 |
|
|
| Our
eyes
|
|
|
|
Visualization is possible because of the brain's ability to understand
information our eyes receive when light is reflected off objects.
|
|
| The front surface of the eye is also known as cornea, which is a
dome-shaped clear structure that allows light to enter the eye. It covers the
iris - the coloured part of the eye, which has the pupil in its centre. The
pupil is actually an opening through which light enters and is passed to the
back of the eye. |
|
| In bright conditions, the muscles of the iris contract to reduce
the size of the pupil, which decreases the amount of light entering the eye. In
poor lighting, the iris muscles expand, making the pupil bigger, to allow more
light to enter the eye. |
|
| Behind the iris is the lens of the eye, which allows us to focus on
objects at different distances. The lens focuses light rays that reflect from
objects and places them as images on the retina, which can be compared to a
camera film for the eye. |
|
| Images received by the retina are transformed into electrical
signals. The retina then sends these signals along the optic nerve to the
brain. Once received by the brain, the signals recreate pictures. |
|
| Following
are few common eye diseases in human being: |
|
| 1.
Amblyopia |
|
| Amblyopia, commonly known as lazy eye, is the eye condition noted
by reduced vision not correctable by glasses or contact lenses and is not due
to any eye disease. The brain, for some reason, does not fully acknowledge the
images seen by the amblyopic eye. This always affects only one eye however may
manifest with reduction of vision in both eyes. It is estimated that three
percent of children under six have some form of amblyopia.
|
|
| Causes
of Amblyopia |
|
| Both eyes must receive clear images during the critical period.
Anything that interferes with clear vision in either eye during the critical
period (birth to 6 years of age) can result in amblyopia (a reduction in vision
not corrected by glasses or elimination of an eye turn). The most common causes
of amblyopia are constant strabismus (constant turn of one eye), anisometropia
(different vision/prescriptions in each eye), and obstacle of an eye due to
trauma, lid droop, etc. If one eye sees visibly and the other sees a blur, the
good eye and brain will ignore the eye with the blur. Thus, amblyopia is a
active process. The inhibition process can result in an everlasting decrease in
the vision in that eye that cannot be corrected with eyeglasses,
lenses
, or laser surgery. |
|
| Diagnosis
of Amblyopia |
|
Amblyopia usually occurs in one eye only; many parents and children
may be unaware of the condition. There are many parents who fail to take their
infants and kids for an early complete vision examination and many children go
undiagnosed until they have their eyes examined at the eye doctor's office at a
later age.
The most important diagnostic tools are the special visual acuity tests other
than the standard 20/20 letter charts currently used by schools, paediatricians
and eye doctors. Examination with cycloplegic drops can be necessary to detect
this condition in the young.
|
|
| The treatment of amblyopia may be followed by:
|
|
| Covering one eye might be required for a period of time ranging
from a few weeks to as long as a year. The better-seeing eye is covered,
forcing the "lazy" one to work, thereby strengthening its vision. |
|
| Medication in the form of eye drops or ointment might be used to
smear the vision of the good eye in order to force the weaker one to work. This
is generally a less successful approach. |
|
| Improvements are possible at any age, but early detection and
treatment offer the best outcome. Amblyopia can cause a permanent loss of
vision with related loss of stereopsis (two eyed depth perception) if not
detected and treated early in life. The 20/20 eye chart screening is not
sufficient, as better vision screenings are needed for young children. |
|
| Amblyopia
causes more visual loss in the under 40 group than all the injuries, and
diseases combined in this age group.
|
|
| 2.
Blepharitis |
|
Blepharitis refers to constant swelling of the eyelids. It
is one of the most common disorders of the eye and is often the basic reason
for eye discomfort, redness and tearing. Other eye symptoms of blepharitis
include: Burning, itching, light sensitivity, an irritating, dirty, gritty
sensation that is worse upon awakening. There are 3 forms of blepharitis staphylococcal,
seborrheic and MGD. All three forms of blepharitis are chronic in
nature. Patients with staphylococcal blepharitis are relatively young between
ages of 42 years with a small record of ocular symptoms (mean 1.8 years).
