• A cataract is a clouding of the normally clear lens of your eye
• A cataract is a dense, cloudy area that forms in the lens of the
eye. A cataract begins when proteins in the eye form clumps
that prevent the lens from sending clear images to the retina.
The retina works by converting the light that comes through the
lens into signals. It sends the signals to the optic nerve, which
carries them to the brain.
• Increasing age (protein break in lens)
• Excessive exposure to sunlight
• High blood pressure
• Previous eye injury or inflammation
• Previous eye surgery
• Prolonged use of corticosteroid medications
• Drinking excessive amounts of alcohol
• an overproduction of oxidants, which are oxygen molecules that
have been chemically altered due to normal daily life
• ultraviolet radiation
• Nutritional deficiency – vitamin - c
Cataracts affecting the center of the
lens (nuclear cataracts).
• A nuclear cataract is caused by central opacity in
the lens and has a substantial genetic component.
It is associated with myopia (ie, nearsightedness),
which worsens when the cataract progresses.
• But with time, the lens gradually turns more
densely yellow and may even turn brown.
Advanced yellowing or browning of the lens can
lead to difficulty distinguishing between shades of
color and clouds your vision.
Cataracts that affect the edges of the
lens (cortical cataracts).
• A cataract in the equator or periphery of the cortex
does not interfere with the passage of light through the
center of the lens and has little effect on vision.
• 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.
• Vision is worse in very bright light. People with the
highest levels of sunlight exposure have twice the risk
of developing cortical cataracts
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.
• Some people are born with cataracts or
develop them during childhood. These cataracts
may be genetic, or associated with an
intrauterine infection or trauma.
• Painless Clouded, blurred or dim vision
• Increasing difficulty with vision at night
• Sensitivity to light and glare
• Need for brighter light for reading and other activities
• Seeing "halos" around lights
• Frequent changes in eyeglass or contact lens prescription
• Fading or yellowing of colors
• Double vision in a single eye
• color shift (the aging lens become progressively more
absorbent at the blue end of the spectrum)
• brunescens (color values shift to yellow-brown)
• Phacoemulsification: your surgeon makes a tiny incision in the
front of your eye (cornea) Phacoemulsification is a modern
cataract surgery in which the eye's internal lens is emulsified
(brokened)with an ultrasonic handpiece and aspirated from the
eye. Aspirated fluids are replaced with irrigation of balanced
salt solution to maintain the anterior chamber.
Extracapsular Cataract Extraction
• larger incision is made and remove the front
capsule of the lens, cortex, lens nucleus and
the cloudy lens comprising the cataract. The
very back capsule (Posterior) of your lens is
left in place to serve as a place for the artificial
lens to rest. With the larger incision, stitches
• Involves the removal of the whole of the lens
as well as capsule. The procedure has a
relatively high rate of complications due to the
large incision required and pressure placed on
the vitreous body. May be retinal detachment
• After removal of the crystalline lens, the patient
is referred to as aphakic (ie, without lens).
lens replacement options:
• Aphakic eyeglasses
• Contact lenses
• IOL implants.
• although effective, are rarely used. Objects are magnified by
25%, making them appear closer than they actually are. This
magnification creates distortion. Peripheral vision is also
limited, and binocular vision (ie, ability of both eyes to focus
on one object and fuse the two images into one) is impossible
if the other eye is phakic (normal).
• provide patients with almost normal vision,
but because contact lenses need to be
removed occasionally, the patient also needs a
pair of aphakic glasses. Contact lenses are not
advised for patients who have difficulty
inserting, removing, and cleaning them.
Frequent handling and improper disinfection
increase the risk of infection.
• Insertion of IOLs during cataract surgery is the
usual approach to lens replacement. After
cataract extraction,or phacoemulsification,
the surgeon implants an IOL.
• IOL implantation is contraindicated in patients
with recurrent uveitis, proliferative diabetic
retinopathy, neovascular glaucoma