Wednesday, February 21, 2007

ANSI lumen - Lumen

Ansi Lumen
Measurement of light that has been standardized by ANSI(American National Standart Institute). It is commonly used to rate the brightness of a data projector. An ANSI lumen rating uses an average of several measurements taken across the face of the light source. A small room typically requires from 200 to 300 ANSI lumens, whereas a large room may require from 400 to 600. A large auditorium may need 2000 or more.

The light output of projectors (including video projectors) is typically measured in lumens. A standardized procedure for testing projectors has been established by the American National Standards Institute, which involves averaging together several measurements taken at different positions. For marketing purposes, the luminous flux of projectors that have been tested according to this procedure may be quoted in "ANSI lumens", to distinguish devices that have been so tested from those tested by other methods. ANSI lumen measurements are in general more accurate than the other measurement techniques used in the projector industry. This allows projectors to be more easily compared on the basis of their brightness specifications.

Wednesday, February 14, 2007

Aikido Key terms

KEY TERMS

The one point, in the lower abdomen, is the centre of your universe, wherever you go. Keeping your mind concentrated there will calm brain-waves, cause relaxation and clarity of mind. Correct judgement follows naturally and the ability to respond quickly to changing circumstances in your surrounding environment.

The following are some of the Japanese Terms you may encounter during your training :

AI - love, harmony, compassion, wisdom.

AIKI - harmony with the universe.

AIKIDO - the way of spiritual harmony.

ATEMI - distracting strike or blow.

BUDO - the spiritual path of a warrior.

DOJO - a place for practise of the way.

HARA - centre of gravity where energy is stored.

IRIMI - entering.

KI - spiritual energy.

KI-AI - a release of physical, mental and spiritual power.

KOKYU - breath expansion and contraction - Ki flow.

KOTOTAMA - chanting the sound spirit.

MA-AI - correct distance.

MANTRA - word repeated in meditation.

MISOGI - purification and breath control exercises.

MUSHIN - a mind without attachment or ego.

MOKUSU - a period of meditative calm.

NAGE - the one being attacked.

SEIZA - kneeling position.

TAI SABAKI - body movement.

TENKAN - turn or pivot.

UKE - the attacker.

UKEMI - the art of falling.

WAZA - technique.

ZANSHIN - unbroken concentration.

Aikido Basics

LISTS OF TECHNIQUES
  1. Tachiwaza - mae (standing, attacks from the front)
  2. Tachiwaza - ushiro (standing, attacks from the rear)
  3. Suwariwaza (tori and uke sitting)
  4. Hanmi handachiwaza (tori sitting, uke standing)
  5. Tantodori (defense against knife)
  6. Tachidori (defense against sword)
  7. Jodori (defense against staff)
  8. Kaeshiwaza (counter techniques)
  9. Henkawaza (changed techniques)
  10. Kogeki (attacks in aikid

GENERAL PRINCIPLES
  1. The basics are not all the executable techniques, but a wide selection of them. Aikido contains a number of throwing and pinning techniques, which vary slightly depending on the attack. All cannot be considered basic, but most of them should indeed be.
  2. The system of basics should make compatibility with other aikido systems possible. In regard to how the techniques are done, as well as to what techniques are included, a system of basics should be such that the aikido student is able to train and adapt to the training in another dojo than his or her own.
  3. Basic techniques should be reasonable to perform. Too complicated solutions are not basics. Some techniques are basic against certain attack forms, but not against others where they are very awkward or difficult to do. Furthermore, any basic technique should in itself be reasonably straigthforward.
  4. Attack forms that are not reasonably feasible, are not included in the basics. Some attacks, or combinations of attacks, are so difficult or awkward for the attacker that they are quite unlikely, therefore not to be included in a basic system.
  5. Also other techniques than these basics may be executable and trained. It is important to train more than the basics, to progress well in aikido. Also variations and complicated non-basics should be tried with some frequency. Otherwise the aikido in a dojo risks shrinking to something less than it can be.

Tori principles
  1. Always start with taisabaki, an evasive movement! It is not aikido if not started by avoiding the oncoming attack - even if the attack is a mild or slow one.
  2. Blocking the attack should not be necessary. To block the oncoming force is not really aikido, which should avoid confrontation. Sometimes blocking is practical, but if it is necessary, then the technique needs modification.
  3. Techniques should function to execute. An aikido technique should be possible to perform, and to do it in a way that avoids as well as controls the attacker.
  4. Similar solution for gotai, from static, and jutai, in movement. If a basic technique that works in movement needs to be significantly changed when done from a static start, it should be modified.
  5. Basic training should be done with low postures. The balance and control of low stances is essential to have as standard for basic techniques.
  6. Forces should be united (aiki). In aikido techniques the forces of the attacker and the defender should be joined, and not work against each other.
  7. The need for atemi, strike, should be limited. The aikido techniques should be possible to do with few or no atemi, which otherwise tends to be 'an easy way out'.
  8. Tori�s starting position should be such that uke�s attack is reasonable. The target that uke is supposed to aim for, must be easily reached - not hidden or blocked or otherways awkward for uke.
  9. Tori�s starting position should not be such that only one aikido technique is appropriate. It is no good if tori is positioned ideally for one aikido technique, but awkwardly for other techniques. Tori should stand able to do many different techniques.
  10. Tori should control the situation all through the technique. From the start to the finish, whether it is a pinning or a throw, tori should be in charge and remain aware.
  11. The fundamentals (such as center, ki, posture, etc.) should be stressed in training the basic techniques. The techniques are mere expressions of the fundamentals, and do not work well without them.

Uke principles
  1. It is part of aikido basics to learn correct attacks. Uke is obliged to learn and to do attacks with as much sincerity as with the aikido techniques when being tori. Otherwise, aikido is not learned properly.
  2. Attacks should normally be done with low postures. The balance and control of low stances is essential to have as standard for most basic attack techniques, in order to do them sincerely.
  3. Uke should not intentionally resist the technique. There is no point in resisting a particular technique, thereby being additionally vulnerable to other techniques. Also, resisting somebody who is trying to learn a technique is counter-productive.
  4. Uke should have a continued spirit of attack, through the technique. Uke should remain in an attacker mind all through, keeping an aim at tori.
  5. Uke should not change direction of the attack, during the technique. Uke's initial aim toward tori should remain all through, unless the exercise specifies differently.
  6. The fundamentals (such as center, ki, posture, etc.) should be stressed in training the attacks. The attack techniques are mere expressions of the fundamentals, and do not work well without them.
  7. More about attacks in aikido Explanations and instructions on kogeki, attack techniques.
site:www.stenudd.com

Tuesday, February 13, 2007

Yeterli ve dengeli beslenme nedir ?

