is diabetic retinopathy?
retinopathy is degeneration of the retina as a result of
diabetes induced changes in retinal vasculature. It affects
over half of diabetics and advances with age. As the diabetes
progresses, the capillaries of the eye swell and leak. Abnormal
blood vessels are formed, a process called neovascularization.
These blood vessels do not supply the retina with adequate
oxygen and bleed into the vitrious humor. Some people also
develop a macular edema which is swelling of the macula
caused by the fluid and lipids that leak onto it from the
does diabetic retinopathy affect vision?
early warning sign is blurring of vision and a loss of acuity.
Blindness can result from this if not treated. The retinal
bleeding can interfere with the passage of light to the
retina or retinal detachment can occur. This causes the
photoreceptors to separate from the RPE (retinal pigment
epithileum) and die, causing blindness wherever detachment
first step in treatment for diabetic retinopathy is controlling
the diabetes. This involves stablizing blood sugar levels.
If neovascularization has already occured, laser photocoagulation
can be used to seal off the leaking blood vessels. Panretinal
photocoagulation is another treatment which uses a laser
to create hundreds of small holes in the retina to reduce
its metabolic needs. This reduces the retina's oxygen requirements
and causes the blood vessels to dry up. A vitrectomy can
be performed if the blood vessels have invaded the vitreous.
This procedure uses a hollow needle to eliminate the blood
and vitreous humor within the eye. The area left empty is
then filled with a saline solution to restore clarity of
are changes in the lens of the eye that decrease its ability
to transmit light and to deliver a clear image to the retina.
They can occur alone or as a secondary consequence of other
eye problems or diseases such as retinitis pigmentosa, ocular
contusion, smoking, diabetes, injury, complications of eye
surgery, or systematic use of steroids. Cataracts are usually
identified by their location in the lens, or by their general
cause. The major types of cataract identified by their origin
or appearance during development are:
/ Infantile: present in the first year of life
caused by an eye disease
caused by an injury
occur in later adult life.
most common type of cataracts are senile cataracts. They
develop in 75% of people over 65 years of age and in 95%
of those over 85 years of age.
do cataracts affect vision?
scattering and reducing the light reaching the retina, cataracts
reduce image luminance and contrast. Some common symptoms
of cataract include a reduction in acuity, night vision,
light sensitivity, and color discrimination, especially
for blues. Blurring and yellowing of vision, and increased
sensitivity to glare are also common. During old age the
hardening of the lens associated with cataract can induce
myopia, allowing an eldery observer to regain the ability
to read up close. This phenomenon is called second
photos below simulate the possible effects of a cataract
on vision. Notice the decreased illumination, acuity,
and color saturation in the view through a cataract compared
to the view without a cataract.
is the only treatment for cataracts. Nowadays, cataract
is usually treated using the technique of phacoemulsification,
in which the lens is broken up using an ultrasonic vibrating
probe (40Hz) and aspirated through a small incision at the
margin of the eye. A small, plastic intraocular lens (IOL)
is then inseted into the eye to replace the refractive power
lost by the removal of the lens. Some cataract patients
experience blurry vision after surgery due to scar tissue
that results from the surgery. For most, however, cataract
surgery is highly effective. About 95% of post-operative
patients have excellent vision, with improved acuity, color
discrimination, and sensitivity in low light.
The link that follows (with permission of the author), provides more detailed information on cataracts, cataract surgery and cataract care:
Information on Cataracts
| Cézanne | Degas
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