Amblyopia is commonly known as'lazy eye. It is a vision development disorder, which affects eyes and the brain during infancy and childhood. It signifies that the eye does not achieve a normal visual acuity even with refractive correction in form of glasses or contact lens. During normal visual development, the eye and brain learns to'see' and develop binocularity, that is the ability to perceive depth (stereoacuity). This occurs in the first 8 to 10 years of life. 

Each eye transmits a clear and identical image from retina to the brain, which fuses the two images into a single image with 3 dimensions (adding depth). When the image is formed on the retina of two eyes is too dissimilar, the brain cannot fuse the two images and suppresses the more blurred image. As a result, the worse eye does not learn to'see' and becomes'lazy. This condition is seen in 1-4% of population.

The common causes for dissimilar images or amblyopia are:
1. Misalignment of the eyes or squint: it is the primary reason for amblyopia is misalignment of the eyes. In case, both your eyes are not aimed in the same direction, the image captured by each eye is different, resulting in diplopia. The brain will see from the dominant eye and suppress image from the other eye. Over a prolonged period of time, the eye dissociates from the visual cortex of the brain.

2. Refractive amblyopia:
A. Unequal refractive error in both eye. When the eye power of both eyes differ by more than 1.5d of spherical equivalent, which results in dissimilar images between the two eyes. As a result, the visual development in restricted in the worse eye.
B. High refractive error or astigmatism in both eyes, since there is a blurred image in both eyes, the normal vision development does not occur in either eyes resulting in bilateral lazy eyes.

3. Cloudiness in visual system or visual deprivation amblyopia: any kind of obstruction or cloudiness in the normal visual axis of the eye tissues can lead to amblyopia. Disorder of any kind, which blocks a clear image from being focused blocks the formation of a clear image on your retina. Commonly due to congenital or developmental cataracts or corneal opacities or prolonged closure of one eye in early childhood (drooping of one eyelid, eyelid swelling, patching of one eye).

Treatment for amblyopia
For treatment of amblyopia, a child must be compelled to utilize his affected, weaker eye. This can be done by correction of causative factor such as, treating refractive error with glasses, surgical correction of misalignment of eyes followed by patching and vision therapy, cataract surgery.

Patching or occlusion of the good eye
This is done to force the brain to pay attention to visual input from the worse eye. This allows nerve connections between affected eye and brain to develop due to, which the eye'learns to see. Eye drops such as atropine are also used for blurring the vision of the good eye. Some form of vision therapy may also be required to train both eyes to see together and develop some degree of depth perception.

To be effective, treatment should be implement as early as possible, within the period of normal visual development best within first 8 years of life. Some visual gain has been seen in selected patients up to age of 14 to 18 years. This also highlights the importance of a comprehensive eye examination as a routine in young children.

About Amblyopia or Lazy Eye

A common headache can have a number of reasons behind it, such as defective vision, hetrophoria or convergence deficiency, etc. Now, the question arises as to how they can cause headache. Read on to know more...

Q. Why should defective vision cause headache?

To attain a perfect vision, eyes with defective vision have to make sustained extra efforts, which results in headache. Even if the refractive error is very small, it can be the cause of headache. More prolonged the working and smaller the print, higher the incidence of headache.

Q. Can this occur at all ages?

Yes, it can occur at all ages. However, with age, the resistance decreases and hence elderly people are more prone to get headache. More the use of computer, mobiles, TV or prolonged studies precipitates headache

Q What is Hetrophoria?

Normally, both eyes always remain parallel, but in some cases, eyes have slight tendency to develop minor squint, may be convergent or divergent. This is called Hetrophoria or Latent squint. Such patients have to take extra strain to keep the eyes straight

Q. What is convergence deficiency?

For reading, both eyes have to converge and if there is weakness of convergence, extra strain has to be put on the eyes, which cause headache.

Q. What is the ideal method of refraction in young patients, I,e below 40 years?

Ideal method is to dilate the pupil with Tropicasyl plus drops. This has the advantage that the doctor can see the retina and Optic Disc. This is important to exclude any involvement of brain as the cause of headache. It also relaxes accommodation and hence provides correct refraction. In cases of Hypermetropia, it is extremely essential to dilate the pupil.

Q. What is the role of Autorefractmeter (a computer) in refraction?

It is a very important instrument to provide correct refraction, but it cannot be totally relied upon. Some opticians rely on it and give wrong numbers.

Q. What is acceptance Test?

You have refracted the eyes with Autorefractmeter or Streak Retinoscope but exact power is what a patient accepts. This is very important.

Q. What is astigmatism?

There is a difference in refraction in different meridians and it is important that a cylinder number is prescribed in correct axis. This is a difficult task and needs lot of experience.

