Symptoms of Alzheimer's disease

The onset of Alzheimer's disease is usually gradual, and it is slowly progressive. Memory problems that family members initially dismiss as "a normal part of aging" are in retrospect noted by the family to be the first stages of Alzheimer's disease. When memory and other problems with thinking start to consistently affect the usual level of functioning; families begin to suspect that something more than "normal aging" is going on.

Problems of memory, particularly for recent events (short-term memory) are common early in the course of Alzheimer's disease. For example, the individual may, on repeated occasions, forget to turn off an iron or fail to recall which of the morning's medicines were taken. Mild personality changes, such as less spontaneity, apathy, and a tendency to withdraw from social interactions, may occur early in the illness.

As the disease progresses, problems in abstract thinking and in other intellectual functions develop. The person may begin to have trouble with figures when working on bills, with understanding what is being read, or with organizing the day's work. Further disturbances in behavior and appearance may also be seen at this point, such as agitation, irritability, quarrelsomeness, and a diminishing ability to dress appropriately.

Later in the course of the disorder, affected individuals may become confused or disoriented about what month or year it is, be unable to describe accurately where they live, or be unable to name a place being visited. Eventually, patients may wander, be unable to engage in conversation, erratic in mood, uncooperative, and lose bladder and bowel control. In late stages of the disease, persons may become totally incapable of caring for themselves. Death can then follow, perhaps from pneumonia or some other problem that occurs in severely deteriorated states of health. Those who develop the disorder later in life more often die from other illnesses (such as heart disease) rather than as a consequence of Alzheimer's disease.

What are risk factors for Alzheimer's disease?

The biggest risk factor for Alzheimer's disease is increased age. The likelihood of developing Alzheimer's disease doubles every 5.5 years from 65 to 85 years of age. Whereas only 1%-2% of individuals 70 years of age have Alzheimer's disease, in some studies around 40% of individuals 85 years of age have Alzheimer's disease. Nonetheless, at least half of people who live past the 95 years of age do not have Alzheimer's disease.

Common forms of certain genes increase the risk of developing Alzheimer's disease, but do not invariably cause Alzheimer's disease. The best-studied "risk" gene is the one that encodes apolipoprotein E (apoE). The apoE gene has three different forms (alleles) -- apoE2, apoE3, and apoE4. The apoE4 form of the gene has been associated with increased risk of Alzheimer's disease in most (but not all) populations studied. The frequency of the apoE4 version of the gene in the general population varies, but is always less than 30% and frequently 8%-15%. Persons with one copy of the E4 gene usually have about a two to three fold increased risk of developing Alzheimer's disease. Persons with two copies of the E4 gene (usually around 1% of the population) have about a nine-fold increase in risk. Nonetheless, even persons with two copies of the E4 gene don't always get Alzheimer's disease. At least one copy of the E4 gene is found in 40% of patients with sporadic or late-onset Alzheimer's disease.

This means that in majority of patients with Alzheimer's disease, no genetic risk factor has yet been found. Most experts do not recommend that adult children of patients with Alzheimer's disease should have genetic testing for the apoE4 gene since there is no treatment for Alzheimer's disease. When medical treatments that prevent or decrease the risk of developing Alzheimer's disease become available, genetic testing may be recommended for adult children of patients with Alzheimer's disease so that they may be treated.

Many, but not all, studies have found that women have a higher risk for Alzheimer's disease than men. It is certainly true that women live longer than men, but age alone does not seem to explain the increased frequency in women. The apparent increased frequency of Alzheimer's disease in women has led to considerable research about the role of estrogen in Alzheimer's disease. Recent studies suggest that estrogen should not be prescribed to post-menopausal women for the purpose of decreasing the risk of Alzheimer's disease. Nonetheless, the role of estrogen in Alzheimer's disease remains an area of research focus.

Some studies have found that Alzheimer's disease occurs more often among people who suffered significant traumatic head injuries earlier in life, particularly among those with the apoE 4 gene.

In addition, many, but not all studies, have demonstrated that persons with limited formal education - usually less than eight years - are at increased risk for Alzheimer's disease. It is not known whether this reflects a decreased "cognitive reserve" or other factors associated with a lower educational level.

Alzheimer's disease

Alzheimer's disease is a progressive disease that destroys memory and other important mental functions.

