People may suffer from visual impairment even though their eyes are perfectly normal. Such loss of vision may result from neurological impairment.

Vision is the combination of image formation and perception of various attributes of the image by the brain. When the brain is not able to perceive images or various attributes of images, the patient may suffer from neurological impairment of vision. Such impairment owes its origin to the nervous system.

Causes of Visual Impairment:

There are various areas in the brain that process some or the other attribute of the image that has formed on the retina. Occipital cortex, the area situated at the rear side of the brain is a very important site. It is responsible for processing visual stimuli and allowing people to make an idea about shape, distance, movement, color, etc. The severity of loss of vision depends on the extent and location of damage in the brain.

Neurological loss of vision may result from acquired brain injury, difficulties with visual perception, impairment in coordination of the eyes, etc. All these may stem from damage areas in the brain that are responsible for vision. There are many areas in the brain that are responsible for vision.

These areas can get damaged from various accidents like:

Stroke: If a person suffers a stroke, a part of his or her brain is likely to get damaged due to a haemorrhage or a blocked blood vessel.

Traumatic Brain Injury: A traumatic brain injury such as in a car accident or a violent fall can damage visual perception of the brain.

Infections: Infections such as meningitis attack the brain and may impair various areas of it.

Lack of Oxygen: People may suffer from lack of oxygen if they experience accidents like a near-drowning episode or a heart attack or something else, which has the effect of interrupting blood flow to the brain.

Diseases: Diseases such as brain tumors, multiple sclerosis etc. can precipitate neurological vision loss.

Symptoms of Visual Impairment:

Symptoms of neurological vision loss depend on the type of vision impairment and the location of damage in the brain. It may include:

Blurry vision: In Blurry vision, a person will not see things clearly or may see something in light but find it difficult to see them in dim light.

Double vision: In double vision, the patient sees a single object as two and cannot merge them as one.

Problems with depth perception of objects

Problem with bright light: In this type of problem, a person experiences difficulty seeing an object in a bright light. One may also feel pain or discomfort in the eye in bright light.

Difficulty with interpreting the object the person is looking at

Partial loss in the visual field: In this problem, half of the visual field in each eye is missing.

Treatment of Visual Impairment:

There is hardly any treatment for such vision loss since the rectification of visual acuity is of no help. Depending on the location and degree of neurological impairment, vision may improve over time. Some children with acquired brain injury or impairment in the coordination of the eyes and difficulties with visual perception also tend to improve with age.

Conclusion:

This is a type of vision loss where glasses, contact lenses, surgeries, or eye drops are not going to help. Such vision loss is usually permanent. Children with similar symptoms need to be presented with pictures, bright light, etc., which may help to form an idea about the object.

Visual Impairment Related To Nervous System!

Cataract is clouding of clear natural lens present inside the eye, this is a major cause of decreased vision in elderly. Cataracts can occur in one or both eyes, usually developing very slowly. Things look blurry, hazy, less colourful and less sharp with cataract. 

Most cataracts are related to ageing, however many other factors can either increase the rate of formation or cause cataract formation. 

Causes of Cataract Formation-

Ageing: Most common cause. As the proteins present in the lens of the eye degenerates over the years ( just like any other organ) cataract is formed. If you are having Diabetes or hypertension, the rate of formation gets accelerated.

Radiation: Prolonged exposure to ultraviolet rays, especially UV-B rays, results in cataract in your eyes. Wearing sunglasses in the daytime helps in slowing down the process of cataract.

Genes: Many genetic disorders can result in congenital cataract ( cataracts present since birth) or early formation. Like in Lowe syndrome or Down's syndrome. 

Lifestyle Choices: Cigarette smoking, long hours of sun exposure regularly, antioxidant, poor diet etc. are responsible for the onset of cataract.

How To Detect Cataract?

Certain signs and symptoms suggest the existence of cataract in the eye. Depending on the type and level of cataract, problems in vision occurs. The main symptom is foggy cloudy vision as if seeing through a dirty glass window. 

Other Symptoms are- 

inability to see clearly in bright light (during the day) which becomes better in dim light ( evening and night) and vice versa. 
watery, tired eyes - mild pain in and around eyes. 
yellow tinge in vision 
Halos around light bulbs or bright light. 
If you are experiencing above symptoms and having problems in viewing things clearly, visit an ophthalmologist and get your eyes checked.

Foggy and Cloudy Vision - A Sign Of Cataract?