Q. Is it important to correct astigmatism?

To relieve headache and strain on the eyes, it is very important that exact cylinder is prescribed.

Q. What is the role of exact centring of Optical Lenses?

You may give correct number, but if the centre of the Optical lenses and cornea do not coincide, satisfactory results are not obtained. To dispense correct lenses is a big art and the Optician must be qualified and well experienced.

Q. Does the quality of lens affect the visual comfort?

Yes, it is important that quality of lenses should be good, preferable fibre lenses which are Ant reflect coated. Crizal coating with capability to block the UV rays are very popular.

Conclusion: Refractive errors are important cause of headache and needs proper examination of the eyes, preferably after dilating the pupil. Astigmatic error even if too small may be the cause of headache. Spectacle dispensing is an art and a patient must select proper optician. Spectacles if advised for constant use must be used constantly to get full relief.

Defective Vision - Can it be a Cause of Your Headache?

7 Ways To Care For Your Eyes 

Eyes do more than we give them credit for and require more care than what we actually give them mostly. It isn't very difficult to ensure that your eyes are healthy and taken care of.

Here are 7 ways to care for your eyes everyday.

1) Splash water - Always clean your eyes with cold (filtered) water, from time to time. The clean water washes the eyes and keeps them healthy and free of diseases.
2) Don’t look into the sun - Never look into the sunlight directly. In fact, avoid looking at any sort of light that is harsh on the eyes. Direct rays of any kind of bright light can have damaging effect on the retina.
3) Get eyes examined - Have regular eye exams to check for diabetes and high blood pressure, if these health problems already exist in the family.
4) Do not smoke - People who smoke are more risk of having age-related eye problems.
5) Exercise your eyeballs - Roll the eyeballs up and down, and lift and right without moving your position. Repeat this exercise about 5 to 10 times. This helps relax the muscles in your eyes.
6) Distance eyes from screens - If you work on the computer, make sure there is enough distance between the screen and your eyes. Sit at least 22-28 inches away from the screen. The same applies while using smartphones and tablets. Do not view the screen from too close. Viewing the screen from too near as well as from too far; can increase the strain in your eyes.
7) Give them a break - People who work on the computer all day should ensure that they rest their eyes after regular intervals. Look in a long distance every few minutes. 


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7 Ways To Care For Your Eyes Without Making Any Effort

Allergic conjunctivitis is the result of a foreign particle (allergen) coming in contact with the eye. Once this happens, the immune system overreacts resulting into an inflammation of the eye. The eyes sore with pain. The over secretion of the histamine dilates the blood vessels causing the nerve to irritate and blood vessels of the eyes to expand. Some common reasons of allergic conjunctivitis include eye drops, pollen, dust mites, makeup and animal fur. The good news is that allergic conjunctivitis is easily treatable. Here are top five ways to deal with this condition:

Taking care of the eye: It is advised not to wear contact lenses until the symptoms go away fully. If any medication is used, a person must wait for at least 24 hours before putting on the contact lenses. Sometimes our hands carry major pollens that result in allergic conjunctivitis. It is equally important not to rub the eye without washing both the hands. Many studies have also reported that frequent bathing of the eye with cold water helps to clear the symptoms quickly. Some even say that frequent splash of warm water does the trick.
Avoid the allergen: Allergen being the villain behind the occurrence of this condition, it is very important to stay away from it. In peak pollen times, it makes sense to close the door. In case a person must go out, it makes sense to wear a sunglass. A pillow made of feathers should be changed every week to stay away from the infection. The number of dust mites at home should be decreased as much as one can.
Antihistamines: To quickly get rid of allergic conjunctivitis, doctors often prescribe antihistamines. It can be in the form of eye drop or oral presentation. They can successfully counter the effect of histamine which the body produces because of the hyper activity of the immune system. An antihistamine can block the aggressive effect of the immune system in a short time. Some of the commonly prescribed histamines include loratadine, cetirizine, emedastine, and ketotifen. People taking this form of the medicine for the very first time should refrain from carrying heavy load or driving.
Mast cell Stabilizers: These takes a little longer to act as compared to antihistamines. Their effects, however, are more lasting compared to its peers. Some of the popular mast cell stabilizers include nedocromil and lodoxamide. This medicine belongs to a non-steroid family and can successfully block the chemicals that cause inflammation.
Corticosteroids: These medicines are only prescribed by doctors when the symptoms of allergic conjunctivitis are serious. They belong to the steroid family of medicine produced synthetically. They can reduce the immune response of the body quickly and reduce the swelling as well. They can have possible side-effects. It is therefore wise, to consult a doctor before using it.

Allergic Conjunctivitis - 5 Top Ways To Deal With It!

