other, less common, possible complications and side effects that your ophthalmologist can discuss with you.
Can cross-linking be combined with other treatments?
Cross-linking can be combined with Corneal Rings, Phakic Lens Implants, Refractive Lens Exchange, ARK, PRK, and LASEK.
Can cross-linking be redone if needed?
Yes, but during the past 13 years, a one-time treatment has generally been shown to be enough to treat progression.
Can I wear soft contact lenses after cross-linking?
One of the goals of cross-linking is to make the cornea more regular, allowing for soft contact lenses to replace the need for rigid gas permeable lenses. Rigid gas permeable lenses are good for vision in Keratoconus, but without warning can cause central scarring and can aggravate the condition. Your ophthalmologist will tell you if soft contact lenses are possible after cross-linking and how soon after treatment you may begin wearing them.
Are there any limitations or restrictions as to what I can do after cross-linking?
The blurring mentioned earlier may affect some people, especially in the first few days, and could limit work and driving during that time. However, consult your ophthalmologist.
Can anyone tell by my appearance that I have had cross-linking?
No. There is no change in the appearance of your eyes following cross-linking.
How many people have undergone a cross-linking procedure?
Tens-of-thousands of people have had their corneas cross-linked during the past 13 years. Due to the universal acceptance of the benefits of cross-linking among ophthalmologists, and recent advances in technology, the annual number of cross-linking procedures is expected to increase substantially.
Is cross-linking approved for general use in treating keratoconus?
Cross-linking was fully approved for use in the EU in January 2007, and almost all other countries have now adopted its general use to treat Keratoconus. It has been endorsed recently by FDA in the USA as well.
Can both eyes be cross-linked at the same time?
Technically yes, and that is our practice in most of the cases.
Will other eye treatments be a problem to perform after cross-linking?
No. It has no effect on any future surgery as far has been determined until now.
What other eye conditions can be treated with cross-linking?
Although most research to date has related to the treatment of Keratoconus, a role for CXL has also been suggested for other forms of corneal ectasia and some unrelated corneal conditions.The Indications Include: Keratoconus Pellucid marginal degeneration Iatrogenic keratectasia (post laser in situ keratomileusis) Prevention of keratectasia (prior to refractive surgery) Bullous keratopathy Microbial keratitis Corneal (stromal) ulceration Donor tissue modification prior to keratoplasty Although cross-linking has been used in all these circumstances, other than for progressive Keratoconus, there is currently little published evidence to support these applications.
