Who Is a Good Candidate for PDT
Age-related macular degeneration, also known as AMD, is a condition that affects the macula. The macula is the central part of the retina responsible for sharp, detailed vision. In the wet form of AMD, abnormal blood vessels grow under the macula and leak fluid or blood. Age-related macular degeneration affects more than 11 million people in the United States (BrightFocus Foundation, 2023). PDT may be recommended for certain subtypes of wet AMD, particularly when the abnormal vessels are located beneath the center of the macula or when they have specific growth patterns that respond well to this treatment.
Your retina specialist will use detailed imaging of your eye to determine whether your type of wet AMD is a good match for PDT. Some patients benefit from PDT on its own, while others may receive it alongside other therapies. The goal is to slow or stop the leaking vessels and help preserve the vision you still have.
Central serous chorioretinopathy, sometimes shortened to CSR or CSCR, is a condition in which fluid builds up under the retina. This fluid causes a small detachment of the retina that can blur or distort your central vision. CSR often affects younger adults and may be linked to stress or the use of certain medications such as corticosteroids.
PDT has become one of the preferred treatments for chronic or recurring CSR. The treatment targets the area where fluid is leaking without causing significant damage to the overlying retina. Many patients with CSR notice improvement in their vision after PDT, and the treatment can reduce the chance of the fluid coming back.
Polypoidal choroidal vasculopathy, or PCV, is a condition where abnormal blood vessels beneath the retina develop bulging, polyp-like endings. These polyps can leak fluid and blood, leading to swelling and damage in the macula. PCV shares some features with wet AMD but has distinct characteristics that may require a different treatment approach.
PDT has shown particular effectiveness for PCV. The laser treatment can help seal the polypoidal lesions and reduce leaking. In many cases, your care team may recommend combining PDT with injection therapy to achieve the best possible outcome for your vision.
Many retinal conditions are first treated with injections of medication directly into the eye. These injections, known as anti-VEGF therapy, work by blocking a protein that drives the growth of abnormal blood vessels. While anti-VEGF injections are effective for many patients, some people continue to have persistent leaking or fluid despite regular treatments.
PDT can serve as an important addition to the treatment plan for these patients. By directly targeting the abnormal vessels with the laser-activated medication, PDT may help reduce the amount of leaking that injections alone cannot fully control. This combination approach can sometimes reduce the total number of injections a patient needs over time.
Not every patient with a retinal condition is the right fit for PDT. Your retina specialist will perform a thorough evaluation that includes several types of imaging. Fluorescein angiography is a test that uses a special dye and camera to photograph the blood vessels in your retina. Optical coherence tomography, or OCT, creates detailed cross-section images of the retina to show fluid, swelling, or other changes.
These imaging tools help your care team see exactly where the abnormal vessels are located, how large they are, and how they are behaving. Based on this information, your specialist can determine whether PDT is likely to benefit you. Factors such as the location and size of the abnormal vessels, your overall eye health, and your response to previous treatments all play a role in this decision.
How Photodynamic Therapy Works
PDT relies on a special medication that is sensitive to light. This medication is given through an intravenous infusion, which means it is delivered into a vein in your arm through a small needle and drip line. The infusion typically takes around ten minutes. Once the medication enters your bloodstream, it travels throughout your body and collects in areas where abnormal blood vessels are actively growing.
The medication on its own does not cause any changes to the blood vessels. It only becomes active when it is exposed to a specific wavelength of light. This is what makes PDT so targeted. The medication sits quietly in the abnormal vessels until the laser is applied, at which point it begins its work.
After the medication has had time to concentrate in the abnormal blood vessels, your retina specialist directs a low-energy laser into your eye. This laser uses a very specific wavelength of red light that activates the medication. The laser light itself is not hot enough to burn tissue. Instead, it triggers a photochemical reaction, which is a chemical change caused by light.
When the laser activates the medication, it produces a form of oxygen that damages the inner lining of the abnormal blood vessels. This damage causes the vessels to close off and stop leaking. Because the medication concentrates mainly in the abnormal vessels, the surrounding healthy tissue is largely spared from this reaction.
One of the key strengths of PDT is its selectivity. The light-sensitive medication tends to accumulate more in abnormal, rapidly growing blood vessels than in normal, healthy ones. When the laser is applied, the reaction occurs primarily where the medication has gathered. This means the treatment can shut down the problem vessels while causing minimal disruption to the normal structures of your retina.
