New surgical technique protects against blindness
Diseases of the eye sometimes need to be treated with a constant supply of medication. Direct delivery into the affected organ is an option, but previous methods have shown unpleasant side effects. In a new technique, a drug dispenser is permanently implanted in the eye. Physicians at the University Eye Clinic in Frankfurt have found a way to permanently implant drug dispensers in the eye. This is of particular benefit to people suffering from AIDS. "Aids patients no longer die blind," announced Christian Ohrloff, chief physician at the Frankfurt eye clinic, at a symposium of the university eye clinics. The doctors are also testing drug dispensers that consistently suppress the chronic inflammation of the choroid uveitis in the eye. They plan to use their development to treat other eye conditions as well.
Up to thirty percent of AIDS patients contract an insidious virus infection, cytomegalovirus retinitis. This retinal inflammation leads to blindness within two months. The usual treatment by supplying medication via the vascular system or directly into the eye is time-consuming, expensive and requires a long stay in the hospital. The drugs administered also have serious side effects. Doctors are therefore researching a way of implanting drug dispensers directly in the eye. In this way, the helping substances could reach their target site directly and would not burden the body.
Previous surgical methods, however, had only limited success and regularly led to complications: The "sausage seam" used leaves behind visible scars and distorts the cornea. The implant must therefore be removed again after about eight months. The method developed in Frankfurt by Hermann Gümbel, Frank Koch and their colleagues is therefore a breakthrough: it makes it possible to leave the implant in the eye for several years. It can then be supplemented with another implant. "I even argue in favor of leaving the old remedy in mind, since removing the implant can also cause difficulties," explains Koch. In the surgical method, the eye is opened next to the iris. A piece of dermis is then divided into two layers with a scalpel, much like one pulls apart damp leaves that are stuck together. In this way, a U-shaped lamella can be cut out of the top layer of the dermis. This is folded back and the surgeon makes another incision in the lower half of the sclera, through which he can access the vitreous of the eye. There he cuts a small depression into which he pushes the medication dispenser, which is about five millimeters in size. The surgeon then sews the implant to tabs and folds back the flap to cover the drug carrier. Two threads are enough to close the slat. In this way, there is no visible scar, the cornea remains in its original form, and patients can see again immediately after the operation. "We have been operating with the new method for over two years and there have been no complications so far," explains Gümbel. The surgery is also about 50 percent cheaper than conventional treatments.
Clinical trials are currently underway to help people suffering from uveitis with a permanent implant. This tissue inflammation in the eye can be caused by an autoimmune reaction in the body. In standard treatment, patients are given cortisone. But cortisone also has numerous side effects. Instead, an implant could deliver immunosuppressive substances directly into the eye with significantly fewer side effects. The doctors do not want to comment on the results of the clinical trials so far.
But you are already planning to use the surgical technique to treat macular degeneration. Most blindness in Germany is due to this disease, which is caused by circulatory disorders in the eye. In animal experiments, calcium antagonists, which are introduced directly into the eye, were able to promote blood circulation and thus effectively prevent degeneration.
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