Keratoconus Treatment – Corneal Cross Linking

What is keratoconus?

Keratoconus is a corneal disease that occurs when the normally round dome-shaped cornea (the clear outer area of the eye) progressively thins causing a cone-like bulge to develop. The condition is typically diagnosed during adolescence and early adulthood with a variable rate of progression.

The bulging or "cone-shaped" protrusion is caused by the normal pressure of the eye pushing out on the thinned areas of the cornea. Since the cornea is responsible for refracting most of the light coming into your eye, an abnormal-shaped cornea can create reduced visual acuity and affect the way you see. This reduced visual acuity can make even simple daily tasks, such as driving, watching television or reading, difficult to perform.

Prior to use of corneal collagen cross-linking 10% of keratoconus patients required a corneal transplant.



» Corneal Cross Linking FAQ
» Advanced Treatment for Keratoconus – Corneal Crosslinking (CXL) and Photorefractive Keratectomy (PRK)
 
Keratoconus Treatment at Bochner Eye Institute

The Bochner Eye Institute established the first Keratoconus Clinic in Canada in 2008. The practice utilizes the latest technology to help Toronto keratoconus patients restore lost vision. In fact, Bochner Eye Institute introduced keratoconus treatment technology to Canada, and their physicians are widely regarded as the most experienced in North America.

Sophisticated imaging for keratoconus diagnosis at the Bochner Eye Institute includes a Pentacam diagnostic test that measures more than 20,000 data points of the cornea. This test determines curvature of the anterior surface, elevation of both the anterior and posterior surface, and generalized pachymetry readings. This imaging is the most sensitive indicator of early keratoconus, which frequently shows bulging on the posterior surface before changes occur to the anterior surface. The Ocular Response Analyzer (ORA) is a device that measures the biomechanical properties of the cornea and is helpful in confirming the diagnosis of keratoconus.

 
Main goals of Bochner Keratoconus Clinic
  1. Detection of keratoconus using Pentacam and ORA imaging.
  2. Determination of progressive disease or stability with repeat imaging.
  3. Counseling keratoconus patients on therapeutic or refractive options, which include contact lenses, corneal crosslinking, topographically-guided PRK, intrastromal corneal rings, and phakic implants.
 
What is corneal collagen cross-linking with riboflavin and UV-A light?

The Bochner Eye Institute was the first centre in Canada to introduce corneal crosslinking (CXL) in 2008. The procedure is used to stiffen corneas and prevent progressive ectatic disease. Crosslinking is widely considered to be the standard of care to stabilize corneas and prevent the risk of corneal transplant.

Corneal collagen cross linking in Toronto involves the application of Riboflavin Eye Drops on the cornea. Once absorbed by the cornea, UV-A light is applied for approximately 30 minutes. This combination increases the collagen cross-links to increase the mechanical strength of the stroma. After the treatment, antibiotic and other eye drops are used and a protective bandage contact lens is inserted for four to five days. Postoperative instructions are given.

The method works by increasing collagen cross linkings, which are the "anchors" within the cornea. These "anchors" and formation of links between nearby filaments of collagen are responsible for preventing the cornea from bulging out and becoming steep and irregular. The procedure has been performed in Europe over the past six years. The success rate at stability corneas is 98%, and in addition 60% of eyes achieve an improvement of one or more lines in best-corrected spectacle acuity.

 
Benefits of Corneal Collagen Cross-linking

  • Enhance corneal rigidity
  • Increase the corneal resistance and biomechanical stability of the cornea
  • Prevent disease progression
  • May defer the need for a corneal transplant procedure
  • May reduce the nearsightedness and astigmatism associated with keratoconus
  • Enhance contact lens wear
  • Reduce risk of ectasia with excimer laser treatment

 
Who is a Candidate?
  • Keratoconus patients between 10 and 35 years of age with or without evidence of progressive disease. Earlier treatment of the disease results in best-uncorrected and best-corrected visual acuity.
  • Keratoconus patients over 25 years of age with a history of progression. This may be determined by steeping on topography, an increase in myopia or astigmatism, or a decrease in best-corrected spectacle acuity.
  • Toronto keratoconus patients with corneas less than 320 microns, or those who have significant corneal scarring may not be eligible for the procedure. During a comprehensive consultation, the physicians at Bochner Eye Institute can help you decide which treatment is best for you.
 