Beslenme ve diyet denince; hemen aklımıza kilo verme, kilo alma, hastalıklarda beslenme gelir. Ama bunlardan daha önemli olan yeterli ve dengeli beslenmeye çalışmaktır.Ki zaten böyle bir günlük beslenmesi olan kişinin bu tür sorunları da olmayacaktır.
Beslenme;İnsanın büyümesi ve gelişmesi (anne karnında ve daha sonra) sağlıklı üretken olarak yaşamını sürdürebilmesi için gerekli olan besinlerin alınmasıdır. Sağlıklı büyüme ve gelişme ve özellikle zeka gelişimi için yeterli ve dengeli beslenme şarttır.Beslenme dokuların yenilenmesini ve bağışıklık sisteminin sağlıklı olarak çalışmasını sağlar.Yetersiz ve dengesiz beslenme vücut direncini azalttığında hastalıklara yakalanma olasılığı artmakta ve hastalıklar ağır seyretmektedir. İş yaşamında verimlilik ve üretkenlikte de beslenme önemli rol oynar.Yeterli ve dengeli beslenme; vücudun büyümesi, yenilenmesi ve çalışması için gerekli olan besin öğelerinin her birinin yeterli miktarda alınması ve vücutta uygun şekilde kullanılmasıdır...
Beslenme ve diyet denince; hemen aklımıza kilo verme, kilo alma, hastalıklarda beslenme gelir. Ama bunlardan daha önemli olan yeterli ve dengeli beslenmeye çalışmaktır.Ki zaten böyle bir günlük beslenmesi olan kişinin bu tür sorunları da olmayacaktır.
Yaşam için gerekli besin öğeleri:Besinlerin bileşiminde değişik miktarda 'besin öğesi' dediğimiz kimyasal moleküller bulunmaktadır.İnsanın büyüme, gelişme ve sağlıklı olarak yaşamını sürdürebilmesi için gereksinimi olan besin öğelerini 6 grupta toplayabiliriz. 1- Karbonhidratlar :( Un ve unlu gıdalarla ve tahıllar.)Vücuda enerji veren besin öğelerinden biridir. Vücudun harcadığı enerjinin büyük bir bölümünü sağlarlar. Beyin dokusu enerji için genellikle karbonhidratları kullanır. Ağır fiziksel hareketler için karbonhidratların daha elverişli enerji kaynağı olduğu bilinmektedir. Proteinlerin enerji olarak kullanılmasını önleyerek proteine olan gereksinimi azaltırlar.(kas yıkımını önler) Normal olarak günlük alınan enerjinin % 50-60'i karbonhidratlardan gelmelidir. Diyetimizde günlük en az 100-125g karbonhidrat bulunmalıdır. Buda 400-500 kalorilik enerji verir.
2- Vitaminler (Sebze ve meyveler)Normal büyüme ve yaşamın sürdürebilmesi için gerekli olan yiyecekler de doğal olarak bulunan organik bileşiklerdir.Vitaminlerin büyüme ve sağlıklı nesillerin oluşmasına , sinir ve sindirim sistemlerinin normal çalışması , besin öğelerinin elverişli kullanılması ve vücut direncine yardım gibi görevleri vardır. Vitaminlerin yetersiz alınımında vücut çalışmasında bozukluk ortaya çıkar.B grubu ve C vitaminleri suda eriyen vitaminler olduğundan, vücudun ihtiyacından fazla alınması durumunda idrar yoluyla atılırlar. Yağda eriyen vitaminler A, D, E, K'dir. Vücuda fazla alındığında, vücutta depo edilerek zararlı etki gösterebilirler.
3- Proteinler:(Et, balık, tavuk, yumurta ,süt, yoğurt, peynir, kuru baklagiller.)Proteinler kas ve diğer yumuşak dokular ile enzimlerin temel yapıtaşlarıdır. Büyüme ve gelişme, doku yapımı ve onarımı , enfeksiyonlara karşı savaşan bağışıklık hücrelerinin oluşumunda, kan proteini olan hemoglobin ile vücut çalışmasında görev alan enzimler ve hormonların yapımı en başlıca görevleridir. Proteinler enerji sağlamaktadır fakat bu onların temel görevi değildir.Amino asitler proteinlerin yapıtaşlarıdır. Kimyasal olarak proteinler, 22 amino asidin çeşitli kombinasyonlarda bir araya gelmesinden oluşurlar. 10 tane amino asidi vücudumuz yapamaz. Bu amino asitlere ' esansiyel amino asitler ' denir ve mutlaka gıdalarla alınmalıdır
4- YağlarYağlar en çok enerji veren besin öğesidir.Elzem yağ asidi ve yağda eriyen vitaminler vücuda yağ ile alınır. Deri altı yağ tabakası vücut ısısının kaybını önler. Yağ, organları çevreleyerek dış etkenlerden korur, midenin boşalmasını geciktirir.Hayvansal yiyeceklere dayalı diyetlerin yağ oranı, tahıla dayalı diyetlerden yüksektir. Vücuda alınan yağın genellikle yarısı yiyeceklerin bileşimindedir ve görünmez. Günlük alınan enerjinin % 30'u yağlardan gelmelidir.
5-MinerallerVücutta yapılamayan ve beslenme yolu ile dışardan alınması gerekli öğelerdir. Vücudun sağlıklı olarak büyümesi ve yaşamını sürdürmesi için elzem olduğu bilinen minerallerin başında kalsiyum, fosfor, sodyum, potasyum, klor, magnezyum, manganez, kükürt, demir, bakır, iyot, çinko, flor gelmektedir. Kobalt, krom, selenyum, molibden, silikon gibi minerallerinde vücudun çalışması için gereklidir.Bütün minerallerin vücutta farklı etkileri olmasına karşın, genel olarak kemik gelişimi, büyüme, kas kasılması, kan yapımı, sinir iletimi ve su dengesinin sağlanması gibi önemli görevler üstlenirler.
6-SuVücuda enerji vermediği, içinde bazı mineraller dışında besin öğesi bulunmadığı halde, su içmeden 3 gün kadar yaşayabiliriz. Su, yediğimiz gıdalardaki besin öğelerinin çözünüp sindirilmesi ve emilmesi, vücut sıcaklığının ayarlanması ve vücuttan atık maddelerin uzaklaştırılmasını sağlar. Yeterince su içilmediği zaman kalsiyum gibi bazı mineraller böbreklerde çökerek böbrek taşına neden olabilir. Sağlık açısından yetişkin bir insanın günde 8-10 bardak su içmesi gereklidir.
Beslenme Eyleminin Temel İlkeleri:Yeterli beslenme; kişinin yaşamını sürdürmesi için yeteri kadar besini almasını ifade eder ama gerekenden az alırsa yetersiz beslenme olur, ihtiyacından fazla alması halinde ise alınan fazla besinler yağa dönüşerek depolanır ve şişmanlık olur. Demek ki sadece yeterli beslenmek yetmiyor.Yeterli beslenirken, dengeli beslenmemiz de gerekiyor .
Dengeli beslenmek; vücudumuzun ihtiyacı olan enerjiyi tek bir besinden değil, vücudun büyümesi,yenilenmesi ve çalışması için gerekli olan besin öğelerinin her birinden yeter miktarda alarak mümkündür.Bunun içinde 5 ana başlık altında toplanan her bir besin grubundan;-Et grubu,-Süt grubu ,-Tahıl grubu,-Sebze ve meyveler-Az ölçüde yağ ve şeker
Bir gün için, önerilen miktarlar kadar alınmalıdır.Sağlıklı bir yetişkin için yeterli ve dengeli beslenme doğru bir beslenme şeklidir.Ama;-kişi egzersiz yapıyorsa-sağlık problemi varsa-aldığı bir ilacın besinle etkileşimi varsayeterli ve dengeli beslenmesi, onun doğru beslendiğini göstermez.
Doğru beslenme;İçinde bulunduğumuz özel durumlarla, yeterli ve dengeli beslenmenizin bir bütün haline gelmesidir.Bunun yanında; günlük ihtiyacınız olan tüm besin çeşitlerini yeterli ve dengeli miktarda tüketiyor olabiliriz, ama bunları öğünlere bölmeyip tek bir öğün veya 2 öğüne sığdırarak yapıyorsak; o zaman doğru değil yanlış besleniyoruz demektir.Bu nedenle yeterli ve dengeli beslenme kuralları çerçevesinde kendimize en uygun ve doğru beslenmeyi vücudunuzu ve kendimizi tanıyarak bu konudaki uzmanlara danışarak oluşturabiliriz.
site:www.hospitalium.com

Friday, February 09, 2007

How Does A Proxy Server Work?

