Category Archives: Medicine

Biology, Medicine, Trivia

Can a pocket laser damage our eyesight?

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Can a pocket laser damage our eyesight? The answer to this question depends on many factors. It is a bit like trying to establish a single safe speed for driving a car. Under normal conditions, a speed of 30 mph is safe, but not during storm or heavy fog. It is similar with defining the safety limit for the laser pointer. The likelihood of eye damage depends on many factors. It includes the laser color, divergence (beam dispersion), distance from the source, the time our eyes are exposed to it and, above all, power. It is the power that is the main determinant of marketability. Depending on the country there are different standards (with divisions into special classes), but generally lasers up to 5 mW are considered to be the upper safe limit. In the United States the limit is 3.5mW.

The power of lasers is given in milliwatts (mW). Theoretically, 3.5 mW is a safe value because it represents about one-tenth of the actual damage threshold, but history records cases of permanent vision damage from a pocket laser. Why? First, there are cheap Chinese products on the market the power of which may differ from that declared on the housing. Second, users of the laser may be children. In 2018, a 9-year-old became blind in one eye by looking into a green laser beam several times.

Why worry about 5 mW at all? After all, it’s only 5 thousandths of a watt, or less than one percent of one percent of the power of a 60-watt light bulb. The reasons are two. First, a light bulb converts only about 10 percent of that energy into light (the figure is different for an energy-saving bulb). Second, the bulb shines in all directions, thus we see only a small portion of the light it emits. We reduce this amount even further by moving away from it. A laser emits light in one small focused beam.

Despite meeting safety requirements, small lasers can still be dangerous. The reason for this is known as flash blindness. Everyone knows the feeling of temporary blindness after a camera flash or after moving from a dark to a bright room. A laser beam can lead to such temporary blindness, which can have extremely severe consequences for e.g. drivers, or machine operators. There are known cases of attempts to blind airplane pilots. The effect is particularly strong at night, when pupils are dilated. Lasers are also used during protests and riots. They are used to damage drones, CCTV cameras and to blind police. IR (infrared) and UV (ultraviolet) lasers are particularly dangerous. Normally the eye exposed to a laser should blink in reflex, but UV and IR rays our body is not able to detect. Recently, lasers were used in the riots following the death of George Floyd. Three officers were blinded by lasers (authorities report that permanently).

Regardless of the power, lasers should be used with caution and under no circumstances should a child be allowed to play with them.

Sources:

https://www.laserpointersafety.com/

https://www.imperial.ac.uk/safety/safety-by-topic/laboratory-safety/laser-safety/laser-pointer-safety/laser-pointer-safety-guidance/

https://www.ehs.harvard.edu/sites/default/files/laser_pointer_safety.pdf

Lasers: The Future of Protests

https://www.the-sun.com/news/1483420/portland-black-lives-matter-protester-laser-cops-eyes/

Biology, Medicine

Why do some people have dimples in their cheeks?

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Dimples are small depressions found in various areas of the body, including cheeks, chin and lower back. They are commonly considered an appearance feature that adds to attractiveness. In this article, we will try to answer the question why dimples are considered attractive, how do they appear and what is their function?

Cheek dimples

Dimples in cheeks are caused by a specific structure of facial muscles, specifically the zygomaticus major. This is the muscle responsible for smiling – when we smile it pulls the corners of our mouth up. Normally, the zygomaticus has two attachments – one above the corners of our mouth and the other on the zygomatic bone (cheek, on the outside of the eye socket). However, people with dimples have a third attachment – to the inner skin of the cheeks. When such a person smiles, the muscle pulls the cheek skin attached to the muscle, forming dimples.

As cheek dimples develop during the fetal period, they are sometimes mistakenly referred to as a birth defect. Although cheek dimples have no biological function, they also have no negative health effects. They simply are, just because they are.

Zygomaticus major muscle (wikimedia commons)

A chin dimple (cleft chin)

Dimples in chin most often appear due to the jawbone structure. The mandible is formed during the fetal period, fusing together from two parts: the left and the right. If the halves do not fuse together completely, it causes a small dimple to form at the junction. As with cheek dimples, this has no biological significance.

In some cases, the chin muscle is responsible for the dimple.

Dimples above buttocks (Venus dimples)

Venus dimples are tiny depressions above the buttocks. They are located in the area of lumbar region completely devoid of muscles. They are most commonly found in women, but some men also have them. In this case we refer to Apollo dimples. As with facial dimples, Venus dimples have no biological significance, although some researchers suggest that dimples above the buttocks indicate better blood supply to the intimate area, which may have a positive effect on sexual experience.

Why are cheek dimples considered attractive?

There are two reasons. First, dimples accentuate a smile, making it appear more sincere and joyful. Second, they look adorable because we associate them with a baby face. Some studies suggest that the presence of dimples can convey more information about the intensity of facial expression.

Can you get dimples in your cheeks from exercise?

Unfortunately, no. Exercising your facial muscles will improve your facial contours and overall appearance. However, it does not make dimples appear by any means. The only solution is a procedure called dimpleplasty. Your physician will make a small incision on the inside of your cheeks through which he will cut a small piece of muscle and remove a bit of fatty tissue, then place a suture connecting the skin to the muscle. The suture is dissolvable, so you will not need to make additional visits to have it removed. In place of the suture, a scar will appear to permanently connect the skin to the muscle. The procedure is very simple and the chances of complications are relatively low.

Cleft chin correction

When it comes to chin dimples, it is a completely different matter. Although in most cases they are celebrated positively, in some cases they can cause disruption to the symmetry of the face. The dimple may be too deep, or unevenly placed. In this case, it is essential to consult the physician. He must determine the cause of dimple and suggest a method of correction. The simplest is to use a filler – hyaluronic acid. Such a procedure takes several minutes and is almost painless. If muscles are responsible for the problem, the physician may recommend an injection of botox, i.e. botulinum toxin. This substance paralyzes the muscles, which will reduce their tension and loosen the pulled skin. Depending on the substance used, the treatment will have an effect of several months to two years. A permanent option is chin surgery. Depending on the need, the physician may file the excess bone, fill the gap with a special implant, correct the muscle position, or use a combination of the above methods. The disadvantage is a long convalescence. There is also a price difference. A cosmetic procedure costs from $200 to $400, whereas a surgical intervention involves the cost up to $2,000.

Sources:

https://medlineplus.gov/genetics/understanding/traits/dimples/

https://www.healthline.com/health/dimpleplasty

https://www.huffingtonpost.co.uk/2018/06/01/dimpleplasty-5-things-to-know-about-new-plastic-surgery-trend_a_23448435/