Tag Archives: Ophthalmology

Truths about protecting our eyes

 

Fact: Eye exercises will not improve or preserve vision or reduce the need for glasses. Your vision depends on many factors, including the shape of your eyeball and the health of the eye tissues, neither of which can be significantly altered with eye exercises.
As the eyes age, problems with vision become more common. Learn how to recognize the risk factors and symptoms of specific eye diseases cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy — and what steps one can take to prevent or treat them before your vision deteriorates.

Myth: Reading in dim light will worsen our vision.

Fact: Dim lighting will not damage our eyesight. However, it will tire our eyes out more quickly. The best way to position a reading light is to have it shine directly onto the page, not over the shoulder. A desk lamp with an opaque shade pointing directly at the reading material is ideal.

Myth: Carrots are the best food for the eyes.

Fact: Carrots, which contain vitamin A, are indeed good for the eyes. But fresh fruits and dark green leafy vegetables, which contain more antioxidant vitamins such as C and E, are even better. Antioxidants may even help protect the eyes against cataracts and age-related macular degeneration. Just don’t expect them to prevent or correct basic vision problems such as nearsightedness or farsightedness.

Myth: It’s best not to wear glasses or contact lenses all the time. Taking a break from them allows our eyes to rest.

Fact: If we need glasses or contacts for distance vision or reading, we should use them. Not wearing glasses will strain our eyes and tire them out instead of resting them. However, it will not worsen our vision or lead to eye disease.

Myth: Staring at a computer screen all day is bad for the eyes.

Fact: Using a computer does not damage our eyes. However, staring at a computer screen all day can contribute to eyestrain or tired eyes. People who stare at a computer screen for long periods tend not to blink as often as usual, which can cause the eyes to feel dry and uncomfortable. To help prevent eyestrain, we should adjust the lighting so it doesn’t create a glare or harsh reflection on the screen, it is advised to rest the eyes briefly every 20 minutes, and make a conscious effort to blink regularly so that our eyes stay well lubricated.

It can be a frightening moment. When the doctor diagnoses an eye disease such as glaucoma, cataract, or AMD, we immediately worry about losing our sight or becoming seriously vision-impaired.

It’s important to know what to do not only when disease strikes, but what to do before and after. We should know the warning signs and how a diagnosis is made. And the best treatment options for that.

The good news is, with the proper treatment decisions, those eye diseases can be addressed and controlled and their potential to compromise our sight can be halted.

Our eyes do change as we get older. That’s a truth we can do little about. It’s the consequences we can change.
We we should learn all the facts about treating adult eye diseases.

Resources:
Harvard Health Publication
Harvard Medical School

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Ways to Improve Your Eyesight

Yahoo Health has collected some tips you can use to sharpen your vision. Here are some of them:
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1. Eat Right
Vitamins A, C, E, and minerals like copper and zinc are essential to eyesight. Antioxidants protect your macula from sun damage, and foods rich in sulfur, cysteine, and lecithin help protect the lens of your eye from cataract formation. The omega-3 fat DHA provides structural support to cell membranes that boost eye health.

2. Limit Environmental Toxins
External factors that contribute to eye damage include fluorescent lights, computer screens, environmental allergens, and chlorine in swimming pools.

3. Sleep
Getting enough sleep is essential for eye health. Sleep time allows your eyes to fully rest, repair, and recover.

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Source: Yahoo Health May 20,2011

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Astigmatism

Definition:
Astigmatism is a common, mild and generally easily treatable imperfection in the curvature of your eye. The condition can cause blurred vision.

Astigmatism occurs when the front part of the eye, the cornea, is not a regular symmetrical spherical shape. Instead, its shape is rather like that of the back of a spoon – longer in one direction than another. Because the cornea is an irregular shape, the eye can’t focus light passing through it sharply on to the back of the eye or retina. So vision is blurred at all distances.
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Astigmatism is often present at birth and may occur in combination with nearsightedness or farsightedness. Often it’s not pronounced enough to require corrective action. When it is, your treatment options include corrective lenses and surgery.

