Frequently
Asked Questions on Cataract
(21.09.2013)
http://en.wikipedia.org/wiki/Cataract
http://www.nei.nih.gov/health/eyediagram/eyeimages2.asp
What is Cataract?
Cataract is clouding of lens of the eye. Symptoms of cataract
include blurry vision, faded colours, glare, poor night vision, multiple
images and frequent changes in eye glasses. 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 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. However as we age some of the protein may clump together and
start to cloud a small area of the lens. This is cataract. Over time, the cataract may grow larger and cloud more of the
lens, making it harder to see. Clouding of the lens can occur
only in the nucleus, in which case the term nuclear cataract or nuclear
sclerosis is used. If the clouding occurs in the lens cortex only, the
cataract is termed a cortical cataract. If the loss of clarity of the
lens is primarily in the capsule, the term subcapsular cataract is used.
What are
causes of cataract?
The major
cause of cataract is aging. While it is possible to have cataract in 40s
and 50s these cataracts are small and do not affect vision significantly. It is
after 60 that cataract affects vision significantly. Medical Conditions like
diabetes and hypertension can exacerbate and hasten cataracts. Life style
choices like smoking and alcohol can also significantly increase cataract
chances as can perhaps exposure to sunlight. Radiation, trauma and skin
diseases such as eczema can increase chances of cataract. Some drugs such as
corticosteroids can induce cataracts.
What can
you do to prevent Cataracts?
While cataracts cannot be prevented, you can
reduce chances of cataract or delay onset of cataract by healthy choices such
as stopping smoking and reducing alcohol. Wearing sunglasses to reduce impact
of radiation also seems a sensible choice. A diet with significant anti
oxidants such as green leafy vegetables also reduces chances of cataract.
How are
cataracts treated?
While early cataracts can be treated by eye
glasses, surgery is the only effective way of treating
cataracts. Cataract surgery involves removing old damaged lens and
replacing it with new lens. There are
two types of surgery for removing old lens phacoemulsification and
extracapsular. In Phacoemulsification, a small incision is made into cornea
(please check diagram above), A small probe is inserted that emits sound waves
that softens breaks up the lens, so that it can be removed by suction. In
extracapsular surgery, the doctor makes a longer incision on side of cornea and
removes the cloudy core of lens in one piece. The rest of lens is removed by
suction.
After the natural lens is removed, it is replaced by
Intraocular lens (IOL), a clear plastic lens that becomes permanent part of eye and
focuses light onto retina improving vision. For those who cannot have IOL due
to eye disease or surgery problems, a soft contact lens may be suggested. Most
of these surgeries are performed on out patient basis. Patients can start
moving within a day. Post operative care includes, some eye drops and precautions
such as not lifting heavy objects. One is also advised not rubbing the eye or
pressing the eye.
Cataract surgery is usually safe with more than 90% of
patients experiencing improvement in vision. Rare complications include retinal
detachment occurring amoung 0.4% of patients within 5.5 years (almost 2 fold
increase). Endophthalmitis occurs in 1 out of 1000 patients.
Inflammation of cornea(please see diagam) is more common occurring in 1 out 100
patients, but usually treatable with eye drops. Sometimes the eye tissue that encloses the IOL
becomes cloudy and may blur your vision. This condition is called an
after-cataract. An after-cataract is treated with a laser in a procedure called
YAG laser capsulotomy. It is painless and rarely results in increased eye
pressure or other eye problems. As a precaution, your doctor may give you
eyedrops to lower your eye pressure before or after the procedure.