EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: http://digital.eyeworld.org/i/295674
T wo new studies on intraop- erative floppy iris syndrome (IFIS) that I was involved with will be published this month, and they have prompted a renewed joint effort by ASCRS and AAO to educate prescrib- ing physicians about the potential adverse effects of systemic α1-antag- onists on cataract surgery. The first study (Chang DF, Campbell JR, Colin J, Schweitzer C. Prospective masked comparison of intraopera- tive floppy iris syndrome severity with tamsulosin versus alfuzosin. Ophthalmology 2014;121 (April):829– 834) adds to the mounting evidence that tamsulosin creates a higher risk of severe IFIS compared to non-selective α1-antagonists. Of the α1 receptor subtypes, the α1-A receptor predominates in both the iris dilator and prostatic smooth muscle. Among α1-antagonists pre- scribed for benign prostatic hyper- plasia (BPH), only tamsulosin and silodosin are subtype selective and demonstrate the highest affinity for the α1-A receptor. Such receptor uroselectivity reduces the risk of postural hypotension due to block- ade of the α1-B receptors in vascular smooth muscle. All of the α1-antag- onists can impair pupil dilation and cause IFIS. However, a number of prospective and retrospective studies have suggested that the frequency and severity of IFIS is greater in pa- tients taking tamsulosin compared to the non-selective α1-antagonists, such as terazosin, doxazosin, and alfuzosin. 1,2 A 2011 meta-analysis of 17 published studies reported that tamsulosin had a 40-fold higher pooled odds ratio for IFIS compared to alfuzosin and terazosin. 2 In vitro experiments demonstrated that tamsulosin is a much stronger antagonist of rabbit iris dilator muscle contraction than alfuzosin. 3 April 2014 by David F. Chang, MD New studies on IFIS prompt ASCRS/AAO educational update for prescribing physicians CAUTION: Federal (USA) law restricts this device to the sale by or on the order of a phy- sician. INDICATIONS: The AcrySof ® IQ Toric posterior chamber intraocular lenses are intended for primary implantation in the capsular bag of the eye for visual correction of aphakia and pre-existing corneal astigmatism second- ary to removal of a cataractous lens in adult patients with or without presbyopia, who de- sire improved uncorrected distance vision, reduction of residual refractive cylinder and increased spectacle independence for dis- tance vision. WARNING/PRECAUTION: Careful preopera- tive evaluation and sound clinical judgment should be used by the surgeon to decide the risk/beneﬁt ratio before implanting a lens in a patient with any of the conditions described in the Directions for Use labeling. Toric IOLs should not be implanted if the posterior capsule is ruptured, if the zonules are dam- aged, or if a primary posterior capsulotomy is planned. Rotation can reduce astigmatic cor- rection; if necessary lens repositioning should occur as early as possible prior to lens encap- sulation. All viscoelastics should be removed from both the anterior and posterior sides of the lens; residual viscoelastics may allow the lens to rotate. Optical theory suggests that high astigmatic patients (i.e. > 2.5 D) may experience spatial distortions. Possible toric IOL related factors may include residual cylindrical error or axis misalignments. Prior to surgery, physicians should provide prospective patients with a copy of the Patient Information Brochure available from Alcon for this product inform- ing them of possible risks and beneﬁts as- sociated with the AcrySof ® IQ Toric Cylinder Power IOLs. Studies have shown that color vision discrim- ination is not adversely affected in individu- als with the AcrySof ® Natural IOL and normal color vision. The effect on vision of the Ac- rySof ® Natural IOL in subjects with hereditary color vision defects and acquired color vision defects secondary to ocular disease (e.g., glaucoma, diabetic retinopathy, chronic uve- itis, and other retinal or optic nerve diseases) has not been studied. Do not resterilize; do not store over 45° C; use only sterile irrigating solutions such as BSS ® or BSS PLUS ® Sterile Intraocular Irrigating Solutions. ATTENTION: Reference the Directions for Use labeling for a complete listing of indications, warnings and precautions. © 2013 Novartis 2/13 TOR13020JAD www.AcrySofIQTORIC.com 12:40 PM continued on page 11 Finally, a 2008 survey of ASCRS members indicated that 90% of respondents (with enough personal experience) felt that IFIS was more common with tamsulosin than with non-selective α1-antagonists. 