الفهرس 
Adrenergic receptor antagonists and the irisOnly 14 pages are availabe for public view
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Abstract
Intra-operative floppy iris syndrome is a newly recognized syndrome characterized by a triad of signs:
1. A floppy iris that billows in response to normal irrigation currents in the anterior chamber.
2. A marked propensity for the iris to prolapse to the phaco and sideport incisions.
3. Progressive pupillary constriction during surgery.
Two additional characteristics often accompany the IFIS-poor preoperative pupil dilation and elasticity of the pupil margin.
All these elements make cataract surgery more difficult and increase the risk for complications.
The occurrence of intra-operative floppy iris syndrome has been connected with the use of tamsulosin in several case reports and observational studies.
Tamsulosin is an antagonist of alpha1A adrenoceptors and is one of the most commonly prescribed agents to improve urinary outflow in men with benign prostatic hypertrophy.
Alpha-1 adrenergic receptor blockers such as tamsulosin competitively inhibit the sympathetic autonomic nervous system, resulting in relaxation of the smooth muscles in peripheral blood vessels and in the bladder neck and prostatic urethra.
Tamsulosin has 24-fold greater affinity for -1A than -1B receptors.
In addition to blocking the -1A receptors in the prostate, tamsulosin selectively blocks the iris dilator muscle in which the same receptor subtype dominates.
Tamsulosin has a long half-life and relatively constant receptor blockade could result in a form of disuse atrophy of the iris dilator smooth muscle. This might explain not only the poor pupil dilation in patients receiving tamsulosin but also the flaccid and floppy iris stroma observed even after the medication is stopped.
The 3 characteristics of IFIS increase the risk for operative complications. They include minor compli-cations, such as:
1. Focal iris stromal atrophy.
2. Transient postoperative ocular hypertension requiring treatment.
And major complications, such as:
1. Major iris trauma (laceration, dialysis, hemorrhage).
2. Posterior capsule break with vitreous loss.
3. Zonular dehiscence.
4. Retained lens fragments.
5. Postoperative cystoid macular edema.
To avoid these complications a good history should be taken about the use of tamsulosin for BPH.
Preoperative identification of patients on 1-blockers is important as complications can be reduced significantly by using appropriate strategies to deal with this condition.
One should consider temporarily stopping Flomax for 1 to 2 weeks prior to surgery.
Controversy on stopping flomax. It is also important that patients suffering from benign prostatic hyperplasia do not stop using 1A-blocker, especially when preoperative atropine is used, as acute urinary retention may ensue.
Shugar reported the combined use of presurgical topical atropine sulfate 1 %( 3 times daily for 2 days preoperatively) with intraoperative 1:2500 epinephrine hydrochloride as a technique for preventing manifest-tations of IFIS during cataract surgery.
A letter by Shugar effectively demonstrates the safety and efficacy of the intracameral use of preservative-free buffered epinephrine for pupil management in patients with IFIS.
Shugar’s experience suggests that the weakened and possibly denervated dilator muscle of the iris can be stimulated by epinephrine hydrochloride at a 1:2500 dilution; in turn, as Shugar reports, the dilated pupil provides a stable iris and essentially normal operative course during cataract surgery.
However, it is seemingly logical to combine Shugar’s concept of super stimulation of the dilator by intracameral epinephrine with use of atropine iridoplegia, as they are synergistic.
The IFIS is best managed surgically with devices or viscoelastic agents that mechanically hold the pupil open and restrain the iris from prolapsing.
Of all the different viscoelastics, Healon5 (which is extremely viscous and highly retentive) is best able to viscodilate the pupil and is uniquely capable of blocking the iris from prolapsing to the incisions.
Surgeons, however, must use low aspiration flow and vacuum settings (e.g., <22mL/min and <200mmHg respectively) to delay the viscoelastic’s evacuation from the anterior chamber. As the pupil constricts during phacoemulsification, one can repeatedly inject Healon5.
Iris retractors or a pupil expansion ring are the most reliable means of maintaining a safe pupillary diameter during surgery. These devices are costly and time-consuming to insert, and the placement of expansion rings is difficult if the pupil is small or the anterior chamber is shallow. It is safer to insert these devices before, rather than after, initiating the capsulorhexis.
As suggested by Thomas Oetting, one should place iris retractors in a diamond configuration. Doing so requires a separate stab incision just posterior to the clear corneal incision, but it maximizes surgical exposure immediately in front of the incision. This subincisional retractor also draws the iris posteriorly, unlike laterally situated iris hooks (square configuration), which tent the iris up anteriorly in front of the phaco incision.
Stopping Flomax preoperatively should not be necessary if one plans to use iris hooks controversy on stopping flomax.