What is a cataract?
A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

A cataract can occur in either or both eyes. It cannot spread from one eye to the other.



What is the lens?
The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye.

In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain.

The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image you see will be blurred.



What causes cataracts?
The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.

But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.

Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.

How do cataracts affect vision?
Age-related cataracts can affect your vision in two ways:

Clumps of protein reduce the sharpness of the image reaching the retina. The lens consists mostly of water and protein. When the protein clumps up, it clouds the lens and reduces the light that reaches the retina. The clouding may become severe enough to cause blurred vision. Most age-related cataracts develop from protein clumpings. When a cataract is small, the cloudiness affects only a small part of the lens. You may not notice any changes in your vision. Cataracts tend to “grow” slowly, so vision gets worse gradually. Over time, the cloudy area in the lens may get larger, and the cataract may increase in size. Seeing may become more difficult. Your vision may get duller or blurrier.

The clear lens slowly changes to a yellowish/brownish color, adding a brownish tint to vision. As the clear lens slowly colors with age, your vision gradually may acquire a brownish shade. At first, the amount of tinting may be small and may not cause a vision problem. Over time, increased tinting may make it more difficult to read and perform other routine activities. This gradual change in the amount of tinting does not affect the sharpness of the image transmitted to the retina. If you have advanced lens discoloration, you may not be able to identify blues and purples. You may be wearing what you believe to be a pair of black socks, only to find out from friends that you are wearing purple socks.

When are you most likely to have a cataract?
The term “age-related” is a little misleading. You don't have to be a senior citizen to get this type of cataract. In fact, people can have an age-related cataract in their 40s and 50s. But during middle age, most cataracts are small and do not affect vision. It is after age 60 that most cataracts cause problems with a person's vision.

Who is at risk for cataract?
The risk of cataract increases as you get older. Other risk factors for cataract include:

Certain diseases (for example, diabetes).
Personal behavior (smoking, alcohol use).
The environment (prolonged exposure to ultraviolet sunlight).
What are the symptoms of a cataract?
The most common symptoms of a cataract are:

Cloudy or blurry vision.
Colors seem faded.
Glare. Headlights, lamps, or sunlight may appear too bright. A halo may appear around lights.
Poor night vision.
Double vision or multiple images in one eye. (This symptom may clear as the cataract gets larger.)
Frequent prescription changes in your eyeglasses or contact lenses.
These symptoms also can be a sign of other eye problems. If you have any of these symptoms, check with your eye care professional.

Are there different types of cataract?
Yes. Although most cataracts are related to aging, there are other types of cataract:

Secondary cataract. Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid use.
Traumatic cataract. Cataracts can develop after an eye injury, sometimes years later.
Congenital cataract. Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.
Radiation cataract. Cataracts can develop after exposure to some types of radiation.
How is a cataract detected?
Cataract is detected through a comprehensive eye exam that includes:

Visual acuity test. This eye chart test measures how well you see at various distances.
Dilated eye exam. Drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.
Tonometry. An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.
Your eye care professional also may do other tests to learn more about the structure and health of your eye.

Why Is My Vision Blurry?
Do you often find yourself blinking, squinting, or rubbing your eyes to gain a clearer view? If you have blurry vision, you might chalk it up to age or needing new glasses. But it can be a sign of other health problems, too.

Often, treatment for these conditions will clear up your blurred vision. Remember, though, that sudden changes to your eyesight aren't normal, so if they happen, see your doctor right away.

Could It Be Diabetes?
The condition raises your risk for an eye disease called diabetic retinopathy. Over time, high blood sugar can damage the tiny blood vessels in your retina, the part of your eye that senses light. That can lead to swelling in a part of the retina called the macula, new and unwanted blood vessels growing in the eye, and bleeding inside the eye.

Along with blurry vision, diabetic eye disease may also cause:

“Floating” spots in your field of vision
Permanent loss of vision
Early treatment is the best way to ward off permanent damage. So protect your eyes from diabetes by getting them checked at least once a year.

Could It Be a Stroke?
One of the key signs that you're having a stroke is a sudden, painless change in eyesight. You might have blurry or double vision.

