Refractive Power and Astigmatism
In terms of refractive power, the eye has a vertical axis and a horizontal axis. The refractive powers of the horizontal axis and the vertical axis must be equal to each other. When these are equal, the eye provides a balanced vision. If there is a difference between the vertical and horizontal axis, this is called astigmatism. Astigmats see their surroundings crookedly. Astigmatism rarely occurs alone and is usually associated with other refractive errors.
Astigmatism can be corrected with glasses, contact lenses and laser techniques. If there is a low degree of astigmatism, soft lenses can tolerate it, while toric lenses are used for high degree of astigmatism.
Ring Technique in Keratoconus Treatment
Dr. Zeki TUNÇ, in 1987, for the first time in Turkey and in the world, started the ring (ring, Intacs) implantation operations for patients with keratoconus.
Keratoconus is the excessive bulging of the cornea due to thinning of the cornea under the influence of intraocular pressure, causing severe astigmatism. Keratoconus disease is a progressive disease involving the corneal layer of the eye. The bond between the keratocyte cells that form the regular curvature of the cornea in the corneal layer weakens and causes thinning and irregular curvature in the corneal layer.
The curvature of the cornea determines the refractive power of the cornea, accordingly, irregular curvature causes an abnormality in the refractive power and astigmatism occurs first and then when this curvature turns into an asymmetric structure, irregular astigmatism occurs. With irregular astigmatism, the problems are aggravated, the patient is faced with visual impairment despite wearing glasses, he/she cannot wear contact lenses, the lens constantly slips from the eye and the patient cannot see well.
Although keratoconus is not very common, it is found in 100 to 250 people per 100,000 people. As for the causes of keratoconus, % 10 of the disease is genetically inherited and the cause of the other % 90 is not known exactly, but it is more common in people with allergic constitution and especially in those who rub their eyes frequently.
Laser Eximer, LASIK, PRK, Epilasik, Lasek, Intralase cannot be applied to patients with keratoconus to improve their vision and if applied, it causes the disease to worsen and vision to decrease significantly.
Until 1987, the treatment of keratoconus disease was performed with corneal transplantation. Dr. Zeki TUNÇ developed this new technique and for the first time in the world, he started ring (INTACS) implantation operations in patients with keratoconus and shared the technique with Prof. Dr. Colin and simultaneously made the technique widespread. Dr. Zeki TUNÇ has made many presentations in Turkey and abroad about ring (ring, INTACS) treatment in keratoconus.
Eyes with keratoconus show different characteristics in each case, that is, the corneas of people with keratoconus are never alike, they are different in everyone like fingerprints. In each case, the cornea should be analyzed very well and rings of different thicknesses, different shapes and different sizes should be inserted in appropriate combinations and at different angles to the appropriate parts of the cornea.
Ring therapy for keratoconus was approved by CE in Europe and FDA in the USA in the spring of 2006 and has been recognized as a successful treatment by the whole world.
Today, the ring (INTACS, Keraring) technique has been found to be so safe that it is now being used in some cases of astigmatism other than keratoconus and the results are satisfactory. It is a very successful technique in astigmatism that cannot be treated with laser and in astigmatism with thin corneas.
