Intacs are FDA approved for the management of keratoconus through a compassionate device exemption. They have been shown in some studies to slow or halt progression in some patients. They can also significantly improve corneal curvature in most patients and help improve contact lens tolerability and fit. Generally most patients receiving Intacs will continue to need to wear glasses and or contacts even when the treatment is successful. Patients are cautioned to keep in mind that the results with Intacs placement is highly variable. Some patients will experience marked improvement in corneal regularization, while others may have minimal if any effect. In aggregate we see a little more than 2 diopters of corneal flattening and up to 50% reduction in astigmatism measurements.
The best candidates for Intacs have no significant corneal scarring, have a thickness of 450 microns in the incision site and are not progressing. Patients who may not be candidates for cross linking may still be candidates for Intacs.
The procedure is fairly short. We us a femtosecond laser to make channels within the cornea usually about 70-80% of the corneal depth. This process takes about 30 seconds. After which the Intacs are mechanically placed within the corneal tissue under stile conditions. The procedure is performed in our laser suite. There is little down time from work and patients can often return to work the next day. A suture is placed in the cornea that is removed 1 month after the surgery. Generally the vision is stable enough in about 1-2 months after the procedure to fit new glasses or a contact lens.
The first studies published on corneal cross linking (CXL) were by Wollensack in 2003. This innovative treatment uses energy supplied from a UV light source to improve corneal collagen binding and improving the tensile strength of the cornea. This treatment has achieved the European CE mark (counterpart agency to the US FDA) since about 2005 after proving its safety profile. It has been adopted as the standard of care for patients with progressive early to moderate keratoconus by the American Academy of Ophthalmology. It is not however FDA approved in the United States (currently undergoing a lengthy FDA trial).
Early studies have shown a 90 to 95% success rate with CXL in halting progression of the disease. Re-treatment can be performed in patients who have had treatment failure. Studies indicate relatively low change in corneal curvature in the initial six months after treatment, however by 5 to 10 years after treatment, there can be a slow continued flattening in the overall curvature of the cornea, improving vision outcomes over time.
Sun Laser Vision Center is a co-investigator in the POCKET CXL study. This controlled, randomized, multicenter IRB-approved study is comparing whether pulsed or continuous application of the UV energy is more effective. Studies indicate a pulsed application may allow for more oxygen reperfusion of the cornea between pulses and this may be more effective than the standard treatment.
We are currently enrolling patients with keratoconus with evidence of progression. The cornea must be at least 350 microns thick (for hypotonic riboflavin treatment) or 400 microns (for standard riboflavin treatment). The cornea must be free of central scarring. Prior or concurrent Intacs placement is allowed. Patients must be 13 or older to enroll.
The treatment generally takes about an hour in our in-office minor operating room. Under sterile technique the “epi-off” procedure is performed using 30 minute of riboflavin loading of the cornea followed by either a 5 minute continuous application of UV at 18 mW/cm2 or 5 1-minute applications at 18 mW/cm2 with 1 minute rest intervals. A bandage contact lens is placed at the end of the procedure.
Patients generally can return to work in about 3-5 days after the treatment depending upon the rate of his or her healing. Vision stabilizes at about 1-2 months after the procedure, but can be variable (some sooner and some later).
Our results have generally been very good in patients undergoing concurrent placement of Intacs with cross linking and better than our results of Intacs alone. Generally patients with more advanced degrees of keratconus are going to be candidates for both modalities. Patients with lower degrees of keratoconus however often just benefit and are candidates for CXL alone.
In certain patients with normal to near normal corneal thickness and very low degrees of keratoconus, patients may have combined PRK with corneal cross linking. This can reduce corneal astigmatism, improve vision with and without glasses. However this combination does not have long term safety information and patients must understand that there could be a higher rate of treatment failure.
Intacs, CXL and PRK laser with CXL or combinations of treatments have been proven to be effective advances in treating patients with Keratoconus. However, in all cases patients must need to have realistic expectations. The main purpose of these treatments is to stabilize the disease progression and hopefully to have a little gain in vision with glasses or contacts. As with most diseases, the key is early diagnosis. The earlier keratoconus is caught and treated, the greater the likelihood of better, more normal vision. This is especially true in younger patients – teenagers and adolescent children who may have more rapid progression of keratoconus.
Keratoconus is a common disease that occurs in approximately 1 in 750 Americans. In this condition, the cornea becomes weak, progressively thinner, and irregular in shape which can cause high levels of astigmatism. Instead of a normal, relatively round shape resulting in clear vision, the cornea in keratoconus can become cone shaped. This can interfere with the ability to see clearly. Often keratoconus patients first require glasses, then contact lenses, and, if the condition progresses to a severe level, a corneal transplant may be required.
Astigmatism means that the front surface of the eye (the cornea or clear window in front of the eye) is less round and more irregular in shape so the image won’t focus clearly on the retina in the back of the eye. This can result in poor vision and glare.
Normal corneas have crosslinks between its collagen fibers that keep it strong and able to retain its normal shape. In keratoconus, the cornea is weak with too few cross-links or support beams. This weakened structure allows the cornea to bulge outwards. The cross-linking procedure adds cross-links or “cross beams” to the cornea, making it more stable, holding its shape and focusing power better. These new cross-links help strengthen the cornea which stops the thinning process and further loss of vision.
To qualify for the CXL study, patients must be at least 12 years old and their corneas cannot be too thinned or too scarred for the procedure. During your consultation, we will determine if CXL might an option for you. Our practice offers a complimentary, no-touch, painless screening test to see whether CXL might help you.