Call 911 right away if you have either of these changes and other stroke warning signs, such as:

Dizziness
Face drooping
Loss of balance
Slurred speech or other problems speaking clearly
Weakness or numbness in one arm
Could It Be Preeclampsia?
If you're pregnant, you shouldn't take blurry vision lightly. It could be a sign of preeclampsia, a dangerous condition marked by very high blood pressure and protein in your urine. Preeclampsia occurs in women who have never had high blood pressure before and generally occurs late in pregnancy, generally after 20 weeks. It can have serious, life-threatening effects on you and your baby.

Preeclampsia may not cause any symptoms, but blurry vision and other sight changes such as seeing flashing lights or spots could be clues that you have it.

Be sure to contact your doctor if you notice these as well as other possible signs:

Anxiety, shortness of breath, a racing heart, or confusion
Nausea or vomiting that suddenly starts after the first trimester
Pain in your belly, shoulder, or low back
Sudden weight gain
Swelling, especially in your face, around your eyes, or in your hands
Throbbing headaches that don't go away
Could It Be a Migraine?
A migraine is more than a horrible headache. There are a host of other symptoms that you might have with the pain, including blurry vision and sensitivity to light. You may feel these signs even before a migraine starts, and they may last until it's over.

More dramatic changes to your eyesight during a migraine are called an aura. They can include:

Loss of part or all of your vision for a little while
Seeing flashes of light
Seeing wavy lines or spots
To solve these problems, you'll need to work with your doctor to treat your migraines and keep them from starting.

Could It Be Psoriasis?
You may know this condition from these symptoms:

Itchy or sore patches of skin
Joint pain and inflammation
Thick, red, scaly patches on the skin
But psoriasis can affect your eyes, too. It can cause a condition called uveitis, when inflammation leads to swelling that causes blurred vision, pain, redness, and sensitivity to light.

Treatments can get rid of uveitis, but the type you need will depend on which part of your eye is affected.

Could It Be Multiple Sclerosis?
Blurry vision is often one of the earliest symptoms of multiple sclerosis (MS). The disease causes inflammation along the nerve that connects your eyes to your brain, called the optic nerve. That causes a condition called optic neuritis, which can give you blurry sight, loss of color vision, and pain when you move your eyes. It often happens in just one eye.

Besides blurry vision, MS also causes:

Trouble with balance
Bladder and bowel problems
Dizziness
Feeling very tired
Numbness
Stiffness
Weakness
Optic neuritis doesn't necessarily mean you have MS, so talk to your doctor about what's causing it. The problem often goes away on its own, but your doctor can give you some medications to help you heal faster.

Could It Be a Brain Tumor?
Scary, but true: A tumor in any part of your brain can make pressure build inside your skull. That can cause many symptoms, including blurred vision.

Other signs of a possible brain tumor are:

Drowsiness
Headache that won't go away
Nausea
Personality changes
Seizures
Vomiting
If your doctor thinks you might have a brain tumor, she'll use different tests to check how well your brain and spinal cord work, as well as imaging tests to see inside your head.

Could It Be Parkinson's Disease?
Blurry vision is not the first sign of this nerve disease. But as it gets worse, it can affect sight. That's because the condition may change how your eyes move. As your sight seems less sharp, you may strain your eyes because they have to work harder to focus.

Parkinson's disease affects much more than the eyes. It also causes:

Poor balance and coordination
Stiffness in your body
Tremors that affect the hands, arms, legs, and face

Though it starts as a mild disease, Diabetic Retinopathy can cause severe visual impairment and in some cases, blindness. As the name suggests, this disorder strikes diabetic patients, especially those with high sugar levels. As the symptoms are not immediately evident, the disease can often go unnoticed and later diagnosis may make the problem more severe. Since forewarned is forearmed, here is all you need to know about Diabetic Retinopathy.

What is Diabetic Retinopathy?
Diabetic Retinopathy (DR) affects the light-sensitive tissue blood vessels in the retina that line the back of the eye. It can cause the leaking of the blood vessels in the eye and when the fluid gets accumulated in macula–the part of the retina that controls the most detailed vision abilities–blurred vision can be caused.

How is it caused?
Diabetic Retinopathy is caused mainly due to high sugar levels in the blood that damage the network of tiny blood vessels that supply blood to the retina of the eye. The severity of the effect of the sugar on the retina determines the effects of DR.

