Contact Lens For Dry Eyes

Dry eye is a common disorder, caused by the insufficiency of tears in the eyes, or by unwarranted tear disappearance. Dry eyes are associated with a number of causes, such as drug use, inflammation, allergic reactions, and contact lens use. Dry eyes often cause contact lens bigotry. People normally suffering from mild dry eyes may not feel any discomfort until they wear contact lenses, and the discomfort increases with the hours spent in front of the computer. Some doctors recommend switching to Rigid Gas Permeable (RGP) contact lenses for dry eye syndrome. RGP contact lenses are made from polymeric materials and do not contain any water. This is unlike soft lenses, and so water will not evaporate from their surface.

One most important benefit of RGP contact lenses is that they do not lump oxygen flow to your corneas, as they are gas permeable. This is strong for your eyes as lack of oxygen can cause serious eye problems, including inflammation of the cornea. An additional plus point is that as they contain no moisture, they do not dry out. Consequently, they may be perfect for those working in conditions, where there is a chance of dry eye syndrome.

You can also find more info on Bifocal Soft Contact Lens and Buy Contact Lenses Online. Onlinecontactlenseshelp.com is a comprehensive resource to know more about online contact lenses.

Dry Eyes

One way, it has been found, is to reduce the water content of the lens. Some people have responded well to the new hydro gel contact lenses. Contemporary silicon hydro gel lenses are only about 30% water - which is much less than the 50% to 60% of traditional lenses, and the 70% of soft contact lenses. In addition, the new polymers used in the contact lenses maintain the lens soggy.

Most high water content lenses dehydrate rapidly and rely on the eyes tear film to replenish the lost water. For someone that already has dry eyes, this creates a very uncomfortable contact lens environment. Contact lens related dry eye can be very noticeable at the end of the day or during extended computer use.

Soft lenses have a high water content which makes them satisfied primarily and they retain that high water content in most environments. For a person wearing soft contact lens, this means it does not rely on absorbing as many tears as other lenses to maintain a moist state. Whether at the computer, the theatre, or the beach, soft contact lenses for dry eyes stay comfortable.

Eye Surgery Tips

Each eye surgery procedure and each eye surgery patient is unique. Despite the uniqueness of each procedure, there are a number of universal tips that can help you better prepare for your surgery and speed up your recovery time.

So here are 13 tips to help make your eye surgery procedure a successful one.

1) Take the extra time you need to find a reputable surgeon with extensive experience in your type of surgery.

- Finding the right doctor is the critical first step in the surgery process, and this it not a step you want to take lightly. Your eye surgery will only be successful if it is performed by a qualified medical professional. Selecting a doctor based on cost alone is rarely a good move since surgeons offering cheaper solutions usually do so because they are inexperienced in performing that type of surgery. Keep in mind that should complications arise, that having someone who knows how to quickly and effectively deal with the issue will prevent or minimize any damage done to your eye.

You'll also want to find out what kind of track record your doctor has, and how many procedures they have performed.
2) Thoroughly research the procedure you will be undergoing before signing any consent forms.

- This includes taking the time to ask your surgeon any questions you may have about the procedure. A good doctor will take the time to answer all of your questions as well as inform you of any potential risks and side-effects of the surgery. Take advantage of this and be sure you are fully comfortable with the procedure before you agree to undergo the surgery.

3) Follow all of the pre-operative procedures recommended by your doctor.

- Your doctor may advise you to avoid certain medications, foods, or activities (such as smoking and drinking alcohol) before undergoing eye surgery. These restrictions are put in place to ensure your eyes are in good condition for the procedure, giving you the best possible chance of having a successful surgery and a quick recovery. If you don't follow these restrictions you may put your health and the success of your surgery at risk.

4) Stop wearing contact lenses in advance of the surgery, as directed by your doctor.

- Since contact lens rest directly on your eye, they exert pressure on the cornea and can actually change the shape of your eye. This is an important consideration for individuals undergoing eye surgery, especially patients of refractive eye surgery to correct their vision. In order for the procedure to be successful, it is necessary to pinpoint those regions of the eye that need to be treated. If your eye is not in its normal natural shape or state, any attempts to correct visual impairments will not be successful. For this reason, surgeons will request that many eye surgery patients stop wearing contact lenses anywhere from two to four weeks prior to the procedure.