Many people have some degree of astigmatism. In fact, it is rare to find a perfectly formed eye. Astigmatism appears to run in families and is often present from birth. If you have astigmatism, chances are good your children will have it also. It may worsen slowly over time but may remain fairly stable throughout life. Astigmatism often occurs with other vision conditions such as nearsightedness (myopia) and farsightedness (hyperopia.)

Symptoms:
Signs and symptoms of astigmatism may include:

*Blurred or distorted vision
*Headaches
*Eye strain
*Fatigue
*Blurred vision at certain distances

The most common symptom of astigmatism is blurred vision. Some people describe it as double vision but in only one eye. As a result of trying to focus on near or distant objects, a patient may develop eyestrain, squinting and headaches. Note the diagram at right – a person WITHOUT astigmatism would see all the radial lines as perfectly sharp and with the same contrast. The diagram  below illustrates how some lines might appear clearer than others to a person with astigmatism.

Children with astigmatism may be too young to notice or describe astigmatism. They may frown, squint, or pull objects close in an effort to get a clearer picture. They may also tilt or turn their head. This extra effort can lead to eyestrain, fatigue or reduced reading efficiency.

Causes:
As the eye develops in the womb, several factors determine the shape of it, including inherited genetic factors and environment. It would seem that these factors can lead to an irregular curvature of the cornea, although the exact cause isn’t known.

Your eye has two parts that focus images — the cornea and the lens. In a perfectly shaped eye, each of these focusing elements has a perfectly smooth curvature, like the surface of a smooth ball. A cornea or lens with such a surface curvature bends (refracts) all incoming light the same way and makes a sharply focused image on the back of your eye (retina).

However, if your cornea or lens isn’t evenly and smoothly curved, the light rays aren’t refracted properly. This causes a refractive error. Astigmatism is one type of refractive error. In astigmatism, your cornea or lens is curved more steeply in one direction than in another. When the cornea has a distorted shape, you have corneal astigmatism. When the lens is distorted, you have lenticular astigmatism. Either type of astigmatism can cause blurred vision. Blurred vision may occur more in one direction — either horizontally, vertically or diagonally.

Astigmatism may occur in combination with other refractive errors, which include:

*Nearsightedness (myopia).
This occurs when your cornea is curved too much or your eye is longer than normal. Instead of being focused precisely on your retina, light is focused in front of your retina, resulting in a blurry appearance for distant objects.
*Farsightedness (hyperopia). This occurs when your cornea is curved too little or your eye is shorter than normal. The effect is the opposite of nearsightedness. When your eye is in a relaxed state, light is focused behind the back of your eye, making nearby objects blurry.

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Astigmatism may be present from birth, or it may develop after an eye injury, disease or surgery. Astigmatism isn’t caused or made worse by reading in poor light, sitting too close to the television or squinting.

Test & Diagnosis :

The Simple Astigmatism test :
1.If you have contacts or glasses, wear them.
2.Sit about 14 inches away from your computer screen.
3.Cover one eye.
4.Note how the lines and squares appear (for example, wavy or blurred).
5.Test the other eye in the same manner.

To a normal eye, the lines will appear sharply focused and equally dark. If some sets of lines appear sharply focused and dark while others are blurred and less dark, you may have astigmatism. Regardless of your result, see your eye doctor on a regular basis for a complete eye exam.

To diagnose astigmatism, your eye doctor may:

*Measure reflected light. By measuring light reflected from the surface of your cornea, a device known as a keratometer quantifies the amount and orientation of corneal astigmatism.
*Measure the curvature of your cornea. Using light to project rings on to your cornea, a device called a keratoscope measures the amount of curvature to your cornea’s surface and can confirm the presence of astigmatism. Observation through the keratoscope of the reflection of light from your cornea and inspection of the shape and spacing of the rings provide information about the degree of astigmatism.

