What is
KERATOCONUS?
Keratoconus is a progressive disease that affects both eyes and is characterized by the bulging and thinning of the transparent layer (cornea) that forms the front part of the eye.
The cornea is the most important layer of the eye where the rays coming into the eye are refracted. Changes in this area cause the rays to focus incorrectly, seriously impairing the quality of vision.
- The most important complaint in this disease, which is more common in people with a family history and allergic constitution, is low vision that cannot be corrected with glasses.
- Keratoconus usually starts at the age of 15-16 and can progress until the age of 35. The course of the disease can vary from person to person.
- In the early stages of keratoconus, the complaint is usually the frequent change of spectacle size. As the disease progresses, clear vision cannot be achieved with glasses.
KERATOCONUS
Treatment
Since the course and rate of progression of the disease can be extremely different, keratoconus treatment is individualized. There may be patients who can see clearly without even wearing glasses and are unaware of their disease, as well as cases that progress extremely rapidly and require corneal transplantation in their twenties. In fact, there is no complete cure for keratoconus, which is a structural disease.
Methods Used
It usually starts in adolescence and progresses in the 20s. Early diagnosis and treatment is very important to prevent vision loss.
1
CCL
Corneal Crosslinking
It is a method that has been used with increasing frequency in the last 10 years and stops the progression of keratoconus. In this treatment, Ultraviolet A and Riboflavin (vitamin B2) are used to strengthen the structure of the cornea. For this reason, it is the first treatment option for patients with progression, regardless of the level of the disease and the quality of vision of the patients.
CCL not only stops the progression of keratoconus, but also provides some increase in visual acuity.
METHOD
In standard practice, the Dresden protocol is applied. After the eye is anesthetized with drop anesthesia, the epithelial layer on the outermost part of the cornea is peeled off. At 5 minute intervals, riboflavin solution is instilled into the eye for 30 minutes. Then 370 nm UV-A is applied for 30 minutes in an area of approximately 8 mm at a distance of 4-5 cm from the corneal surface. Riboflavin is continued to be instilled every 5 minutes during UV-A application. After the procedure is finished, contact lens is placed on the eye and the patient is sent home. After an average of 4 days, the healing is completed and the contact lens is removed. It usually takes 3 months for the patients’ vision quality to be restored. For this reason, it would be better to do the treatment of the other eye at least 3 months later unless it is not necessary. Studies have shown that 1 CCL intervention stops the progression of keratoconus in a large proportion of patients (95%).
In our hospital, we use accelerated cross-linking treatment with the Avedro device. Recent studies have shown that UV-A application at a higher power for 10 minutes provides the same effect as the Dresden protocol. Since this technique shortens the time, patient comfort increases and corneal thinning during UV-A application is prevented.
2
Rigid - Hybrid Contact Lenses
Since the shape of the cornea is distorted in keratoconus, vision cannot be improved with soft lenses. Hard or Hybrid lenses (hard in the center and soft on the edges) can improve vision by creating a smooth refractive surface in front of the cornea.
Lens wear does not stop the progression of the disease. For this reason, patients using CL should be routinely checked and corneal cross-linking treatment should be applied when necessary.
3
Corneal Rings
(Keraring, Ferrararing, Intacs)
They are transparent, tissue-compatible, tissue-compatible, glass-derived implants that are mounted inside the corneal tissue that is damaged in keratotoconus. Since they are placed inside the cornea, they do not need to be worn and removed like contact lenses. They can remain in the eye for a lifetime without any problems and can be removed from the eye at any time. Although there are different brands and structures of ring segments, the mechanism of action of all of them is the same. The aim here is to make the deformed cornea more smooth and to ensure the correct refraction of the rays coming into the eye.
METHOD
After the eye is numbed with drop anesthesia, a tunnel of the desired depth and diameter is created in the cornea with Femtosecond laser. After this process, which takes approximately 10 seconds, the ring pieces are placed into the cornea with the help of this tunnel. The eye is not closed after the treatment.
We have been practicing ring implantation in our hospital since 2006. In the last few years, we have been combining this treatment with corneal cross-linking treatment to stop the progression of keratoconus and provide a better visual result to our patients.
4
Topography Guided
Excimer Laser Therapy
It is a method applied to correct the irregular corneal surface in keratoconus patients with appropriate corneal thickness. The images taken from the topography device are analyzed and transferred to the Excimer laser device and then the irregular front surface of the cornea is corrected with laser shots. Corneal thickness must be above a certain limit for this method to be applied. This treatment, which is usually applied together with corneal cross-linking treatment, can be very successful in early keratoconus cases.
The aim of both corneal ring and topography-guided Excimer treatment is not to get rid of glasses, but to make the deformed corneal tissue more smooth. When the right treatment is applied in the right patient, at the right time, it is possible to achieve satisfactory results in keratoconus patients with highly impaired visual quality. Success in both methods is higher in the early stages of the disease. For this reason, keratoconus patients should immediately apply to a center with the necessary equipment and experience in this field.
5
Keratoplasty
Cornea Transplant
It is a preferred method when keratoconus progresses and the cornea loses its transparency or when other methods do not yield positive results. Keratoplasty, popularly known as eye transplantation, is an operation in which the cornea of the eye, which has deteriorated as a result of various diseases, is replaced with a donated cornea. In corneal transplant surgery, a circular piece, which can be 6-9 mm in diameter, is removed from the donated healthy cornea and a piece of the same size is removed from the recipient’s (patient’s) cornea and sewn to this area. The surgery is preferably performed under general anesthesia.
Since keratoconus is a disease that occurs at a young age, there is a high chance that the transplanted cornea will develop the same disease or that the newly implanted cornea will be rejected by the body. Therefore, the main goal of keratoconus treatment is to enable patients to live their lives with their own corneas whenever possible.