It's the most common cause of dementia — a group of brain disorders that results in the loss of intellectual and social skills. These changes are severe enough to interfere with day-to-day life.

In Alzheimer's disease, the connections between brain cells and the brain cells themselves degenerate and die, causing a steady decline in memory and mental function.

Current Alzheimer's disease medications and management strategies may temporarily improve symptoms. This can sometimes help people with Alzheimer's disease maximize function and maintain independence.

But because there's no cure for Alzheimer's disease, it's important to seek supportive services and tap into your support network as early as possible.

Alzheimer's and dementia basics

• Alzheimer's is the most common form of dementia, a general term for memory loss and other intellectual abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 50 to 80 percent of dementia cases. 
• Alzheimer's is not a normal part of aging, although the greatest known risk factor is increasing age, and the majority of people with Alzheimer's are 65 and older. But Alzheimer's is not just a disease of old age. Up to 5 percent of people with the disease have early onset Alzheimer's (also known as younger-onset), which often appears when someone is in their 40s or 50s.
• Alzheimer's worsens over time. Alzheimer's is a progressive disease, where dementia symptoms gradually worsen over a number of years. In its early stages, memory loss is mild, but with late-stage Alzheimer's, individuals lose the ability to carry on a conversation and respond to their environment. Alzheimer's is the sixth leading cause of death in the United States. Those with Alzheimer's live an average of eight years after their symptoms become noticeable to others, but survival can range from four to 20 years, depending on age and other health conditions.
• Alzheimer's has no current cure, but treatments for symptoms are available and research continues. Although current Alzheimer's treatments cannot stop Alzheimer's from progressing, they can temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer's and their caregivers. Today, there is a worldwide effort under way to find better ways to treat the disease, delay its onset, and prevent it from developing. 

Genetic Diseases

A genetic disease is any disease that is caused by an abnormality in an individual's genome. The abnormality can range from minuscule to major -- from a discrete mutation in a single base in the DNA of a single gene to a gross chromosome abnormality involving the addition or subtraction of an entire chromosome or set of chromosomes. Some genetic disorders are inherited from the parents, while other genetic diseases are caused by acquired changes or mutations in a preexisting gene or group of genes. Mutations occur either randomly or due to some environmental exposure.

There are a number of different types of genetic inheritance, including the following four modes:

Single gene inheritance

Single gene inheritance, also called Mendelian or monogenetic inheritance. This type of inheritance is caused by changes or mutations that occur in theDNA sequence of a single gene. There are more than 6,000 known single-gene disorders, which occur in about 1 out of every 200 births. These disorders are known as monogenetic disorders (disorders of a single age).

Some examples of monogenetic disorders include:

• cystic fibrosis,
• sickle cell anemia,
• Marfan syndrome,
• Huntington's disease, and
• hemochromatosis.

Single-gene disorders are inherited in recognizable patterns: autosomal dominant, autosomal recessive, and X-linked

Multifactorial inheritance

Examples of multifactorial inheritance include:Multifactorial inheritance, also called complex or polygenic inheritance. Multifactorial inheritance disorders are caused by a combination of environmental factors and mutations in multiple genes. For example, different genes that influence breast cancer susceptibility have been found on chromosomes 6, 11, 13, 14, 15, 17, and 22. Some common chronic diseases are multifactorial disorders.

• heart disease,
• high blood pressure,
• Alzheimer's disease,
• arthritis,
• diabetes,
• cancer, and
• obesity.

Multifactorial inheritance also is associated with heritable traits such as fingerprint patterns, height, eye color, and skin color.

Chromosome abnormalities

Chromosomes, distinct structures made up of DNA and protein, are located in the nucleus of each cell. Because chromosomes are the carriers of the genetic material, abnormalities in chromosome number or structure can result in disease. Abnormalities in chromosomes typically occur due to a problem with cell division.

For example, Down syndrome or trisomy 21 is a common disorder that occurs when a person has three copies of chromosome 21. There are many other chromosome abnormalities including:

• Turner syndrome (45,X),
• Klinefelter syndrome (47, XXY), and
• cri du chat syndrome, or the "cry of the cat" syndrome (46, XX or XY, 5p-).