To measure the change in corneal surface curvature, a process called corneal topography is used. Corneal topography uses a videokeratoscope, which is a keratoscope fitted with a video camera.

Treatment:
The goal of treating astigmatism is to address the uneven curvature that’s causing your blurred vision. Treatments include wearing corrective lenses and undergoing refractive surgery.

Corrective lenses
:
Wearing corrective lenses treats astigmatism by counteracting the uneven curvature of your cornea. Types of corrective lenses are:

*Eyeglasses. Eyeglasses can be made with special lenses that help compensate for the uneven shape of your eye. In addition to correcting astigmatism, eyeglasses can also correct for other refractive errors, such as nearsightedness or farsightedness.

*Contact lenses
. Like eyeglasses, contact lenses can correct astigmatism. A wide variety of contact lenses are available — hard, soft, extended wear, disposable, rigid gas permeable and bifocal. Ask your eye doctor about the pros and cons of each and which contact lenses might be best for you.

Contact lenses are also used in a procedure called orthokeratology, or Ortho-K. In orthokeratology, you wear rigid contact lenses for several hours a day until the curvature of your eye improves. Then, you wear the lenses less frequently to maintain the new shape. If you discontinue this treatment, your eyes return to their former shape. Wearing contact lenses for extended periods of time increases the risk of infection in the eye.

Refractive surgery;
This astigmatism treatment method corrects the problem by reshaping the surface of your eye. Refractive surgery methods include:

*LASIK surgery.
Laser-assisted in-situ keratomileusis (LASIK) is a procedure in which a doctor uses an instrument called a keratome to make a thin, circular hinged cut into your cornea. Alternatively, this same cut can be made with a special cutting laser. The surgeon lifts the flap and then uses an excimer laser to sculpt the shape of the cornea under the flap. An excimer laser differs from other lasers in that it doesn’t produce heat.

*Photorefractive keratectomy (PRK).
In PRK, your surgeon removes the outer protective layer of the cornea before using an excimer laser to change the curvature of the cornea.

*Laser-assisted subepithelial keratomileusis (LASEK).
In this procedure, a much thinner layer of cornea is folded back, which makes your eye less vulnerable to damage should an injury occur. LASEK may be a better option if you have a thin cornea or if you’re at high risk of an eye injury at work or from playing sports.

Radial keratotomy is a procedure that was used in the past to correct astigmatism. However, it’s not commonly performed anymore.

Conclusion:
If you experience a distortion or blurring of images at all distances — nearby as well as far — you may have astigmatism. Even if your vision is fairly sharp, headache, fatigue, squinting and eye discomfort or irritation may indicate a slight degree of astigmatism. A thorough eye examination, including tests of near vision, distant vision and vision clarity, can determine if astigmatism is present. Your eye doctor can answer any questions you may have about the various methods for correcting astigmatism and other vision problems.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
Resources:
http://www.bbc.co.uk/health/physical_health/conditions/astigmatism2.shtml
http://www.dcareaeyecare.com/astigmatism_article.html
http://www.mayoclinic.com/health/astigmatism/DS00230
http://www.lasersurgeryforeyes.com/astigmatism.html#Symptoms
http://www.webmd.com/eye-health/understanding-astigmatism-basics
http://www.jnjvision.com/thinking-whocanwear-test.htm

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Strabismus

Alternative Names: Crossed eyes; Esotropia; Exotropia; Squint; Walleye.

One eye moves normally, while the other points in (esotropia or “crossed eyes”), out (exotropia), up (hypertropia) or down (hypotropia).

Strabismus is often incorrectly referred to as “lazy eye” (which in fact refers to the associated condition amblyopia). It is also referred to as “squint”, “crossed eye”, “codeye” and “wall eye”.

“Cross-eyed” means that when a person with strabismus looks at an object, one eye fixates the object and the other fixates with a convergence angle less than zero, that is the optic axes overconverge. “Wall-eyed” means that when a person with strabismus looks at an object, one eye fixates the object and the other fixates with a convergence angle greater than zero, that is the optic axes diverge from parallel.