What happens in Diabetic Retinopathy?
During the initial stages, the blood vessels in the retina become weak and small bulges called microaneurysms are developed. These may burst and cause tiny blood haemorrhages on the retina, as per Sankara Eye Hospital.

Abnormal retinal blood vessels bleeding causes the appearance of wavy vision and colour changes. When blood vessels leak into the centre of the eye, it is identified as Proliferative Retinopathy. Blurry vision is one of the signs along with spots or floaters, or having trouble with night vision.

How likely is a diabetic patient to get DR?
Whether a person will conceive the disorder depends on the duration of their illness. If they have had diabetes for more than ten years, it is likely that 60 per cent of patients will develop these complications, says Dr S K Wangnoo, diabetologist, Apollo Hospitals.

What are the conditions conducive to DR?
Patients whose sugar level is not controlled are likely to develop DR. Diabetes starts affecting the eye when the HbA1C level (the glucose level in the blood) of the person is higher than seven.

What precautions can be taken?
Dr S K Wangnoo shares some pointers that one can keep in mind to keep DR at bay.

* Keep the HbA1C level less than 7.
* Keep ‘bad’ cholesterol or LDL less than 90.
* Keep the blood pressure less than 140/80.
* Exercise regularly and get the eyes checked every year.

How is it diagnosed?
In the early stages, DR does not cause any noticeable symptoms. Therefore, it tends to be diagnosed as a result of a diabetic eye screening test. This includes a comprehensive eye exam including a slit lamp examination, a dilated retinal check, and the measure of intraocular pressure. Thereafter, additional tests like a Fundus Fluorescein Angiography (FFA), Ultrasound B-Scan or an Optical Coherence Tomography to study the structure of the eye may be done.

What is the treatment for this?
Laser treatment can be performed that focuses on retinal thickening and stopping the bleeding. The Surgical treatment is done for the advanced stages of DR. A procedure called vitrectomy is performed to correct this. In selected conditions, intravitreal injections are also given.

People experiencing blurred vision or decreased colour sensitivity need to get their eyes checked as these seemingly minor problems may actually indicate retinal diseases that account for a significant share of the vision loss burden in the world, experts have warned.

Retinal diseases often get underdiagnosed as people feel no pain when symptoms start showing up and the other eye often compensates for the poor eye, experts from the All India Opthalmological Society (AIOS) said at a workshop on retinal disease here.

Among the various retinal disorders, age-related macular degeneration (AMD) and diabetic macular edema (DME) are the major types that account for about 8.7 per cent and 4.8 per cent of blindness in the world respectively.

“The common symptoms of retinal disorders like AMD include blurred or distorted vision, dark spots in central vision or straight lines appearing wavy,” said Rajvardhan Azad, President of the All India Collegium of Ophthalmology, a fellowship programme of AIOS.

“These diseases often go underdiagnosed as they get noticed only when profound loss of eye sight occurs or the patient closes one eye. It is, therefore, imperative to understand the symptoms and seek expert advice as early diagnosis can help prevent loss of vision,” Azad, who is also an eye specialist at Bharti Eye Hospital in New Delhi, said.

Early detection of AMD and DME increases the possibility of preventing vision loss, and according to Azad, treatment becomes difficult for those who have completely lost their sight.

Some of the treatment options available in India include laser photocoagulation, anti-VEGF (Vascular Endothelial Growth Factor) injections and combination therapy which includes laser and anti-VEGF treatment.

People with diabetes should be especially alert as they are more prone to develop diabetic retinopathy, Azad said.

दृष्टीदोष

दृष्टीदोष म्हणजे कमी दिसणे म्हणजेच सामान्य भाषेत डोळयाला नंबर लागणे. यात जवळचे किंवा लांबचे अंधुक दिसते. डोळयाच्या बाहुलीतून प्रकाशकिरण आत शिरून भिंगातून एकत्र होतात. यामुळे आतल्या पडद्यावर वस्तूची प्रतिमा उमटते. या प्रतिमेचे ज्ञान मेंदूपर्यंत पोहोचून आपल्याला दृष्टीज्ञान होते. जेव्हा प्रकाशकिरण आंतरपटलाच्या मागे किंवा पुढे एकत्रित होतात तेव्हा दृष्टीदोष होतो. डोळयाची बाहुली आणि पडदा यांमधले अंतर कमीजास्त असेल तर प्रतिमा पडद्यावर अचूक व स्पष्ट पडत नाही. अशा वेळेला चष्मा वापरून (भिंग) हा दोष घालवता येतो. यासाठी नेत्रतज्ज्ञाची मदत घ्यावी लागते.