Diseases may also occur because of chromosomal translocation in which portions of two chromosomes are exchanged..

Mitochondrial inheritance

This type of genetic disorder is caused by mutations in the nonchromosomal DNA of mitochondria. Mitochondria are small round or rod-like organelles that are involved in cellular respiration and found in the cytoplasm of plant and animal cells. Each mitochondrion may contain 5 to 10 circular pieces of DNA. Since egg cells, but not sperm cells keep their mitochondria during fertilization, mitochondrial DNA is always inherited from the female parent.

Examples of mitochondrial disease include:

• an eye disease called Leber's hereditary optic atrophy;
• a type of epilepsy called MERRF which stands for myoclonus epilepsy with Ragged Red Fibers; and
• a form of dementia called MELAS for mitochondrial encephalopathy, lactic acidosis and stroke-like episodes.

TEETH VENEERS

Just as you can put new siding on your house to mask a chipped or fading paint job, you can cover up imperfections on your teeth with the help of dental veneers. Also known as dental porcelain laminates, veneers are "false fronts" that are cemented onto your natural teeth to improve their shape and appearance. Veneers give the impression of the wearer having a flawless, bright smile.

Despite the fact that they're only about a half-millimeter thick, veneers can accomplish quite a lot when it comes to fixing your smile . People often get them with one or more of the following goals in mind:

• fixing teeth that are mottled or stained from use of fluoride or drugs such as tetracycline
• covering up chips in teeth
• correcting the appearance and bite of crooked teeth
• filling in gaps between teeth

Veneers are often made from porcelain or resin composite materials. Both materials have advantages. Veneers made of porcelain look more natural than those made of resin composite materials. Resin veneers, on the other hand, are thinner and require less shaving of the enamel before they're affixed to teeth, but they're also more susceptible to staining .

Veneers are generally used to re-face the front eight upper teeth. Since the reasons for getting veneers are largely cosmetic, there's usually no need to have them on teeth that aren't commonly seen when you smile or talk.

While veneers are a good option cosmetically, they're not cheap: They cost anywhere from $800 to $1,300 -- per tooth . And again, since getting them is a cosmetic procedure, you'll likely have to pay the full cost out of pocket.

The process of getting veneers is a little more involved than a bonding procedure (during which a dentist can reshape a tooth using composite resin bonding), but less complicated than getting a crown.

Start to finish, it generally takes three visits to the dentist to get veneers . The first visit is a consultation visit. That's the time to ask any questions you may have about the process. Make sure your dentist is skilled and experienced in this procedure. You can ask to see before-and-after photos of your dentist's previous veneer recipient patients, and to be put in contact with them -- especially if you're getting several veneers.

Next, we'll talk about the most involved part of the process -- the second visit -- and whether or not your pricey veneers will last a lifetime.

On the visit following the initial veneer consultation, your dentist will shave a layer of enamel from the surface of your teeth to accommodate the thickness of the veneers. Then, he or she will make models of the affected teeth and fit you with temporary veneers. The models, in the meantime, will be sent to a dental laboratory that will use them to make your permanent veneers.

On the third visit, your dentist will first ensure your new veneers look and fit right. If the color or size is off in any way, your dentist will trim the veneer as needed, or use various shades of cement to make adjustments for the color. Then the cement and veneer will be placed and positioned, and excess cement cleaned away. Once your dentist is satisfied everything looks right, he or she will use laser light to quickly cure the cement.

There are definite advantages to getting veneers when compared to other options for improving the appearance of your teeth, such as bonding or crowns, or taking no action at all. The biggest plus is that veneers can drastically improve your smile and your self-esteem. They're less expensive than crown work and are resistant to staining. However, staining of adjacent teeth that don't have veneers may cause them to be noticeably different shades.

You should also consider some of the potential disadvantages before getting veneers. For example, errors during the bonding process could result in discolored veneers, due to the selection of cement colors available. If veneers break or crack, fixing them can be an extensive process, especially if the bonding is still strong and intact. Veneers that fall off due to poor bonding can often be reapplied. If a veneer breaks, however, the portion remaining on your tooth will need to be ground down (much like your enamel was when you first received the veneer) and replaced with a new veneer.

