Twins in the Womb - Human Development

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LASIK, or "laser-assisted in situ keratomileusis," is the most commonly performed laser eye surgery to treat myopia, hyperopia and astigmatism. The goal of the treatment is to reshape the cornea to correct the refractive error of the eye.
The cornea is the transparent dome-shaped structure in front of the eye. The cornea refracts light and accounts for about two-thirds of the eye's total optical power. Altering the curvature of the cornea changes the way light rays enter the eye. As a result, the light rays can be focused properly onto the retina for clearer vision.
For nearsighted people, the laser is used to flatten the cornea. For farsighted people, the cornea is made steeper. For patients with astigmatism, the laser is used to smooth the irregularly-shaped cornea into a more regular shape.
The outer layer of the cornea - the epithelium – is capable of replacing itself within a few days after being damaged or removed. The deeper layer of the cornea – the stroma, on the contrary, is a permanent corneal tissue with very limited regenerative capacity. The stroma, if reshaped by a laser, will remain that way permanently.
In this procedure, a thin, circular "FLAP" is created in the surface of the cornea to gain access to the permanent corneal tissue. This can be done with a mechanical cutting tool called a microkeratome, OR, for a blade-free experience, by a femtosecond laser. An excimer laser is then used to remove some corneal tissue to reshape the cornea. Excimer laser uses cool ultraviolet light beams to vaporize microscopic amounts of tissue in a precise manner to accurately reshape the cornea. The excimer laser is computer-controlled and is programmed based on the patient’s refractive error. The flap is then laid back in place and is allowed to heal.
LASIK eye surgery is mostly painless and can be completed within minutes. Improved vision can usually be seen overnight.

PRK, or photorefractive keratectomy, was the first type of laser eye surgery for vision correction and is the predecessor to the popular LASIK procedure. In PRK, NO flap is created. Rather, the epithelial cells on the eye surface are simply removed. An excimer laser is then used to reshape the cornea just like it does in LASIK.
The vision correction outcomes of PRK surgery are comparable to those of LASIK, but the recovery period is longer. This is because the epithelium is completely removed in PRK and it takes a few days to regenerate. PRK patients also have more discomfort and haziness of vision in the first few days after the surgery. Improved vision also takes longer to achieve.
PRK does, however, offer certain advantages. Because PRK does not involve creation of a flap, which contains both epithelial and deeper stromal tissue, the entire thickness of the stroma is available for treatment. The treatment range is therefore higher. This is particularly useful for patients with high levels of myopia or for those whose cornea is too thin for LASIK. PRK is also free of flap-related complication risks.

Gallbladder cancer is cancer that begins in the gallbladder. Your gallbladder is a small, pear-shaped organ on the right side of your abdomen, just beneath your liver. The gallbladder stores bile, a digestive fluid produced by your liver. Gallbladder cancer is uncommon. When gallbladder cancer is discovered at its earliest stages, the chance for a cure is very good. But most gallbladder cancers are discovered at a late stage, when the prognosis is often very poor. Gallbladder cancer is difficult to diagnose because it often causes no specific signs or symptoms. Also, the relatively hidden nature of the gallbladder makes it easier for gallbladder cancer to grow without being detected. Symptoms ShareTweet Aug. 07, 2014 References Products and Services Book: Mayo Clinic on Digestive Health Give today to find cancer cures for tomorrow See also Abdominal pain Can you recommend a diet after gallbladder removal? Chemo Targets Chemotherapy Chemotherapy and hair loss: What to expect during treatment Chemotherapy and sex: Is sexual activity OK during treatment? Chemotherapy nausea and vomiting: Prevention is best defense Show more Advertisement Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Advertising & Sponsorship PolicyOpportunitiesAd Choices Mayo Clinic Store Check out these best-sellers and special offers on books and newsletters from Mayo Clinic. NEW! – The Mayo Clinic Diet, Second Edition Relief for America's epidemic of indigestion Keeping your bones healthy and strong Manage blood pressure for better health The Mayo Clinic Diet Online

An estimated 20 million LASIK procedures have been performed since 1998. The FDA website is filled with stories of complications, including pain, dizziness and detached retinas. CBS2's Chris Wragge reports.

Frontotemporal degeneration (FTD) is a disease process that results in progressive damage to the temporal and/or frontal lobes of the brain. It causes a group of brain disorders that share many clinical features.

Insertion of a CSF shunt

To diagnose COPD, your doctor will probably do the following tests: Medical history and physical exam. These will give your doctor important information about your health. Lung function testsLung function tests, including an FEV1 test. These tests measure the amount of air in your lungs and the speed at which air moves in and out. Spirometry is the most important of these tests. Chest X-rayChest X-ray. This helps rule out other conditions with similar symptoms, such as lung cancer.