How Does A Proxy Server Work?


A normal web transaction takes place between a piece of software called a web browser and a web server. The browser, running on a local machine, contacts the web server running at a different location on the Internet and requests a particular document or other piece of data (based on the URL).

Many of our resource providers limit access to their websites and web servers through a technique called "domain restriction"; in this case, the web server checks to see from which domain the request originated, i.e. on what part of the Internet the requesting browser is running.

Our resource providers restrict requests to the set of networks collectively referred to as "Muhlenberg Campus Network". You are on the Muhlenberg Campus Network domain if your computer is physically located on campus and connected to the campus network. In this case, the resource provider's web server will see you as part of the Muhlenberg Campus Network, and will allow you to connect and use their resources.

Diagram

You are not part of the Muhlenberg Campus Network if your computer is physically located somewhere other than Muhlenberg's campus, or you connect to the Internet through a non-Muhlenberg Internet Service Provider (e.g. Verizon, Penn TeleData or PDT, RCN, AOL, etc.), or both. In these cases, the resource provider's web server will see that you are not part of the Muhlenberg Campus Network domain, and will deny access to their resources.

Diagram

For the provider, this is the most efficient way to enforce licensing restrictions over the Internet. Unfortunately, it means that any of our patrons using non-Muhlenberg internet service providers will be denied access to "domain restricted" resources.

A proxy server solves this problem by relaying ("proxying") requests between a web browser and a restricted domain. Once the web browser has been told which proxy server to use, that machine servers as a "go between", forwarding transactions between the browser and the actual websites from which documents are being requested. In most browsers, once proxying is turned on, this "extra step" is transparent, handled automatically and invisibly.

By proxying all requests through a proxy server located on the Muhlenberg Campus Network, you gain access to all resources that are "domain restricted". The resource provider's web server sees only the forwarded request from the proxy server, located on the Muhlenberg Campus Network, and thus allows the connection.

Diagram

To ensure that only legitimate library users are granted access to restricted resources, their names and College ID numbers are verified by their records in the Library user database before they are allowed to use the proxy service.

Lightning and Eye

Lighting in our homes can have a profound effect on the quality of our life. Proper illumination may compensate for many age-related changes in the visual system. A sixty-year-old needs ten times as much light as a normal twenty-year-old to perform the same seeing task with equal speed and accuracy.

Lighting makes a significant contribution to our physical and psychological functioning. Better lighting can help increase personal independence, promote health and well-being, and prevent injuries.

In general, we should attempt to provide higher levels of illumination throughout the entire house. As we age, patterns of activity change. The visual tasks associated with a normal life (i.e. matching clothing colors, grooming and getting up in the middle of the night to read or use the bathroom) all need to be considered in the lighting design. Kitchens and bathrooms particularly need better lighting because work there is detailed.

Reading small print on a medicine bottle in the middle of the night is standard and not being able to do this is potentially hazardous. Accent lighting adds visual interest and becomes important for orientation and safety. As we age, it becomes more critical to clearly define hallways, stairs, and potential changes in surfaces or levels. Proper lighting can do this effectively.

Lighting design must balance between creating visual interest and visual disruption. This is particularly critical with older eyes that find blurred vision or changes in contrast unsettling. Scallop lighting effects on hallway walls or alternating high and low illumination levels within a space create a visual distraction. Shiny floors provide another source of glare and the resulting light patterns can be disorienting. It is also helpful to visually define where the wall meets the floor and avoid shadows which effect detail perception a higher ambient light level is helpful in creating pleasantly lit areas.

Outside light can be up to 1000 times brighter than the interior. Excessive differences in lighting levels should be avoided in transition areas between driveways, garages, entries, lobbies and corridors. Doors should be clearly delineated and pathways well illuminated. Older eyes adapt more slowly to changes in the light levels between rooms so having a more even distribution of light makes navigation easier.

As eyes age, they lose their ability to distinguish color, particularly in the short wave lengths (blue,violet). Living with effective light is a combination of designing good lighting and using it correctly. The primary consideration is the location and selection of lighting fixtures and controls. Fixtures should be carefully selected for their light quality. Bare bulbs fixtures should be avoided because they cause glare spots to which the older eye is painfully sensitive. Task light should be selected to provide adequate light for the task and to be adjustable in location, direction and intensity for individual needs. In both cases, high illumination per fixture does not add to the quality of light, in fact often the opposite is the rule. More fixtures with lower wattage create a more comfortable environment.

Controls are essential for the lighting systems to perform adequately. Controls for turning on and off lighting can include basic switches, dimmers, automatic sensor switches and scene controls. Although we want to consciously control our environment, we must consider whether it is appropriate to hunt for a light switch where issues of safety are involved. Motion sensors can turn lights on as we pass through an area.

This is particularly effective in hallways, stairs or in areas where hazards must be avoided. Timing lights to switch on or off can be an effective way to insure adequate ambient lighting as the daylight changes. A group of light switches may be controlled together providing scenes that balance light from many sources by simply pushing one switch. Switches can be located to control groups of lights for convenience, effect and safety. A single switch located at your bed can turn on a night light pathway to the bathroom or kitchen. Lighting can be incorporated into the security system so adequate light is turned on to safely mark an exit path in case of emergency.

Some general rules to consider

  • As we age, quality lighting becomes more important than ever
  • Since we spend more time in our home, lighting through the day should be a normal consideration
  • Ambient lighting should be available at sufficient levels to positively effect us physically and psychologically
  • General lighting levels should be significantly higher than is normal practice
  • Task lighting must be carefully arranged to illuminate the task while avoiding glare
  • Accent lighting should be used to provide interest and information and avoid visual noise
  • Daylighting is the most significant element in lighting a home. It must be filtered to prevent glare and sharp contrasts from area to area.
  • Lighting should have controls that are is easy to use.

Eye Health

Total Eye health at Spectacle World

We carry Lutien tablets as well as anti-oxidant, omega 3 and flaxseed capsules for your convenience.

Research suggests that antioxidants reduce your risk of cataracts and macular degeneration. Specific antioxidants can have additional benefits as well; for example, vitamin A protects against blindness, and vitamin C may play a role in preventing or alleviating glaucoma. Essential fatty acids appear to help the eye in a variety of ways, from alleviating symptoms of dry eye syndrome to guarding against macular damage.