People are well aware of the harmful effects that UV rays have on the skin, but very few know that UV rays can damage their eyes as well. The tissue that human eye is made up of is one of the most sensitive tissues in the body and hence, the most vulnerable. The increasing level of UV radiation reaching the Earth s surface every minute has made it indispensable to take the required precautionary measures to protect the eyes.

What are UV rays?

Sunlight consists of 3 types of radiations - Infrared, Visible light and UltraViolet. Artificial sources like lasers, tanning beds and welding machines also emit UV radiation.

There are three types of UV radiations - UV-A, UV-B and UV-C. 

UV-C is absorbed by the ozone layer and does not possess any risk. It is UV-A and UV-B radiations that adversely affect the eyes and vision.

Impact of UV rays on  eyes

Too much exposure to UV rays can affect vision, harm the eyes, and deteriorate overall eye health. There are various eye problems that are aggravated by excessive exposure to UV radiation:

Macular Degeneration: It is caused by damage to the retina over time by UV rays. It leads to age-related blindness. Too much exposure to UV rays increases the risk of developing macular degeneration.
Cataract: It is the clouding of eye s natural lens - the part of the eye that focuses the light we see. Too much exposure to UV rays increases the risk of developing cataracts. 
Pterygium: Often known as  surfer s eye , pterygium is a pink, non-cancerous growth that is formed on the conjunctiva. UV rays are believed to be responsible for the development of this growth.
Skin Cancer of the Eyelids: Too much exposure to UV rays can cause skin cancer in and around the eyelids.
Photokeratitis: Popularly known as corneal sunburn or  snow blindness , photokeratitis is caused due to excessive short-term exposure to UV-B rays. Photokeratitis occurs when you spend long hours at the beach or skiing. It sometimes leads to temporary vision loss. 
How to protect the eyes from harmful UV rays?

Here are some tips to help ensure that eyes are protected against harmful UV rays:

Always use quality sunglasses that block out 99-100 percent of both UV-A and UV-B radiation when outdoors.
Stay away from tanning beds, and if you use them occasionally, always wear eye protection. 
Wrap around frames should be used if you spend a lot of time outdoors.
Be sure to see your doctor at least every two years.

UV Rays - Are They Damaging Your Eyes?

As you reach the age of 40, you will likely notice changes in your vision. Perhaps you have difficulty reading a book without glasses, or distinguishing between colours. These changes occur as an effect of ageing. However, nowadays people in their teens are also exposed to a host of eye disorders and vision problems, mostly resulting from eye injuries and visual stress.

The most common disorders of the eye, which affect the age group 19-40, are Refractive errors. The following signs and symptoms characterize such disorders-

  Haziness
  Double vision
  Halos or glares when you are surrounded by bright lights
  Headaches
  Squinting
  Eye strain

What are the Refractive errors?

Refractive errors develop when light cannot focus on the retina (the light-sensitive tissue situated at the rear side of the eye) directly due to the shape of the eye. The change in the cornea s shape, the ageing of the lens, or the length of your eyeball can lead to refractive errors. Most people suffer from one or more of the above conditions.

Type of Refractive Errors:

Following are the most common types of refractive errors-

  Myopia or Nearsightedness - If you have this condition, you will see nearby objects clearly but distant objects will appear blurry. This happens because the light comes to focus right in front of the retina, instead of on the retina.

  Hyperopia or Farsightedness - This condition is just the opposite of myopia. Distant objects are clearly visible but those located close to you appear blurry. However, some people may not observe any problem with their vision at a young age. If you have significant hyperopia, objects at any distance, far or near, can appear blurry.

  Presbyopia - This age-related condition affects your ability to focus on things closely. This happens because as you age, the lens of the eye is unable to change shape to allow the eye to focus on nearby objects clearly.

  Astigmatism - In this condition, the eye cannot focus light onto the retina evenly. As a result, images appear stretched out and blurry.

  Amblyopia or Lazy eye - This vision development disorder begins during early childhood and infancy. In this condition, the eye does not achieve normal visual acuity despite using contact lenses or prescribed glasses. Usually, amblyopia affects only one eye.

Can early diagnosis help treat the problem?

Yes, it can. Your eye care specialist can diagnose refractive errors and detect what exactly is impeding your vision with a comprehensive dilated eye examination. Upon encountering the symptoms mentioned above, one should consult an ophthalmologist at the earliest and get oneself checked.

If the condition is detected early, vision problems due to refractive errors can be treated. The common treatment options include the use of contact lenses, prescription glasses, and surgery (in severe cases).
People with visual problems should also adopt some lifestyle changes to correct their vision - eat more veggies, get adequate sleep and rest, abstain from smoking etc. Additionally, you should get periodic eye check-ups to monitor the condition.

Difficulty In Vision - It Can Be Better If Treated On Time!

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