In intravireal therapy, a drug is injected into the eyeball, more precisely into the vitreous space.
The macula or yellow spot is a small area of approximately three millimeters in diameter in the center of the retina. The visual axis of the human eye runs precisely through this point. Since the density of color-sensitive sensory cells is highest in the area of the macula, the highest resolution is achieved there, i.e. when we read a text, it is displayed exactly in this area. Retinal changes in this area are correspondingly dramatic and have a major impact on visual acuity.
In macular oedema, fluid builds up inside the retina. This can only be guessed during fundus examination at the slit lamp. In order to be able to accurately diagnose macular oedema, so-called ocular coherence tomography (OCT) is used today.
Macular oedema worsens visual acuity and straight lines are typically perceived as curved.
The Amsler grid can be used to diagnose macular oedema. The test subject looks at a central point and pays attention to dark areas and whether the grid lines around them appear straight or curved.
The fine capillaries of the central retina leak and fluid leaks into the surrounding macular tissue. There are various reasons for capillary leakage:
Depending on the cause of the oedema, different treatment routes are taken:
Diabetes, AMD or vascular occlusions cause increased release of VEGF (vascular endothelial growth factor) in the eye. These growth factors result in:
Anti-VEGFs are artificially produced antibodies that bind VEGF and thus inhibit its effect. The vessels are therefore virtually sealed by the anti-VEGFs.
The patents for ranibizumab and aflibercept have recently expired and the first so-called “biosimilars” have come onto the market. In contrast to generic drugs, the structure of “biosimilars” differs more from the original drug. Like the original products, “biosimilars” are also subject to an approval process, which is significantly shorter. As a result, these new “biosimilars” are less well tested compared to the original preparations. We therefore recommend that you only use original preparations at present.
The active ingredient is injected into the eye as a liquid solution using a syringe. An injection in the eye may sound very alienating and cause anxiety for many patients, but pain is very rare. The majority of patients report that any anxiety about the injection has disappeared after the first treatment.
The treatment takes a few minutes and is performed on an outpatient basis. Intravireal injections generally do not require anesthesia. Before the procedure, the surface of the eye is made insensitive with anesthetic eye drops.
In order to minimize the risk of an infection in the eye, the treatment takes place on a couch in a sterile operating room. The eye is disinfected with a chlorhexidine or iodine solution and then covered in a sterile manner. An eyelid holder is used to keep the eye open, after which the conjunctiva is also rinsed with disinfectant. Using a very thin cannula, the medication is slowly injected through the connective and sclera into the vitreous body inside the eye.
The areas below and above the cornea are best suited for injection as they are protected by the eyelids and are less sensitive. In order to reach these areas, the patient should look up or down.
Many patients are afraid of the injection, which is completely understandable. After the treatment, most agree that it was almost painless and the anxiety disappears.
As a result of the treatment, the eye often feels sandy for a few hours. Shortly after the injection, floating black dots may also be noticed in the visual field, which usually disappear after a few hours to days. In addition, bleeding visible from the outside may occur in the area of the connective or sclera. The blood dissolves again after a few days. In rare cases, there may be bleeding in the vitreous cavity. This can lead to a temporary impairment of vision. The blood usually dissolves within four to six weeks.
Sudden head movements during injection may damage the lens or retina, resulting in cataracts, slipping of the artificial lens, or retinal detachment.
Moisturizing eye drops or eye ointment (e.g. vitamin A eye ointment) can provide relief if you feel sandy.
Prophylactic antibiotic eye drops are generally not needed after intravireal injections.
Visual acuity usually only noticeably improves after several treatments at first.
During each follow-up, an eye test is carried out, the eyes are checked for possible side effects of the injection and the extent of the macular edema is visualized using an OCT examination and compared with the previous measurements.
Each patient responds differently to anti-VEGF agents; as a rule, several injections over several years are required to treat macular edema in the long term.
As a result of the OCT images, the time intervals from one injection to the next can be extended if improved or shortened again if worsened. This treatment regimen is called “Treat and Extend” and is currently the gold standard for treating most types of macular edema. The aim of intravireal therapy is to achieve a good, stable condition with as long distances as possible.
Like anti-VEGF preparations, cortisone is also effective in treating macular edema in particular in:
If the anti-VEGF preparations do not work or do not work well enough, steroid injections are used as so-called “second line” therapy:
After the injection, there may be an increase in eye pressure or clouding of the natural lens. In addition to Triamcinolone® (solution), there are also fixed dexamethasone implants (Ozurdex®), which, like a depot, evenly release cortisone into the eye over several months.
The patient can perceive these implants until they are completely dissolved. Steroids can cause clouding of the natural lens, which later leads to cataract surgery can make necessary. In patients who have already had eye surgery, the implant can enter the anterior chamber and damage the cornea from there.
If left untreated, visual acuity that makes it possible, for example, to recognize faces, read and watch television, is unlikely to be maintained. A further worsening or loss of visual function is very likely if left untreated. If macular oedema persists over a long period of time, structural damage occurs that is not reversible.