Eating healthily will also help protect your eyes. Try these foods to make sure you get enough eye-protecting nutrients:

  • Vitamin A carrots, sweet potatoes, butternut squash.
  • Lutein and zeaxanthin: spinach, kale.
  • Vitamin C: sweet peppers (red or green), kale, strawberries, broccoli, oranges, sweetmelon.
  • Bioflavonoids: citrus fruits, cherries, grapes, plums.
  • Vitamin E: sunflower seeds, almonds, hazelnuts.
  • Selenium: brazil nuts, yeast, seafood.
  • Zinc: oysters, wheat, nuts.
  • Fatty acids: Flax seed, cold-water fish (salmon, mackerel, trout).

Is eating carrots really good for the eyes, or do moms just say that to inflict the vegetable on their kids? Well, one average-sized carrot contains twice the Recommended Daily Allowance (RDA) of vitamin A, which happens to be very good for your eyes. If you don't like carrots, don't worry — lots of yummy (and some notso- yummy) foods contain vitamin A and other nutrients your eyes need.

Antioxidants

Anti-oxidants help scavenge and “neutralize” free radicals (OH hydroxyl radicals). Free radicals are atoms or molecules that are missing a pair of electrons, making them unstable. Because of this instability, free radicals can damage healthy cells: cross linking of collagen can occur (leading to wrinkles) and oxidation can harm lipids and proteins essential for healthy skin.

Therefore, free radicals are a major cause of aging skin and anti-oxidants a major weapon against free radicals. Free radicals can also cause damaging cellular inflammation and anti-oxidants can diminish or eliminate this inflammation. All anti-oxidants have anti-inflammatory properties.

More and more people are talking about antioxidants these days, and their probable role in reducing the risks of all sorts of diseases. Eye disease is no exception: research suggests that certain antioxidants can reduce the risk of cataracts, macular degeneration and more.

Vitamin A and Carotenoids: Antioxidants for Sight. Is carotenoid a fancy word for carrot? Not quite, but they are related. Carotenoids give carrots their orange color. You can find them in many red, yellow and orange fruits and vegetables, as well as in green, leafy vegetables (which are a great source of the carotenoid lutein).

Vitamin C and Bioflavonoids: The Batman and Robin of Eye Health. Ever-popular vitamin C may reduce your risk of glaucoma, cataracts and macular degeneration. Bioflavonoids help your body to absorb vitamin C and sometimes work as antioxidants themselves.

Vitamin E and Minerals: Nutrition from Nuts. Like vitamins A and C, vitamin E may reduce your risk of cataracts and macular degeneration. The minerals selenium and zinc help your body to absorb antioxidant vitamins and may have their own protective effects as well.

Essential Fatty Acids (EFAs) EFAs: Fat You Can Use. You're getting too much fat in your diet ... and not enough: we consume way too much omega-6 fatty acid and not nearly enough omega-3. These fatty acids affect the eyes in a wide variety of ways.

Dictionary of Eye

Acanthamoeba
A free living protozoa in tap water, in the air and in the tear film. Can cause devastating corneal infection and blindness. Strong association with contact lens wearers who make their own saline, but due to changing technology and cleaning methods this is no longer a risk.

Accommodation
The ability to focus from one object to another at different distances.

Aphakia
Absence of the eye's internal lens due to surgical removal of a cataract, and where extremely high prescription spectacles were worn to compensate. Seldom seen now due to lens implants.

Astigmatism
An irregularity of the shape of the cornea. Unlike myopia and hyperopia where poor vision is due to lens function, Astigmatism causes poor vision for both near and distance. Best demonstrated by squeezing a half tennis ball.

Base curve
The flatter of the two curves on a lens.

Cataract
The opacification of the crystalline lens. The lens turns milky, most often with age. Result is like looking through a dirty window. Easily remedied with lens removal and implant of synthetic replacement. Most successful of all operations today, often performed under local anaesthetic.

Cone cells, or cones
These are cells in the retina of the eye which only function in relatively bright light. There are about 6 million in the human eye, concentrated at the fovea. They gradually become more sparse towards the outside of the retina. Cones are less sensitive to light than the rod cells in the retina (which support vision at low light levels), but allow the perception of color. They are also able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods.

Concave lens
A lens thinner at its center than at the edges, for correcting myopia or short-sightedness.

Conjunctavitus
A condition which usually affects both eyes, usually one at a time. Extremely contagious, and drops are usually prescribed to give comfort and prevent further bacterial infection. It is not dangerous but must be correctly diagnosed.

Convex lens
A lens which is thicker in the center than at the edge, used to correct hyperopia or farsightedness. Prescriptions are in + dioptres.

Convergence
The ability to move both eyes in at the same degree as the object moves closer.

Cornea
The transparent layer that forms the front wall of the eye, covering the iris.

Dark Adaptation
The time taken for the rods of the retina to become active.

Diabetes
Changes often occur in the retina, at the back of the eye where the blood vessels become fragile and leak. This is often detected by the optom before the GP, as due to sugar level variances the vision fluctuates. Untreated diabetes can result in blindness.

Dioptre
Unit used to measure the power of a lens in measures of .25.

Divergence
The ability to move both eyes out as object moves away.

Fundus
See retinal fundus.

GPC
Giant Papillary Conjunctivitis is pimple like bumps found under the upper lid, and often associated with dirty contact lenses. Disposable contact lens wearers who take their lenses out daily don't get this condition which is extremely difficult to treat.

Glaucoma
Fluid comes into the eye at one point and leaves at another. If the fluid is not moving out at the same rate that it is flowing in, pressure begins to build up. This will kill off the fibres of the optic nerve and cause irreparable loss of sight. Chronic glaucoma has no symptoms to indicate warning, therefore this is an essential part of the visual examination. There are four tests, the internal pressure test using the non-contact Tonometer, the visual fields (these two usually performed by one of our pre-testers) and the optometrist uses the opthalmoscope. The disease can be hereditary and it is important that family members are screened.

Hyperopia - "Farsightedness"

The ability to see far, however, requires intense focusing in order to see. The closer the object the greater the difficulty in focussing. These customers complain of headaches, teary eyes and poor concentration.

Intra-ocular pressure
The pressure of the viscous fluid inside the eye. The measurement is recorded in mm of mercury. Anything under 20mmHg is usually acceptable but one cannot rely only on the pressure for a diagnosis.

Kerataconus
The cornea bulges in the shape of a cone.

Lazy Eye
Correct term Amblyopia. The amblyopic eye is one which, even with the best optical correction, has reduced vision but no pathology.

Low vision
Abnormal vision despite the best visual correction.

Monovision
A form of contact lens fitting whereby one lens used is for distance vision and the other for near vision. It usually works extremely well. Indicated for over 40's who are current contact lens wearers who dislike the thought of spectacles. Multifocal contact lenses are now easily available and are more popular.

Myopia - "Short-sighted"
Can see up close but poor distance vision. A farsighted eye is too “short,” causing light to converge behind the retina and blurring near vision.

Macular Degeneration
Breakdown of the macular, the back wall of the eye, often through age, resulting in central blindness which spreads outward.

Opthalmologist
A specialist of eye surgery and pathology.

Opthalmoscope
Instrument with a light source used to detect abnormalities within the eye.

PDPupillary Distance
Measured from the inner of one pupil to the outer of the other.

