biology

Photorejuvenation

Photorejuvenation is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Photorejuvenation rather than just read about it. In short: Photorejuvenation is a skin treatment that uses lasers, intense pulsed light, or photodynamic therapy to treat skin conditions and remove effects of photoaging such as wrinkles, spots, and textures. The process induces controlled wounds to the skin.

Key takeaways

Photorejuvenation belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Photorejuvenation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Photorejuvenation from memory before moving on to harder problems.

Reference excerpt

Photorejuvenation is a skin treatment that uses lasers, intense pulsed light, or photodynamic therapy to treat skin conditions and remove effects of photoaging such as wrinkles, spots, and textures. The process induces controlled wounds to the skin. This prompts the skin to heal itself, by creating new cells. This process—to a certain extent—removes the signs of photoaging. The technique was invented by Thomas L Roberts, III using CO2 lasers in the 1990s. Observed complications have included scarring, hyperpigmentation, acne, and herpes.

Skin rejuvenation Skin rejuvenation can be effected through various modalities, including thermal, chemical, mechanical, injection, and light.

Laser resurfacing

Laser resurfacing is a laser surgery technique that disassociates molecular bonds. It is used for the treatment of wrinkles, solar lentigenes, sun damage, scarring (acne scars and surgical scars), stretch marks, actinic keratosis, and telangiectasias. It can be combined with liposuction to help tighten and smooth over the new contours after removal of excess fat. Resurfacing can be ablative, which vaporizes tissue and creates wounds, or non-ablative which keeps the skin intact. Laser resurfacing can be performed using non-ablative lasers, such as the 1540 nm Er:glass laser, or ablative lasers, such as the 2940 nm Er:YAG laser or the 10,600 nm CO2 laser Complete resurfacing was first done with a CO2 laser. Both erbium and CO2 are used to treat deep rhytides, sun damage and age spots. Through the heating of the deep dermis, fibroblasts are stimulated to form new collagen and elastin helping to bring increased turgor and thickness to the skin. A variety of modes have been developed including Nd:Yag lasers and a plasma device. CO2 resurfacing has been shown to have an increased risk of hypopigmentation and scarring than erbium lasers. This is due to the high degree of coagulation and thus heat production that occurs as a nature of the CO2 wavelength.

Fractional laser Fractional laser photothermolysis (FP) is a form of laser-based skin resurfacing, with several devices on the market, such as Fraxel. A fractional laser delivers laser light to the skin. Hundreds or thousands of laser pinpoints may be used per square inch, leaving healthy skin between the ablated areas. Complications observed in a study of 961 treatments included acne and herpes outbreaks. There have been anecdotal negative accounts of bad scarring and hyperpigmentation. Erbium and CO2 fractional systems have a better safety profile than lasers of the past.

Intense pulsed light Intense Pulsed Light (IPL) uses flashlamps (and not lasers) to produce high intensity light over broad visible and infrared wavelengths with filters that select the desired range. IPL is used to treat dyschromia, rosacea, melasma, acne, photodamage, vascular and pigmented lesions, and rhytides. One study conducted by a group of four researchers from the Weill Cornell Medical College of Cornell University in 2004 found IPL to be a "non-invasive, non-ablative method for rejuvenating photoaged skin with minimal adverse events". Other studies, however, have noted that exposing cells to direct heat can cause DNA damage—not only in those cells, but also in surrounding tissue that was not directly exposed, and concluded treatments can cause microscopic thermal injuries, and that further research is warranted. IPL is effective for pigmentation and telangiectasias, but has lesser results for wrinkles.

Photodynamic therapy Photodynamic therapy (PDT) uses photosensitive compounds that are activated by light. It is used to treat actinic keratoses, acne, photoaging, and skin cancer.

Worked examples

Example 1 — a first encounter with Photorejuvenation

Start with the simplest possible case. Write down what Photorejuvenation claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Photorejuvenation before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Photorejuvenation ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Photorejuvenation

In research: Photorejuvenation appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Photorejuvenation in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Photorejuvenation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dermatologic surgery, Laser medicine, so understanding it makes those chapters shorter.
In everyday life: Look for Photorejuvenation outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Photorejuvenation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Photorejuvenation means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Photorejuvenation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Photorejuvenation in simple terms?

Why does Photorejuvenation matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Photorejuvenation?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Photorejuvenation.