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What is the Side-Effect of Photodynamic Therapy?

Medical advancements have genuinely changed the way treatments are carried out in today’s world. While there is still no cure for cancer, the treatment procedures for the disease have improved over the years. Have you heard of Photodynamic Therapy and its side effect?

Photodynamic Therapy is a new form of cancer treatment. The side effect of this treatment is giving humans a slight level of night vision. During the course of this treatment, the retina is able to process light at wavelengths higher than visible light.

What is Photodynamic Therapy?

Photodynamic Therapy (PDT), or Dynamic Phototherapy, is a treatment involving light and a photosensitizing chemical used to promote cell death or phototoxicity. 

The procedure is widely used by dermatologists in treating acne but has gained popularity in other fields of medicine. Today it is being used for psoriasis, atherosclerosis, and malignant cancers. Photodynamic Therapy is minimally invasive and less toxic than other procedures.

As of February 2019, scientists announced that iridium attached to albumin could penetrate cancer cells when a photosensitizer molecule is created after being irradiated with light. The cancer cell will then be destroyed. (Source: Mayo Clinic)

Why is Photodynamic Therapy Done?

Photodynamic Therapy is utilized in various fields of medicine. It is more commonly used for specific skin diseases like actinic keratosis. It has also shown success with malignant cancers in the pancreas, bile duct, esophagus, and lungs. (Source: Mayo Clinic)

The Side-Effect of Photodynamic Therapy

Photodynamic Therapy has revealed an unexpected side effect. Patients who have undergone the therapy have seemed to develop night vision. With molecular simulation, scientists have now clarified the mechanisms behind the side effect.

With Photodynamic Therapy, light and photosensitive medication are used to treat certain cancers of the skin, bronchi, esophagus, and some bacterial infections.

In the early 2000s, published articles reported on patients being treated with chlorine e6, a photosensitive molecule, who were upset to start seeing silhouettes and outlines in the dark.

Antonio Monari, Chemist at the LPCT

During the process, light is collected by the retina, cones, and rods of the eye. The rods contain large quantities of rhodopsin. Rhodopsin is a photosensitive protein that also has the ability to absorb visible light because of retinal, which is derived from vitamin A.

When it receives light, the retinal changes its chemical structure and dissociates itself from the protein, allowing translation of the light signal into an electrical signal that can be interpreted by the visual cortex. Under low light levels, and particularly at night, the predominant light radiation is no longer in the visible domain but at higher wavelengths, the infrared level to which retinal is not sensitive. That is why we cannot see in the dark like many other animal species. 

Antonio Monari, Chemist at the LPCT

(Source: CNRS News)

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