Presbyopia
The inability to focus on close objects due to the ageing process. The crystalline lens loses its flexibility, and one has to hold reading material further away in order to focus. This results in the need for reading spectacles or contact lenses suitable prescribed.

Pinguecula
Soft yellow patches over the sclera (the white of the eye) at 3 and 9 o'clock.

Prism
A pyramid shaped glass through which light is bent and is always refracted toward the base.

Pterigium
Membranes extending over the visible section of the cornea, at the inner corner of the eye. Causes light and dust sensitivity. Easily removable when pterigium starts extending over the iris.

Ptosis
Droopy eyelid.

Radial Keratometry
An operation initially performed with a scalpel and now utilises the Excima Laser. Fine cuts are made in the cornea to collapse it to reduce myopia. Only certain prescriptions are acceptable for this procedure.

Refract
To bend light. As glass is a denser medium than air, the path of light passing through it is altered. The optometrist changes the focus point with spectacles, in order to cause the light to fall correctly on the retina in a point of focus.

Refraction
The method used to determine what prescription is required for the best sight of the eye.

Retinal Detachment
This is a real optometric emergency, where visual disturbances like flashing lights and a "curtain" coming down over the eye is noticed. Callers with these symptoms should be seen immediately. This will then be referred to an opthalmologist for treatment.

Retinal fundus
The interior lining of the eyeball, including the retina (the light sensitive screen), optic disc (the head of the nerve to the eye), and the macula (the small spot in the retina where vision is keenest). The fundus is the portion of the inner eye that can be seen during an eye examination by looking through the pupil.

"Fundus" is the Latin word for the bottom. In medicine, fundus refers to the bottom or base of an organ.

Retinitus Pigmentosa
Untreatable inherited disease of the eye, which begins with night blindness and progresses through tunnel vision to blindness.

Retinoscope
Instrument with a light source (like a torch) used to objectively determine the prescription of the eye.

Rod cells, or rods
These are photoreceptor cells in the retina of the eye that can function in less intense light than can the other type of photoreceptor, cone cells. Since they are more light-sensitive, rods are responsible for night vision. Named for their cylindrical shape, rods are concentrated at the outer edges of the retina and are used in peripheral vision. There are about 100 million rod cells in the human retina.

Slit lamp
Magnifies the eye, enables the optom to view the layers of the cornea, lens, a contract lens fit and general observation of the eye. Also known as a biomicroscope.

Strabismus
The eyes do not align in the same direction - a squint.

Stye
A common bacterial infection of a little canal within the lid. Does not respond well to antibiotics. The best treatment is to hold hot compresses against it. The bump is a collection of fluid in a little sac inside the lid.

Ultra Violet
Light travels in wavelengths measured in nanometers. The short wavelengths below 400 nm are called Ultra Violet. UVA causes ageing through a breakdown of the tissue and UVB causes burning. Sunglasses must provide 100% protection from UV rays.

Vertex distance
The distance between the back surface of the spectacle lens and the front of the cornea. This becomes relevant with prescriptions of 4 dioptres and over. Contract lens and spectacle lens prescriptions start to differ, and all measurement pertaining to the processing of spectacles must be exact for Rx's of 4 dioptres and over.

Vision Examination

Don’t be surprised if at your next visit, we photograph of the back of your eye. These pictures are necessary to document the health of the optic nerve, vitreous, macula, retina and its blood vessels. The photographs are used for comparison, documentation, and sometimes to diagnose certain eye conditions and also help with the detection of hypertension (high blood pressure) and cholesterol, among other things. It is the only way we can see what is happening in the body without surgery – the eye is far more than the window to the soul!

Fundus photography is a process using special optical imaging equipment e.g., cameras to photograph structures of the eye. Fundus photography allows for interpretation and report to document a disease process or follow the progress of a disease. Photographs may also be necessary to plan treatment for a disease process.

Because fundus photography is a highly specialized form of medical imaging, it can’t be done with an ordinary camera. It requires a customized camera that is mounted to a microscope with intricate lenses and mirrors. These high-powered lenses are designed so the photographer can visualize the back of the eye by focusing light through the cornea, pupil and lens.

Fundus is the bottom or base of anything. In medicine, it is a general term for the inner lining of a hollow organ.

Have you ever taken a fundus photograph? If you have taken photographs of your family or friends using a flash attachment on your camera and noticed that they have "red eyes", then you have! Photographic red eye is nothing more than a reflection of light off of the fundus of the eye. When performing ophthalmic fundus photography for diagnostic purposes, a special camera called a fundus camera is used to focus on the fundus. The resulting images can be spectacular, showing the optic nerve through which visual "signals" are transmitted to the brain and the retinal vessels which supply nutrition and oxygen to the tissue set against the red-orange color of the pigment epithelium.

Color images like the one above provide documentation of the ocular fundus. The retina is the "film" of the eye. Images passing through the clear structures of the cornea and lens are focused there to give us our view of the world. The fundus camera can document the condition of this miraculous anatomical structure. Retinal abnormalities are among the first complications to develop in persons with glucose intolerance, and retinopathy is an extremely sensitive indicator of diabetes.

UV light

The photochromic or variable tint lenses of old were a fantastic innovation, and as with all things, improved technology and specific needs and requirements have resulted in Transitions® Lenses, which act like a sun block for the eyes and also new Acuvue ® Oasys contact lenses that block up to 99% of Ultra Violet rays.

As people spend more time outdoors and the diminishing ozone layer filters out less of the ultraviolet radiation, the incidence of skin cancer, human immune system disorders, cataracts as well as other eye diseases has increased. Most important is the damaging effect that long-term UV exposure has on our eyes. This has caused individuals to be more concerned with protecting their eyes from ultraviolet light.

Why is UV protection important?
Many people routinely take precautions to protect their skin against UV rays. But most people are unaware of the need to protect their eyes against UV damage. Research indicates that long-term, unprotected exposure to the sun’s UVA and UVB rays can lead to age-related macular degeneration, cataracts and other eye conditions that can compromise the quality of your vision. Most eyecare professionals now recommend that people protect their eyes against UV exposure at all times. Transitions Lenses help provide convenient protection by blocking 100% of harmful UV rays.

It is essential to protect our eyes from the harmful effects of Ultra Violet light, which causes ageing, burning and cancer. 50% of UV light can be blocked by simply wearing a broad rimmed hat. The balance requires a lens that blocks 100% of UV rays up to 380 nanometers of UV light. This might be in the form of your spectacles or with a pair of prescription or non-prescription sunglasses.

Transitions® Lenses are the ideal choice for your everyday lenses. They are clear indoors and go to sunglass-dark outdoors. They provide convenient protection from UV radiation and glare, helping you to achieve healthy sight. Transitions Lenses are the #1 recommended photochromic lenses in the world.

Transitions Lenses change from clear to dark in the presence of ultraviolet light, and block 100% of harmful UV rays. Our innovative photochromic technologies have produced unparalleled lens performance in nearly every lens design and material, including shatterresistant lenses, bifocals, trifocals, progressives, and standard and high index materials.

