Until a few years ago, we only had corneal transplants for people with keratoconus when glasses or contact lenses were not sufficient to give them good vision for as long as they needed to wear them to do their daily tasks. Now we have many new modalities. The new modalities are: 1. Collagen Corneal Cross linking, 2. Intacs, 3. ICL’s and 4. PRK, 5. DALK with the IntraLase. Cross linking will stop the progression of keratoconus in most cases. This can be combined with Intacs and these will help to reshape the cornea and improve the quality of the vision in about 80% of patients. Later, a small amount of cornea can be removed with the excimer laser and this often results in further improvement in vision. If the person still has a lot of near-sightedness or astigmatism, an ICL can be inserted. If however, the keratoconus is too far advanced, we can do a deep lamellar keratoplasty, to remove the thin part of the cornea and replace it with a normal donor.
While there are many more choices availble, we at YELC are able to offer the full range of treatments that are available for our keratoconus patients.

The IntraLase is a most amazing device for refractive and corneal surgery. Not only is Yonge Eglinton laser the centre with the most experience with this technology, we are also using it to modify astigmatism after corneal transplants. Normally, astigmatism is very common occurrence. This describes the oval shape of the cornea that occurs when the transplant is healed. This can be treated with glasses, but these cause a lot of distortion. Contact lenses of the hard variety can also correct the problem. But this doesn’t fix the problem, only masks it, and gives relatively good vision. To permanently change the astigmatism, something must be done to the cornea. We see the challenge of rehabilitation after a new cornea is to have the person achieve good vision with glasses or even without any correction at all. When corneal transplants began over 100 years ago, just getting a clear new transplant was a miraculous thing. We have moved ahead a lot in the past 3 decades, yet still patients after a corneal transplant cannot see, due to high astigmatism. We believe that the time has come to move beyond just a clear transplant and obtain good vision for the patient. How do we do this? First, if there is a very high astigmatism, we use the IntraLase to make very precise curved incisions in the cornea. these incisions can be done to incredible precision and with a perfect curve, resulting in a marked decrease in the amount of astigmatism. This may not correct all the astigmatism though. We then use the Excimer laser (Visx Star S4) to do a custom reshaping of the cornea. Many of our patients can now see well with a thin glasses prescription or even without glasses. This is a much more advanced and better goal for somewhat undergoing a transplant for Keratoconus or other problem.

Keratoconus is a common condition of the cornea that affects approximately 1 in 1000 people. The cornea acts as the major focusing lens of the eye. The cornea is the clear dome of the eye made up of hundreds of layers that are linked to each other with collagen. In keratoconus, these collagen links may be deficient and this leads to progressive corneal thinning and stretching. The cornea can start to bulge forward causing an irregular cone shape (similar to a distorted football) and therefore affects how images are focused. Keratoconus normally affects both eyes, although at differing points of onset and rates of progression. In most people it usually starts as early as the teenage years and typically continues until the mid-30s. It is thought that there may be an inherited component to this condition.

Symptoms that you may have Keratoconus

During the early stages, keratoconus may be treated by wearing glasses to focus images. However, as the disease progresses, glasses are no longer sufficient to correct the distorted vision. Typically vision becomes impaired at all distances; night vision is usually worse. As well, patients usually develop a significant distortion of vision, with multiple images, streaking and sensitivity to light. Generally though, there no sensation of pain.

Diagnosis

The diagnosis of keratoconus can be made by an ophthalmologist or optometrist once a detailed eye exam has been performed. In very early cases, a clinical eye exam may not be sufficient. Usually these cases can be diagnosed with advanced corneal imaging using a corneal topographer or a Pentacam. In this situation, the image that is produced will reveal a characteristic steepness and irregularity of the cornea.

Treatment

Most patients with mild to moderate keratoconus can wear contact lenses to improve vision but others may experience contact lens intolerance of failure. Regardless, contact lenses do not treat the fundamental problem: progression of disease. With minimal options available, many of these patients required corneal transplantation.

Corneal collagen cross linking by ultraviolet light with riboflavin is the first treatment proven to help slow down the progression of keratoconus and sometimes improve the amount of astigmatism – even in its early stages. The success of this treatment is based on its ability to strengthen the abnormal stretchiness of the keratoconic cornea by increasing corneal stiffness and rigidity. It has been used by eye surgeons in Europe for the past 10 years on hundreds of patients and the device we use has been approved by Health Canada. When corneal collagen cross linking is teamed together with other modalities such as Intacs corneal implants, ICL’s and laser reshaping of the cornea, it can help to prevent the need for a corneal transplant.

How is Collagen Cross Linking Done?

The treatment is performed on one eye at a time, although both eyes can be treated on the same day. The treatment is conducted under sterile conditions. The eye is frozen with drops and held open for you. The front covering layer of the cornea is removed and riboflavin drops are applied to the cornea for 30 minutes. After this, UV-A light is applied for another 30 minutes. At the end of the treatment a contact lens is placed over the cornea to aid in healing, and several drops are applied. The contact lens will be left in place for several days and you will continue with drops for several weeks. Over the following 2-3 days, that front covering layer on your cornea will regenerate. You will be given a prescription for pain medication which you may use over the first few days. There is often considerable discomfort on the first night. During this period, the eye may feel very dry and irritated. The vision will be very blurry at first but will improve gradually over several weeks.