Replacing veneers at some point, whether they break or not, is almost inevitable. This is because veneers are considered semi-permanent. In other words, they're permanent enough that you won't want to replace them before their time, but they generally last only about 5 to 10 years, at which point the bonding begins to fail . And once your enamel has been scraped away to make room for the veneer, there's no going back -- you'll have to keep wearing them.

Veneers are durable, but treat them with care: You'll want to break habits like chewing your fingernails or ice. Teeth grinding may chip or crack veneers to the point of needing replacements, as well.

There's a newer type of veneer available, called Lumineers. Learn more about what they are and how they compare to regular veneers on the next page.

Teeth bridge

What are dental bridges?

When you have one or more missing teeth, then a dental bridge may be used to restore the resulting gaps. The dental bridge is basically a false tooth, beautifully created from porcelain that fills the gap and is supported by adjacent teeth or implants.

One of the most crucial skills in the placement of a dental bridge is to create the illusion that the missing tooth emerges from gum just a natural tooth. Our skills in cosmetic dentistry, gum manipulation and our in-house implantologist can combine ensure no-one will know that you ever had a missing tooth!

There are several types of bridge:

1. Traditional Fixed Dental Bridge

Here the “false tooth” is fused between two porcelain crowns to fill the gap left by a missing tooth. There are two crowns holding it in place attached onto your teeth either side of the false tooth. This type of dental bridge can be used to replace one or more missing teeth.

2. Cantilever Dental Bridge

In areas of your mouth that are under less stress, such as your front teeth, a cantilever dental bridge may be used. A cantilever dental bridge is when the “false tooth” is only supported on one side. The result is just as aesthetic but has the benefit that fewer teeth have to be treated.

3. Resin Bonded Dental Bridges / Maryland Dental Bridge

The type of dental bridge is almost always used for your front teeth. The main benefit of this type of dental bridge is that healthy teeth either side need either minimal or no preparation. The “false tooth” is fused to metal or ceramic “wings” that are bonded very firmly to the supporting or “abutment” teeth with a resin. The wings are hidden from view so that only the porcelain, which appears just like a natural tooth, is visible.

4. Implant Supported Dental bridges

Implants are the modern way to replace missing teeth. An implant is placed in the bone where the tooth root would have originally been. When it has fused to the bone it can be restored with individual crowns or, when more than one tooth is missing, with an implant supported dental bridge. Even if you have no teeth in one or both jaws, implants can be placed and an implant supported dental bridge securely fixed.

There are three primary types of dental bridges, but the concept behind all of them is the same: Either one or several artificial teeth known as pontics are placed in the mouth and anchored to implanted posts or neighboring teeth (known as abutments). They literally bridge a space between two teeth.

• A fixed bridge contains a crown at either end with one or more false teeth attached between them. The crowns slip over the natural teeth found immediately to the right and left of the gap made by missing teeth, and the bridge's false teeth rest on the gums. This is a very durable bridge that's appropriate for placement anywhere in the mouth.

• A resin-bonded bridge -- also known as a Maryland bonded bridge -- contains false teeth that span a gap in the mouth. But in this case, the false teeth are attached via metal bands that are glued to neighboring teeth instead of anchored with crowns. It is a viable option when the anchoring teeth are still in good shape and don't need to be restored through the crowning procedure. It is also often used in the front of the mouth where the stress is minimal and the metal bands can be hidden behind the teeth. It is a less invasive process, although the bridge itself isn't as secure as a fixed bridge.

• A cantilever bridge is similar to a fixed bridge except, instead of anchoring to a tooth on either side of the gap, it attaches to only one tooth. This might be used in the very back of the mouth where there is only one tooth to which the bridge can anchor, or anywhere there is only one healthy tooth to which the bridge can attach.

As with all bridges (large or small), the key to success is planning, which in this case, means a visit to your dentist. He or she will evaluate your overall dental health and decide whether or not you're a good candidate. If your gums and teeth are in reasonably good health and no gum disease is present, your dentist will green light you for the bridge procedure.

In creating a fixed or cantilevered bridge, the dentist first numbs your mouth in the area where the bridge will eventually be inserted. He then prepares the teeth that will anchor the bridge, which usually involves shaving them down so that the crowns will fit over them. If the teeth are in poor shape, however, he might need to first build them up.