When you choose Transitions Lenses, you choose visual quality, visual comfort and convenient protection with these performance features:

  • Virtually as clear as regular clear lenses indoors
  • Even clearer with an anti-reflective coating
  • As dark as most sunglasses outside in bright light
  • Fast to activate
  • Fast to fade back
  • Block 100% of harmful UV rays
  • Reduce the effects of glare
  • Reduce eye fatigue
  • Improve contrast
  • Offer the right tint at the right time in changing light

The smartest choice for everyday lenses
It’s never too early to start caring for your children’s eyes. Children are excellent candidates for Transitions Lenses. It is estimated that 80% of total lifetime exposure to UV rays occurs before age 18. Children are more susceptible to UV radiation because their eyes continue to develop into the teen years. Children also require safe, shatter-resistant lens materials.

Transitions Lenses are the perfect solution available in sturdy, lightweight, shatter-proof materials. Transitions Lenses provide the convenience of automatic protection by blocking 100% of harmful UV rays. They also offer increased comfort by reducing eye strain and fatigue. Transitions Lenses help you instill a lifetime of healthy eye habits by promoting good eye health in children.

Don't forget your baby's eyes. When outdoors ensure your little one is wearing a broad rimmed hat, which can reduce UV exposure by up to 50%, to help shield their sensitive eyes from the sun and reflected glare. Children should also wear a hat or junior sunglasses when outdoors. (Buy sunglasses from a reputable dealer)

Patients with Special Needs
Certain people develop a heightened sensitivity to light, known as photosensitivity, and are more susceptible to visible light. Photosensitivity can develop with conditions, such as diabetes or recent eye surgery. The condition can also be caused by taking certain prescription medications. Some medications, even those used to treat conditions not related to vision, can cause the eyes to be more susceptible to damage from UV rays.
During product testing, eyecare professionals were asked if Transitions Lenses seemed a good choice for people with specific visual needs. After wearing the lenses for two weeks, the number of professionals who answered “yes” increased by more than 10 times. Patients with special needs are excellent candidates for Transitions Lenses.

Active Adults
Protection from glare and UV rays is important for the comfort and quality of your vision today. It’s also important for long-term care of your eyes. It’s never too late to help protect against the cumulative effects of UV rays, which can lead to eye conditions that compromise the quality of your vision. Source: *Guideline Research, Inc., NY, NY, product testing among eyecare professionals, June 2004.

While it’s important to protect your eyes from too much visible light, it’s also important to protect them from light you don’t see ? ultraviolet radiation. Research shows that long-term unprotected exposure to the sun’s UVA and UVB rays can lead to age-related macular degeneration, cataracts and other eye conditions that can compromise your vision health.

Most people understand the need to protect their skin from UV rays, but most are not yet aware of the need to protect their eyes. Unfortunately, the effects of UV rays are cumulative. Research also shows that by age 18, most people have accumulated 80% of their total lifetime exposure to the sun. What’s more, children’s eyes continue to develop as they grow, and are more susceptible to UV radiation during their first 18 years. By addressing eye health while your children are young, you can instill a lifetime of healthy habits. After all, the lenses you choose for them today can help determine how well they’ll see in the future.

Transitions® Lenses meet high quality standards.
Transitions block 100% of harmful UVA and UVB rays for automatic protection. In fact, Transitions Lenses were the first to earn the American Optometric Association (AOA) Seal of Acceptance for UV Absorbers and Blockers. Additionally, Transitions Lenses meet internationally recognized standards for UV blockage, including ANSI Z80.3, ISO 8980-3, EN 1836 and AS/NZS 1067.

It’s no wonder that people who have tried them like them or that Transitions Lenses are the #1-recommended photochromic lenses in the world.
Light is essential to vision. But too much or too little light diminishes visual quality. Simply put, too much light causes glare. It can happen day or night in a number of ways, such as moving from shade into bright sunlight or when light reflects from shiny surfaces. The results of glare are squinting, eye strain, eye fatigue and, in extreme cases, temporary blindness. Glare impairs visual comfort and visual quality.

Transitions® Lenses reduce glare.
Transitions Lenses with an anti-reflective (AR) coating are the optimal everyday choice for reducing glare.* You can improve the overall quality of your vision by reducing glare with transitions. We can help ensure that the quality of your vision will be at its best at all times, all day, every day.

Transitions Lenses reduce glare and provide these important benefits:

  • Help prevent the loss of visibility
  • Improve visual quality and visual comfort
  • Provide a comfortable level of light
  • Reduce squinting and eye fatigue

SOME ANSWERS TO FREQUENTLY ASKED QUESTIONS

How do Transitions® Lenses work?

Transitions Lenses contain special photochromic dyes that cause the lens to activate, or darken, when exposed to ultraviolet rays from sunlight. When the UV light diminishes, the lenses fade back. As light conditions change, the level of tint adjusts, offering the right tint at the right time. It’s important to note that the UV blockage remains constant. Transitions Lenses provide automatic protection from UV rays in both the clear and darkened states.

Are Transitions Lenses a good alternative to clear lenses?

Yes. Transitions Lenses are as clear as clear lenses indoors, and as dark as sunglasses outdoors in bright sunlight. As light conditions change, the lenses adjust quickly to provide the appropriate level of tint. They block 100% of UVA and UVB rays, providing convenient protection. Transitions Lenses are compatible with all frame styles, and available in all types of lens materials and designs, from high index to shatter-resistant materials, from single vision lenses to progressives.

How fast do Transitions Lenses work?

Transitions Lenses begin to darken the moment they are exposed to UV light. The greater the intensity of UV rays, the darker the lenses become. The moment UV rays are no longer present the lenses begin to fade back. In short, Transitions Lenses quickly darken when you go outdoors, and fade back fast when you return indoors. Most wearers report that the adjustment happens so smoothly, they are unaware of it. They are aware, however, of their continued visual comfort.

How well do Transitions Lenses protect against UV rays?

Unlike most clear lenses, Transitions Lenses block 100% of both UVA and UVB rays. In fact, Transitions Lenses are the first to earn the American Optometric Association (AOA) Seal of Acceptance for UV Absorbers/Blockers. Additionally, Transitions Lenses meet internationally recognized standards for UV blockage, including ANSI Z80.3, ISO 8980-3, EN 1836 and AS/NZS 1067.

Can I use Transitions Lenses like sunglasses?

In most outdoor conditions, Transitions Lenses are perfect for reducing the sun's glare. They actually lighten and darken as the sun goes in and out of the clouds. However, since extremely high temperatures tend to affect lens performance, Transitions Lenses may not always get as dark as sunglasses. Ask us for advice.

Are Transitions Lenses suitable for driving?

Windshields in today’s vehicles block most of the UV rays that cause Transitions Lenses to activate, or darken. As a result, when worn inside a car where less UV light is present, the ability of the lenses to darken is reduced. Ask us if you need a pair of polarized prescription sunglasses for driving.

Are Transitions Lenses available in different lens designs?

Yes. Transitions Lenses are available in a wide range of lens designs including singlevision, bifocals, trifocals and progressives. They are also available in shatter-resistant, and both standard and high index lens materials. Regardless of your prescription or lens preference, you may choose either gray or brown Transitions Lenses.

Are Transitions Lenses appropriate to wear while working at a computer?

Yes. They can be worn any place that you would wear regular, clear lenses all day, every day. Transitions Lenses help you see more comfortably inside and out, day and night.

How do Transitions Lenses reduce glare?

Transitions Lenses react quickly to changing light and become as dark as sunglasses outside in bright sunlight. As light conditions change, the level of tint adjusts to provide the right tint at the right time. This convenient protection is automatic.

