乐城医院光动力疗法治疗黄斑变性

There is a particular kind of fear that comes with vision loss in older age. It is not the fear of darkness itself — it is the fear of losing the ability to read a grandchild’s face, to navigate a familiar street, to recognize the expression of someone you love. I have seen this fear in the eyes of patients sitting in my consultation room. And I have watched what happens when that fear is met with something more than resignation.

One of the most common causes of this fear is age-related macular degeneration, or AMD. It is the leading cause of irreversible central vision loss in adults over 50, and the numbers are sobering. Globally, AMD affects approximately 200 million people, with projections suggesting that figure will rise to 300 million by 2040. In China, the burden is growing as the population ages — AMD is now the third leading cause of blindness among adults aged 50 and older in major Chinese cities, and its prevalence continues to climb.

To understand why photodynamic therapy matters, it helps to understand what macular degeneration actually is.

The macula is the central portion of the retina — a tiny, densely packed cluster of photoreceptor cells responsible for the sharp, detailed vision we rely on for reading, driving, and recognizing faces. When the macula degenerates, central vision blurs, distorts, or disappears. Peripheral vision often remains intact, but the loss of central vision is profoundly disabling.

AMD comes in two forms. The dry form, which accounts for approximately 85% of cases, involves the gradual thinning of the macula and the accumulation of drusen — yellow deposits beneath the retina. The wet form, which accounts for only about 15% of cases but is responsible for 80% to 90% of severe vision loss, is characterized by the growth of abnormal blood vessels beneath the retina. These vessels are fragile and prone to leaking blood and fluid, which damages the photoreceptors and leads to rapid, often sudden, vision deterioration.

Wet AMD is driven primarily by vascular endothelial growth factor (VEGF), a protein that promotes the growth of these abnormal vessels. It typically strikes one eye first, often without warning. Patients describe straight lines appearing wavy, central vision blurring, or a dark spot appearing in the middle of their visual field. Without treatment, the damage can progress within weeks to months.

For years, the only tool available for treating wet AMD was thermal laser photocoagulation — essentially burning the abnormal vessels with a high-energy laser. The problem was that this approach also destroyed the healthy retina overlying the vessels. It was effective, but at a terrible cost: the treatment itself created a permanent blind spot.

Photodynamic therapy (PDT) represented a fundamental departure from this destructive paradigm. It is a two-stage process that requires both a light-activated drug and a specific wavelength of non-thermal laser light. The drug, verteporfin — marketed as Visudyne — is a photosensitizing agent derived from porphyrin. It is administered intravenously and, because it binds to low-density lipoprotein, it preferentially accumulates in the rapidly proliferating endothelial cells of the abnormal choroidal neovascularization (CNV) — the very vessels that cause wet AMD.

Once the drug has reached its target, the physician activates it with a non-thermal red laser at a wavelength of approximately 689 nm. In the presence of oxygen, the light-activated verteporfin generates highly reactive singlet oxygen and free radicals. These short-lived, highly reactive molecules cause local damage to the neovascular endothelium, resulting in vessel occlusion. Critically, this photochemical reaction is confined to the area where the drug has accumulated — and because verteporfin concentrates preferentially in the abnormal vessels, the surrounding healthy retinal tissue is largely spared.

The result is selective vascular occlusion. The abnormal vessels that are leaking and causing damage are closed off, while the overlying photoreceptors and the healthy retinal architecture remain largely intact. This is what makes PDT fundamentally different from thermal laser: it is not about destroying tissue with heat, but about triggering a biological response with light.

The clinical significance of PDT lies in its selectivity. Conventional thermal laser photocoagulation inevitably damages the neurosensory retina overlying the CNV, creating an immediate scotoma — a blind spot — in the treated area. For lesions located at or near the fovea, the center of the macula responsible for the sharpest vision, this approach is untenable. The treatment itself would destroy the very vision it is meant to preserve.

PDT avoids this problem. Because it targets the abnormal vessels selectively and spares the overlying retina, it can be used to treat lesions in the subfoveal region — the area of the macula responsible for the finest visual acuity. This is precisely the area where treatment is most needed and where conventional laser cannot safely be applied.

Another advantage is the potential for repeat treatment. PDT can be administered multiple times if the abnormal vessels persist or recur, without the cumulative thermal damage that would occur with repeated thermal laser. This is particularly important for a chronic, progressive condition like AMD, where long-term management is the norm rather than the exception.

More recently, clinical research has demonstrated that PDT is not merely an alternative to anti-VEGF injections — it is a powerful adjunct. A comprehensive meta-analysis published in 2025 evaluated 23 studies and found that the combination of anti-VEGF therapy and PDT resulted in better best-corrected visual acuity (BCVA) at 12 months compared to anti-VEGF alone. The combination group also had significantly fewer injections — a reduction of 1.76 injections per patient — without any difference in ocular safety. For patients who require frequent intravitreal injections, this reduction in treatment burden is not a minor convenience. It is a meaningful improvement in quality of life.

PDT is not a novel or experimental therapy. It has a long and well-documented clinical history. Verteporfin PDT was first approved for clinical use in Switzerland in December 1999, followed by approval from the U.S. Food and Drug Administration in April 2000 for the treatment of age-related macular degeneration. Japan added PDT to its national health insurance coverage in 2004. In China, the drug was approved for import in late 2004 and became commercially available in 2005.

Today, verteporfin PDT has been used clinically in more than 140 countries worldwide. The efficacy data supporting its use are robust, drawn from well-controlled clinical trials and accumulated over two decades of real-world experience. In one early clinical trial, patients treated with PDT experienced approximately half the visual acuity decline of untreated patients over a one-year period — a difference that established PDT as a disease-modifying intervention rather than a mere symptomatic treatment.

The clinical indications for PDT have also expanded beyond classic wet AMD. It is now used in the treatment of polypoidal choroidal vasculopathy (PCV), a subtype of neovascular AMD that is particularly common in Asian populations. In PCV, PDT is especially effective at inducing regression of polypoidal lesions — the abnormal vascular structures that characterize the condition — and combination therapy with anti-VEGF agents has been shown to produce consistently better outcomes than monotherapy in terms of complete polyp regression.

The Boao Lecheng International Medical Tourism Pilot Zone has made PDT accessible to patients in China through its internationally recognized ophthalmic services.

In March 2026, the Zhongshan Ophthalmic Center of Sun Yat-sen University officially launched its Hainan International Eye Health Service at the Lecheng Pilot Zone. As one of China’s leading academic ophthalmic institutions, the Zhongshan Ophthalmic Center identified PDT as one of its first key demonstration projects, alongside ophthalmic gene therapy, innovative device translation, international corneal transplantation, and artificial iris and lens implantation. The service brings together world-class ophthalmic expertise and the policy advantages of the pilot zone to offer patients access to internationally synchronized diagnostic and therapeutic options.

The Hainan Boao Eye Hospital, also located within the pilot zone, has similarly announced that it will leverage Lecheng’s “pioneering pilot” policy to introduce advanced PDT technologies and other international innovations, allowing patients in Hainan to access global ophthalmic advancements earlier than would otherwise be possible.

For patients with wet AMD, PCV, or other conditions characterized by choroidal neovascularization, the availability of PDT at Lecheng means that a well-established, evidence-based therapy with a two-decade track record of safety and efficacy is now within reach — without the need to travel abroad or wait years for domestic access.