UNDERSTANDING CATARACT AND ITS IMPACT ON VISION

A cataract is caused by the clouding of the normally clear natural lens of the eyes. This natural lens helps focus light onto the retina. For a person with cataracts, the clouding or fogginess of the lens causes the light to be blocked or scattered resulting in an image to become blurred or distorted. In its early stages, the cloudiness may affect only a small part of the lens and it may not disturb your vision much. Clouded vision may make night driving difficult because of increased glare, difficulty in reading, recognizing faces etc. 

As the density of the cloudiness of the lens increases, the vision becomes more blurred and results in general dimming of vision. This will ultimately progress to almost complete loss of vision if left untreated.

SYMPTOMS / VISION PROBLEMS WITH CATARACT:

If you are developing cataracts, you may notice some of the following symptoms:

• Clouded, blurred or dim vision
• Frequent changes in eyeglass or contact lens prescription
• Increasing difficulty with vision at night such as with night driving
• Difficulty in reading in dim light
• Sensitivity to light and glare or haloes around lights
• The need for brighter light for reading and other activities
• Dullness or fading of colours
• Double vision that is noticeable when looking out of just one eye
• Problems with light. These can include headlights that seem too bright at night; glare from lamps or very bright sunlight; or a halo around lights.
• Poor night vision.
• Double or multiple vision (this symptom often goes away as the cataract grows).

Any of these symptoms can also be a sign of other eye problems. If you have any of these symptoms, check with your eye care professional. 

WHEN TO SEE A DOCTOR

Make an appointment for an eye exam if you notice any changes in your vision. At first, stronger lighting and change in eyeglasses can help you deal with cataracts. But if impaired vision interferes with your usual activities, you might need cataract surgery. 

 If you develop sudden vision changes, such as double vision or flashes of light, sudden eye pain, or sudden headache, see your doctor right away.

RISK FACTORS FOR DEVELOPING CATARACTS

Cataracts most commonly occur due to degenerating changes as part of ageing process, although it can affect younger people and rarely, new-borns. Contrary to popular belief, Cataract is not caused by eye strain or reading too much. There might be other causes of cataracts such as:

• Medical Conditions like Diabetes, high blood pressure, 
• Life-Style risk factors like smoking, excessive alcohol consumption, obesity,
• Previous eye injury, eye surgery or eye inflammation
• Certain Medications specially steroids
• Long-term exposure to ultraviolet light, too much of sunlight exposure
• Exposure to radiation
• Genetic factors may increase your chances of developing cataract

TYPES OF CATARACTS:

Though the cataracts essentially develop in the natural lens of the eye, but their point of origin inside the different parts of the lens will determine the progression of the symptoms and how soon the cataractous lens will need to be removed.

• Cataracts affecting the center of the lens (nuclear cataracts). A nuclear cataract may at first cause more nearsightedness or even a temporary improvement in your reading vision. But with time, the lens gradually turns more densely yellow and further clouds your vision.

As the cataract slowly progresses, the lens may even turn brown. Advanced yellowing or browning of the lens can lead to difficulty distinguishing between shades of color. Though the symptoms will remain less severe for a very long time but as they are a hard variety of cataract, so early removal is advised to decrease the risk of complications during surgery. The amount of energy delivered by the Phaco machine to break up this type of Cataract is higher and exposes the delicate eye structures to stronger energy waves. 

• Cataracts that affect the edges of the lens (cortical cataracts). A cortical cataract begins as whitish, wedge-shaped opacities or streaks on the outer edge of the lens cortex. As it slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens.
• Cataracts that affect the back of the lens (posterior subcapsular cataracts). A posterior subcapsular cataract starts as a small, opaque area that usually forms near the back of the lens, right in the path of light. A posterior subcapsular cataract often interferes with your reading vision, reduces your vision in bright light, and causes glare or halos around lights at night. These types of cataracts tend to progress faster than the other types. Also, they produce disproportionately more visual disturbances even in early stages of their development and may require early removal.
• Cataracts you’re born with (congenital cataracts). Some children are born with cataracts or develop them during childhood. These cataracts may be genetic, or associated with an intrauterine infection or trauma. These cataracts usually interfere with the development of vision at the brain level and if treatment is delayed, it will cause irreversible loss of vision (lazy eye).

These cataracts also may be due to certain conditions, such as myotonic dystrophy, galactosemia, neurofibromatosis type 2 or rubella. Congenital cataracts don’t always affect vision, but if they do they’re usually removed soon after detection.

PREVENTION

No studies have proved how to prevent cataracts or slow the progression of cataracts. But doctors think several strategies may be helpful, including:

• Have regular eye examinations. Eye examinations can help detect cataracts and other eye problems at their earliest stages. Ask your doctor how often you should have an eye examination.
• Quit smoking. Ask your doctor for suggestions about how to stop smoking. Medications, counselling and other strategies are available to help you.
• Manage other health problems. Follow your treatment plan if you have diabetes or other medical conditions that can increase your risk of cataracts.
• Choose a healthy diet that includes plenty of fruits and vegetables. Adding a variety of colourful fruits and vegetables to your diet ensures that you’re getting many vitamins and nutrients. Fruits and vegetables have many antioxidants, which help maintain the health of your eyes. Studies haven’t proved that antioxidants in pill form can prevent cataracts. But, a large population study recently showed that a healthy diet rich in vitamins and minerals was associated with a reduced risk of developing cataracts.
• Wear sunglasses. Ultraviolet light from the sun may contribute to the development of cataracts. Wear sunglasses that block ultraviolet B (UVB) rays when you’re outdoors.
• Reduce alcohol use. Excessive alcohol use can increase the risk of cataracts.

DIAGNOSIS OF CATARACT

To determine whether you have a cataract, your doctor will review your medical history and symptoms, and perform an eye examination. Your doctor may conduct several tests, including:

• Visual acuity test. A visual acuity test uses an eye chart to measure how well you can read a series of letters. Your eyes are tested one at a time, while the other eye is covered. Using a chart or a viewing device with progressively smaller letters, your eye doctor determines if you have 20/20 vision or if your vision shows signs of impairment.
• Slit-lamp examination. A slit lamp allows your eye doctor to see the structures at the front of your eye under magnification. The microscope is called a slit lamp because it uses an intense line of light, a slit, to illuminate your cornea, iris, lens, and the space between your iris and cornea. The slit allows your doctor to view these structures in small sections, which makes it easier to detect any tiny abnormalities.
• Retinal exam. To prepare for a retinal exam, your eye doctor puts drops in your eyes to open your pupils wide (dilate). This makes it easier to examine the back of your eyes (retina). Using a slit lamp or a special device called an ophthalmoscope, your eye doctor can examine your lens for signs of a cataract.