How does Collagen Cross Linking halt the progression of Keratoconus?

Until recently, there has not been a proven treatment which could strengthen the cornea in patients with keratoconus. Although the welding of the fibers that occurs during the corneal cross linking procedure has little effect on the clarity of the cornea, it has been proven in many European studies to slow down and even halt the progression of keratoconus. The procedure itself is simple: vitamin B2 is applied to the cornea, followed by exposure of the cornea to ultraviolet light for a short time. The light activates molecules called free radicals that act to weld adjacent fibers in the cornea, much like a coiled electrical wire. This process is similar to the one used in the creation of many of our modern polymers that are used to make many household plastics. It is also similar to the bonding procedure that dentists use to attach materials, such as those used in fillings, to our teeth. The whole process takes about one hour.

What are the Benefits to C3R?

About 2/3 of all patients treated with collagen cross linking and riboflavin drops will have improved vision and in some cases mild regression of the steepness of their cornea. Compared with the untreated eye, collagen cross linking has been shown to slow the progression of disease in all patients. Also, unlike contact lenses, collagen cross linking can stop the progress of disease and may even cause regression of disease. These results are permanent and do not involve injections or stitches. It is a relatively simple, single – one hour treatment with quick recovery times and long-lasting results. Most importantly, it serves as an alternative to corneal transplantation – a far more invasive procedure than C3R or Intacs Corneal rings and thus should be considered only after exploring all options.

It is important to note that this collagen cross linking does not restore the cornea to a completely normal shape (similar to a soccer ball or football). Glasses and contact lenses will still be required and further treatment may be needed. In some cases, the treatment is not completely effective and the progression of the keratoconus may not be halted.

What are the risks of the treatment?

Very few risks have been reported to date. The dose of the ultraviolet light is designed to prevent damage to the cells that line the back of the cornea and other structures of the eye.

1. There have been no reports of cataracts, glaucoma or retinal injury to date.
2. A transient self limited haze will be seen in almost all patients after treatment. Usually this resolves after 6-12 months and is not visually significant.
3. Transient edema which is self limited may occur but usually resolves once the epithelium has healed.
4. The treatment may effect the measurement of intraocular pressure in the future.
5. There has been 1 case report of Diffuse Lamellar Keratitis which resolved with appropriate treatment.
6. There has been 1 case report of Herpes simplex keratitis which resolved with appropriate treatment.
7. It may not be effective and other forms of treatment will later be needed.

Patients will experience some discomfort which typically subsides within the first week. Some patients may not be able to wear their contact lenses for several weeks after the treatment. A new contact lens fitting may be required as well as a change in prescription.

As with any treatment, there may be long term risks which have not yet been identified. The increased corneal rigidity may wear off over time and further treatments may be required.

We are proud to announce the arrival of the corneal collagen cross linking treatment to the Yonge Eglinton laser eye centre. After waiting patiently, the treatment device has finally been approved by Health Canada. We are pleased to be among the first in Canada with the approved ultraviolet delivery light source for this treatment. We are excited to have done several of these treatments over the past few weeks with excellent success so far.
We didn’t have any treatment before to help prevent progression of keratoconus. Now, at least we can offer an alternative to just waiting for the disorder to get worse.
Who it is good for? Kerataconus tends to progress in the 20’s and 30’s of life. If we can stop it in its tracks, we may be able to prevent a large number of young people who go on to require a corneal transplant. Therefore young people, late teens and twenties, with keratoconus may want to elect to have the cross-linking to keep there vision stable and keep them seeing well with glasses.
The treatment is quite simple, and takes about an hour. We use Riboflavin (vitamin B2). Why? it is not the vitamin that strengthens the cornea, but rather it is its yellow color in solution that does the work. It absorbs the UV light that is applied to the cornea which generates free radicals. What are they? They are part of molecules that have a high charge and stimulate some chemical reactions. Since the cornea is made up of collagen, a protein, not unlike the protein that makes up your hair, it can react with the free radicals to forms bond, or cross-links. Yes, just like your hair, when you get a perm at the hair dressers. Their chemicals help form bonds between the collagen in your hair to make it curly. In the cornea, the cross-linking bonds the fibers in the cornea, resulting in a much stronger mesh that resists the tendency to bulge outward that happens in Kertatoconus. Therefore, the kerataconus is slowed down, or even halted in progression. It is like reinforcing concrete or vulcanizing latex to make it hard enough for use in commercial purposes.
It is painful? The treatment does not hurt, and takes about 1 hour to perform. Afterwards, the eyes are watery and sore for 24 to 48 hours during the initial healing phase. Vision will be blurred for a week or so afterwards while the eye heals. Not a lot of fun, but worth it in the long run if a corneal transplant is prevented.
It is exciting to finally have another option for the treatment of this important disorder.