5) Get a good night’s sleep the night before the surgery.

- A well-rested patient is less likely to be unduly anxious and will recover more quickly than someone who is stressed and suffering from lack of sleep. Remember – adequate sleep is necessary to stay healthy, and this is especially true before surgery.

6) Make arrangements to have someone you trust drive you home from the surgery.

- Your vision will be blurry and you may be under the effects of a sedative after undergoing your eye surgery. Regardless of the type and extent of the procedure, patients are in no condition to drive immediately after eye surgery. Ensure your safety and well-being by arranging for a ride home in advance. If you aren't able to have a family member of friend drive you home, then take a taxi cab.

7) Know what side-effects you may experience before undergoing the procedure.

- Inquire about potential side-effects and make sure you know what to expect during the recovery period before you go in for the procedure. On your surgery day, you will likely be distracted and anxious and will not retain much information. It’s important to know what to look out for after your surgery so you can catch any potential problems before they can cause damage.

8) Call your doctor immediately if you experience any unusual side-effects.

- If you experience anything unusual or are concerned about how you are recovering from your procedure, contact your doctor immediately. Refer to the potential side-effects of the procedure as discussed above, and use these as your guidelines for what is normal and to be expected. If in doubt, err on the side of caution and call your doctor – it’s always better to be safe than sorry.

9) Take all medication as prescribed.

- The medication prescribed by your surgeon is designed to speed the healing process and protect your eye from adverse side effects. Therefore, it is imperative that you take all medication as prescribed.

10) Avoid touching, rubbing, or bumping your eye while it is healing.

- Any direct contact with your eye while it is healing can result in damage to the eye and may result in severe complications. Wearing an eye shield as needed, especially while you are sleeping, can help you avoid contact with your eye.

11) Avoid makeup, lotions, and creams while your eye is healing.

- These items can interfere with the eye’s natural healing ability and prolong your recovery period.

12) Stay away from medications that can interfere with your body’s natural healing process, such as steroids.

- Some medications can prevent your eye from properly healing and delay the recovery process. Be sure to talk to your doctor about any medications you're on prior to surgery.

And last, but not least...

13) Give yourself time to recover from the surgery before jumping back into your busy life.

- Keep in mind that you are recovering from an invasive procedure. It will take some time before you start feeling like your normal self. Taking it easy for a few days will enable your body to rest and heal faster than it will if you subject it to unnecessary stress.

Eye Treatment

There could be light at the end of the tunnel for those suffering from eye ailments and awaiting eye transplants due to damaged corneas. Chennai-based microbiologist H N Madhavan of Sankara Netralaya, along with Japanese polymer scientist Prof Muri from the Vasada University of Tokyo, has devised a method to treat corneal damage that regenerates destroyed cells without the need for transplants. With tests on rabbits completed successfully, the duo is now waiting to carry out similar trials on human subjects.

Speaking from Chennai, Madhavan told DNA, We have applied to the India Council for Medical Research for permission to conduct the experiment on humans. We proved that rabbits could accept the treatment and hope that humans would also be able to benefit from it.

Advances in Laser

The advances in lasers, coupled with the creation of new and safer refractive surgical techniques in the past 10 years, have more people going to ophthalmologists than ever before to have their vision improved.

With all the hoopla attached to corrective laser eye surgery, one may ask: what does corrective eye laser surgery mean? What are these surgical techniques? How does it improve one’s quality of life?

Corrective laser eye surgery essentially means, laser eye surgical techniques that will correct your vision.

You’ve probably heard these four most popular corrective laser eye surgery techniques mentioned.

Laser-Assisted In Situ Keratomileusis (LASIK) recommended for nearsightedness, farsightedness and astigmatism eye conditions.

Laser Epithelial Keratomileusis (LASEK) is similar to LASIK; except the flap is created in the epithelium.

Photorefractive Keratectomy (PRK) for persons who have nearsightedness, mild to moderate farsightedness and astigmatism. The surgeon uses the laser to remove tiny tissue on the surface of the cornea.

CK or Conductive Keratoplasty uses a probe that’s as thin as a strand of human hair, utilizing radiofrequency (RF) energy. The probe reshapes the cornea by shrink small areas of the tissue.