Once the teeth are prepared (which is not necessary for a resin-bonded bridge), the dentist will take a mold of your mouth using a soft putty. This mold is then sent off to a lab so that the bridge can be manufactured. In the meantime, the dentist will fit you with a temporary bridge to protect the exposed teeth and gums. When the permanent bridge is ready, you will return to the dentist's office, the temporary bridge will be removed and the permanent one set in place with super-strong cement.

Teeth Straightening

      

Teeth can be straightened using either orthodontics or porcelain veneers or a combination of both. Only mild to moderate crowding or protrusion can be aligned with veneers alone, but orthodontics can straighten any teeth, however severely misaligned. Combination treatments are ideal for crowded and misaligned teeth that are also heavily worn, discoloured or broken down.

Orthodontic options to straighten teeth:

Inman aligner. The Inman aligner is the fastest way to straigthen teeth with a removable appliance. It is excellent for aligning mainly just crowding of the front four teeth. For adults this the most common form of crowding so it can be used in many different cases. Treatment times typically take from 6 to 16 weeks.

Invisalign. Invisalign use a very high-tech manufacturing process to make a series of removable clear plastic aligners which makes them almost invisible. Invisalign can straighten teeth over a slightly broader range of cases than the Inman aligner but still cannot be used for severe crowding. Invisalign has the added advantage of having little effect on speech. However, treatment times are typically from 6 to 18 months.

Lingual braces. These are like conventional fixed braces except the brackets are bonded to the inside of the teeth so they are invisible to others. Lingual braces can be used to straighten teeth from almost all case types. Treatment times vary depending on case type typically from 6 to 24 months.

Porcelain veneers to straighten teeth:

Teeth can be straightened using porcelain veneers as part of a smile makeover. Porcelain veneers are a thin layer of porcelain that are a new front surface for a tooth. Teeth are prepared by trimming a thin layer from the enamel on the front of the tooth, just enough to make space for the veneer. If teeth are crowded, some teeth or parts of teeth protrude more than others. To straighten the teeth, more is trimmed back from those areas that protrude so that when the veneers are placed on these teeth it will have the appearance of having straightened them.

The advantage of this approach is that it is very quick with treatments being completed in as little as 2 weeks. Many other aesthetic improvements can be made at the same time such as changing the length, the overall shape and whitening the teeth. The smile can be designed and tailored using computer aided smile design and a process is used which creates very predictable and beautiful results.

The disadvantage of this approach is that very crowded or protruding teeth may need significant amounts of their tooth structure to be trimmed back.

Combination treatments to straighten teeth

Teeth can be quickly straightened using an Inman aligner prior to further cosmetic treatment such as asmile makeover with porcelain veneers. If the teeth are heavily worn and discoloured but also crowded this is an excellent way to achieve the very best aesthetic results, whilst maintaining a very conservative approach. This means even severe cases can be treated without the heavy trimming back of teeth that would be required if the case was attempted with veneers alone.

False Teeth

False teeth are devices that are utilized to perform the function of natural teeth when they are no longer present. Also known as dentures, false teeth sometimes become necessary due to the deterioration of natural teeth or due to some type of accident that severely damages the teeth. False teeth may be permanently inserted into the gums or be constructed into plates that can be placed over the gums and removed when appropriate.

The use of false or fake teeth has a long history. There are indications that false teeth have been around since at least 700 BC. During the Middle Ages, false teeth made from ivory or animal bone made it possible for people to enjoy the benefits of teeth even after circumstances had made it necessary to remove natural teeth. Using false teeth also tended to cut down on the harvesting of natural teeth from the recently deceased, as well as limiting the opportunity for people to have healthy teeth extracted in return for some type of financial gain.

During the 20th century, false teeth became more sophisticated. The idea of making dental impressions so that the configuration of the upper and lower plates of false teeth would be an exact fit came into common use. The dentures also began to take on a look that was closer to that of natural teeth. By the middle of the century, high quality false teeth were difficult to distinguish from a mouthful of healthy natural teeth.

While many people think in terms of false teeth being a completely manufactured set of teeth, that is not always the case. Sections of false teeth, known as partials, are sometimes utilized to fill in a gap where several teeth are missing. The partials slide into place and sometimes are fashioned to connect with the existing teeth. False teeth also come in the form of dental implants. The implants are permanent false teeth that are inserted to take the place of one or two teeth that have been removed for some reason. The dental plants fit neatly into the tooth socket of the gum and blend in with the natural teeth.