Seborrheic blepharitis and MGD blepharitis patients are generally older and
have a longer history of ocular symptoms.
In staphylococcal blepharitis there is scaling and crusting along the eyelashes
whereas in seborrheic blepharitis there is greasy scaling along the eyelashes.
Seborrheic dermatitis is very frequent in patients as well. In Meibomian gland
dysfunction (MGD) there are prominent blood vessels crossing the eyelid margin.
In addition there is disappointment of meibomian gland openings as patients are
noted to have coexisting rosacea and seborrheic dermatitis with MGD frequently.
Use of isotretinoin (Accutane), an oral medication for severe cystic acne, has
also been implicated as a cause of blepharitis.
|
|
| Blepharitis
Treatment |
|
| It is a chronic disease, which is tough to manage because it tends
to reoccur, and require long-term treatment to keep it under control. Treatment
consists of 2 phases known as acute phase and Maintenance phase. |
|
| Acute phase treatment involves intensive therapy to bring
the disease under control swiftly.
|
|
| In the maintenance phase the objective is to forever
continue the minimum amount of therapy that is necessary to keep the disease
quiet. Herein we will not focus on the treatment of specific steroid responsive
complications of blepharitis like marginal ulcers and phlyctenules, as they are
less common and require specific diagnosis. Treatment depends on the type of
blepharitis you have. It may consist of applying warm compresses to the
eyelids, cleaning them, using an antibiotic or massaging the lids. The doctor
may also prescribe artificial tears or lubricating ointment if your blepharitis
makes your eyes feel dry. |
|
| The warm compact segment of treatment is designed to loosen crusts
on your eyes before you rinse them; it can also warm up and loosen the plugs
blocking the meibomian glands in meibomianitis. Wash your hands, then wet a
clean washcloth with warm water and place it over your closed eyes. The doctor
will probably suggest that you do the above procedure four times a day, for
about five minutes each time when you first begin treatment. Later on, you
might apply the compress once a day, for a few minutes. Your doctor will tell
you the specific treatment needed for your eyes. |
|
| Cleaning the eyelids is important in blepharitis treatment. Your
doctor will recommend what to clean them with: warm water only, salt water,
baby shampoo diluted with warm water or a special product exclusively made for
cleaning the lids. First wash your hands, and then dip a clean washcloth,
cotton swab or gauze pad into your cleaning solution. Gently wipe it across
your lashes and lid margin. Rinse with cool water. Use a different washcloth,
swab or pad for your other eye, and repeat the process. When you first begin
treatment, your doctor may ask you to clean your lids numerous times a day.
Later on doctor can instruct you to clean them about once a day. |
|
| 3.
Cataract |
|
| It is a condition in which the lens of the eye becomes thick or
opaque and does not properly transmit light. A cataract is a clouding of the
normally clear lens of the eye.
|
|
| Common
symptoms of cataract include:
|
|
 |
A painless blurring of vision;
|
|
|
|
|
Glare, or light sensitivity; |
|
|
|
|
Poor night vision;
|
|
|
|
|
Double vision in one eye; |
|
|
|
|
Needing brighter light to read; |
|
|
|
|
Fading or yellowing of colors. |
|
|
| The amount and pattern of cloudiness within the lens can vary. If
the cloudiness is not near the center of the lens, you may not be aware that a
cataract is present.
|
|
| What
causes cataract? |
|
|
|
Family history;
|
|
|
|
|
Medical problems, such as diabetes; |
|
|
|
|
Injury to the eye;
|
|
|
|
|
Medications, especially steroids; |
|
|
|
|
Long-term, unprotected exposure to
sunlight; |
|
|
|
|
Previous eye surgery; |
|
|
|
|
Unknown factors. |
|
|
| In most cases, a cataract is a natural part of aging. In fact, if
they live long enough, every individual will develop a cataract. Some people
develop dense cataracts at age sixty, while others remain cataract-free until
the age of ninety. |
|
| While aging accounts for most cataracts, there are also other
causes. Certain diseases, such as uveitis (inflammation inside the eye), can
lead to cataracts. Exposure to radiation such as
ultraviolet
(like that from the sun) and infrared rays can also lead to cataracts. Poor
nutrition may cause cataracts to develop earlier and progress faster, as often
happens in underdeveloped countries. A cataract can also be caused from injury
to the eye and by certain prescription drugs, such as steroids.