How do these corrective laser eye surgery procedures improve ones’ quality of life? In a survey conducted by The Eye Surgery Education Council (ESEC), the public education arm of the American Society of Cataract and Refractive Surgery (ASCRS) the following respondents agreed on these facts.

• Ability to see upon waking

• Freedom from glasses and contacts

• Improvement in personal safety

• Increased confidence in personal appearance

• Better participation in sports or fitness activities

This information was collected from approximately 3 million Americans who have undergone the corrective laser eye surgery since 1995.

The most noteworthy finding that emerged from this surgery was the fact that a significant number felt that after undergoing corrective laser eye surgery they began a new lease on life.

Corrective Eye Surgery

Corrective eye surgery can open your eyes to a colorful bright new world free from glasses and contact lenses

Or perhaps you would like to go on holiday without the hassles of carrying glasses, sunglasses, contact lenses and solutions.

To date over twelve million people worldwide have turned to ground breaking corrective eye surgery as a genuine alternative.

Whether you are short or long sighted or have astigmatism, glasses and contact lenses could now be a thing of the past thanks to revolutionary corrective eye surgery techniques.

Lasik is by far the most popular method of corrective eye surgery, which is routinely carried out throughout the world.

Lasik is an abbreviation for: Laser-Assisted-In-Situ-Keratomileusis. It is a procedure where the outer surface of your eye (the Cornea) is delicately reshaped using a laser to improve how your eye focuses, Therefore miraculously improving your vision.

Lasik corrective eye surgery is normally performed without the need for a general anesthetic, as eye drops will prevent any pain during treatment.

The life changing corrective eye surgery procedure normally proceeds as follows:
1.Your surgeon delicately created a thin layer of Corneal tissue on the front of the eye.
2.They then lift this layer (the Corneal flap) to expose the middle section of the Cornea.
3.The laser treatment is then applied to remove the necessary amount of Corneal tissue.
4.The Corneal flap is gently eased back into place.

This amazing treatment is usually carried out on both eyes at the same visit, and you will normally be in the treatment room for as little as twenty minutes.

After your life changing corrective eye surgery has been completed you may experience some mild discomfort and your vision will be hazy or blurry, but this will improve hour by hour throughout the rest of the day and is well worth it as by the following day most patients experience an eighty to one hundered percent improvement in their vision.

For the first four to eight weeks following your corrective eye surgery you may experience some fluctuation in your vision. For a while your vision may be dimmer in the evenings and you could experience some sensitivity to light. These and any other discomforts will, however, subside with each day leaving you with a much clearer view of the world.

The first thing you need to do before taking this fantastic opportunity is to find a trusted surgeon in your area. Whether you are in the U.S.A, Canada, Mexico or the UK and Europe there is a Lasik Center or Surgeon near you.

Eye Surgery

If your eyes are the window to your soul then doesn't it make sense to maintain their appearance and keep them looking like the grand entrance way they should be. Eye surgery techniques have improved immensely during the last few years with more and more people taking the opportunity to improve both their vision and appearance.

Lasik eye surgery has been a godsend for people wanting improved vision. In Lasik eye surgery, the precise and controlled removal of corneal tissue; reshaping of the cornea and giving it renewed focusing power, has literally turned eye surgery "on it's head." Where once glasses or contact lenses compensated for the eye's imperfections, now people are turning to Lasik eye surgery. Patients with conditions such as myopia, astigmatism, hyperopia or combinations of the aforementioned, have become aware of the success rate of Lasik eye surgery and are going "under the laser."

Laser Eye Surgery Procedures

Lasik is not the only laser eye surgery available to people. Non-laser refractive procedures are also available. This involves inserting artificial lenses into the eye; the resultant low heat radio waves reshape the eye.

The average cost of Lasik eye surgery has steadily risen in the last few years mainly due to the popularity of the procedure. The cost however, has not deterred people from going under the surgeon's laser.

Cataract eye surgery is another procedure with an extremely high success rate; estimates have it at about 99%. Cataracts can only be removed through surgery. No medications or eye drops will make cataracts disappear.

