Before refractive treatment, the eye is measured with various diagnostic devices to determine the refractive power of the artificial lens. The optimal visual result requires an exact positioning of the lens. Even the smallest deviations lead to suboptimal visual quality. With the high precision of the laser, exact implantation is much safer than with manual incision.
Among other things, the LenSx® laser cuts up the natural lens and thus facilitates the removal of the lens by the surgeon. In order to aspirate it, it requires around 40 % less ultrasound energy than without the laser.
Since the femtosecond laser can cut much more accurately than an experienced surgeon, the procedure is considered safer compared to manual cataract surgery. In addition, the video-supported OCT control allows the exact planning of the incisions as well as the more precise alignment of the artificial lens, so that in a considerably larger percentage a better visual result was achieved with presbyopia.
The word Keratoconus derives from two Greek words: “kerato”, which means cornea, and “conus”, which means cone. Keratoconus is a genetically inherited disease that affects the normal form of the corneal structure, causing it to lose its stability and bow forward irregularly, resulting in a reduction and distortion of vision. Generally one eye is more affected than the other.
A keraring is a polymer ring consisting of two semi-circular segments with a diameter of 5 mm and a variable thickness. The kerarings are made from Perspex CQ Acrylic, the same material as the inraocular lenses used for cataracts. The kerring is tolerated by the cornea and there is no risk of repulsion. The main reason for surgery is to improve visual acuity. Kerarings can usually stop the progression of the keratoconus and thus delay the corneal transplantation indefinitely. If the Keraring is seated, a crosslinking (collagen cross-linking) is often performed to stabilize the keratoconus.
In the early stages, glasses will do the trick. However, at some point the glasses are no longer sufficient and it is common to wear hard contacts. When the contact lenses have become intolerable, kerarings are implanted. These kerarings (intracorneal Ring segments) can stall this progressive protuberance of the cornea, and thereby significantly postpone the need for a corneal transplant. In case it does come to this stage, we offer corneal transplants in our clinic in Munich. So far, a cornal transplant has been necessary for more than 20% of all patients.
First the visual axis is marked on the cornea, then a tunnel is prepared using the femtosecond laser. The femtosecond laser places the incisions very precisely in six seconds. The rings are inserted into the tunnel and a bandage contact lens is inserted.
The risks are quite low, however any operation can result in an infection. If this were to happen, the kerarings would have to be removed. This is also necessary if the kerarings migrate out of the tunnel. Despite surgery, corneal transplantation may be necessary at a later date. Keraring is not a substitute for corneal transplantation.
The eye recovers very quickly, visual acuity stabilizes within a few days and improves over 3 to 6 months. Fluctuations in vision in the first few weeks are quite normal. Often vision is better in the morning and slightly blurred in the evening. Since it is not a cosmetic correction, it may still be necessary to wear glasses or contact lenses in order to completely correct the defective vision. In spite of a residual defective vision, visual acuity can be very good.