|
|
| Children are born with cataracts on rare occasions. They require
immediate treatment to prevent permanent loss of vision. |
|
| Children are born with cataracts on rare occasions. They require
immediate treatment to prevent permanent loss of vision. |
|
| Congenital Cataracts may be present at birth or may develop in
infancy or early childhood. Surgery must be done on time or the eye will not
develop fundamental connections to areas of the brain that allow individuals to
interpret the images they see. If not treated on time, the condition of
amblyopia or lazy eye can lead to permanent visual loss. |
|
| Prevention |
|
| Currently medications are not available to prevent or treat
cataracts. However, exposure to ultraviolet radiation (from the sun) and a poor
diet have been linked with cataracts, so it is wise to wear a hat and
sunglasses to protect yourself and eat a balanced diet that includes the major
antioxidants like vitamins C, E, and A or beta-carotene. Researchers also
believe good nutrition can help reduce the risk of age-related cataract. They
recommend eating green leafy vegetables, fruit, and other foods with
antioxidants. Antioxidants are found in green leafy vegetables, carrots, citrus
fruits, melons, eggs, garlic, avocado, asparagus, onion and red meat. If you do
not have a balanced diet, taking multi-vitamins on a regular basis may be
useful. If you are of age 60 or older then you should have a complete eye exam
at least once every two years.
|
|
| Symptoms |
|
| Vision may be reduced or people may notice blurring of their
vision. Objects may also be out of shape and may appear washed out and colours
less bright. This may be noticed more in poor lighting conditions and in bright
light conditions glare may reduce vision. In the evening, cataracts may lead to
the look of halos around car headlights and other lights. As cataracts become
increasingly opaque, reading, watching television and driving at night become
more complicated they are one of the major reasons because of which people stop
driving. |
|
| Some people might also experience "second sight" in the early
stages of a cataract and would find that they are able to see without their
reading glasses. This will last a few months, but as the cataract becomes
denser, vision will begin to blur. |
|
| The
treatment of cataract |
|
| With new eyeglasses, brighter lighting, anti-glare sunglasses
or magnifying lenses the symptoms of cataract has been approved. However if
these measures do not help then surgery is the only effective treatment. It
will remove the cloudy lens and replace it with an artificial lens. It needs to
be removed only when vision loss your everyday activities, such as driving,
reading, or watching TV.
|
|
| Delaying cataract surgery will not cause long-term damage to your
eye or make the surgery more difficult in most cases. However sometimes a
cataract should be removed even if it does not cause problems with your vision.
If your eye care professional finds a cataract, you may not need cataract
surgery for several years or might never need cataract surgery.
|
|
| Many people who need cataract surgery also have other eye
conditions, such as age-related macular degeneration or glaucoma. If you have
other eye conditions in addition to cataract, consult your doctor.
|
|
| 4.
Chalazion |
|
| It is a small bump that develops on the upper or lower eyelid.
Inflamed meibomian glands that produce the oil in tears cause it. Chalazion is
a lump in the eyelid that is caused by inflammation of a gland within the skin.
The lump grows from days to weeks and is occasionally red, temperate, or
painful.
|
|
| In the formation of a chalazion the gland is a modified sweat gland
that lies within the eyelid. This gland produces oil and when it becomes
blocked, it can break and the inflammation process will begin. Inflammation is
a process in which the body reacts to a condition and produces a biologic
reaction. This reaction can cause swelling, redness, pain, or warmth.
|
|
| It is caused by the oil in the gland becoming too broad to flow out
of the gland and blocks the gland however the gland still produces more oil.