Cosmetic Eye Surgery - Maintaining A Youthful Appearance

It's not just vision improvement people are after. Let's face it, age catches up with all of us but in the 21st. century, eye lift plastic surgery techniques have become so advanced that ending up on the surgeon's table is no longer a tough decision for patients.

Baby boomers, responsible for a myriad of trends during the last 50 years, are wanting to stay looking young and cosmetic eye surgery, eye lift plastic surgery, eye lift surgery...call it what you like; these forms of appearance enhancing procedures are now an attractive option for people despite the costs and risks involved.

The eyesurgeryplace.com will keep you informed and updated with the latest news, views and reviews in the world of eye surgery.

Dry Eye

Dry Eye refers to a condition that results due to inadequate or ineffective wetting and lubrication of the eye. It primarily occurs due to reduction in quality or quantity of the tears and tear film. With increase in the use of computers, this condition is becoming more prevalent and is known by the name of Computer Vision Syndrome.

What are the symptoms of Dry Eye?
Dry eye commonly presents as the following problems:

• Burning sensation in the eyes
• Grittiness & foreign body like feeling in the eye
• Irritation in the form of itching & stinging
• Redness of the eye
• Sensitivity to light
• Decreased tolerance to contact lenses
• Blurred vision that improves on blinking
• Excess watering of the eye
• Mucus discharge from the eye
• Increased eye discomfort on reading, watching TV, sewing, working on a computer etc.

Are there any known causes for Dry Eye?
Causes for dry eye can be broadly categorised as follows:

• Natural Aging Process as we grow older, there is areduction in the production of natural tears and their effectiveness.
• Environmental Conditions such as hot, dry or windy climate, air pollution, air conditioning, dusty or smoky atmosphere, over heated rooms etc.
• Occupational - working on computers for long periods of time, results in less blinking thus leading to eye strain and dry eye.
• Systemic Diseases - such as Sjogren's Syndrome, Rheumatoid Arthritis, Systemic Sclerosis, Thyroid conditions, Steven Johnson Syndrome.
• Hormonal Changes - like during menopause.
• Medication Side Effects - diuretics, antihistamines, anti depressants, antimuscarinics are known to cause dry eye.
• Vitamin A Deficiency
• Prolonged Contact Lens use
• Radiation Therapy of the head and neck
• Refractive Eye Surgery such as LASIK and PRK
• Eye Trauma
  
• Frequent Air Travel
• Infections and certain eye diseases such as Blepharitis.
• Personal Habits such as smoking, reduced blinking thus leading to excess tear evaporation etc.

Child Poor Vision

How to know if my child has poor vision?
Normally a child should be able to recognize mother and have a social smile by 6-8 weeks of age. If the child has poor vision in both the eyes, then he/she may not recognize the mother or may not respond to the visual stimuli. Once the child starts walking, he/she may frequently bump into objects.

If the child has poor vision in only one eye then it may be difficult to notice it. The eye with poor vision may not be aligned properly with the other eye, thus causing squint (strabismus). The child may also have rhythmic jiggling movements of the eyes (nystagmus).

Sometimes the cause of poor vision may be visible as a whiteness of the cornea or whiteness behind the pupil. In some cases the eyes of child with glaucoma may be watering and very sensitive to light.

The poor vision may also be noticed incidentally when the child is being examined by a doctor or during vision screening in the school.

What are the causes of poor vision in a child?
These causes are:

• Refractive error
• Cataract
• Glaucoma
• Squint (strabismus)
• Injury to the eye (sometimes the child may not tell about the injury to parents)
• Diseases of cornea
• Diseases of retina and optic nerve
• Inherited disorders
• Tumor (Retinoblastoma)
• Other eye abnormalities

What to do if I suspect that my child does not see properly?
As we see, there can be many causes for poor vision in a child. Some of these are very simple and treated easily, while others may be very difficult to manage and sometimes may even be life threatening. Therefore it is prudent to contact an ophthalmologist at the earliest if you suspect poor vision in your child. He or she will confirm poor vision and then look for the cause of the same. A timely treatment is very crucial in saving the sight and sometimes the life of the child.

How can one determine the vision in a small child who will not cooperate for vision testing?
There are many special tests available which help the doctor in determining the visual acuity of children in all age groups. The ophthalmologist will decide which tests to use and will get an idea of the visual loss and the chances of getting good vision after treatment.

