AILMENTS

CATARACT

Overview

A cataract is a condition where the lens of the eye loses its clarity, becomes clouded and affects vision. Clouding causes the lens to become yellowish-brown in color.

Lens is a transparent structure that lies behind the iris and the pupil and works like the lens of a camera. It helps focus light on the retina (light sensitive tissue at the back of the eye) to form an image. In normal condition since the lens is clear, you see a sharp image of the objects around you. In cataract, since the lens

is not clear, the images you see are blurred. Most cataracts occur in older people and are age related. Cataract can affect one or both eye but it cannot spread from one eye to another.

Types of Cataract

Apart from age related cataracts, which begin forming when you are in your 40s or 50s and mature by the time you are in your 60s, other types of cataracts are:

  • Congenital cataract: These are seen in new-born or in early childhood, usually in both the eyes. They are often very small in size and do not affect vision. If they start affecting vision, they need to be removed
  • .
  • Secondary cataract: These can form secondary to eye surgeries such as surgery for glaucoma. Cataracts can also form due to other health problems such as diabetes or if you have been using steroids for some time.
  • Traumatic cataract: Some people develop a cataract after an eye injury, sometimes after several years of injury.
  • Radiation cataract: This cataract develops in people exposed to some types of radiation.

Causes

The lens is made of water and protein, with the proteins arranged in such a way that the lens remains clear and allows light to pass through it. As you age, the proteins lose their precise arrangement, clump together and form a small cloudy area on the lens. This reduces the amount of light passing through the lens and affects the sharpness of the image formed. With time the cloudy area enlarges and affects the vision. However the growth of an age-related cataract is slow and may take years and the vision slowly turns dull. Finer detailing as in reading is the last to go. The vision becomes tainted with brown color and you may lose your sense of colors.

Smoking and diabetes can also affect the quality of lens and so also repeated use of steroid eye drops.

Prolonged exposure to UV radiation can also cause cataracts (in people who work outdoors and are exposed to direct sunlight.

Symptoms

The most common symptoms of a cataract are:

  • Cloudy or blurred vision
  • Colors look faded
  • The lamps, headlights etc appear too bright or glare
  • Halo appears around lights
  • Frequently changing eyeglasses or contact lenses as 'power' changes
  • Poor night vision
  • Double vision or diplopia
  • Multiple images (in large cataracts)

Diagnosis

To diagnose whether you have cataract or not, your doctor will conduct a comprehensive eye examination which includes:

When to screen

  • Visual acuity test: Your doctor will ask you to read a chart at different distances to assess how clearly you can see the alphabets.
  • Dilated eye exam or Ophthalmoscopy: Your doctor will put some eye drops into your eyes and ask you to wait for some time with your eyes closed. This will help dilate your pupils. One eye is tested at a time. Your eye specialist will use a special magnifying glass (ophthalmoscope) to look into your eyes to examine the retina and the optic nerve. After the eye examination your near vision may remain blurred for some hours so you will not be able to drive back home.
  • Tonometry: Your doctor will use a special instrument (tonometer) to measure the IOP. Your doctor will put some eye drops to numb the white of your eyes. One eye is tested at a time. The instrument will then be placed on the white of the eye to take the eye pressure. Normal IOP varies between 10 and 21 mm Hg, and is generally around 21mmHg for most eyes.

Treatment

  • Conservative Management In the early stages, cataract can be managed by changing your eyeglasses or lenses and using anti-glare lenses. If you have regular eye exam and your cataract does not mature completely, and your vision can be corrected by glasses or eye lenses, then you may not need any other treatment.
  • Surgery Once the cataract matures completely (your vision interferes with your daily activities such as reading, driving, watching TV etc.), surgery is the only way to restore vision. Sometimes a cataract may be removed earlier if it hampers treatment for other eye disorders such as diabetic retinopathy or age-related macular degeneration.
In cataract surgery, the cloudy lens is replaced by an artificial lens. Your doctor will inform you about the risks and benefits of surgery. You and your doctor can then take a decision regarding surgery. This is not an emergency surgery. You can take your time to decide but it should not be delayed too much. Delaying cataract surgery can cause irreparable damage to eye. Also if you have other eye disorders such as diabetic retinopathy and age-related macular degeneration, then the risks of surgery are higher. If you decide to go ahead with surgery, your doctor will refer you to an eye surgeon. Your surgeon will perform surgery on one eye at a time. So, if you have cataracts in both the eyes, you will need to undergo cataract removal in two sittings, usually four to eight weeks apart. The vision improves after surgery in 90% of cases.

Types of Cataract Surgery

There are two types of cataract surgeries to remove the lens.

  • Phacoemulsification, popularly called phaco: In this surgery, the lens is broken by ultrasound waves and sucked out through a tiny probe
inserted through a small incision on the side of cornea (the clear layer that covers the dome shaped surface of the eye).
  • Extracapsular surgery: In this surgery, your doctor removes the cloudy portion of the lens as a single piece.
  • After the natural lens is removed, it is replaced by an artificial clear plastic lens or intraocular lens (IOL), which then becomes a permanent part of your eye and behaves like the natural lens. If you have an eye condition such that you cannot have an IOL, your doctor will prescribe glasses or soft contact lens with high magnification.

    After surgery, a patch is put on the operated eye. Your surgeon will watch over you for signs of bleeding. Usually most patients can go home the same day.

    Precautions after Cataract Surgery

    There are two types of cataract surgeries to remove the lens.

    • After the surgery, your vision may remain blurred for some days as the operated eye adjusts with the other eye. So, you will not be able to drive home after surgery and may not be able to drive for some days.
    • Your doctor may prescribe some eye drops to put in the eyes. You need to follow your doctor's instructions carefully.
    • You may experience some itch, discharge and increased sensitivity to light for a day or two. If the symptoms persist, immediately inform your doctor.
    • Do not bend to lift objects off the floor.
    • Do not lift heavy weights.
    • You can climb stairs and do light household chores.
    • Women should not resume cooking until allowed by their doctor

    Usually complete healing takes about eight weeks.

    Complications of Cataract Surgery

    • Infection: So it is important to maintain good personal hygiene. Do not touch your eyes. Wash your hands well with soap and water before putting any eye drops. This can become serious and cause vision loss.
    • Bleeding: Hence you may be asked to stop certain medications before surgery as these medications increase the risk of bleeding (e.g. Aspirin).
    • Retinal detachment: this complication is more likely if you have high myopia (near sightedness). If you notice sudden flashes or streaks of light or floaters in the vision, it can be sign of retinal detachment. Inform your doctor immediately.
    • High intraocular pressure
    • Inflammation (pain and redness)
    • Double vision
    • After cataract: The tissue around the IOL may become cloudy months or years after surgery. You will again experience blurred vision. This is usually treated by a laser procedure.
    • Prevention of Cataract

    • Use a broad rim hat and sunglasses if you work outdoors every day
    • Do not smoke
    • Keep diabetes under control
    • Have regular eye exams
    • Eat green leafy vegetables, fruits and other anti-oxidant rich foods.

    External Links/References