In most cases,
refractive surgery of all kinds should be avoided in a patient
with diabetic retinopathy. conventional or custom
wavefront
Lasik,
Epi-Lasik, and
All-Laser Lasik require a
microkeratome that increases
IOP when affixed to the eye with suction.
PRK and
LASEK do not require this dramatic rise in IOP and may (emphasis
on "may") be appropriate in some cases. Any patient with diabetic
retinopathy should be fully evaluated by a retina specialist before
considering refractive surgery.
Diabetic retinopathy damages
the tiny blood vessels that supply the
retina (the light-sensitive nerve tissue at the back of the
eye that transmits visual images to the brain). In the early stages
of this disease-called non-proliferative or "background" retinopathy,
the retinal vessels weaken and develop bulges (microaneurysms) that
may leak blood (hemorrhages) or fluid (exudates) into the surrounding
tissue. Vision is rarely affected during this stage of retinopathy.
If proliferative retinopathy
is left untreated, about half of those who have it will become blind
within five years, compared to just 5% of those who receive treatment.
Yet only half of all diabetic patients in the U.S. have a yearly
eye examination by an
ophthalmologist , even though regular eye exams offer the best
chance of catching retinopathy at its treatable stage.
Proliferative retinopathy,
a later stage of the disease, involves the growth of fragile new
blood vessels on the retina and into the
vitreous -- a jelly-like substance inside the eyeball. These
vessels can rupture and release blood into the vitreous, which causes
blurred vision or temporary blindness. The scar tissue that may
subsequently develop can pull on the retina and cause retinal detachment,
which may lead to permanent vision loss. Macular edema - swelling
due to fluid accumulating around the macular, the part of the retina
most crucial for fine vision - may also occur.
Much later on, however,
fragile new blood vessels may begin to grow on the retina and into
the vitreous (the jelly-like substance inside the back of the eye).
These abnormal vessels are prone to rupture and bleed into the vitreous,
causing blurred vision or temporary blindness. As a result, the
formation of scar tissue can eventually pull the retina away from
the back of the eye (retinal detachment), and lead to permanent
vision loss. In addition, at any stage of retinopathy, severe blurring
of vision may occur if fluid accumulates around the
macula-the most sensitive portion of the retina that is crucial
for seeing fine detail-a condition called macular edema.
Lowering blood glucose levels
can significantly reduce the risk of developing retinopathy or slow
its progression, even in people who have had diabetes for a number
of years, according to a recent study.
This study involved 834
people who were over 30 when they developed diabetes and who were,
on average, 65 at the start of the study. A glycohemoglobin test
was performed at the start of the study and at a four-year follow-up.
Eye exams were conducted at both these points in the study and then
again at a ten-year follow-up. In non-insulin treated participants,
those with the highest levels of glycohemoglobin at the start of
the study had a nearly three-fold greater chance of having developed
retinopathy after ten years than those with the lowest levels. Among
those who already showed evidence of retinopathy at the start of
the study, elevated glycohemoglobin resulted in a 4 times greater
risk of retinopathy progression and a 14 times greater risk of proliferative
retinopathy. In people taking insulin, those with the highest glycohemoglobin
levels had a 90% increased risk of developing retinopathy than those
with the lowest levels; patients with the highest levels also had
twice the risk of retinopathy progression and triple the risk of
proliferative retinopathy.
The researchers concluded
that reduction in hyperglycemia at any time in the course of diabetes
will result in a significant decrease in the long-term incidence
and progression of retinopathy and in the development of visual
loss.