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

Cataract can be defined as the clouding of the natural lenses in the eyes. This is caused by the clumping of protein in the eye lens. Cataract is a common eye disorder and the leading cause of loss of vision in people who are past their fortieth birthday. Cataract can occur in one or both eyes. When diagnosed properly, cataract can be treated with surgery to prevent blindness.

Depending on where and how they develop, there are many types of cataract. The most common amongst these are:

1.        Subcapsular cataract

These occur at the back of the eye lens. Diabetic patients are very susceptible to this kind of cataract.

2.        Nuclear cataract

Yellowish-brown cataract that form in the center of the lens are called nuclear cataract. This is usually seen in cataract caused by ageing.

3.        Cortical cataract

Cataract in the lens cortex are known as cortical cataract. These are wedge shaped and whitish in color. Spokes protruding out of these opaque wedges can be seen moving towards the center of the eye.

4.        Congenital cataract

Though they are not common, babies can also have cataract. Cataract formed at birth or within the first year of a baby's birth are known as congenital cataract.

5.        Secondary cataract

Cataract is one of the known side effects of diabetes and glaucoma. Some steroids and medicines are also linked to cataract.

6.        Traumatic cataract

If your vision becomes cloudy years after an eye injury, it could be a traumatic cataract. It can take several years for this to happen.

7.        Radiation cataract

Exposure to radiation can also lead to cataract. This is seen sometimes in patients who have undergone radiation therapy to fight diseases like cancer.

Though the type of cataract might differ from person to person, the symptoms are usually the same. Some of the common symptoms of cataract are:

1. Blurred vision
2. Reduced night vision
3. Increased sensitivity to light and glare
4. Seeing halos around lights
5. Colors appearing faded
6. Double vision

A reading test is the first step towards diagnosing cataracts. This is followed by tests to measure the eye pressure. Your doctor will also need to dilate the pupil to check the condition of the optic nerves and retina.

Surgery is the safest way to remove a cataract. Surgery is usually recommended when cataract begin inhibiting your daily life such as preventing you from driving, interfering with reading etc.
 
In most cases, this can be done as an outpatient procedure. The earlier it is diagnosed, the easier it is to treat. Hence, if you notice any of the symptoms mentioned above, get your eyes checked at once. The surgery is a day-care surgery only, so a person can go home the same day.

Is Your Vision Clouded? It Could Be Cataracts

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?

Blurred vision is most often a sign that you need corrective spectacles for near sightedness, far sightedness or astigmatism but it could also be a sign of a bigger problem including eye diseases or neurological problems. Blurred vision involves the loss of sharpness of vision and objects appearing hazy and out of focus. It can affect one eye or both eyes simultaneously.

Whatever be your age, it is a good idea to consult a doctor as you begin to experience a blurred vision. To measure the extent of your vision problem, a doctor will do a comprehensive eye examination including spatial contrast sensitivity and a standard eye chart test. Some of the factors that trigger blurred vision are:

1. Myopia or nearsightedness
2. Hypermetropia or farsightedness
3. Astigmatism caused by an irregularly shaped cornea
4. Presbyopia - the diminished ability to focus on objects due to the hardening of the lens in the eye
5. Dry eyes or the lack of lubrication on the surface of the eyes
6. Hormonal changes during pregnancy
7. Migraine headaches
8. Temporary floaters in the eye formed by the liquefying of the gel in the eyes
9. After effects of lasik surgery
10. Eye drops or medication
11. Overuse of contact lenses
12. Diabetes

Blurred vision can also be a symptom of a serious condition such as cataract, glaucoma, macular degeneration, diabetic retinopathy and cardiovascular diseases.

Treatment for blurred vision depends on the factors triggering it. Wearing corrective glasses can cure blurred vision caused by myopia, hypermetropia and astigmatism. These conditions can also be treated by lasik surgery. For blurred vision related to diabetes, check your blood sugar and get it into its optimal range.

Exercises for the eye muscles can also help sharpen vision and lower the rate of eye muscle degeneration. Some of these exercises are:

1. Alternately focus on an object close to you and another far from you for ten seconds each.
2. Blink your eyes and hold for two seconds
3. Roll your eyes clockwise and anticlockwise. Repeat 15-20 times.
4. Rub your palms together to generate heat and place over your eyes to relax them.

A healthy diet with plenty of vitamin a can help keep your eyes healthy and prevent blurring of vision. Wearing sunglasses can also protect your eyes from harmful uv radiation and lower their rate of wear and tear. Lastly avoid reading in moving vehicles and holding a book too close to your face.

Is Your Vision Blurry? What Should You Do?

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