While it is possible to obtain false teeth that are intentionally distinct from natural teeth, the vast majority of people who require dental replacements prefer to have the appearance be as close to real teeth as possible. Thus, cosmetic teeth are made of materials such a porcelain or synthetic resins and plastics that will retain a white appearance for many years and hold up to the usual wear and tear placed on any set of teeth.

Milk teeth

A baby’s gummy smile is adorable! Equally adorable is the sight of that first pearly white appearing in their mouth. Before you know it, your baby will have a full set of milk teeth. However, milk teeth are often neglected by parents who think that they are not ‘permanent’ and will ‘fall off anyway’. So, here are some facts about milk teeth which will hopefully increase awareness among the parents of young children:

 FACT 1

Children have 20 milk teeth. These start to appear any time between the age of 6 months to a year. They continue to erupt until the child is around 3 to 4 years of age.

FACT 2

Milk teeth shed (fall) when the permanent teeth below them are ready to erupt. Only the lower two front teeth fall at approximately 6yrs of age. Every year thereafter, the child will lose roughly two to four milk teeth. The milk molars shed between 10 and 13 years.

FACT 3

The first dental visit should coincide with the eruption of the first milk tooth or latest by the child’s first birthday. You can then be counselled on appropriate oral hygiene measures and infant feeding habits. This can go a long way in preventing severe early childhood caries.

FACT 4

Babies often experience sore gums, increased drooling, loss of appetite and disturbed sleep when they cut their milk teeth. They may become cranky and want to chew on a toy or their fingers to get relief. Chewing on unclean objects/ fingers may lead to diarrhoea, fever. This is not caused by teething and you must contact your paediatrician if the child is unwell.

FACT 5

The sooner you start cleaning your baby’s teeth, the better! From birth until one year of age, wipe the gum pads and teeth with a clean damp cloth. Introduce a soft baby brush by one year.

FACT 6

Paediatric fluoride toothpaste (500 ppm) could be started by two years. Switch over to fluoridated toothpaste containing 1000 ppm of fluoride once your child learns to spit and gargle, and accepts the taste. These recommendations hold good when non-fluoridated water is consumed. Most parts of the country do not have natural fluoride in the drinking water. The municipal water supply in India is also not fluoridated. If you live anywhere in the areas which have fluoride in the drinking water, introduce a fluoride toothpaste at 6 years of age.

FACT 7

When the baby falls asleep whilst feeding, the last mouthful of milk (breast & bottle) is not swallowed. This milk pools around the teeth and causes decay. The upper front teeth and molars are the ones to be affected the most.

FACT 8

A twice-a-year check-up is recommended for most children. Regular dental visits help your child stay cavity free. Some children need more frequent dental visits because of increased risk of tooth decay, unusual growth patterns or poor oral hygiene.

LASIK SURGERY

What is LASIK?

LASIK stands for laser in situ keratomileusis, which means using a laser underneath a corneal flap (in situ) to reshape the cornea (keratomileusis). This procedure utilizes a highly specialized laser (excimer laser) designed to treat refractive errors, improve vision, and reduce or eliminate the need for glasses or contact lenses. This laser procedure alters the shape of the cornea, which is the transparent front covering of the eye. Though the excimer laser had been used for many years before, the development of LASIK is generally credited to Ioannis Pallikaris from Greece around 1991.

How does LASIK work?

During the LASIK procedure, a specially trained eye surgeon first creates a precise, thin hinged corneal flap using a microkeratome. The surgeon then pulls back the flap to expose the underlying corneal tissue, and then the excimer laser ablates (reshapes) the cornea in a unique pre-specified pattern for each patient. The flap is then gently repositioned onto the underlying cornea without sutures.

What are the advantages of LASIK surgery?

In summary, despite the risks outlined above, LASIK has been proven to be safe and effective for most people. With careful patient screening and selection, reasonable expectations, and in the care of an experienced surgeon, most patients will be very pleased with their results. These are some of the other advantages of LASIK:

• LASIK is able to accurately correct most levels of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.
• The procedure is fast, usually lasting only five to 10 minutes, and is generally painless.
• Because the laser is guided by a computer, it is very precise and results are very accurate.
• In most cases, a single treatment will achieve the desired outcome; however, enhancements are possible if needed, even many years after the initial surgery.

