Night blindness is also called nyctalopia.It's a type of vision impairment. People with night blindness experience poor vision at night or in dimly lit environments. It is not a disease in itself, but rather a symptom of an underlying problem, usually a retina problem.

What Causes Night Blindness?
A number of eye conditions can cause night blindness, including:
1. Nearsightedness or blurred vision when looking at faraway objects.
2. Cataracts or clouding of the eye's lens.
3. Retinitis pigmentosa, which occurs when dark pigment collects in your retina and creates tunnel vision.
4. Vitamin A Deficiency
5. Zinc Deficiency
6. Dry Eyes
7. Diabetes

Are the Symptoms of Night Blindness?
The sole symptom of night blindness is difficulty seeing in the dark. You're more likely to experience night blindness when your eyes transition from a bright environment to an area of low light, such as when you leave a sunny sidewalk to enter a dimly lit restaurant. You're likely to experience poor vision when driving due to the intermittent brightness of headlights and streetlights on the road.

How can I Prevent Night Blindness?
You can't prevent night blindness that's the result of birth defects or genetic conditions, such as Usher syndrome. You can, however, properly monitor your blood sugar level and eat a balanced diet to make night blindness less likely. 

Orange colored foods are excellent sources of vitamin A, including:
1. Cantaloupes
2. Sweet potatoes
3. Carrots
4. Pumpkins
5. Butternut squash
6. Mangoes

What are the Treatment Options for Night Blindness?
The treatment will depend on its causes.
1. Nutrient deficiency (Vitamin A and Zinc) is the easiest to treat. 
2. If the cause is cataract, you can go for cataract surgery to remove the clouded lens and replace it with artificial intraocular lens. Vision is usually dramatically improved after surgery. 
3. For dry eye syndrome, lubricate your eyes with artificial tear drops as they provide instant relief. Just make sure that they are without preservatives. 
4. Diabetic retinopathy can be prevented with tight control over blood sugar, active lifestyle and good dietary habits.
5. As for retinitis pigmentosa, unfortunately there are no treatments available. Thankfully, new research is showing that vitamin A might have a slowing effect on the progression of this eye disease.

Night Blindness: Causes and Symptoms

78% of urban youth are in front of the computer screen/ mobile screen for about 12 hours a day. Such extensive strain to the eyes can have long term effects on vision.  Act now to protect your eyes by following these tips-

1) Ensure appropriate glasses or contact lens prescription which is also adequate for computer use. 
2) For prolonged exposure, use glasses to help with contrast, glare, and eye strain when using a computer.
3) Adjust your computer such that your eyes are level with the top of the monitor. This allows you to look slightly down at the screen.
4) Avoid any glare on your computer from windows or lights. Use an anti-glare screen if required.
5) Choose a comfortable, supportive chair. Position it so that your feet are flat on the floor.
6) If your eyes feel dry, blink more often.
7) Every 20 minutes, rest your eyes by looking 20 feet away for 20 seconds. At least every 2 hours, get up and take a 15-minute break.

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Protect Your Eyes While Working. 7 best ways.

If your eyes suddenly look reddish and feel extremely itchy, you may be suffering from allergic conjunctivitis. Allergic conjunctivitis is triggered by exposure to allergens like pollen or mold spores. An allergy to eye drops or contact lens solution can also trigger this condition. Allergic conjunctivitis is a very common health condition and more common during the hay fever season.

There are two types of allergic conjunctivitis; acute allergic conjunctivitis and chronic allergic conjunctivitis. Acute allergic conjunctivitis is characterized by the swelling of eyelids and intense itchiness and burning. Amongst the two, this is a more common condition. Chronic allergic conjunctivitis can occur during any season and has symptoms that come and go. It is a milder response to allergens such as dust, food, pollen, chemical scents etc.

On presenting the symptoms of conjunctivitis to a doctor, he may ask for an allergy skin test, a blood test or a scraping of the conjunctival tissue to understand the type of conjunctivitis you are suffering from. Allergic conjunctivitis can be treated with a combination of medication and home care.

Antihistamines are the most common form of treatment for this disease. This can reduce and block the release of histamines in the body. Artificial eye drops may also be used to create a screen over the eye and prevent the eye from coming in contact with the allergen. Eye drops may also be used to shrink swollen blood vessels in the eye. Steroid eye drops may also be used along with anti inflammatory eye drops.

Home care to treat allergic conjunctivitis focuses on preventing the trigger. Today, apps on your phone can update you n the pollen levels in the air. Close your windows every time you notice a higher than normal pollen count and keep your home as dust free as possible. You could also use an air purifier in your home. Also, avoid exposure to strong chemicals, dyes, perfumes etc.

To avoid the condition from worsening, avoid rubbing your eyes and wash your hands every time you touch your eyes. Disinfect your towels, sheets and pillowcases that come in contact with your eyes every few days with hot water. Wash eyes with cold water twice daily especially after coming home from outside. Do not share your make up or brushes with other people. This is a healthy habit to follow even when you are not suffering from this condition. While you suffer from pink eye you should also not wear contact lenses. Once the eye has healed, discard the old lenses and replace them with a new pair.

Allergic Conjunctivitis - How It Can Be Treated?

There are many common measures people take to improve their eyesight or to improve their vision, including wearing glasses, lenses, and many more. Here are some effective exercises, which can prove to be highly beneficial to improve your eye health:

1. Stretching
This is the most common and also one of the easiest to do. It requires you to just look up, hold for two seconds, look down, hold for two seconds and then repeat this procedure for each corner of your eye, which means top-left, top-right, bottom-left and bottom-right corners.

2. Flexing
This is simply rotating your eyes in circles. Roll your eyes in the clockwise direction for one minute and then roll your eyes in the anticlockwise direction for one minute.

3. Focus switching
This particular eye exercise is probably the most useful one to improve eye health. In this eye exercise, you have to hold something at a reading distance and cover the other eye. You then have to find something that is at least twenty feet away and trace its shape with one eye closed. With one eye closed, trace more shapes, which are twenty feet away.

4. Palming
This exercise is also very simple to perform. All you have to do is cover your eyes with your palms. Once you have done this, just wait and see that there are no bright flashes of light. If you see that there is a bright flash of light, just wait till they go. This is used primarily to distress the eyes.

5. Deep blinking
This is also an incredibly useful exercise for distance vision. What you have to do is to place some large letters are at a fair distance and then sit on a chair. You have to then close your eyes and tighten all your muscles for 5 seconds. After 5 seconds are over, you have to open your eyes and then you have to see the letters for a second or two. The more number of times you do this, the more clearly you will be able to see the letters after reopening your eyes.

However, these eye exercises are not universally accepted by all doctors.

Exercises to Improve Eye Health

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?

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