Can Transitions Lenses enhance my quality of vision?

Yes. Transitions Lenses enhance the ability to discern objects of varying size, brightness and contrast, enabling you to see better in all light conditions.

OLYMPIC GAMES SILVER MEDALISTS BELBIN & AGOSTO SEE GOLD WITH ACUVUE® OASYS?!

Prior to competing in the 2006 Winter Olympic Games, both skaters were fitted with the new ACUVUE® OASYS? contact lens, a breakthrough for lens wearers when their eyes feel tired and dry in challenging environments such as dry, cold ice skating rinks.

SAY GOODBYE TO DRY!

Today's environments can create tired, dry eyes. With ACUVUE ® OASYS? IN, Dry is OUT. Whether you’re inside or outside, challenging environments can make your eyes feel tired and dry. Even long hours in front of a computer can leave your eyes craving moisture.

Find relief with ACUVUE® OASYS? with HYDRACLEAR? PLUS Brand Contact Lenses.

  • Feels almost like you’re wearing no lens at all
  • Helps soothe the discomfort from eyes feeling tired and dry
  • Reduces the need for rewetting drops
  • Contains HYDRACLEAR? PLUS ? the next generation of proprietary technology that creates a more wettable, ultra smooth contact lens
  • Visibility tint so your lenses are easy to see and handle
  • Highest UVA and UVB Blocking to help protect against harmful UV rays, blocking 96% of UV-A rays and 99% of UV-B rays
  • Inside - Out Mark so you’ll insert your lenses correctly every time

WHO SHOULD WEAR ACUVUE® OASYS?

  • People who experience contact lens dryness in dry challenging environments
  • People whose eyes get tired from long days at work
  • People who like to wear their lenses comfortably all day
  • People who spend extended periods of time in front of a computer

ULTRA VIOLET LIGHT PROTECTION

Consumer research has shown that UV protection is an important lens attribute for patients. In fact, 3 of want UV protection from their contact lenses, and 1 of 2 say they would switch brands for UV protection.

Since 1997, ACUVUE® Brand Contact Lenses have led the way in UV blocking. All ACUVUE approved to help provide protection against transmission of harmful UV radiation to the cornea and into ACUVUE® ADVANCE? Brand Contact Lenses block approximately 90% of UV-A radiation and 99% of ACUVUE® Brand Contact Lenses block approximately 82% of UV-A radiation and 97% of UV

WARNING: UV-absorbing contact lenses are NOT substitutes for protective UV-absorbing eyewear such as sunglasses, because they do not completely cover the eye and surrounding area. You should continue to use directed.

NOTE: Long-term exposure to UV radiation is one of the risk factors associated with cataracts. Exposure is such as environmental conditions (altitude, geography, cloud cover) and personal factors (extent and nature Blocking contact lenses help provide protection against harmful UV radiation. However, clinical studies have that wearing UV-Blocking contact lenses reduces the risk of developing cataracts or other eye disorders.

Baş Dönmesi Neden Olur?

VERTİGO NEDİR?

Bazı insanlar denge problemlerini baş dönmesi olarak nitelendirirler. Çevrenin dönmediği bu denge bozukluğu bazen iç kulağa bağlı bir problemden dolayı ortaya çıkar. Bazı insanlar ise denge sağlamaktaki zorluklarını vertigo kelimesiyle açıklarlar. Bu kelime Latince "dönmek" fiilinden gelmektedir. Bu hastalar sıklıkla kendilerinin veya çevrenin döndüğünü söylerler. Vertigo çoğunlukla iç kulak probleminden kaynaklanır.

HAREKET HASTALIĞI VE DENİZ TUTMASI NEDİR?

Bazı insanlar uçağa bindiklerinde veya arabada bulantı hissederler, hatta bazen kusarlar. Bu duruma taşıt tutması denilir. Bir çok insan bu rahatsızlığı gemiye bindiği zaman çeker bu yüzden aynı olay olmasına rağmen buna deniz tutması denir. Deniz tutması sadece ufak bir rahatsızlıktır. Bunun dışında herhangi bir tıbbi bozukluğun ifadesi değildir. Ancak bazen yolcular bu rahatsızlıktan dolayı çok kısıtlanabilirler. Çok az bir kısmında da bu rahatsızlık yolculuk bitse dahi birkaç gün daha sürmektedir.

DENGE SİSTEMİNİN ANATOMİSİ

Baş dönmesi (Dizzines, vertigo) ve taşıt tutması denge sistemi ile ilgilidir. Uzay araştırmacıları bu duyguya uzaysal oriantasyon demektedirler. Denge sistemi iç kulaktadır ve beyine vücudun uzay içinde nerede olduğunu, pozisyonunun yönü, hangi yönde hareket ettiği ve dönüyor mu yoksa sakin durumda mı olduğunu bildirir. Denge duygunuz sinir sisteminin aşağıda belirtilen bölümleri arasındaki kompleks ilişkilerle sağlanmaktadır.

  1. İç kulak (aynı zamanda labirent adını da almaktadır.) hareketin yönünü yani dönüp dönmediğini, ileri veya geri, bir yandan diğer yana ve yukarı veya aşağıya doğru olduğunu belirler.
  2. Gözler vücudun uzay içindeki yerini (baş aşağı vs.) ve hareketin yönünü belirler.
  3. Eklemlerde ve omurgada bulunan basınç reseptörleri vücudun hangi parçasının aşağıda olduğunu ve neresinin yere değdiğini belirler.
  4. Kaslardaki ve eklemlerdeki algılama reseptörleri vücudun hangi parçasının hareket ettiğini belirler.
  5. Merkezi sinir sistemi (beyin ve omurilik) daha önceki dört sistemden gelen uyarıları işler ve sonuçta koordinasyonu sağlanmış bir algılama ortaya çıkar.

Taşıt tutmasının bulguları ve baş dönmesi, merkezi sinir sistemine diğer dört sistemden birbirine zıt mesajlar geldiğinde ortaya çıkmaktadır. Örnek olarak fırtınalı bir günde uçağa bindiğinizi düşünün ve uçağınız hava akımlarından dolayı sallanmaktadır. Fakat gözleriniz bu hareketi algılamamaktadır. Çünkü bütün gördüğünüz uçağın içidir. Bunun sonucunda beyniniz birbiriyle uyuşmayan mesajlar almaktadır. Sizi bundan dolayı uçak tutabilir. Veya bir arabanın arka koltuğunda oturmuş kitap okuduğunuzu düşünün. İç kulağınız ve deri reseptörleriniz yolculuğun hareketini algılayacaktır. Ancak gözleriniz sadece kitabı görecektir. Bu nedenle sizi taşıt tutabilir. Gerçek bir tıbbi örnek vermek gerekirse bir darbeden dolayı yalnızca bir taraftaki iç kulağınızın hasarlandığını düşünün. Hasarlı iç kulak normal iç kulakla aynı mesajları göndermez. Bu beyine dönme eylemiyle ilgili yanlış bilgi verir. Kişi vertigodan veya dönüyormuş hissinden şikayetçi olabilir. Bazen bulantı da görülür.

HANGİ TIBBİ RAHATSIZLIKLAR BAŞ DÖNMESİNE NEDEN OLUR?

