Information for patients undergoing Photo Dynamic Therapy

This guide has been designed to help you understand what Photo Dynamic Therapy (PDT) is and how it works in treating Wet Age Related Macular Degeneration (AMD) and other Macular diseases.

It also contains useful information on what you can expect during treatment as well as some advice on what you should do before and after treatment.

If, after reading this guide you have any questions about PDT or your eye condition, be sure to discuss them with your Consultant.

The macula is at the centre of the retina at the back of the eye, where incoming rays of light are focused. It is very important because we use it to see straight in front of us (central vision) and for seeing detail; for instance, when reading, writing, telling the time, recognising faces, driving or watching television.

Sometimes the delicate light sensitive tissues of the macular can become damaged (degenerate) and do not work as well.

There are two types of AMD, WET and DRY AMD. Dry AMD occurs when fatty deposits build up in the tissues in the retina. Its impact on vision is not as rapid as Wet AMD. The treatment will not help and Dry AMD is generally managed with tools and techniques to make the best use of your sight.

The other type, Wet AMD, is caused when faulty blood vessels grow under the macula. These leak fluid (which is where the term ‘Wet’ comes from) and will eventually scar, leading to distortion of sight and loss of central vision.

AMD is a very common cause of poor vision in older people but it is not painful. It does not lead to complete loss of sight because, as it affects only the central vision, the sight in the outer edges of the eye is retained. This is an alternative treatment to intravitreal injections for some types of Wet AMD. Whether it is suitable for you depends on which type of AMD and the stage it is at.

PDT is a treatment for the wet neovascular form of Age Related Macular Degeneration (AMD). It uses a combination of;

1. A photosensitive (light-activated) drug called Verteporfin.

2. A red light produced by a non-thermal laser

The aim of PDT is to reduce the potential for loss of central vision caused by Wet AMD. PDT works by destroying abnormal blood vessels that grow behind the retina at the back of the eye. These abnormal blood vessels leak and bleed leading to deterioration of the macula (an area of the retina that provides your central vision). Unlike other treatments for Wet AMD, PDT uses non thermal laser; the light produced by this laser does not burn the retina.

In the majority of patients, PDT initially slows down the progressive loss of sight normally experienced by patients with Wet AMD. Thereafter, the majority of patients experience stabilisation of their vision on PDT. In clinical trials, 6 out of 10 patients experience stabilisation of vision over 2 years while some patients (16%) actually experience an improvement in vision.

Some patients experience adverse reactions to PDT, these include;

• Injection-site reactions such as pain, swelling, inflammation, leakage into the area surrounding the vein, bleeding at the injection site and hypersensitivity.

• Blurred vision and other visual disturbances

• Backache during infusion (around 2.2% of patients reported backache).

• Severe vision decrease (occurred in 1%-4% of patients).

• Photosensitivity, photo-sensitivity means sensitive to sunlight and certain types of lights for 48 hours after laser treatment.

Please speak to your eye specialist if you experience any of these effects after PDT.

If you have had a severe reaction to previous intravenous injections or if you have a strong allergic history, porphyria or severe liver disease, bring this to attention of your doctor.

If you think that you might have a sensitivity (allergy) to any component of PDT or if you feel there is any reason why you should not be treated with Verteporfin, do not hesitate to discuss these matters thoroughly with your eye doctor (Consultant Opthalmologist).

PDT will cause your skin and eyes to become more sensitive to light. Therefore, you MUST avoid direct sunlight and bright lights for 48 hours immediately after treatment.

To protect your skin and eyes please bring (or wear) the following items with you to the Medical Retina Unit:

• Wide Brimmed Hat.
• Dark sun-glasses. A good pair of sunglasses should help to protect the eyes from the harmful light rays that can cause damage. • Clothing that will fully cover your arms and legs.
• Socks and shoes.

You will be given an infusion (slow injection) of the light-activated drug called Verteporfin into one of the veins in your arm. This lasts for ten minutes. The nurse will then numb your eye with eyedrops. He or she will then escort you to the laser room to complete your treatment. Your eye specialist will place a special contact lens on your eye. Shortly after this a red light will be directed through the contact lens and onto the affected area of the retina. The light is applied for exactly 83 seconds. Because the red light is produced by a non-thermal laser there is no heating or burning. At the end of treatment you will be given a green bracelet to wear for the first 48 hours. This is a precaution and is intended to remind you and other health professionals that you have received PDT. Your cannula will be removed and a dressing applied, this should remain in place for 48 hours to reduce reaction occurring.

As mentioned before, PDT will cause your skin and eyes to become more sensitive to light. Therefore you must avoid direct sunlight and bright lights for 48 hours immediately after treatment. Bright lights include but are not limited to;

• Bright sunlight
• Solariums
• Halogen lighting in homes and offices (including bright halogen lamps and reading lamps)
• Undraped windows

Stay away from undraped windows or skylights for 48 hours and do not rely on UV suncream to protect against photosensitivity; they will not be effective.

After PDT you may have some vision problems. If this happens to you, you should not drive or use machinery until your vision improves.

If you do go out during daylight hours within the first 48 hours following treatment, it is recommended that you wear:

• Wide brimmed hat
• Dark sunglasses
• Long sleeved shirt and trousers
• Socks and shoes
• After 48 hours, you may resume normal outdoor activities without any special precautions.

Please note

You should not stay in the dark. In fact exposing your skin to indoor light helps inactivate any remaining drug in the skin.

You may have some blurring of eyesight in the 48 hours following treatment, but this is usually short lived.

If you are due to have surgery within 48 hours of the treatment please ensure to notify your Consultant Surgeon. Avoid visiting the dentist in the immediate 48 hours following treatment.

PDT normally involves more than one treatment to permanently close the leaking blood vessels. Your eye doctor will normally ask you to come back every three months to assess your eyes. He/ she will usually check your vision, take some pictures of your eye and carry out a dye test (Fluorescein Angiography) to determine if another treatment would be beneficial. You can expect to receive between two and four treatments in the first year, decreasing in the second and third year of treatment.

You will usually have had a fluorescein angiography already before attending for your PDT appointment and been issued with the following leaflet: “Information for patients undergoing Retinal Fluorescein Angiography” The Angiography however will usually be repeated at every PDT appointment as it helps the doctor to see where the laser needs to be applied should you need treatment.

You will have the fluorescein angiography in the morning and then have a consultation with the doctor in the afternoon, he or she will then tell you if PDT treatment would be beneficial or not based on their examination of your eye/eyes and the findings from the angiogram.

You will be able to leave the department to get some lunch and will be advised on what time to return. We would strongly advise you not to leave the hospital in between your morning and afternoon appointments.