As you may know, keratoconus is a condition that often runs in families, so it’s important to arrange a screening for all family members of patients with keratoconus. If caught early, there is a good chance that CXL can halt the progression of keratoconus and prevent the need for uncomfortable contact lens wear and/or corneal transplant.
Many research studies have shown that CXL may prevent further vision loss in over 95% of patients and improves vision in 60-81% of patients treated.
No. LASIK is a procedure that reduces or, in some cases, may even eliminate the need for glasses or contact lenses by removing corneal tissue. The CXL treatment does not remove tissue. The purpose of CXL is to prevent further deterioration of vision for most patients and to potentially improve vision. Patients will typically require a lower eyeglass prescription or can have an easier time being fit with contact lenses.
Many studies have shown that CXL can often prevent the need for a corneal transplant and allow patients to wear contact lenses or glasses more comfortably and safely again.
If CXL does not prevent the need for a corneal transplant, then a corneal transplant can generally be performed.
Each patient and each patient’s eyes are different. In some cases CXL can be performed after corneal transplantation.
CXL is an in office procedure that does not involve surgical incisions into the eye or stitches. It is a relatively non-invasive procedure that is done with vitamin drops and light. Corneal transplants are performed in an operating room, involving incisions into the eye and a lifelong risk of rejection of the corneal tissue.
Based on CXL study results over more than a decade, the beneficial effects of CXL appear to last for many years and there is evidence that this strengthening effect may be permanent.
Corneal collagen cross-linking has been performed since 1999. The results and safety profile of CXL have been very positive in numerous studies throughout the world. In fact, by September of 2006, CXL had been approved by all 25 European Union nations. CXL procedures are now routinely performed on patients as young as 10 years old in Europe to prevent the development of keratoconus.
In many studies, the majority of patients responded to a single vitamin and light CXL treatment and did not need to have the procedure repeated. CXL can often be repeated when treatment is not effective.
The CXL treatment is an outpatient procedure performed in the doctor’s office using only numbing eye drops and a mild sedative like a Valium tablet. You’ll need to lie flat on your back in a reclining chair and look up at a soft blue light during the treatment. The epithelium, a thin layer of clear, protective tissue (like skin) that covers the cornea is removed for the CXL procedure. Next, vitamin eye drops (riboflavin) are used in the eye and you will be asked to look at a special blue (ultraviolet) light while lying comfortably on a reclining chair. It’s generally easy to look at this light because your eyes are numb and we use drops so your eyes won’t feel dry.
In this less invasive CXL treatment, the surface skin layer (epithelium) of the cornea is not removed so the recovery is much faster than the traditional CXL technique. This less invasive technique can only be done on corneas that are thicker than 400 microns12,13. Your surgeon will be able to determine if you might be a candidate for transepithelial CXL treatment.
If two eyes are being treated at once, the procedure takes approximately an hour and a half. If only one eye is being treated at a time, the procedure takes approximately one hour.
No. The cross-linking procedure is painless. Anesthetic eye drops are used to avoid any discomfort during the procedure. Some patients have some discomfort after the procedure and your surgeon can tell you whether you are or are not likely to do so.
Yes, your doctor will discuss the advantages and disadvantages of treating one eye or two eyes at a time.
As with most conditions, prevention of a problem is better than treatment of a problem. The best time to treat keratoconus is before astigmatism has become severe and vision has been lost. This does not mean that people with very poor vision from keratoconus cannot be helped by CXL. However, the results of CXL for patients with advanced keratoconus have not been as good as for patients with early disease.
Some patients may be able to have an excimer laser treatment (PRK) or Intacs to improve their vision without glasses after they have healed from the CXL procedure.
We recommend that you stay out of contact lenses for a week or two if possible before your consultation visit to see if you might benefit from the investigational CXL procedure. This can vary based on how difficult it is for you to see without your contacts. We often suggest patients not wear their lenses for 3 days before their CXL procedure.
Most patients can return to wearing contact lenses 2 to 6 weeks after having the cross-linking procedure depending on whether you are a candidate for transepithelial CXL. Your surgeon will determine how long this might take in your case.
Because cross-linking often improves vision, patients find that their old contacts or glasses are too strong for them and they need to be refit with new, glasses and/or contact lenses. Most of the time, patients can wear their old glasses until several months after the procedure when their doctor will prescribe new ones. Because the effects of CXL occur slowly, patients don’t generally have to change their glasses very often.
With the traditional CXL procedure, most patients find that immediately after the cross-linking treatment, their vision is actually worse than it was before the procedure. This usually goes on for roughly 3-6 weeks. Patients may start to notice positive effects 4-8 weeks after the procedure and may experience major improvement in vision at least 3-6 months after the investigational procedure. In some studies patients’ vision and astigmatism were still continuing to improve five years after the cross-linking procedure2 so visual improvement is a long process. With the less invasive transepithelial CXL, some patients found their vision improved as early as several weeks after treatment.
We want to help you be able to work or do other things you need and want to do as quickly as possible. Based on the type of CXL procedure, your doctor can tell you when you can return to your usual activities. With traditional CXL, most people can usually do so after 5-7 days. With transepithelial CXL, most people return to their usual activities the next day.
Because of the regulatory environment in the US, this procedure is investigational so CXL treatment is not covered by insurance.
You will be charged for the procedure and will still have to pay for the costs of your regular medical care. Since this procedure is investigational, insurance plans typically do not cover the costs for participating. Financing is available to help our patients pay for this investigational procedure. To find out more about costs, ask the study doctor or staff. For more information about keratoconus, and/or our diagnostic screenings and treatments, please call our practice and ask to speak with a CXL coordinator or visit our website.