The North Shore-LIJ Department of Ophthalmology has three full-time, board-certified and cornea fellowship-trained specialists — Dr. Ira Udell, Dr. Carolyn Shih and Dr. Anne Steiner — who offer a wide range of vision-correction procedures and complex treatments for corneal diseases.
What Is Keratoconus?
The cornea is the transparent tissue that covers the anterior surface of the eye and is responsible for focusing incoming light rays onto the retina. A healthy cornea focuses incoming light rays onto the retina (the back of the eye). This can either be done naturally or with the aid of corrective lenses. The cornea is composed primarily of collagen and water and is susceptible to various diseases that can block its ability to focus light rays correctly onto the retina.
Not to be confused with a “regular” astigmatism, which is a common corneal condition in which the cornea is shaped like a football instead of a basketball and is correctable by glasses or contact lenses, keratoconus is a disorder that creates blurred vision associated with an “irregular” astigmatism. The progressive thinning of the cornea leads to a “cone-like” shape leading to distorted vision — light rays are improperly focused on the retina and cannot be corrected with glasses or contact lenses.
Keratoconus usually affects both eyes equally in both males and females. It generally is first diagnosed during puberty and can progress through a person’s 30s at various rates. More mild forms can go undetected for many years.
What Is Post-LASIK Ectasia?
Post-LASIK ectasia can be characterized as keratoconus in someone who has previously undergone a laser vision correction procedure. It is thought that the LASIK procedure — since it involves the removal of corneal tissue with the laser — results in a permanent weakening of the cornea, which then leads to post-LASIK ectasia.
Post-LASIK ectasia can occur after LASIK as well as PRK (photorefractive keratectomy). These patients can develop symptoms of decreasing vision years following the laser vision correction procedure. This condition is diagnosed using our office’s latest generation of corneal topography and the Pentacam device.
What Causes Keratoconus?
Genetics can play a role in development of keratoconus. Various genetic conditions associated with keratoconus are Down syndrome, Ehlers-Danlos syndrome and Leber’s congenital amaurosis.
There are several theories regarding the root cause of keratoconus, but none have proven. Patients with keratoconus often report that they frequently rub their eyes, a source of one theory. Eye rubbing may be a response to allergies, which in turn may lead to the development of keratoconus. Precautions are taken to advise patients not to rub their eyes in hopes to prevent the progression. In patients who have undergone LASIK, eye rubbing may also be a cause of post-LASIK ectasia: the same precautions are given.
A reduction of collagen bonds in the cornea can be another potential cause of keratoconus. This process, called crosslinking, helps provide the biomechanical stability of the cornea. Corneal crosslinking using riboflavin and ultraviolet light has been used to halt and reverse the progression of keratoconus in a number of studies. The North Shore-LIJ Department of Ophthalmology is part of an FDA clinical trial in the Long Island / New York Metro area for crosslinking as a treatment for keratoconus.
Corneal Collagen Crosslinking
CXL, an advanced keratoconus and post-LASIK ectasia treatment, involves ultraviolet light in combination with topically applied riboflavin (vitamin B) eye drops to increase the crosslinking of the collagen fibers, which in turn strengthens the cornea.
One of North Shore-LIJ’s cornea specialists, Dr. Carolyn Shih, has been selected as a principal investigator for Avedro’s FDA clinical trial for corneal crosslinking. Our cornea specialists at North Shore-LIJ (Dr. Ira Udell, Dr. Shih and Dr. Anne Steiner) and our cornea specialists at the Manhattan Eye & Ear Infirmary (Dr. Richard Braunstein and Dr. Amilia Schrier) are specially trained to perform CXL.
In the early stages of keratoconus, patients are often able to see clearly with glasses or soft contact lenses. Eventually, as the condition progresses, hard (rigid gas permeable, or RGP) lenses are required. RGP lenses further help to reduce the irregularity of the cornea.
The North Shore-LIJ Department of Ophthalmology also is one of only 11 sites in the United States that provides a highly customized contact lens called the PROSE lens for patients who are intolerant to RGP or hybrid lenses. Please call Monica Falconi, our PROSE coordinator, at (516) 465-8509 to set up an appointment with Dr. Anne Steiner, Director of the Ocular Surface Center.
Corneal Transplant/Deep Anterior Lamellar Keratoplasty Procedures
This corneal transplant procedure is performed on patients with advanced keratoconus who cannot wear contact lenses or who would not improve with the corneal crosslinking procedure.
A new procedure called DALK (deep anterior lamellar keratectomy) is increasingly being performed on patients with keratoconus or ectasia. The treatment spares the endothelial layer of the patient’s cornea. The endothelial layer is the back layer of the cornea that is usually not affected by keratoconus or ectasia. In the DALK procedure, the cornea anterior to the endothelium is replaced with a donor cornea. The patient’s own endothelium is preserved.
If you would like more information about DALK or would like to make an appointment with our cornea specialist, Dr. Carolyn Shih, please call our office at (516) 470-2020.