Keratoconus is a non-infectious eye condition in which an individual’s normally round cornea progressively thins and becomes cone-shaped. This irregularity causes images to be distorted when projected onto the retina, resulting in significant visual impairment. Keratoconus generally affects both eyes, though one eye will typically advance more quickly than the other.
The incidence of Keratoconus has been reported to affect 1 out of every 2,000 people and is often diagnosed in patients in their late teens. Males, females, and all ethnicities are affected equally. In the early stages of Keratoconus, glasses or soft contact lenses may be used to correct any vision issues. As the cornea progressively thins and bulges into a more cone-like shape, rigid gas permeable (RGP) or scleral contact lenses are often needed to provide a clear surface in front of the cornea, allowing the light rays to be projected clearly to the retina. For many years, this was the main treatment option for keratoconus patients until they eventually required a corneal transplant.
There are now new treatment options available, including Corneal Collagen Cross-linking and Intacs®.
Intacs® are clear, thin inserts called intrastromal corneal ring segments (ICRS) that are placed in the outer edge of the cornea. They are inserted into a small channel that is created by a femtosecond laser, the most precise method available.Intacs® reshape and normalize the cornea without removing any corneal tissue, allowing for a better contact lens fit.
According to FDA guidelines, Intacs® corneal implants for the treatment of Keratoconus are intended for the reduction or elimination of myopia and astigmatism in patients with Keratoconus who are no longer able to achieve adequate vision with their contact lenses or glasses so that their functional vision may be restored and the need for a corneal transplant procedure can potentially be deferred.
Scleral or RGP Lenses
Scleral and Rigid Gas Permeable (RGP) contact lenses are unlike soft lenses in that they are rigid lenses made of durable plastic that transmits oxygen. The use of gas permeable contact lenses has remained at the core of the optical management of keratoconus. RGP lenses are typically smaller lenses that rest on the cornea, while scleral lenses are larger lenses that rest on the white part of the eye, called the sclera.
These lenses, manufactured in a large variety of unique designs, provide a regular surface over the cornea to neutralize the visual distortions caused by an irregular cornea. Fitting hard lenses for patients with keratoconus may take time, as no one design is best for every type of keratoconus. Each lens design has unique characteristics, and the practitioner needs to carefully evaluate the needs of the individual and find the lens that offers the best combination of clear vision, comfort, and corneal health.
Scleral and RGP contact lenses offer some outstanding benefits for patients diagnosed with keratoconus. Because they are made from a firm plastic, they retain their shape when you blink, which can provide sharper vision than pliable soft lenses. These lenses additionally allow oxygen to reach your eye, which promotes eye health and wearable comfort. Scleral and RGP lenses do not contain water as soft lenses do, and therefore proteins and lipids from the eye do not adhere to the lenses as readily.
Corneal Transplant Surgery
While there are many treatment options for keratoconus to avoid a corneal transplant surgery, also known as keratoplasty, sometimes it is necessary in advanced cases. Patients with severe corneal thinning or those who cannot achieve acceptable vision with specialty contact lenses or other surgical options may be good candidates for a corneal transplant. This can be done by transplanting a full-thickness or partial-thickness cornea from healthy donor tissue. Thankfully, there have been many recent advances in this procedure, including the use of lasers to enhance precision.
A corneal transplant surgery does have different risks, including rejection of the donor tissue and glaucoma. It is important to note that rejection can occur years after surgery, but oftentimes can be reversed if detected early. Visual results vary depending on the severity of the keratoconus and your body’s individual response. Close follow up care is extremely important after a corneal transplant surgery, and many patients will remain on eye medications for an extended period of time.