Cataract surgeons were
much relieved when they discovered what was causing a complication called
intraoperative floppy iris syndrome (IFIS). In 2005, researchers from
California, David Chang and John Campbell reported that the drug tamsulosin, an
alpha-adrenergic blocking agent, and other alpha blockers can cause this
syndrome during a cataract surgery.
A Canadian study of
100,000 men undergoing cataract surgery, found that patients taking the drug
had 2.3 times the risk of severe postoperative complications. The postoperative
complications ranged from severe iris defects such as pupil deformity,
photophobia, and glare to retinal detachment and lost lens fragments.
generally prescribed to patients suffering from benign prostate
or in women with urinary incontinence and those patients
with high blood
Dr. Chang and his team
have been conducting researches on alpha-adregenic blockers and IFIS since
their discovery of the cause of complication. Their newest research indicated
that severe IFIS was more likely with tamsulosin than alfuzosin. So, they
recommended cataract patients to try alfuzosin first to avoid this eye
What is intraoperative floppy iris syndrome?
iris syndrome is a condition that results in loss of iris (colored part of the
eye) muscle tone that occurs during cataract surgery. It is characterized by
A floppy or flaccid iris that billows when the eye is irrigated during cataract
Prolapse of iris at the main point or side port of incision (where the surgeon
makes the incision to break down the cloudy lens).
Progressive pupil constriction that makes it difficult for the surgeon to
proceed with the extraction of cataract. How the cataract surgery is
During a cataract
, surgeons use an ultrasonic device to break up (emulsify) and
then remove the cloudy lens (cataract) from the eye to improve vision. This
process is known as phacoemulsification.
Before making the
incision, the surgeon anesthetizes the area behind the eyeball. Then they apply
pressure on the eyeball to check if there is any bleeding. This pressure also
decreases intraocular pressure thus lowering the chances of complications.
The surgeon then makes
a tiny circular incision in the membrane that surrounds the cataract. A water
stream or irrigation that contains hormone norepinephrine is then done to free
the cataract from the cortex of the eye. The ultrasonic device then breaks down
the cataract and then it is removed by suction. What causes intraoperative
floppy iris syndrome
To understand what
causes IFIS, we should know what adrenergic receptors are and how they
are specialized proteins attached to the cell membrane that
communicate between the cell and the 'outside world'. Hormones, epinephrine and
norepinephrine in this case, attach to these receptors (binding sites) and
bring about a change in the way the cells in the sympathetic nervous system
functions. One of the functions of sympathetic nervous system is the
fight-or-flight response that helps you respond to dangerous situation. This
response is characterized by body changes such as dilating pupil, mobilizing energy, and diverting blood flow to the
skeletal muscles so that you can run or fight
. Adrenergic receptors can be
alpha or beta depending on their function. Here we are concerned about alpha
adrenergic receptors in which the hormone norepinephrine attaches.
Now, alpha adrenergic blocking agents are
chemicals that bind to and inhibit adrenergic receptors from functioning
that is, they do the opposite of what alpha adrenergic receptors do.
Alpha blockers relax
certain muscles by preventing the hormone norepinephrine from tightening the
walls of the arteries and veins, thus keeping small blood vessels to remain
open. This is the reason why it is commonly used in hypertension. These drugs
are also used in prostate problems to help improve urine flow by relaxing the
concerned muscles. Unfortunately, the same drugs, especially tamsulosin and
alfuzosin, increase the risk of complications such as IFIS in the cataract
surgery. This is how:
relax the smooth dilatory muscles of the iris thus
preventing the pupils from dilating. Unfortunately, this is sort of a permanent
The relaxing of the muscles also causes the iris to billow and prolapse (fall
out of place).
Muscle relaxing is again responsible for vitreous prolapse. Vitreous is the
jelly-like substance that makes up the bulk of the eye and this is the area
through which light passes.
Why tamsulosin? That's
because this drug is highly selective for the alpha-1 receptor subtype, the
blocking of which causes IFIS.
The saving grace is
now that ophthalmologists can now anticipate IFIS by finding out the past or
current use of alpha blockers by the patients and then decide on alternative