Carpal Tunnel Syndrome Ergonomics

Cocaine in human brain

Anatomy of The Infratemporal Fossa

Histology of Heart Cardiac Muscle

t’s the brain, after all, that devises experiments and interprets their results. How the brain perceives, how it makes decisions and judgments, and how those judgments can go awry are at least as important to science as knowing the intricacies of nonbiotic experimental machinery. And as any brain scientist will tell you, there’s still a long way to go before understanding the brain will get crossed off science’s to-do list. But there has been progress. A recent special issue of the journal Neuron offers a convenient set of “perspective” papers exploring the current state of understanding of the brain’s inner workings. Those papers show that a lot is known. But at the same time they emphasize that there’s a lot we don’t know.

The deep veins play a significant role in propelling blood toward the heart. The one-way valves in deep veins prevent blood from flowing backward, and the muscles surrounding the deep veins compress them, helping force the blood toward the heart, just as squeezing a toothpaste tube ejects toothpaste.

A hiatus hernia or hiatal hernia is the protrusion (or herniation) of the upper part of the stomach into the thorax through the esophageal hiatus because of a tear or weakness in the diaphragm. Hiatus hernias often result in heartburn but may also cause chest pain or pain with eating. The most common cause is obesity.

A wisdom tooth or third molar is one of the three molars per quadrant of the human dentition. It is the most posterior of the three. Wisdom teeth generally erupt between the ages of 17

A heart attack is a medical emergency. A heart attack usually occurs when a blood clot blocks blood flow to the heart. Without blood, tissue loses oxygen and dies. Symptoms include tightness or pain in the chest, neck, back, or arms, as well as fatigue, lightheadedness, abnormal heartbeat, and anxiety. Women are more likely to have atypical symptoms than men. Treatment ranges from lifestyle changes and cardiac rehabilitation to medications, stents, and bypass surgery.

A narrowing of the major artery (the aorta) that carries blood to the body. This narrowing affects blood flow where the arteries branch out to carry blood along separate vessels to the upper and lower parts of the body. CoA can cause high blood pressure or heart damage.

Obstetrical emergencies of pregnancy ECTOPIC PREGNANCY. ... PLACENTAL ABRUPTION. ... PLACENTA PREVIA. ... ECTOPIC PREGNANCY. ... PLACENTAL ABRUPTION. ... PLACENTA PREVIA. ... Amniotic fluid — The liquid in the placental sac that cushions the fetus and regulates temperature in the placental environment.

What Is a Hair Transplant? It's a type of surgery that moves hair you already have to fill an area with thin or no hair. Doctors have been doing these transplants in the U.S. since the 1950s, but techniques have changed a lot in recent years. You usually have the procedure in the doctor's office. First, the surgeon cleans your scalp and injects medicine to numb the back of your head. Your doctor will choose one of two methods for the transplant: follicular unit strip surgery (FUSS) or follicular unit extraction (FUE). With FUSS, the surgeon removes a 6- to 10-inch strip of skin from the back of your head. He sets it aside and sews the scalp closed. This area is immediately hidden by the hair around it. Next, the surgeon’s team divides the strip of removed scalp into 500 to 2,000 tiny grafts, each with an individual hair or just a few hairs. The number and type of graft you get depends on your hair type, quality, color, and the size of the area where you’re getting the transplant. If you’re getting the FUE procedure, the surgeon’s team will shave the back of your scalp. Then, the doctor will remove hair follicles one by one from there. The area heals with small dots, which your existing hair will cover. After that point, both procedures are the same. After he prepares the grafts, the surgeon cleans and numbs the area where the hair will go, creates holes or slits with a scalpel or needle, and delicately places each graft in one of the holes. He’ll probably get help from other team members to plant the grafts, too. Depending on the size of the transplant you’re getting, the process will take about 4 to 8 hours. You might need another procedure later on if you continue to lose hair or decide you want thicker hair. Expectations and Recovery After the surgery, your scalp may be very tender. You may need to take pain medications for several days. Your surgeon will have you wear bandages over your scalp for at least a day or two. He may also prescribe an antibiotic or an anti-inflammatory drug for you to take for several days. Most people are able to return to work 2 to 5 days after the operation. Within 2 to 3 weeks after surgery, the transplanted hair will fall out, but you should start to notice new growth within a few months. Most people will see 60% of new hair growth after 6 to 9 months. Some surgeons prescribe the hair-growing drug minoxidil (Rogaine) to improve hair growth after transplantation, but it’s not clear how well it works. Risks and Costs of Treatment The price of a hair transplant will depend largely on the amount of hair you’re moving, but it generally ranges from $4,000 to $15,000. Most insurance plans don’t cover it.

Lysosomal storage diseases (LSDs; /ˌlaɪsəˈsoʊməl/) are a group of approximately 50 rare inherited metabolic disorders that result from defects in lysosomal function. Lysosomes are sacs of enzymes within cells that digest large molecules and pass the fragments on to other parts of the cell for recycling.