23.7.2024
Lesezeit:
10 minutes

Intravitréal therapy

By injecting into the eye, the fluid in the retina can be treated efficiently.

Dr. Valéry Vinzent Wittwer

What is the macula?

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.

1. macula
2nd optic nerve optic disc
3rd retinal artery
4. retinal vein

What is macular edema?

In macular edema, fluid builds up inside the retina. This can be detected on the slit lamp during fundus copy (retinal endoscopy). In order to be able to accurately diagnose macular edema, so-called ocular coherence tomography (OCT) is used today.

OCT image of a patient with macular edema

How does macular edema affect vision?

Macular edema worsens visual acuity and straight lines are typically perceived as curved.
The Amsler grid can be used to diagnose macular edema. The test subject looks at a central point and pays attention to whether the grid lines around it appear straight or curved.

Right: perception of the amsler grid in a patient with normal macula
Left: Perception of the Amsler grid in a patient with macular edema

How does macular edema develop?

The fine capillaries of the central retina leak and fluid leaks into the surrounding macular tissue. There are various reasons for capillary leakage:

  • Age-related macular degeneration (AMD)
  • blood sugar disease (diabetes mellitus)
  • Retinal vascular occlusion
  • inflammation in the eye (uveitis)
  • Side effect of drugs (e.g. prostaglandin analogs)
  • hereditary diseases (e.g. retinitis pigmentosa, retinoschisis)

How can macular edema be treated?

Depending on the cause of the edema, different treatment routes are taken:

  • Intravitréal injection of anti-VEGF
  • Anti-Inflammation (NSAID)
  • carbonic anhydrase inhibitors (e.g. Diamox)
  • cortisone supplements
  • laser treatment

How does anti-VEGF work?

Diabetes, AMD or vascular occlusions cause increased release of VEGF (vascular endothelial growth factor) in the eye. These growth factors cause blood vessels in the area of the retina to leak and fluid to leak into the macula. Anti-VEGFs are artificially produced antibodies that bind VEGF and thus inhibit its effect. The vessels are therefore virtually sealed by the anti-VEGFs.

OCT of macula with macular edema
OCT of the macula a few days after intravireal therapy

Which anti-VEGF preparations are there and how do they work differently?

  • Bevacizumab (Avastin®) was the first anti-VEGF used on the eye (off-label) and was originally used to treat tumors in oncology
  • Ranibizumab (Lucentis®) is the first VEGF inhibitor approved for ocular use
  • Aflibercept (Eylea®) is another VEGF inhibitor approved for ocular use, the effect is comparable to ranibizumab
  • Brolucizumab (Beovu®) is the latest generation of anti-VEGF and is said to work longer and stronger than previous preparations. Since the risks of inflammation inside the eye after administration of brolucizumab are greater than with older anti-VEGFs, they are usually only used when the elderly are not effective enough
  • Vabysmo® is the latest generation of anti-VEGF and is more effective than older products with a similar risk profile. It is used primarily in patients who do not respond or do not respond sufficiently to ranibizumab or aflibercept

Are there generic drugs for the expensive anti-VEGF supplements?

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 currently only recommend original preparations.

How is the medication administered?

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.

1. eyelid holder
2nd injection with anti-VEGF through conjunctiva and sclera
3rd vitreous space
4. macula

How does the treatment proceed?

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.

What should be considered after treatment?

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.

Is it useful to use eye drops after the injection?

Moisturizing eye drops or eye ointment (e.g. vitamin A eye ointment) can help if you feel sandy. Prophylactic antibiotic eye drops are generally not needed after intravireal injections.

When should you see an ophthalmologist immediately after an intravireal injection?

  • Increasing pain
  • Permanent vision of black spots or flashes of light
  • vision loss
  • Neurological symptoms such as (paralysis or sensitive lapses in the face or extremities, speech disorders, visual field defects)

How is the improvement noticeable after the injection?

Visual acuity usually only becomes visibly better after several treatments at first.
During follow-up checks, we perform an eye test, examine the eyes for possible side effects of the injection and document the macular edema with an OCT examination.

How long must treatment be continued?

Each patient responds differently to anti-VEGF agents; as a rule, several injections 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.

When are cortisone supplements injected into the eye?

Like anti-VEGF preparations, cortisone is also effective in treating macular edema in particular in:

  • uveitis (non-infectious inflammation inside the eye)

If the anti-VEGF preparations do not work or do not work well enough, steroid injections are used as a so-called “second line” therapy:

  • Diabetes mellitus
  • Retinal vascular occlusion

What is special about injecting steroids?

There may be an increase in eye pressure after the injection. 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.

1. eyelid holder
2nd injector with Ozurdex
3rd vitreous space
4. macula

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.

What can happen if the intravireal injection is rejected by the patient?

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 edema persists over a long period of time, structural damage occurs that is not reversible.

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