How is the Procedure Performed?

The procedure begins with the administration of anesthetic eye drops. Next, the central corneal epithelium is removed with a very soft brush. PRK is used to smooth the cornea. In the next step, riboflavin drops are administered for 20 minutes. Finally, ultraviolet light (UVA) is applied for no more than 10 minutes to activate the drops.

 
Post-Operative Instructions
  • A soft contact lens is worn until the epithelium becomes intact, which is usually in 5 days. Rarely is there a delay in epithelial healing.
  • Vision is typically worse than pre-op during the first month. The epithelium gradually undergoes hyperplasia and hypoplasia to smooth the corneal surface and restore vision.
  • Patients can return to contact lens wear after 2 weeks.
  • It is recommended that patients wait 2 months before changing an eyeglass or contact lens prescription.
 
Possible Complications

CXL treatment has an extremely low complication rate. The risk of infection is rare as the UVA light kills all bacteria and parasites. In some cases, there is a delay in the healing of the corneal epithelium, which can delay vision correction results; however, this is not permanent.

 
Other Treatment Options
 
INTACS or Intra-Corneal Rings

Intacs were first introduced to the refractive surgery market approximately 10 years ago for the treatment of low myopia. The effectiveness of this product has been best demonstrated in patients' with keratoconus. The Intracorneal ring is a clear, thin prescription insert that is placed in the periphery of the cornea to change the curvature of the cornea from within. With strategic insertion, the ICR can reduce irregularity caused by keratoconus without removing tissue and it is believed that it may delay the progression of keratoconus. Although extremely rare, the ICR can be exchanged or removed if needed. At the Bochner Eye Institute, we use the Intralase FS create the channels in which the intracorneal ring is inserted.

 
Implantable Contact Lens

When a patient requires vision correction, but the cornea is too thin or the prescription is too high for laser vision correction, the Implantable Contact Lens is an option to consider. Patients with early stages of keratoconus have benefited from the Implantable Contact Lens. Your surgeon will assess your candidacy for this procedure during your evaluation. Please visit our Lens Implants page to learn more about the different types of treatment.

 
PRK

In some cases, PRK is a reasonable option for patients following corneal collagen cross linking for vision correction. Your surgeon will assess your candidacy for this procedure during your evaluation. Please visit our PRK page to learn more about this vision correction procedure.

 
Corneal Crosslinking and PRK Combination Treatment

The surgeons of Bochner Eye Institute, who introduced corneal crosslinking (CXL) in Canada, strongly believe that by combining this treatment with PRK, they can offer patients the best possible keratoconus treatment results. The purpose of CXL is to strengthen the cornea, thereby preventing progressive bulging. PRK is then used to flatten the irregularly-shaped cornea and enhance vision with glasses or contact lenses.

 
Advantages of Combining PRK and CXL

PRK is most effective when the cornea is at its strongest, which is generally immediately after CXL treatment. Performing PRK and CXL at the same time ensures the best possible results. PRK results become less predictable in the weeks or months following the CXL procedure.

 
How Successful Is CXL?

The doctors of Bochner Eye Institute have treated more than 3,000 eyes over the past four years – more than any other eye center in the world. Their efforts in this procedure have led to excellent outcomes, with a success rate of more than 98 percent.

 

Keratoconus treatment is only one of the specialties the surgeons at the Bochner Eye Institute Dr. Raymond Stein & Dr. Albert Cheskes' surgical team are known for. In addition to the other procedures listed before, they are also noted Toronto LASIK surgeons, and are the first surgeons in Canada to perform laser cataract surgery.