Why is it important to detect poor vision in child?
If the poor vision in child is not treated early enough, the eye may not develop properly and develop a condition called amblyopia (lazy eye). Therefore, if the eye is treated at a later stage, the eye may not get good vision. It is very important to treat the cause of poor vision, e.g., refractive error, cataract, glaucoma, diseases of cornea etc. as early as possible to prevent amblyopia.

Early detection is also very important in case of tumor (retinoblastoma), which if detected early, may be treated easily without having to remove the eye. If it is not detected, then it may even lead to loss of life.

I have a child with poor vision. Can my other children also have some eye problem?
The chances of other children getting affected depend upon the cause of poor vision. Many of these conditions may be hereditary and may require examination of other siblings of the child. Also in hereditary diseases, a genetic counseling may be done to the parents if they plan to have another baby in future.

Eye & Diabetes

How can diabetes affect eye?
Diabetes can affect the eyes and vision in a number of ways. It may lead to frequent fluctuations in vision, cataract in young age, decreased vision due to involvement of optic nerve, temporary paralysis of the muscles controlling the movement of eyes and thus double vision. The most significant complication of diabetes in eye is diabetic retinopathy and its complications.

What is diabetic retinopathy?
Retina is the layer at the back of the eye that is sensitive to light. Diabetes affects the small vessels of the retina in the eye. There are various stages of diabetic retinopathy:

Non-proliferative or background diabetic retinopathy: When blood vessels in the retina are damaged, they can leak fluid or bleed. This causes the retina to swell and form deposits called exudates. This is an early form of diabetic retinopathy and may not lead to any decrease in vision, but it can lead to other more serious forms of retinopathy that affect the vision.

Macular edema: The fluid and exudates collects in the macula (the part of the retina that allows us to see fine details), thus decreasing the vision. Sometimes there may be a macular edema without any loss of vision. Therefore it is important to have periodic checkup to detect and treat these conditions at an early stage.

Proliferative diabetic retinopathy: This is an advanced stage of diabetic retinopathy, where the blood supply of retina is compromised. In response to this, new fragile blood vessels grow on the surface of the retina (neovascularization). These new vessels are very fragile and bleed easily. These may lead to serious vision problems if they bleed into the vitreous (the clear, jelly-like substance that fills the center of the eye) which is known as vitreous hemorrhage. This prevents the light from reaching the retina and thus can blur the vision.

The new blood vessels and the bleed into the vitreous can also cause scar tissue to develop, which can pull the retina away from the back of the eye. This is known as retinal detachment, and can lead to blindness if untreated.

In addition, abnormal blood vessels can grow on the iris (the colored part in the front of your eye, which can lead to glaucoma).

What are the risk factors for diabetic retinopathy?
The longer the person has diabetes, the greater are his/her chances to develop diabetic retinopathy. Almost 80% of people, who have diabetes for 15 years or more, have some damage to the blood vessels in their retina. The other risk factors are high blood pressure, anemia, kidney diseases, and pregnancy.

Can something be done to prevent diabetic retinopathy?
There is no treatment that can prevent diabetic retinopathy altogether. Persons with any form of diabetes may develop diabetic retinopathy. But it has been proven that a good control of diabetes can delay and slow down the rate of progress of diabetic retinopathy and its complications. Besides a good control of blood sugar, one must exercise regularly, keep the blood pressure under control, avoid smoking, and avoid obesity.

How do I know if I have diabetic retinopathy?
You might not know that you are having diabetic retinopathy, as there are no symptoms in the earlier stages of the disease. Therefore it is essential to have periodic evaluation of your eye by an ophthalmologist to detect the condition early. Early diagnosis and timely treatment is very essential in preventing the complications of this disease and thus maintaining vision.

How frequently should I get my eye examined?
If you have diabetes, you should get a yearly examination with your ophthalmologist. Your pupils may be dilated with eyedrops, so that your ophthalmologist may have a good look at the back of your eye. Once you develop diabetic retinopathy, then your ophthalmologist will advise you if you need some investigations, treatment or just need to follow up. In these cases the frequency of follow up visits is decided on basis of the severity of the disease.