Your specialist carefully controls several factors during the procedure to optimize this selectivity.
- The dose of medication is calculated based on your body size
- The timing between the infusion and the laser application is precisely controlled
- The size of the laser spot is matched to the area of abnormal vessels seen on your imaging
- The energy level and duration of the laser are set to specific parameters
You may have heard of other laser treatments used for eye conditions. Traditional thermal laser treatment uses heat to seal or destroy abnormal tissue. While effective in certain situations, thermal laser can also damage healthy retinal cells in the treated area. This can sometimes cause a blind spot in your field of vision that does not go away.
PDT works through a completely different mechanism. Instead of using heat, it relies on a photochemical process. The low-energy laser used in PDT does not generate enough heat to burn tissue. This makes PDT a gentler option, especially when the abnormal vessels are located directly under the center of your macula where your sharpest vision originates.
Types of Conditions Treated with PDT
Wet AMD can present in different patterns depending on how the abnormal blood vessels grow beneath the retina. These patterns are sometimes described using terms like predominantly classic or occult choroidal neovascularization. Choroidal neovascularization, or CNV, refers to the growth of new, abnormal blood vessels from the choroid layer beneath the retina.
PDT was originally developed with wet AMD in mind and has been studied extensively for this condition. It tends to work best for certain vessel patterns and locations. Your care team will review your imaging carefully to determine which subtype of wet AMD you have and whether PDT is the most appropriate treatment or should be combined with other approaches.
CSR can appear in different forms. Acute CSR often resolves on its own within a few months without treatment. Chronic CSR, however, persists for longer periods and can lead to lasting changes in vision if left untreated. There is also a recurrent form where episodes come and go over time.
PDT has become a widely used treatment for chronic and recurrent CSR. In many cases, a modified version of the treatment is used, where the dose of medication or the laser energy may be adjusted. This tailored approach helps address the leaking while minimizing any risk to the overlying retinal tissue. Your specialist will determine the best protocol for your specific situation.
PCV is a distinct condition that is sometimes mistaken for typical wet AMD. It is characterized by a network of abnormal vessels beneath the retina with polyp-like dilations at their tips. These polyps can bleed or leak fluid suddenly, sometimes causing significant vision changes.
Research has shown that PDT is particularly useful for treating PCV. The treatment can effectively close the polypoidal lesions. Many retina specialists consider a combination of PDT and anti-VEGF injections to be the standard approach for managing PCV, as the two treatments work together to address different aspects of the condition.
While wet AMD, CSR, and PCV are the most common conditions treated with PDT, the technology has also been explored for other situations. In some cases, PDT may be considered for certain types of retinal or choroidal tumors, or for other rare vascular conditions affecting the back of the eye.
These uses are less common and are typically considered on a case-by-case basis. If your retina specialist believes PDT may help with a less typical condition, they will discuss the reasoning, expected benefits, and any uncertainties with you before recommending the treatment.
What to Expect with Photodynamic Therapy
Your care team will schedule your PDT session and provide you with detailed instructions ahead of time. You will be asked to arrange for someone to drive you home after the procedure because your pupils will be dilated and your eyes may be sensitive to light. It is also important to let your care team know about all medications you are currently taking, as some can increase sensitivity to light.
On the day of your treatment, wear dark, protective clothing that covers your skin. This includes long sleeves, long pants, a wide-brimmed hat, and sunglasses. Because the light-sensitive medication will be in your system after the procedure, your skin and eyes will be more sensitive to light for a period of time. Coming prepared with the right clothing helps protect you from the start.
The PDT procedure is performed in the office or a treatment suite. You will be seated comfortably, and the light-sensitive medication will be delivered through an intravenous line in your arm over a period of ten minutes. After the infusion is complete, there is a waiting period of several minutes to allow the medication to travel through your bloodstream and concentrate in the abnormal vessels in your eye.
Once the waiting period is over, your specialist will place a special contact lens on your eye to help direct the laser. You will look straight ahead while the laser is applied. The laser treatment itself is painless and lasts for just over a minute. You may see a bright light during the procedure, but you should not feel any discomfort. The entire visit, including preparation and treatment, typically takes one to two hours.