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Definition:-Strabismus  is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles that prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely affect depth perception. Strabismus can be either a disorder of the brain coordinating the eyes or a disorder of one or more muscles, as in any process that causes a dysfunction of the usual direction and power of the muscle or muscles. Difficult strabismus problems are usually co-managed between orthoptists and ophthalmologists.

It is a disorder in which the eyes do not line up in the same direction when focusing. The condition is more commonly known as “crossed eyes.”

Causes:-
Strabismus is caused by a lack of coordination between the eyes. As a result, the eyes look in different directions and do not focus at the same time on a single point.

In most cases of strabismus in children, the cause is unknown. In more than half of these cases, the problem is present at or shortly after birth (congenital strabismus).

In children, when the two eyes fail to focus on the same image, the brain may learn to ignore the input from one eye. If this is allowed to continue, the eye that the brain ignores will never see well. This loss of vision is called amblyopia, and it is frequently associated with strabismus.

Some other disorders associated with strabismus in children include:

*Apert syndrome
*Cerebral palsy
*Congenital rubella
*Hemangioma near the eye during infancy
*Incontinentia pigmenti syndrome
*Noonan syndrome
*Prader-Willi syndrome
*Retinopathy of prematurity
*Retinoblastoma
*Traumatic brain injury
*Trisomy 18 (a child has 3 copies of chromosome 18, instead of the normal 2 copies)

Strabismus that develops in adults can be caused by:

*Botulism
*Diabetes (causes a condition known as acquired paralytic strabismus)
*Guillain-Barre syndrome
*Injuries to the eye
*Shellfish poisoning
*Stroke
*Traumatic brain injury
*Vision loss from any eye disease or injury

A family history of strabismus is a risk factor. Farsightedness may be a contributing factor. In addition, any other disease causing vision loss may cause strabismus.

Diagnosis:-
During eye examinations, orthoptists, ophthalmologists and optometrists typically use a cover test to aid in the diagnosis of strabismus. If the eye being tested is the strabismic eye, then it will fixate on the object after the “straight” eye is covered, as long as the vision in this eye is good enough. If the “straight” eye is being tested, there will be no change in fixation, as it is already fixated. Depending on the direction that the strabismic eye deviates, the direction of deviation may be assessed. Exotropic is outwards (away from the midline) and esotropic is inwards (towards the nose).

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A simple screening test for strabismus is the Hirschberg test. A flashlight is shone in the patient’s eye. When the patient is looking at the light, a reflection can be seen on the front surface of the pupil. If the eyes are properly aligned with one another, then the reflection will be in the same spot of each eye. Therefore, if the reflection is not in the same place in each eye, then the eyes aren’t properly aligned.
Differential diagnosis: pseudostrabismus
Pseudostrabismus is the false appearance of strabismus. It generally occurs in infants and toddlers whose bridge of the nose is wide and flat, causing the appearance of strabismus. With age, the bridge of the child’s nose narrows and the folds in the corner of the eyes go away. To detect the difference between pseudostrabismus and strabismus, a Hirschberg test may be used.

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Exams and Tests:
A physical examination will include a detailed examination of the eyes. Tests will be done to determine the strength of the eye muscles.

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Eye tests include:

*Retinal exam
*Standard ophthalmic exam
*Visual acuity
*A neurological examination will also be performed.
Laterality
Strabismus may be classified as unilateral if the same eye consistently ‘wanders’, or alternating if either of the eyes can be seen to ‘wander’. Alternation of the strabismus may occur spontaneously, with or without subjective awareness of the alternation. Alternation may also be seen following the cover test, with the previously ‘wandering’ eye remaining straight while the previously straight eye is now seen to be ‘wandering’ on removal of the cover. The cover-uncover test is used to diagnose the type of strabismus (also known as tropia) present.

Onset
Strabismus may also be classified based on time of onset, either congenital, acquired or secondary to another pathological process, such as cataract. Many infants are born with their eyes slightly misaligned. The best time for physicians to assess this is between ages 3 and 6 months.