What are the tests done for diabetic retinopathy?
Your vision is assessed by the usual charts. The back of your eye is examined after dilating your pupils, using an instrument called ophthalmoscope. Sometimes your ophthalmologist may advise a special test called Fluorescein angiography.

What is fluorescein angiography?

It is test in which a series of photographs of the retina are taken with the help of a special camera. These photographs are taken after giving the patient an injection of a yellow dye. This dye reaches the retina through the blood stream and helps in seeing the blood vessels of retina more clearly. This test helps the doctor to determine which areas to be treated with laser.

Cataract

Cataract ('safed motia') is a clouding or opacity of the normally transparent lens inside the eye. To understand why this leads to loss of vision, it is important to understand the functioning of a normal eye.

Inside the eye, behind the colored part of the eye (iris) with the black hole in the center (pupil) is a lens. In the normal eye the lens is clear or transparent. It helps to focus light rays on to the tissue at the back of the eye (retina). When cataract develops the lens becomes cloudy and prevents the light rays passing into the retina. The picture that the retina receives becomes dull and fuzzy. Cataract usually forms and progresses slowly and therefore leads to a gradual blurring of vision.

What causes cataract?
Most forms of cataract develop in adult life. The normal process of aging causes the lens to harden and become cloudy (opaque). This is called age-related cataract and it is the most common type. It can occur anytime after the age of 40. In younger people they can result from an injury, certain drugs, long-standing inflammation or illnesses such as diabetes. Babies can be born with this condition. This is called congenital cataract.

What are the symptoms of cataract?

• Blurring of Vision - Cataract leads to a painless, progressive blurring or dimming of vision. The things may seem blurred around the edges, or your glass may seem dirty or scratched. The opacity affecting the central part of the lens may cause poor vision in bright light.
• Frequent change of glasses - Some forms of cataract lead to a change in refractive power of your lens and thus cause frequent changes in power of your glasses. Because of this, some patients may no longer need the reading glasses for near work, this phenomenon is known as 'second sight'.
• Glare - Cataract may also lead to sensitivity to light and glare, especially in bright sunlight or while driving at night.
• Double Images - The cloudiness in the lens may occur in more than one place, so that the light rays that reach the retina are split, causing a double image.
• Change in color vision - Cataract may also cause change in color vision. As the cataract develops its center becomes more and more yellow, giving everything you see a yellowish tinge.

What is the treatment? Can it be cured by medicines?
There are no medications, eye drops, exercises or glasses that will cause cataracts to disappear once they have formed. Surgery is the only way to remove a cataract. Cataracts cannot be removed with a laser, only through a surgical incision. In cataract surgery, the cloudy lens is removed from the eye. In most cases, the focusing power of the natural lens is restored by replacing it with a permanent intraocular lens implant.

When should I have the surgery?
Usually, you can decide if, and at what stage to have the operation. The cataract may need no treatment at all if the vision is only a little blurry. A change in your eyeglass prescription may improve vision for a while. If visual impairment interferes with your ability to read, to work, or to do the things you enjoy then you will probably want to consider surgery.

In the past, eye specialists often waited until the cataract became 'ripe' before suggesting you had it removed. Nowadays, with modern surgery the operation can be carried out at any stage of the cataract's development, and in fact, is a little safer to do before the cataract becomes 'ripe'.

What are the surgical options for cataract surgery, and which one is the best?
Today there are so many options in cataract surgery, e.g., routine extracapsular surgery with lens implant, phacoemulsification with a foldable or non-foldable lens implant, with or without stitches. The best procedure for a patient is usually the one with which his or her ophthalmologist feels the most comfortable, since these variations of cataract surgery are all quite effective. The patient should discuss the options with his or her ophthalmologist and the decision should be made on the basis of the requirements of the patient and expertise of the ophthalmologist. At Visitech, the surgeons routinely perform Phacoemulsification with foldable intra ocular lens implantation.