What are the disadvantages of LASIK surgery?

• Because each patient will heal slightly differently, results may vary from patient to patient.
• LASIK could make some aspects of your vision worse, including night vision with glare and halos.
• LASIK may make dry-eye symptoms worse in certain individuals.
• In rare circumstances, LASIK can make your vision worse and not correctable with regular glasses or contact lenses.

One of the most common physical ailments that people suffer from is poor vision. The eye is a complicated organ that requires a very exact arrangement of components to function properly. If even one of these components is not precisely the correct shape, then light that falls on the eye will not be focused correctly.

For centuries, people have relied on external lenses to alter the angle of the light entering the eye. Whether in glasses or contact lenses, these appliances have proven invaluable in the correction of poor vision. While external lenses will remain popular for the foreseeable future, advances in technology have made it possible for surgeons to alter the shape of the eye itself.

There are several types of vision correction surgery. One of the most popular is LASIK, which stands for laser-assisted in-situ keratomileusis. In this article, you will find out exactly what happens during a LASIK procedure as you follow this author through his own eye surgery. You will learn what LASIK is, what is involved in the surgery, what equipment is used and how to know if you're a candidate for LASIK. You will also learn what the other forms of eye surgery are and how they differ from each other.

In its simplest sense, your eye is like a camera. Your eye has:

• A variable opening called the pupil
• A lens system, which includes the transparent covering called the corneaand a spherical lens
• A reusable "film" called the retina
• Various sets of muscles(The muscles control the size of the opening, the shape of the lens system and the movements of the eye.)

On the back of your eye is a complex layer of cells known as the retina. The retina reacts to light and conveys that information to the brain. The brain, in turn, translates all that activity into an image. Because the eye is a sphere, the surface of the retina is curved.

In the retina, sensory cells called rods and cones change the photons of light into electrical signals, which are then transmitted to and interpreted by the brain. The ability to focus the light on the retina depends on the shapes of the cornea and the lens, which are controlled by their inherent shapes, their stretchiness or elasticity, the shape of the eyeball and sets of attached muscles. So, when you look at something, muscles attached to the lens must contract and relax to change the shape of the lens system and keep the object focused on the retina, even when your eyes move; this is a complex set of muscle movements that is controlled automatically by your nervous system.

When you look at something, three things must happen:

• The image must be reduced in size to fit onto the retina.
• The scattered light must come together -- that is, it must focus -- at the surface of the retina.
• The image must be curved to match the curve of the retina.

The basis for all laser eye surgery is to reshape the cornea so that it changes the focal point of the eye. Ideally, the focal point is changed so that it focuses perfectly on the retina, just like a normal eye.

As stated in the previous section, myopia (nearsightedness) usually results from the eye being too long. The cornea has a more pronounced curve than a normal eye. Laser eye surgery is great for myopia because it is relatively easy to remove a little of the cornea to flatten out the curve.

Hyperopia (farsightedness) normally means the eye is too short, which means that the cornea needs to curve more to properly focus the light on the retina. Although more intensive than correcting myopia, laser eye surgery can treat hyperopia by reshaping the cornea to make it rounder.

Laser eye surgery works by pulsing a tightly-focused beam of light (laser) onto the surface of the eye. Upon contact with the surface of the cornea, the laser vaporizes a microscopic portion of the cornea (more on this later). By controlling the size, position and number of laser pulses, the surgeon can precisely control how much of the cornea is removed.

LASIK combines the best features of ALK and PRK (see above). Like ALK, LASIK uses a microkeratome to create a "flap" of the outer corneal tissue that can be folded out of the way and then replaced. Once the flap is folded out of the way, LASIK uses the same Excimer laser used in PRK to reshape the underlying corneal tissue. Then the flap is replaced over the reshaped area and conforms to the new shape.

The great thing about the cornea is how quickly it heals. As soon as that flap is replaced, it begins to naturally seal itself to the rest of the cornea. This approach greatly speeds the overall healing process when compared to PRK, which leaves the reshaped area open.