  1. Dolaşım: Dolaşım bozuklukları baş dönmesinin en sık nedenleri arasındadır. Eğer beyniniz yeterince kan almazsa başınız dönmeye başlar. Hemen hemen herkes yatarken aniden ayağa kalktığında birkaç defa hissetmiştir, ancak bazı insanlar sık veya kronik nedenlerden ötürü baş dönmesi şikayetlerinde bulunurlar. Bu arterioskleroz (damar sertliği) dan dolayı olur. Bu rahatsızlık çoğunlukla yüksek tansiyon hastalarında, şeker hastalarında ve kan yağları yüksek olanlarda görülür. Bazen de kalp fonksiyonları yetersiz olanlarda veya kansızlık şikayeti olanlarda rastlanır. Bazı ilaçlar özellikle nikotin ve kafein beyne giden kan akımını azaltır. Dietteki çok miktarda tuz da kan akımının azalmasına neden olur. Bazen dolaşımında strese, sinirlenmeye veya gerginliğe bağlı olarak bazı bozukluklar olabilir. Eğer iç, kulak yeterince kan alamazsa daha özel bir baş dönmesi durumu olan vertigo ortaya çıkar. İç kulak kan dolaşımındaki değişikliklere çok hassastır. Bu yüzden beyin için bahsedilen zayıf kan dolaşımı durumlarının hepsi iç kulak için de geçerlidir.
  2. Yaralanma: Kafatasında meydana gelen, iç kulağı da zedeleyen bir kırık sonrasında aşırı,kısıtlayıcı bir vertigoyla birlikte bulantı ve işitme kaybı gelişir. Baş dönmesi birkaç hafta sürer. Bu süre içinde normal taraf yavaş yavaş karşı tarafın fonksiyonlarını üstlenir.
  3. Enfeksiyon: Virüslerden örneğin soğuk algınlığına neden olanlar iç kulağı ve onun beyinle olan sinir bağlantılarını etkileyebilirler. Bu kötü bir vertigoya neden olurken işitme genellikle etkilenmez. Buna rağmen bakteriler sonucunda oluşan enfeksiyonlarda hem denge hemde işitme fonksiyonlarının bozulmasına neden olur. Baş dönmesinin şiddeti ve iyileşme zamanı kırıklarda olduğu gibidir.
  4. Allerji: Bazı insanlar allerjik oldukları besinlerle veya havadaki parçacıklarla karşılaştıklarında baş dönmesi veya vertigo ile karşılaşabilirler.
  5. Nörolojik hastalıklar: Multipl Skleroz, sifiliz, tümör gibi sinir sistemini etkileyen hastalıklar dengenin bozulmasına neden olur. Bunlar nadir nedenler olmasına rağmen doktorunuz muayene sırasında bunları da düşünecektir.

ARAÇ TUTMASINA KARŞI NE YAPABİLİRİM?

  1. Her zaman vücudunuzun hareketinin iç kulağınız ve gözleriniz tarafından aynı şekilde algılanabileceği bir yerde oturun. Örnek olarak arabanın ön tarafında oturup uzak manzaralara bakabilirsiniz veya geminin güvertesi ne çıkıp ufku izleyebilirsiniz yada uçakta cam kenarında oturup dışarıyı seyredebilirsiniz. Uçak yolculukların da hareketin en az olduğu kanat üstüne denk gelen koltukları tercih edin.
  2. Eğer araba sizi tutuyorsa kitap okumayın yada zıt yöndeki koltuklara oturmayın.
  3. Araç tutması olan bir başka yolcuyla konuşmayın veya onu izlemeyin.
  4. Yolculuktan hemen önce yada yolculuk sırasında keskin kokulardan, baharatlı ve yağlı yiyeceklerden uzak durun. Araştırmalar halk arasında yaygın olarak kullanılan formüllerin etkinliğini bilimsel olarak kanıtlayamamıştır.
  5. Doktorunuz tarafından tavsiye edilen ilaçlardan birini yolculuğunuzdan önce alın. Bu ilaçlardan bazıları reçetesiz olarak da satın alınabilir. Sakinleştirici veya sinir sistemini etkileyen ilaçlar için doktorunuzun reçetesi gerekir. Bazıları hap veya fitil şeklindedir bazıları ise (scopolamine) kulak arkasına yapıştırılabilen bantlar şeklindedir.

Şunu hatırlayın: Baş dönmesi ve araç tutması olaylarının büyük çoğunluğu hafiftir ve kişi bunu kendi kendine tedavi edebilir. Ancak ağır veya giderek daha da ağırlaşan vakalar Kulak Burun Boğaz, denge ve sinir sistemi konusunda uzman bir doktor tarafından takip edilmelidir.

DOKTOR BAŞ DÖNMESİ İÇİN NE YAPAR?

Doktorunuz baş dönmesini tarif etmenizi isteyecektir. Bunun bir göz kararması mı yoksa bir hareket hissi mi olduğunu, ne kadar sürdüğünü, işitme kaybı veya bulantı ve kusma olup olmadığını soracaktır. Hangi durumların baş dönmesi oluşturduğu da sorulabilir. Genel durumunuz, ilaç alıp almadığınız, kafa travması, son zamanlarda geçirilmiş bir enfeksiyon, ve kulağınızla, sinir sisteminizle ilgili birçok soruya cevap vermek durumunda olabilirsiniz. Doktorunuz kulağınızı, burnunuzu ve boğazınızı muayene ettikten sonra sinir sistemiyle ilgili bazı testler yapacaktır. İç kulak hem işitme hem de dengeyle ilgili olduğu için dengedeki bir bozukluk işitmeyi de etkileyecek veya bunun tersi olacaktır. Bu nedenle doktorunuz işitme testi (odiogram) isteyebilir. Bazı durumlarda kafatasınızın röntgenini, tomografisini veya manyetik rezonans ile görüntülenmesini veya iç kulağınızı uyarmak için kullanılan sıcak veya soğuk sudan sonra göz hareketlerinizi izleyecek bir test (elektronistagmografi - ENG) isteyebilir. Bazı durumlarda da kalbinizin değerlendirilmesini veya bazı kan testlerini önerebilir. Her hasta için her test gerekmemektedir. Doktorunuzun kararı hangi testlerin gerekli olduğunu belirleyecektir. Benzer olarak önerilen tedavi de konulan teşhis ile ilişkili olacaktır.

BAŞ DÖNMESİNİ AZALTMAK İÇİN NE YAPABİLİRİM?

  1. Ani pozisyon değişikliklerinden kaçının. Örnek olarak yatar durumdan aniden ayağa kalkmayın veya bir taraftan diğerine ani olarak dönmeyin.
  2. Aşırı kafa hareketlerinden (özellikle yukarı bakmak) veya hızlı baş hareketlerinden kaçının.
  3. Dolaşımı bozacak (nikotin, kafein ve tuz) ürünlerinin kullanımını azaltın.
  4. Baş dönmenize neden olan stresden, sinirlilikden uzak durun ve allerjiniz olan maddelere maruz kalmamaya çalışın.
  5. Baş dönmeniz olduğunda araba kullanmak tehlikeli alet kullanmak veya merdiven tırmanmak gibi zarar verebilecek aktivitelerden uzak durun.