Since there is no place to go the oil builds up inside the gland and forms a
lump in the eyelid. Finally, the gland ruptures and releases the oil into the
tissue of the eyelid, causing inflammation. |
|
| The
symptoms of chalazion |
|
| Swelling of the upper eyelid may occur gradually over weeks. The
condition rarely involves the lower eyelid. It will appear as a restricted hard
lump that may grow as large as an eighth of an inch. You may feel pain and your
eyelid may be red occasionally.
|
|
| Treatment
of Chalazion |
|
| They require intensive steroid therapy as chalazion reside deep
under the skin, no relevant medications will be able to penetrate adequately.
Antibiotic eye drops or ointment are sometimes used for the initial acute
infection, but are of little value in treating a chalazion. You shoul consult
your doctor for the treatment. |
|
| 5.
Conjunctivitis |
|
| It is also called pink eye. It is an inflammation of the blood
vessels in the conjunctiva the membrane that covers the sclera and inside of
the eyelids. Inflammation of this membrane is called conjunctivitis. Bacteria
or viruses, making it very contagious, may cause conjunctivitis. |
|
| Viral conjunctivitis causes excessive eye watering and a
light discharge usually affects only one eye. |
|
| Bacterial conjunctivitis causes a heavy discharge, sometimes
greenish affects both eyes. |
|
| Allergic conjunctivitis causes itching and redness in the
eyes and sometimes the nose, as well as extreme tearing affects both eyes. |
|
| Giant papillary conjunctivitis (GPC) causes contact lens
intolerance, itching, a heavy discharge, tearing and red bumps on the underside
of the eyelids usually affects both eyes.
|
|
| To locate the cause and then choose an appropriate treatment, your
doctor will ask some questions. |
|
| 6.
Diabetic Retinopathy |
|
| It is found in some people who have diabetes. It is a disorder of
the retina resulting from changes in the eye blood vessels. It is the most
common diabetic eye disease and an important cause of blindness in adults.
|
|
| In some people suffering from diabetic retinopathy, blood vessels
might swell and leak fluid. However in other people, abnormal new blood vessels
grow on the surface of the retina. The retina is the light-sensitive tissue at
the back of the eye. A healthy retina is necessary for good vision. |
|
| If you are suffering from it then at first you might not notice
change to your vision. But as the time will go, it can get worse and cause
vision loss. Diabetic retinopathy usually affects both eyes. |
|
| Diabetic
retinopathy has four stages: |
|
| Mild Nonproliferative Retinopathy. This the first stage
where micro aneurysms occur. They are minute areas of balloon-like swelling in
the retina's tiny blood vessels.
|
|
| Moderate Nonproliferative Retinopathy. In this stage the
disease progresses and some blood vessels that nurture the retina are blocked |
|
| Severe Nonproliferative Retinopathy. In the third stage more
blood vessels are blocked and depriving several areas of the retina with their
blood supply. These areas of the retina send signals to the body to grow new
blood vessels for nourishment.
|
|
| Proliferative Retinopathy. In the advanced stage, the retina
sends the signals for nourishment activate the growth of new blood vessels.
This condition is called proliferative retinopathy. These new blood vessels are
inconsistent and breakable. They grow along the retina and along the surface of
the plain, vitreous gel that fills the inside of the eye. By it these blood
vessels do not cause symptoms or vision loss. However, they have thin, delicate
walls. If they leak blood, severe vision loss and even blindness can result |
|
| The content of this web site including all text and graphics is
provided for informational purposes only and is not a substitute for
professional medical advice. buymeglasses.com does not accept any liability for
the consequences arising from the application, use, or misuse of any
information contained herein, including any injury and/or damage to any person
as a matter of product liability, negligence, or otherwise. In no event shall
buymeglasses.com be liable for any incidental, consequential, punitive, or
special damages, direct or indirect. Neither the products nor any information
appearing on this web site is intended to assist or encourage site visitors to
diagnose their own medical conditions or the medical conditions of others. This
web site offers no diagnoses or endorsements. Any liability on the part of
buymeglasses.com shall not exceed the fees paid by the user for the particular
information or service provided. The products and information presented on this
web site are provided "as is," with no warranty regardless of whether the
damages are incidental, indirect, direct, or consequential. We are NOT
authorized to answer questions related to a specific medical condition. In case
of medical emergency, please contact your local doctor or hospital for
immediate care. |
|
|
|
|