लघुदृष्टी
सर्वसाधारणपणे लहान वयात येणारा दृष्टीदोष लघुदृष्टी प्रकारचा असतो. म्हणजे जवळचे दिसते पण लांबचे कमी दिसते या स्वरुपाचा हा दोष असतो. याचे कारण म्हणजे हा नेत्रगोल लांबट अंडाकृती असतो. त्यामुळे लांबची चित्रप्रतिमा नेत्रगोलाच्या आतल्या नेत्रपटलावर पोचत नाही म्हणून धूसर दिसते. भिंगापासून नेत्रपटलापर्यंतचे अंतर जास्त असणे हे याचे कारण असते. यामुळे मुले पुस्तक जवळ धरतात. मुलांना फळयावरचे नीट दिसत नाही. मुलाला ही अडचण नेमकी न सांगता आल्यामुळे वर्गात बोलणीही खावी लागतात.

(घरात टी.व्ही. असल्यास मूल टी.व्ही. जवळ बसून बघते.)

दृष्टीदोषाची लक्षणे

डोळयांवर ताण पडल्याने डोके दुखते. (ही डोकेदुखी कपाळावर दोन्ही डोळयांच्या मधल्या भागात येते). फळयावरील छोटी अक्षरे मुलांना वाचता न येणे. फळा किंवा टी.व्ही., इ. दूरच्या वस्तूंकडे बघताना डोळे बारीक करणे. वाचताना पुस्तक तोंडाजवळ धरणे. जवळचे किंवा लांबचे नीट न दिसणे. जास्त तास वाचन केल्यास डोळयांवर ताण पडणे. तिरळेपणा दिसणे. डोळे किंवा डोकेदुखी. सुईत दोरा ओवताना, धान्य निवडताना त्रास होतो. दृष्टीदोषावरील उपचार
दृष्टीदोषाच्या प्रकाराप्रमाणे योग्य चष्मा वापरावा लागतो.

लहान वयात येणा-या या दृष्टीदोषावर योग्य प्रकारचे भिंग (चष्मा) वापरून दृष्टी सुधारता येते. वयाच्या 15व्या वर्षानंतर यासाठी योग्य कॉन्टॅक्ट लेन्स वापरता येईल. यासाठी नेत्रतज्ज्ञ मदत करतील. कॉन्टॅक्ट लेन्सचे अनेक प्रकार आहेत. यात सॉफ्ट (लवचिक) आणि सेमी सॉफ्ट (अर्ध लवचिक) असे मुख्य प्रकार आहेत. हल्ली यात अगदी अल्प किमतीत महिनाभर वापरून झाल्यावर टाकून देण्याचे (डिसपोझेबल्स) कॉन्टॅक्ट लेन्स उपलब्ध आहेत. लघुदृष्टी किंवा दीर्घदृष्टीवर लेसर किरणोपचार करून बुबुळाचा आकार सूक्ष्मरित्या बदलता येतो. याला 'लेसिक' असे नाव आहे. या उपचाराने चित्रप्रतिमा नेत्रपटलावर आणता येते. यामुळे चष्मा किंवा कॉन्टॅक्ट लेन्सच्या ऐवजी डोळयाचा नंबर दुरुस्त करता येतो. ही शस्त्रक्रिया 18च्या वयानंतरच केली जाते. मात्र ही पध्दत पूर्णपणे निर्धोक नाही. यातून बुबुळाच्या आकार-वक्रतेचा फरक एकदा झाला की तो बदलता येत नाही. या उपचारासाठी खर्चही बराच आहे.

अस्टिगमॅटिझम (बुबुळ वक्रता)

- बुबुळ वक्रतेमधील होणा-या बदलामुळे स्पष्ट दिसत नाही. यात डोळयामध्ये स्पष्ट प्रतिमा कोठेच निर्माण होत नाही. या विकारावर भिंग म्हणजे चष्मा लावावाच लागतो.