Photodynamic Therapy for Retinal Conditions
What Is Photodynamic Therapy?
Photodynamic therapy is a two-step procedure that uses a light-sensitive medication and a low-energy laser to close abnormal blood vessels beneath the retina. It works differently from traditional laser treatments and offers a more precise approach for certain retinal conditions.
The first step involves injecting a medication called Visudyne (verteporfin) into a vein in the arm. This drug travels through the bloodstream and concentrates in abnormal blood vessels at the back of the eye. In the second step, a retina specialist directs a low-energy laser into the eye to activate the drug.
Once activated, Visudyne produces reactive molecules inside the abnormal vessels. These molecules damage the vessel walls and cause them to close. Because the drug collects specifically in the abnormal vessels, healthy surrounding retinal tissue is largely protected.
Traditional laser treatments use heat to destroy tissue directly. While effective at sealing leaking vessels, this approach can also damage healthy retina in the treated area. PDT uses what is often described as a cold laser, meaning it does not burn tissue. Instead, it triggers a targeted chemical reaction within the drug to selectively close abnormal vessels. This makes PDT a better option when abnormal vessels are located directly beneath the center of vision.
PDT was a landmark treatment when it first received FDA approval in 2000, making it the first pharmacological therapy for wet AMD. Later research showed that anti-VEGF injections, medications that block the growth signal driving abnormal blood vessels, produced better outcomes for most wet AMD patients. Today, PDT plays a more focused role, used alone or alongside other treatments depending on the specific diagnosis and how the eye has responded to prior care.
Conditions PDT Can Treat
PDT is appropriate for several retinal conditions involving abnormal or leaking blood vessels. The specific diagnosis, location of the abnormal vessels, and how the eye responds to other treatments all influence whether PDT is recommended.
Wet AMD occurs when abnormal blood vessels grow beneath the macula, the part of the retina responsible for sharp central vision, and leak fluid or blood. PDT is FDA-approved for certain patterns of wet AMD, particularly when abnormal vessels are located beneath the center of vision. It is now most often used when anti-VEGF injections have not been fully effective on their own, or as a combination approach to reduce the number of injections a patient needs over time.
Central serous chorioretinopathy, known as CSC, is a condition in which fluid accumulates beneath the central retina. The chronic form, where fluid persists for months or keeps returning, can cause lasting changes to vision. PDT, particularly a modified approach called half-dose PDT, is widely regarded as the first-choice treatment for chronic CSC and has shown strong results in closing the source of leakage.
Beyond wet AMD and chronic CSC, PDT can be used for choroidal neovascularization, meaning abnormal new blood vessel growth, caused by other underlying conditions. These include pathologic myopia, a severe form of nearsightedness, and ocular histoplasmosis syndrome, an eye condition related to a fungal infection. A retina specialist will determine whether PDT is appropriate based on the specific diagnosis and imaging findings.
Risk Factors and Who Is Affected
Understanding what conditions increase the risk of developing diseases treated by PDT can help patients stay informed and seek care at the right time. Risk factors differ depending on the underlying diagnosis.
AMD is one of the most common causes of vision loss in older adults. The wet form develops when abnormal blood vessel growth begins beneath the macula. Factors that increase the likelihood of developing wet AMD include advancing age, a family history of AMD, smoking, high blood pressure, and a diet low in leafy green vegetables. Regular eye exams become especially important for anyone with these risk factors.
CSC most commonly affects men between the ages of 20 and 50, though it can occur in women and older adults as well. Corticosteroid medications, whether taken by mouth, applied to the skin, or inhaled, are a well-recognized trigger. High levels of psychological stress have also been linked to CSC, possibly because stress causes the body to produce its own natural corticosteroids that may trigger fluid buildup in people who are prone to the condition.
Symptoms to Watch For
The symptoms that prompt consideration of PDT depend on the underlying condition. Recognizing changes in your vision early gives your care team the best chance to protect your sight.
Patients with wet AMD often notice blurred or distorted central vision, difficulty reading, or a dark area in the center of their visual field. Straight lines may appear wavy or bent. A retina specialist may recommend PDT when wet AMD has not responded adequately to anti-VEGF injections, or as part of a combination treatment plan.
Chronic CSC typically causes blurry central vision, a dimming or washing out of colors, and subtle distortion in straight lines or shapes. When these symptoms last for several months or return repeatedly, PDT is often the recommended next step. Many patients with chronic CSC notice meaningful improvement in clarity after treatment as the fluid beneath the retina resolves.
Diagnosis and Imaging Tests
Before recommending PDT, our retina specialists use specialized imaging to map the abnormal blood vessels and confirm the diagnosis. These tests guide exactly where and how treatment will be applied.
Fluorescein angiography involves injecting a yellow dye into a vein in the arm. As the dye circulates through the blood vessels in the retina, a specialized camera takes a rapid series of photographs. The resulting images reveal the location, size, and type of abnormal vessels. This information helps determine whether PDT is appropriate and where to aim the laser precisely.