Eye as a Camera

The function of our eyes is to enable us to see clearly the objects in our surroundings at variable distances and under various conditions of lights. This function is achieved by a very complex arrangement of structures in the eye. Our eye can be thought of as a very advanced camera. There are many similarities between our eye and a camera. Like in a camera the aim is to provide a well-focused image of the object onto the film at the back of the camera. Similarly in the eye, the retina, which is situated towards the back of the eye, works as the photographic film. The image is formed there and then the signal is sent from there to our brain through the optic nerve, and thus we perceive the objects around us. In fact, the retina is much more advanced than a photographic film because it can automatically change its sensitivity depending upon the amount of illumination present.

The rays of light enters the eye and passes through cornea and lens, which converge them so that it gets focused at the retina and a sharp image is formed. This function is akin to that of the lens of a camera. Once again the eye is superior, because the lens of the eye has the property to automatically adjust its power depending upon the location of the object of interest. Therefore, whenever we see from distance to near object, the lens of eye increases its curvature and thus is able to focus the image clearly onto the retina. The aperture (pupil) in the colored part (iris) of the eye is also adjustable according to the illumination of the surroundings. This is akin to the aperture of the diaphragm in a camera.

In a normal eye, the rays of light coming from a distant object gets focused by the cornea and the lens of the eye onto the retina and form a sharp image. When looking at a near object, the lens of the eye becomes more convex (accommodation) and thus its converging power is increased. This helps in focusing the near object clearly on the retina.

Eye Parts

• Cornea -- the transparent front window of the eye. The cornea transmits and focuses light into the eye.
• Iris -- the colored part of the eye. The iris helps regulate the amount of light that enters the eye.
• Pupil -- the dark center in the middle of the iris. The pupil changes size in response to various degrees of illumination to control the amount of light that is let into the eye.
• Lens -- the transparent structure behind the iris that focuses light rays onto the retina.
• Retina -- the nerve layer that lines the back of the eye. The retina senses light and creates impulses that are sent through the optic nerve to the brain.
• Macula -- a small specialized area in the retina that contains special light sensitive cells. The macula allows us to see fine details clearly.
• Optic Nerve -- the nerve that connects the eye to the brain. It carries the impulses formed by the retina to the brain, where it is interpreted as images.
• Vitreous -- the clear, jelly-like substance that fills the middle of the eye.

Eye Movements

The stabilization of eye movement is accomplished by six extraocular muscles that attach to each eyeball and perform their horizontal and vertical movements and rotation. These muscles are controlled by impulses from the cranial nerves that tell the muscles to contract or to relax. When certain muscles contract and others relax, the eye moves.

The six muscles and their function are listed here:

• Lateral rectus–moves the eye outward, away from the nose
• Medial rectus–moves the eye inward, toward the nose
• Superior rectus–moves the eye upward and slightly outward
• Inferior rectus–moves the eye downward and slightly inward
• Superior oblique–moves the eye inward and downward
• Inferior oblique–moves the eye outward and upward

There are five different types of eye movements:

• Saccades–looking from object A to object B
• Pursuit–smoothly following a moving object
• Convergence/divergence–both eyes turning inward/outward simultaneously
• Vestibular–eyes sensing and adjusting to head movement via connections with nerves in the inner ear
• Fixation maintenance–minute eye movements during fixation

Anatomy & Physiology

The eye is a complex organ composed of many small parts, each vital to normal vision. The ability to see clearly depends on how well these parts work together.

Our Eyes

The ability to see is dependent on the actions of several structures in and around the eyeball. The graphic below lists many of the essential components of the eye's optical system.

When you look at an object, light rays are reflected from the object to the cornea, which is where the miracle begins. The light rays are bent, refracted and focused by the cornea, lens, and vitreous. The lens' job is to make sure the rays come to a sharp focus on the retina. The resulting image on the retina is upside-down. Here at the retina, the light rays are converted to electrical impulses which are then transmitted through the optic nerve, to the brain, where the image is translated and perceived in an upright position!

Think of the eye as a camera. A camera needs a lens and a film to produce an image. In the same way, the eyeball needs a lens (cornea, crystalline lens, vitreous) to refract, or focus the light and a film (retina) on which to focus the rays. If any one or more of these components is not functioning correctly, the result is a poor picture. The retina represents the film in our camera. It captures the image and sends it to the brain to be developed. The macula is the highly sensitive area of the retina. The macula is responsible for our critical focusing vision. It is the part of the retina most used. We use our macula to read or to stare intently at an object.