4 Because many of the prior studies were retrospective and not masked, my co-investigators and I decided to conduct a multicenter prospective, masked, controlled comparison of tamsulosin and alfu- zosin—the two α1-antagonists with the fewest reported cardiovascular adverse events. Undoubtedly one of the reasons that tamsulosin became the most prescribed treatment for BPH was its theoretical uroselectivity and reduced incidence of postural hypotension. Although it is a non- selective α1-antagonist, alfuzosin is often referred to as "clinically urose- lective." The reduction in postural hypotension with alfuzosin is not due to receptor specificity, but rather to pill reformulation to slow release of the molecule in the GI tract. The study was conducted in France, where alfuzosin is more commonly prescribed than in most other countries. Sanofi Aventis, the manufacturer of alfuzosin (Uroxatral), is a French pharmaceuti- cal company. Eight study surgeons from four sites enrolled 113 consec- utive patients taking either tamsu- losin or alfuzosin. Each time a study patient was enrolled, a control patient with no prior history of α1- antagonist use was enrolled by the same cataract surgeon on the same day. All 226 cases were videotaped and two masked ophthalmologists (John Campbell, MD, and myself) then graded every video for the presence and severity of IFIS. Severe IFIS—defined as iris billowing and prolapse with ≥2 mm of pupil con- striction—was more common with either α1-antagonist compared to control eyes. However, severe IFIS was noted in 34.3% (24/70) of the tamsulosin eyes and 16.3% (7/43) of the alfuzosin eyes (P<0.05). Therefore, if an α1-antagonist with a lower risk of cardiovascular side effects is indicated, patients with cataracts may want to try alfuzosin first. Unfortunately for cataract surgeons, tamsulosin continues to be the most frequently prescribed medication for BPH, and its use will surely rise now that it is generic in the United States. As an alternative to α1-antagonists, 5-α reductase in- hibitors (dutasteride and finasteride) are also effective and approved as medical monotherapy of BPH. However, a large multinational ran- domized trial demonstrated that the combination of dutasteride and tamsulosin was superior to either drug alone in the prevention of BPH progression. 5 Ophthalmologists must therefore recognize that Jalyn is the brand name for this specific drug combination. Finally, silodosin (Rapaflo) is the most recent α1- antagonist to be approved for BPH and most resembles tamsulosin in its α1-A receptor subtype specificity. The second study (Doss EL, Potter MB, Chang DF. Primary care physicians still lack awareness of IFIS. J Cataract Refract Surg 2014;40 (April):685–686) was a survey of pri- mary care physicians from the Uni- versity of California, San Francisco (UCSF) designed to assess their α1- antagonist prescribing patterns and their awareness of IFIS. A brief questionnaire was emailed to 350 healthcare providers in the UCSF Collaborative Research Network and 133 responded. Forty percent initiate BPH medical treatment at least twice a month. Overall, only 35% were aware that α1-antagonists can cause cataract surgical complications; only half (17%) factored this into treat- ment considerations. Less than 10% inquire about a history of cataract prior to initiating α1-antagonist treatment, and only 31% regularly advise patients to inform their ophthalmologist about taking these drugs. Most respondents (96%) desired more information on this topic. Based on the new information from these two studies, the ASCRS Cataract Clinical Committee decided that a renewed effort to educate prescribing physicians treating BPH should be initiated. We have collab- orated with AAO in writing a joint educational document that was formally issued in April. This new document updates the 2008 joint ASCRS/AAO IFIS educational state- ment, which asked prescribing physicians to consider 1) involving the ophthalmologist prior to initiating α1-antagonists in patients with known cataracts and 2) reminding patients taking