Photodynamic therapy (PDT)

Photodynamic therapy, abbreviated to FDT or PDT (photodynamic therapy) in English, is a medical treatment that was primarily used for wet age-related macular degeneration. In this form of macular degeneration, abnormal blood vessels grow beneath the retina; these can leak and thus impair central vision.

The treatment takes place in two stages. First, a light-sensitive substance, usually verteporfin, is administered via a drip. This substance attaches itself to the walls of the abnormal blood vessels in the eye. After a waiting period of around fifteen minutes, the ophthalmologist directs a special, non-thermal laser at the affected area of the macula. The laser light activates the light-sensitive substance, triggering a reaction that can cause the abnormal blood vessels to close.

FDT was mainly used between 2000 and 2010. Nowadays, the treatment is used less frequently, as other treatments have since become available, such as anti-VEGF injections, which are considered more effective for many patients with wet age-related macular degeneration. In certain specific situations, however, FDT may still be considered.

After treatment, you will be temporarily more sensitive to light, as the light-sensitive substance is still present in your body. You are therefore advised to avoid direct sunlight and bright artificial light for a few days.

When is FDT used?

Photodynamic therapy was developed for the treatment of wet age-related macular degeneration, particularly in certain types of lesions such as so-called ‘predominantly classic’ neovascular membranes. The ophthalmologist will assess, using imaging techniques such as OCT scans and fluorescein angiography, whether this treatment may be appropriate in your case.

Since the introduction of anti-VEGF therapy (injections of medicines such as ranibizumab, aflibercept or bevacizumab), FDT has become less common. Anti-VEGF treatments are often regarded as the first-line treatment for wet age-related macular degeneration. FDT may still sometimes be considered in combination with other treatments or in specific cases where other options are not suitable.

What can you expect?

The treatment itself takes around ten to fifteen minutes and is usually painless. During the laser application, you sit in front of a device similar to a slit lamp. As the light-sensitive substance remains in your body for a few days, you must be careful about exposure to light after the treatment: wear sunglasses, avoid direct sunlight and also be mindful of bright light from lamps or screens indoors.

The ophthalmologist usually schedules follow-up appointments to assess how the eye is responding. Sometimes, multiple treatments are required. Always discuss with your ophthalmologist what to expect and what precautions you should take.

Contact your optician

Photodynamic therapy is a medical procedure that is carried out only by an ophthalmologist. If you have any questions about the treatment, preparation or aftercare, please contact your ophthalmologist or the eye clinic where you are receiving treatment.