Of course, there are potential problems with LASIK. The three most common problems are:

• Undercorrection - Not enough tissue is removed during the procedure.
• Overcorrection - Too much tissue is removed during the procedure.
• Wrinkling - The corneal flap has a small fold or wrinkle in it when it is replaced, causing a small blurry area in your vision.

Under most circumstances, each of these problems is easily corrected with a second surgical procedure. If the undercorrection or overcorrection is very slight, the surgeon will most likely advise the patient not to attempt to refine his or her vision any further. In fact, many recipients of laser eye surgery never achieve normal vision but are able to reduce their corrective-lens prescription significantly.

In addition to the more common problems listed above, there is a potential for other side effectssuch as blurred vision, halos around lights, increased light sensitivity and even double vision. There is also the chance that damage or scarring can happen to the cornea, resulting in a partial or complete loss of vision.

These other problems occur only rarely when you're dealing with reputable ophthalmologists operating on patients who meet the parameters of an ideal candidate. We'll talk more about what makes an ideal candidate later.

The development of theExcimer laser is the key element that has made laser eye surgery possible. Created by IBM, Excimer lasers (the name is derived from the termsexcited and dimers) use reactive gases, such as chlorine and fluorine, mixed with inert gases such as argon, krypton or xenon. When electrically stimulated, a pseudo molecule (dimer) is produced that, when lased, produces light in the ultraviolet range. 

The Excimer laser is a cool laser, which means that it does not heat up the surrounding air or surfaces. Instead, a very tightly-focused beam of ultraviolet light is emitted. The ultraviolet light is absorbed by the upper layer of the surface that it contacts. The sheer amount of ultraviolet light is too much for most organic materials (such as the cornea of the eye) to absorb, resulting in the breakdown of the molecular bonds of the material.

The ultraviolet beam of light only penetrates a microscopic amount, less than a nanometer (a billionth of a meter), into the surface of the cornea. The heat created from the energy released by the laser is dissipated along with this microscopic layer of the cornea. This process is known asphotoablation.

The Excimer laser is incredibly precise. It has the ability to focus a beam as small as 0.25 microns. Considering that a typical human hair is 50 microns in diameter, that means that the Excimer laser is capable of removing 0.5 percent of a human hair's width at a time!

The operation of the Excimer laser is a complicated and delicate process. In fact, a dedicated technician is used just to set up and operate the machine in conjunction with the ophthalmologist performing the surgery.

LASER EYE SURGERY

Eye surgery, while once a tricky procedure that required working with microscopic structures, is now performed on a regular basis. Eye surgery ranges from corrective procedures to vision-saving surgeries that correct cataracts, glaucoma or eye tumors. If you have eye surgery, a period of healing afterward is essential to allow the eyes to rest and to heal, and your doctor will give you instructions as to how to care for your eyes during this time.

LASER EYE SURGERY HALO EFFECT

Laser eye surgery is a surgical method of permanent vision correction. The goal of laser eye surgery, sometimes referred to as LASIK, is to eliminate or reduce the need for eyeglasses or contact lenses. In some cases, however, a halo effect may persist in those who have had the surgery done.

Definition

A halo is what looks like a sunburst or a ring around lights at night. After having LASIK, people often experience halos when out at night, around streetlights and car headlights, according to Red Orbit. This can make night driving unsafe or impossible in some cases.

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Causes

Most patients who experience the halo effect after laser eye surgery have large pupils. USA Eyes, a website operated by the Council for Refractive Surgery Quality Assurance, states that the halo is caused by the outside edge of the cornea not being treated during the surgery, dry eyes and swelling.

Incidence

Approximately half of people who undergo laser eye surgery have large pupils, according to Red Orbit. While seeing halos is a common side effect, USA Eyes states that the condition eventually resolves itself in most people.

Time Frame

According to USA Eyes, the halo effect can last for up to six months while the eyes heal from the surgery. In some cases, however, this effect may last longer.

Prevention/Solution

The "large zone" technique of performing laser eye surgery can reduce or eliminate the incidence of halo vision by treating a larger portion of the cornea. Another option for treating this condition is to use brimonidine tartrate eye drops, according to a study done by the Yonsei University College of Medicine in Seoul, Korea.