Keratoconus occurs when the cornea, the top clear tissue covering the eye, becomes less spherical and more cone-like in shape and structure. This affects how light is focused, in turn creating vision problems. Most instances of keratoconus are diagnosed in a patient’s teens or early 20s. The condition can occur in one or both eyes.
Your eye doctor may notice symptoms during your annual eye exam, but common signs of keratoconus are:
- Constantly changing of vision in one or both eyes
- Blurred vision at both near and far distances
- Seeing halos or ghost images
- Double vision
- Spectacles often do not correct the vision satisfactorily
There is no proven cause for keratoconus, but a family history of the condition is believed to be a major factor. If you are experiencing any of these symptoms, you should schedule an appointment with your ophthalmologist.
Mild cases of keratoconus can often be corrected with glasses, or Dr. Guglielmetti can prescribe soft contacts to smooth out the irregularities of the cornea. Gas permeable contact lenses (hard contacts) are also used to correct keratoconus, because they are able to fit over the cornea to form a smooth surface and sharpen the patient’s vision. However, because keratoconus is a progressive condition, patients will need to be assessed for corneal collagen cross-linking, a procedure used to stabilize the cornea and to stop progression of the disease). In some cases, mostly with patients intolerant to hard contact lenses, corneal transplants may be needed.
Management of Keratoconus
When managing keratoconus it is first important to stabilize the disease process and then correct the vision. Below are the options available at the Johannesburg Vision Clinic.
- Stabilization of disease process
- Vision Correction
- Spectacles, soft contact lenses
- Hard or hybrid specialized keratoconus contact lenses
- Failed contact lens trial (unable to wear a contact lens)
- Intracorneal ring segments (Keraring / Intacs / Ferrara Ring)
- Topography guided laser vision correction (combined with cross linking)
- Phakic implantable contact lens
- Corneal transplant
Dr. Guglielmetti performs corneal collagen crosslinking as an alternative to corneal transplantation. It is a procedure that uses riboflavin, also known as vitamin B2 and UVA light to strengthen the cornea by increasing the number of bonds between collagen fibers in the tissue. The procedure has been shown to improve vision for patients with keratoconus and other forms of corneal weakness. There are two types of corneal collagen crosslinking:
- epithelium on
- epithelium off
Epithelium on corneal crosslinking is done with the corneal surface intact and requires more time for the riboflavin to attach. Epithelium off corneal crosslinking requires a thin layer of the cornea be removed to allow for faster infusion of the riboflavin. During either procedure, the riboflavin is administered through eye drops, and Dr. Guglielmetti will check for the presence of riboflavin and corneal thickness. Then the eye will be treated with UV light for 30 minutes. The entire procedure can take up to 90 minutes. Most patients return to work about a week after surgery.
Dr. Guglielmetti also offers topography guided laser vision correction combined with corneal collagen crosslinking. It is used as a last resort to avoid complete corneal transplantation for a certain group of patients who cannot tolerate contacts. The excimer laser is used to reshape the cornea to improve vision, and then the cornea is stabilized with a corneal collagen crosslinking procedure.
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Intracorneal rings are another option for keratoconus patients whose vision can no longer be corrected with spectacles or hard contacts. Before the procedure, topical anesthesia is administered and the eye is prepped for surgery. Dr. Guglielmetti uses the femtosecond laser to create a precise channel in seconds. The intracorneal ring is then inserted into the eye through the channel. Dr. Guglielmetti generally uses the Keraring as the preferred intracorneal implant. The Keraring is a small arc-like implant that significantly improves uncorrected visual acuity in about 70 percent of patients. This procedure is also unique because it is reversible.
Corneal Transplants for Keratoconus
If no other treatment is successful, you may require a corneal transplant to correct your keratoconus. Deep anterior lamellar keratoplasty is the current standard of care for keratoconus as it reduces the risk of corneal transplant rejection 20 fold. Dr. Guglielmetti is an expert in partial thickness corneal transplants, and keratoconus patients have the highest rate of success for this procedure. The surgery is an outpatient procedure and normally requires no hospitalization. Many patients who undergo corneal transplants continue to need glasses or contacts to correct their vision, especially for astigmatism. Patients may be suitable for customized laser vision correction or phakic implantable contact lenses once their keratoconus has been treated with a corneal transplant.