Indocyanine green angiography, called ICG, uses a different dye that highlights deeper blood vessel layers beneath the retina, a region called the choroid. ICG is particularly useful for diagnosing CSC and for identifying leaking areas that may not appear clearly on fluorescein angiography. It allows the retina specialist to map the exact area that needs treatment.
Optical coherence tomography, or OCT, is a noninvasive scan that produces detailed cross-sectional images of the retina. OCT shows fluid buildup, swelling, and structural changes within the retinal layers without requiring any injections or dye. Our specialists use OCT both before treatment to assess the extent of the condition and after treatment to monitor whether fluid has resolved and to guide any decisions about additional care.
Your PDT Treatment Plan
The way PDT is used depends on the diagnosis, the location and type of abnormal vessels, and how the eye has responded to any prior treatment. Our retina specialists tailor each treatment plan to the individual patient.
Visudyne (verteporfin) is FDA-approved for treating certain types of wet AMD, specifically when abnormal vessels are located beneath the center of vision in a pattern called predominantly classic subfoveal choroidal neovascularization. For most wet AMD patients today, anti-VEGF injections are the primary treatment. PDT is typically reserved for cases that have not responded well to injections alone, or it may be used in combination with anti-VEGF medications such as Eylea (aflibercept), Lucentis (ranibizumab), Avastin (bevacizumab, used off-label for eye conditions), or Vabysmo (faricimab) to reduce how often injections are needed.
For chronic central serous chorioretinopathy, PDT has become a well-established and preferred treatment. Many retina specialists use a modified protocol called half-dose PDT, where the amount of Visudyne is reduced by half. This approach lowers the risk of side effects while still effectively closing the source of fluid leakage. Research has shown that approximately 80 percent of chronic CSC patients achieve complete resolution of fluid after a single PDT session. Patients with worse baseline vision tend to experience the greatest improvement in visual acuity following treatment.
Anti-VEGF injections work by blocking a protein called vascular endothelial growth factor, which drives abnormal blood vessel growth and leakage. Medications in this class require repeated injections on a schedule that varies by drug and patient response. PDT works through a completely different mechanism, using a photochemical reaction to physically close abnormal vessels rather than blocking a growth signal.
For wet AMD, anti-VEGF injections produce better visual outcomes for most patients and are the current standard of care. For chronic CSC, PDT is often preferred because anti-VEGF injections have shown limited effectiveness for that condition. A retina specialist will recommend the approach best suited to the diagnosis and the individual clinical situation.
In 2023, the FDA approved an updated photodynamic laser system for use with Visudyne (verteporfin), providing retina specialists with newer equipment options for performing PDT with precision. Research also continues into refining dosing protocols, particularly the half-dose and half-fluence approaches for chronic CSC, with the goal of maximizing effectiveness while further reducing the potential for side effects.
What to Expect Before, During, and After PDT
Most patients find PDT to be a straightforward, well-tolerated office procedure. Knowing what to expect at each stage helps you prepare and recover safely.
Before scheduling PDT, your retina specialist will perform a thorough examination and review your imaging results. You should share a complete list of your current medications, especially any that increase sensitivity to light. Arrange for someone to drive you home, as your vision may be temporarily blurry after the procedure. You will also need to have dark sunglasses and protective clothing ready before you leave the office.
The entire PDT procedure takes approximately 20 to 30 minutes and is performed in the office. A nurse or technician will place a small intravenous line in your arm and infuse Visudyne (verteporfin) over about 10 minutes. After a brief waiting period to allow the drug to concentrate in the abnormal vessels, your retina specialist applies a low-energy laser to the targeted area of the retina for approximately 83 seconds. The laser is painless, and you will be seated at an instrument similar to one used during a routine eye exam.
The most important instruction after PDT is to avoid direct sunlight and bright indoor lighting for five full days. Visudyne remains in your body during this time and makes your skin and eyes highly sensitive to light. Sun exposure during this period can cause severe sunburn-like damage to any exposed skin and can harm the eyes. If you need to go outdoors, wear long sleeves, gloves, a wide-brimmed hat, and wraparound dark sunglasses that block light from all angles. Normal indoor lamp lighting is generally considered safe.
Your retina specialist will schedule follow-up visits using OCT and possibly repeat angiography to assess how the eye has responded to treatment. Abnormal vessels can sometimes reopen over time, so additional PDT sessions may be needed. For wet AMD, ongoing anti-VEGF injections are often continued alongside PDT. Many patients with chronic CSC achieve lasting results after a single session, though some require retreatment. Keeping every scheduled appointment is essential for the best possible outcome.
Managing Your Vision and Long-Term Health
PDT is one part of a broader approach to protecting your vision. Understanding what the treatment can realistically achieve, and how to support your retinal health between appointments, helps you stay in the best position possible.
PDT is designed to slow or stop vision loss and, in some cases, improve vision by resolving fluid beneath the retina. It cannot restore vision that has already been permanently lost due to long-standing damage. For wet AMD patients, the primary goal is to preserve as much vision as possible. For chronic CSC patients, resolution of fluid often brings noticeable improvement in clarity and reduced distortion, though some subtle visual changes may remain depending on the duration and severity of the condition before treatment.
