Spectacles/Eyeglasses
In the early stage and in mild keratoconus, eyeglasses may be all that is needed to improve vision. However, as the cornea becomes increasingly irregular, eyeglasses are less effective at correcting vision.
Contact Lenses:
Contact lenses (CL) work by creating an artificial, smooth surface on the front of the eye, improving the cornea’s ability to bend light. The majority of individuals with KC are prescribed CLs after their condition is diagnosed and continue to wear them successfully throughout their lives, allowing them to carry on normal productive lives.
Great care and expertise must be used by doctors who prescribe CLs for their KC patients. Frequent progress visits and changes in contact lens shape and power may be necessary due to changes in cornea shape. Specialty contact lens designs have been developed specifically for those with KC. These custom lenses may offer the best vision and comfort as KC progresses:
Soft Contact Lenses: Traditional disposable or soft contacts are not a typical option for KC patients, but some individuals with mild disease find these useful. There are also soft lenses made especially for keratoconus patients. They are useful for custom soft contacts may provide vision to those who find it difficult to tolerate ‘hard’ lenses. These lenses provide significantly less visual clarity, so the compromise between comfort and optimum vision must be carefully weighed.
Rigid Gas Permeable Lenses: The lens type most frequently used to correct KC are ‘rigid gas permeable’ or ‘gas permeable’ (RGP or GP) lenses. They provide excellent eye health because the lenses allow the cornea to ’breathe’ oxygen through the lens material. RGP lenses can be custom designed for the unique shape of the KC cornea and are easy to apply, remove, and care for. These lenses provide good vision correction, but some patients are unable to tolerate their wear over long periods of time.
Piggyback Lenses:A tandem or piggyback lens is a technique in which a soft contact lens is placed on the cornea and a corneal GP lens or hybrid lens sits on top of the soft lens. Although it takes more work to wear two lenses in oe eye, , some find this dual lens system prevents the rigid lens surface from irritating the sensitive cornea with the protective soft lens.
Hybrid Lenses: These specialty lenses incorporate a GP lens in the center, with a soft peripheral ‘skirt’. The hybrid lens offers the comfort, centration and stability of soft lens but the clear vision afforded by rigid central optics.
Scleral Lenses: Scleral lenses are large-diameter GP lenses, the size of a nickel to quarter, designed to vault over the entire cornea and rest on the sclera (the white part of the eye). Because of the size, the lens bowl must be filled with non-preserved saline before being placed on the eye. Individuals may initially find applying and removing scleral lenses challenging, but the majority achieve exceptional vision and comfort.
Intrastromal Corneal Ring Segments
Intrastromal corneal ring segments (ICRS) are clear, arc-shaped implants made of synthetic material that are surgically placed into precise tunnels created in the outer edge of the cornea by laser or other surgical instrument. ICRS implantation helps to remodel very steep corneas, making them more symmetric and flattening the curvature. In the U.S., these rings are called Intacs®. ICRS do not stop progression of KC. So, the goals of ring segments and corneal crosslinking are distinct. ICRS are designed to improve the corneal optics and reduce refractive error. Crosslinking has the goal of decreasing progression of disease. Some doctors combine ICRS placement and crosslinking into a single treatment; however no significant studies have been published to date with results for this combined procedure. Small scale trials have not demonstrated both procedures performed together to be superior. Even after insertion of ring segments, patients should expect to wear glasses or contacts for vision correction.
Not every patient with KC is a candidate for Intacs®. If this is a treatment option you would like to consider, please ask your eye doctor.
Corneal Crosslinking
Corneal Crosslinking (CXL) represents an important milestone in the treatment of keratoconus. While CXL has been performed for more than two decades internationally, approval by the U.S. Food and Drug Administration took place in 2016.
CXL is a nonsurgical procedure performed in the doctor’s office that takes about an hour. The treatment strengthens the weak corneal structure by allowing collagen fibers in the stroma to form new bonds to each other.
The result is that the progression of KC stops or is slowed. CXL does not reverse KC changes that have already occurred. That is why this procedure is recommended for those who are recently diagnosed or whose KC is still progressing. The procedure is less impactful for those who are no longer experiencing vision changes due to KC.
The only method that currently has FDA approval (as of the printing of this edition) utilizes an instrument manufactured by Avedro, Inc. (Waltham, MA) to deliver ultraviolet light and eye drops containing vitamin B2 (riboflavin). The treatment involves removing the central epithelium (the outermost layer of the cornea) to assure penetration of the eye drops.
This is called the ‘epi-off’ or epithelium-off method and is the standard CXL method. Eye surgeons are testing CXL protocols that do not require disturbing the epithelium (‘epi-on’). These treatments have yet not been shown to be as effective as the epi-off method and still have experimental or investigational status.
Following CXL, patients are told to expect a temporary decrease in vision and increased sensitivity to light for 1-3 months while the eye heals. Vision generally returns to pre-treatment levels in 6-12 months. New glasses and/or contact lenses are often required after treatment. The benefit of CXL is that further vision distortions slow or stop in the majority of cases.
Visit our Answering Your Questions about Crosslinking page for a list of common FAQ’s regarding CXL.
Corneal transplantation involves replacing a diseased or scarred cornea with a clear healthy one, which is donated through a local or national eye bank. The cloudy cornea is removed with a cookie-cutter-like instrument and the new one is secured in its place with sutures. These sutures remain for months or even years until the eye heals properly. Eye drops to promote healing and prevent rejection will be needed for several months to years after the outpatient procedure.
Depending on the reason for your corneal transplant, there are several approaches that your surgeon may suggest.
Conventional Keratoplasty
Conventional keratoplasty refers to a standard corneal transplant using a circular blade, known as a trephine, to create an incision. A conventional corneal transplant requires long periods of convalescence, sometimes upwards of 12 months for patients to enjoy good, stable vision. The traditional corneal transplant procedure requires multiple sutures and a lengthy post-operative recovery period until one reaches their final refraction and ‘best spectacle-corrected vision.’
Femtosecond Laser Keratoplasty
Femtosecond laser keratoplasty is a corneal transplantation or grafting technique using a femtosecond laser. This method uses an ultra-fast laser capable of pulsing more than 60,000 times per second to create a zigzag incision. This new technique results in a faster visual recovery and less astigmatism compared to conventional corneal transplantation methods. Depending on the reason for your surgery, this may be the best option for your corneal transplant.
Deep Anterior Lamellar Keratoplasty (DALK)
Deep Anterior Lamellar Keratoplasty is a special type of corneal transplant in which only the anterior (front) part of the cornea is transplanted. The back layer of your cornea is retained. DALK allows for less chances of corneal rejection.
After corneal transplant surgery, whether full- or partial-thickness, the corneal surface irregularities may be reduced, but you will likely still need vision correction. With a new cornea, contact lenses are often better tolerated.
In a small number of cases, the transplant may fail or be rejected, and your surgeon may need to perform a repeat surgery. Infections are another potential complication you will need to be aware of. There have even been a few extremely rare reports of patients whose keratoconus recurs in the corneal transplant.
Many patients fear they will need to undergo a corneal transplant when they learn they have keratoconus. In most cases, there will not be a need for a transplant: more than 80% of individuals with KC do not require a corneal transplant. However, if needed, corneal transplantation using current eye-banking and surgical techniques is a very successful procedure.