After the laser treatment is finished, the contact lens is removed and your care team will check your eye. You may notice some mild blurriness, which is normal and usually temporary. Your pupils will remain dilated for several hours, so bright lights may feel uncomfortable.
The most important instruction for the period right after treatment involves protecting yourself from light. The light-sensitive medication remains active in your body for a period of time after the procedure. During this window, exposure to bright light, including sunlight, bright indoor lights, and even some types of screens, can cause a reaction on your skin similar to a sunburn. Your care team will give you specific guidance on how long you need to take light precautions.
For a set number of days after your PDT treatment, you will need to take careful steps to protect your skin and eyes from bright light. This does not mean you need to sit in complete darkness. Normal indoor lighting at moderate levels is generally safe. However, direct sunlight and very bright artificial light should be avoided.
Here are the key precautions your care team will review with you.
- Stay indoors as much as possible during the first two days after treatment
- When you must go outside, cover all exposed skin with clothing, gloves, and a hat
- Wear dark, wrap-around sunglasses to protect your eyes
- Avoid bright halogen lights, tanning beds, and direct exposure to strong light sources
- Do not use sunscreen as a substitute for covering your skin, because sunscreen does not block the wavelengths of light that activate the medication
- Gradually increase your light exposure over several days as the medication clears from your body
Most patients can return to their normal daily activities within a day or two after treatment, as long as they follow the light precautions. Your vision may fluctuate in the days and weeks following PDT as the treated area heals and the fluid beneath your retina begins to absorb.
Your care team will schedule a follow-up visit, usually within several weeks of your treatment. At this visit, your specialist will perform imaging tests to see how the treated area is responding. Based on the results, your team will discuss whether additional treatment sessions are needed. Some patients require only one PDT session, while others may benefit from repeat treatments spaced several months apart.
PDT is generally well tolerated, but like any medical procedure, it does carry some risks. The most common side effect is temporary sensitivity to light, which is managed with the precautions described above. Some patients may experience mild discomfort at the injection site on their arm. A small number of patients notice temporary changes in vision, such as blurriness, darker areas in their visual field, or changes in color perception.
In rare cases, more significant side effects can occur, including a sudden decrease in vision. If you experience a noticeable drop in your vision, severe eye pain, or any unusual symptoms after your procedure, contact your care team right away. It is better to call and report a concern that turns out to be minor than to wait and risk a complication going untreated.
Your Journey Through Photodynamic Therapy
Your journey begins with a comprehensive eye examination at Washington Eye Institute. During this visit, your retina specialist will dilate your pupils and carefully examine the back of your eye. You will likely undergo several imaging tests, including optical coherence tomography and fluorescein angiography. These tests create detailed pictures of your retina and the blood vessels beneath it. Your specialist will use these images to identify the location, size, and type of abnormal vessels present.
Based on the findings, your care team will discuss all available treatment options with you. If PDT is recommended, your specialist will explain why it is a good fit for your particular condition and what results you might reasonably expect. This is an excellent time to ask any questions you may have about the procedure.
Once you and your specialist have decided to move forward with PDT, your care team will schedule your treatment session. You will receive written instructions covering everything you need to do before your appointment. Key preparations include arranging a ride home, gathering protective clothing to wear on the day of treatment, and reviewing your current medications with your care team.
Your team may also advise you to adjust your schedule for the days following treatment so you can stay indoors and limit your light exposure. Planning ahead for meals, errands, and other responsibilities can make the recovery period much more comfortable.
On the day of your procedure, you will arrive at the office and be settled into the treatment area. A small intravenous line will be placed in your arm, and the light-sensitive medication will be infused over ten minutes. After a brief waiting period, your specialist will apply the laser to your eye using a special contact lens. The laser application lasts just over a minute and is painless.
Throughout the procedure, your care team will be right beside you, explaining each step and making sure you are comfortable. If you feel anxious, let your team know. They are experienced in helping patients feel at ease during treatment.
After your treatment, you will enter the light protection period. This phase typically lasts for several days. During this time, the light-sensitive medication is still present in your body and can be activated by bright light. Following the precautions your care team provides is essential to avoiding skin reactions.
Most patients find this period manageable with a little planning. You can read, watch television at normal brightness, and move around your home comfortably. The main goal is to avoid direct sunlight and unusually bright light sources. As each day passes, the medication gradually leaves your body and your sensitivity decreases.