PDT is generally well tolerated. The most important safety concern is photosensitivity during the five-day period following treatment. Failing to avoid bright light during this time can result in severe sunburn-like reactions on exposed skin. In rare cases, Visudyne can cause temporary swelling in the eye and a short-term decrease in vision. Other uncommon side effects include back pain during the infusion, injection site reactions, and temporary visual disturbances. Your retina specialist will review all risks with you before the procedure so you can make an informed decision.
Patients recovering from PDT should plan their schedules around the five-day light-avoidance period, particularly if their work or daily activities involve outdoor exposure or bright lighting. Between appointments, using an Amsler grid at home is a simple and effective way to monitor for changes in central vision. This is a small printed chart of lines and a central dot that can reveal distortion or new blind spots. Eating a balanced diet rich in leafy greens and omega-3 fatty acids, avoiding smoking, and managing blood pressure all support overall retinal health and may help slow the progression of conditions like AMD.
When to Seek Urgent Retina Care
Some vision changes need immediate attention, not a wait-and-see approach. Knowing when to act quickly can make a meaningful difference in protecting your sight.
Contact a retina specialist right away or go to an emergency room if you experience any of the following symptoms, as they can signal a sight-threatening emergency:
- A sudden increase in floaters, which are dark spots or strands that drift across your vision
- Flashes of light in one or both eyes
- A dark curtain, shadow, or gray area spreading across any part of your visual field
- Sudden loss of vision in one eye
These symptoms do not always indicate the same condition, but they warrant prompt evaluation to rule out a retinal tear, detachment, or other urgent problem.
Even when your vision feels stable, regular follow-up with a retina specialist is essential after PDT. Conditions like wet AMD and chronic CSC can recur without immediately obvious symptoms. OCT imaging and clinical examination allow early detection of changes before they cause significant vision loss. Report any new or worsening visual symptoms to your retina specialist promptly, and do not skip scheduled appointments.
Frequently Asked Questions
These answers address practical questions patients often have as they prepare for PDT or weigh their treatment options.
The laser portion of PDT causes no pain. The intravenous infusion of Visudyne (verteporfin) feels similar to a routine blood draw. Some patients notice mild back discomfort during the infusion, which typically resolves quickly on its own. No sedation or general anesthesia is required. Standard numbing eye drops are used to keep the eye comfortable during the laser portion of the procedure.
The number of sessions varies based on your diagnosis and how your eye responds. For chronic CSC, research indicates that approximately 80 percent of patients achieve complete resolution of fluid after a single session, though some patients require retreatment. For wet AMD, multiple PDT sessions may be needed, often in combination with anti-VEGF injections. Your retina specialist will assess your imaging results at each follow-up visit and recommend additional treatment only if the eye shows signs of persistent or recurring abnormal vessel activity.
Many patients can return to indoor work the following day as long as the workspace involves only normal indoor lighting and no outdoor exposure. The five-day light-avoidance requirement is the key consideration. If your job involves working outdoors, driving in sunlight, or exposure to bright lighting, you will need to make arrangements to modify your duties or take time off during this period. Discuss your specific work situation with your retina specialist before the procedure so you can plan accordingly.
If you are inadvertently exposed to sunlight or intense light within five days of treatment, move indoors or into shade immediately. Visudyne remains active in your body during this window and can cause a serious photosensitivity reaction, including severe sunburn-like damage to any exposed skin. Contact your retina specialist as soon as possible to report the exposure and receive guidance. Preventing accidental exposure by preparing your protective clothing, sunglasses, and hat before leaving the office is the safest approach.
When anti-VEGF injections were studied in large clinical trials, they were shown to produce superior visual outcomes compared to PDT alone for most wet AMD patients. Anti-VEGF medications block the protein that drives abnormal blood vessel growth, and many patients not only experienced slowed vision loss but also gained vision. As a result, injections became the standard of care for wet AMD. PDT remains a valuable option for patients who do not respond adequately to anti-VEGF therapy alone, and combination approaches using both treatments continue to be used in select cases to help reduce injection frequency.
Half-dose PDT follows the same procedural steps as standard PDT, but the amount of Visudyne (verteporfin) used is reduced to half the usual dose. This modified approach was developed specifically for chronic CSC to lower the risk of unwanted effects on the surrounding retinal tissue while still effectively closing the source of fluid leakage. Research has consistently supported half-dose PDT as a safe and effective approach for chronic CSC, and many retina specialists consider it the preferred technique for that condition.
Visit Rhode Island Eye Institute for Expert Retina Care
Our fellowship-trained retina specialists at Rhode Island Eye Institute bring advanced expertise and state-of-the-art diagnostic technology to every patient visit. Whether you are exploring PDT for the first time or seeking a second opinion on your retinal condition, our team is here to guide you through your options with clarity and care. We welcome patients from across Rhode Island and southeastern Massachusetts and are committed to helping you protect your vision for the long term.