Pathophysiology:-
Strabismus can be an indication that a cranial nerve has a lesion. Particularly Cranial Nerve III (Occulomotor), Cranial Nerve IV (Trochlear) or Cranial Nerve VI (Abducens). A strabismus caused by a lesion in either of these nerves results in the lack of innervation to eye muscles and results in a change of eye position. A strabismus may be a sign of increased intracranial pressure, as CN III is particularly vulnerable to damage from brain swelling.

More commonly however, squints are termed concominant (i.e. non paralytic). This means the squint is not caused by a lesion reducing innervation. The squint in this example, is caused by a refractive error in one or both eyes. This refractive error causes poor vision in one eye and so stops the brain from being able to use both eyes together.
Treatment and management:-Treatment involves strategies to strengthen the weakened muscles and realign the eyes. Glasses and eye muscle exercises may be prescribed.

If the condition is caused by a lazy eye, the doctor may prescribe an eye patch. Some children may need surgery. For more information on treating lazy eye, see: Amblyopia

As with other binocular vision disorders, the primary therapeutic goal for those with strabismus is comfortable, single, clear, normal binocular vision at all distances and directions of gaze.

Whereas amblyopia, if minor and detected early, can often be corrected with use of an eyepatch on the dominant eye and/or vision therapy, the use of eyepatches is unlikely to change the angle of strabismus. Advanced strabismus is usually treated with a combination of eyeglasses or prisms, vision therapy, and surgery, depending on the underlying reason for the misalignment. Surgery does not change the vision; it attempts to align the eyes by shortening, lengthening, or changing the position of one or more of the extraocular eye muscles and is frequently the only way to achieve cosmetic improvement. Glasses affect the position by changing the person’s reaction to focusing. Prisms change the way light, and therefore images, strike the eye, simulating a change in the eye position.

Early treatment of strabismus and/or amblyopia in infancy can reduce the chance of developing amblyopia and depth perception problems. Most children eventually recover from amblyopia by around age 10, if they have had the benefit of patches and corrective glasses.

Eyes that remain misaligned can still develop visual problems. Although not a cure for strabismus, prism lenses can also be used to provide some comfort for sufferers and to prevent double vision from occurring.

In adults with previously normal alignment, the onset of strabismus usually results in double vision (diplopia).

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Prognosis:-With early diagnosis and treatment, the problem can usually be corrected. Delayed treatment may lead to permanent vision loss in one eye.

When strabismus is congenital or develops in infancy, it can cause amblyopia, in which the brain ignores input from the deviated eye. Strabismus can lead to a permanent weakening of vision in the strabismic eye called amblyopia (this may not always happen), sometimes referred to as lazy eye. The appearance of strabismus may also be a cosmetic problem. One study reported that 85% of adult strabismus patients “reported that they had problems with work, school and sports because of their strabismus.” The same study also reported that 70% said strabismus “had a negative effect on their self-image.”

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.nlm.nih.gov/medlineplus/ency/article/001004.htm
http://en.wikipedia.org/wiki/Strabismus

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Laser Cures Retinopathy in Infants

Popular as designer treatment for correcting eye disorders, Laser rays now promise a cure for infants suffering from retinopathy — a  non-inflammatory damage to the retina of the eye.
…………Retionopathy of Prematurity
“Over the years, it has been found that Retinopathy of Prematurity (ROP) has been found in children with birth weight of about 1,500 grams and born within 32 weeks of pregnancy,” Rajvardhan Azad, chief of ROP unit in the AIIMS Opthalmology department, said.

With the help of Laser rays, doctors can now remove or clear the eye of unnecessary blood vessels that may lead to retinal detachment.

“Laser rays treatment is advised to get rid of spectacles and contact lenses. But now it is a saviour for children who stand the chance of turning blind after birth,” Azad claimed.

For more information you may click :->Retinopathy of Prematurity

Source: The Times Of India

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