Several weeks after your PDT session, you will return to Washington Eye Institute for a follow-up evaluation. Your specialist will repeat the imaging tests to assess how the treated vessels have responded. If the abnormal vessels have closed and the fluid is resolving, your team will continue to monitor you with periodic check-ups.
If there are signs that additional treatment is needed, your specialist will discuss the next steps with you. Some patients benefit from a second or third PDT session over the course of several months. Others may transition to a maintenance plan that includes anti-VEGF injections, regular monitoring, or a combination of approaches tailored to their specific needs.
Retinal conditions like wet AMD, CSR, and PCV are often chronic, meaning they require ongoing attention even after successful treatment. Your care team at Washington Eye Institute will work with you to create a long-term monitoring plan. This plan typically includes regular office visits with imaging tests to catch any signs of recurrence early.
Between visits, you can support your eye health by following your care team's recommendations. These may include taking specific nutritional supplements, protecting your eyes from excessive sunlight, managing underlying health conditions like high blood pressure, and reporting any new symptoms promptly. By staying engaged in your care, you give yourself the best chance of maintaining your vision for years to come.
Questions and Answers
Anti-VEGF injections and PDT work through different mechanisms. Injections deliver medication directly into the eye to block a growth signal that drives abnormal blood vessel development. PDT uses a light-sensitive medication given through a vein in your arm, combined with a targeted laser, to physically close the abnormal vessels. The two treatments address the problem from different angles.
In many treatment plans, PDT and injections are used together. The injections help slow the growth of new abnormal vessels, while PDT works to shut down vessels that are already present and leaking. Your retina specialist will recommend the approach or combination that best fits your condition.
Most patients report that PDT is a comfortable experience. The intravenous infusion in your arm feels similar to a standard blood draw or IV placement. You may feel a slight pinch when the needle is inserted, but the infusion itself is painless. During the laser portion of the treatment, a contact lens is placed on your eye after numbing drops have been applied. You may see a bright light while the laser is active, but the treatment does not cause pain.
After the procedure, some patients describe mild sensitivity or a slightly gritty feeling in the treated eye. These sensations are temporary and typically resolve within a day. If you experience discomfort that concerns you, your care team is available to help.
The number of PDT sessions varies depending on the condition being treated and how your eye responds. Some patients see significant improvement after a single treatment and may not need another session for a long time. Others benefit from two or three sessions spaced several months apart. For conditions like wet AMD or PCV, PDT is often part of an ongoing management plan that may include other treatments as well.
Your retina specialist will monitor your progress with regular imaging and will recommend additional sessions only when the evidence supports it. The goal is to use the fewest treatments needed to achieve the best possible outcome for your vision.
The light-sensitive medication used in PDT circulates through your entire body during and after the infusion. While it concentrates in abnormal blood vessels in the eye, it is also present in your skin and other tissues for a period of time after treatment. If your skin is exposed to bright light while the medication is still active, the same type of chemical reaction that closes blood vessels in your eye can occur in your skin. This can lead to a sunburn-like reaction that may be uncomfortable.
Following your care team's light precaution instructions carefully helps you avoid this side effect entirely. The medication clears from your body gradually, and within several days, you can resume your normal activities in daylight without concern.
PDT is primarily a stabilizing treatment. Its main purpose is to close abnormal leaking blood vessels and stop further damage to the retina. In some cases, particularly with CSR, patients do experience improvement in their vision as fluid beneath the retina absorbs and the tissue heals. For conditions like wet AMD, the primary goal of PDT is to preserve the vision you currently have and prevent additional loss.
It is important to have realistic expectations about the outcomes of treatment. Your retina specialist will discuss what you can reasonably expect based on the specifics of your condition, including the extent of any damage that has already occurred and how your eye has responded to previous treatments.
PDT is one part of a comprehensive approach to managing retinal conditions. For many patients, it works best when combined with other therapies. Anti-VEGF injections may be used alongside PDT to control vessel growth. Regular monitoring with imaging tests helps your care team track changes and adjust your treatment plan over time.
At Washington Eye Institute, your retina specialist and care team work together to create a plan that addresses your unique needs. This plan evolves as your condition changes, with the goal of giving you the best possible visual outcome over the long term. Staying consistent with your scheduled appointments and communicating openly with your team about any changes in your vision are two of the most important things you can do to support your own care.