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EW CATARACT 29 December 2015 refractive surgery, the said ratio must change too. The solution of the problem is an additional mea- surement of posterior corneal cur- vature, e.g., by Scheimpflug or OCT techniques." Meanwhile, ray tracing software exists that allows accurate no-history IOL power calculation, even in cases like decentered radial keratotomy with residual corneal astigmatism. Experts worldwide are investi- gating the many applications and benefits of ray tracing—often direct- ly pertaining to IOLs themselves. For example, Korean researchers compared the astigmatic power of various toric IOLs using the iTrace (Tracey Technologies, Houston) toric calculator. Calculations were based on the keratometric values ascer- tained by iTrace ray tracing wave- front aberrometry or iTrace simulat- ed keratometry, automatically. The findings, published in the July 2015 issue of Yonsei Medical Journal, demonstrated that with "the higher calculated astigmatic power values, the values obtained from the iTrace toric calculator using kerato- metric values obtained from iTrace ray tracing wavefront aberrometry or iTrace simulated keratometry showed fair to moderate agreement with those from the other calculator- keratometry pairs." Further, the accuracy of Scheimpflug-based ray tracing IOL power calculations for normal eyes with cataracts works just as well as other calculations, if not better, according to Japanese researchers in the November 2013 issue of Acta Ophthalmologica. In this study, the investigators predicted the postop- erative refractions using different methods—ray tracing calculation using Scheimpflug imaging and Placido topography, ray tracing calculations using Placido topogra- phy, and the SRK/T formula using autokeratometry—and compared the results. "The use of Scheimpflug imag- ing in ray tracing IOL power calcu- lation was as accurate as the other calculations in normal cases, show- ing no bias in the posterior corneal curvature, as is the case with the other calculations," they reported. In other words, the researchers found that the use of Scheimpflug by replacing keratometry by topog- raphy, combined with an adequate algorithm included in the [ray trac- ing] that extracts corneal vertex radii together with corneal asphericity in the optical zone." The so-called "corneal refractive index" can also be tricky. "A second source of error in eyes after refractive surgery is the abovementioned fictitious 'corneal refractive index,' which assumes a constant ratio of anterior and posterior corneal radii," Dr. Preussner reported. "But when anterior radii are modified in Drug Interactions—Consider the following when prescribing SIMBRINZA ® Suspension: Concomitant administration with oral carbonic anhydrase inhibitors is not recommended due to the potential additive effect. Use with high-dose salicylate may result in acid-base and electrolyte alterations. Use with CNS depressants may result in an additive or potentiating effect. Use with antihypertensives/cardiac glycosides may result in additive or potentiating effect on lowering blood pressure. Use with tricyclic antidepressants may blunt the hypotensive effect of systemic clonidine and it is unknown if use with this class of drugs interferes with IOP lowering. Use with monoamine oxidase inhibitors may result in increased hypotension. For additional information about SIMBRINZA ® Suspension, please see Brief Summary of full Prescribing Information on adjacent page. Adverse Reactions SIMBRINZA ® Suspension In two clinical trials of 3 months' duration with SIMBRINZA ® Suspension, the most frequent reactions associated with its use occurring in approximately 3-5% of patients in descending order of incidence included: blurred vision, eye irritation, dysgeusia (bad taste), dry mouth, and eye allergy. Adverse reaction rates with SIMBRINZA ® Suspension were comparable to those of the individual components. Treatment discontinuation, mainly due to adverse reactions, was reported in 11% of SIMBRINZA ® Suspension patients. © 2015 Novartis 3/15 SMB15018JAD SIMBRINZA ® Suspension — Signifi cant IOP Reductions at All Studied Time Points When Added to a PGA 1 * Prescribe SIMBRINZA ® Suspension as adjunctive therapy to a PGA for appropriate patients SIMBRINZA ® Suspension should be taken at least fi ve (5) minutes apart from other topical ophthalmic drugs. * PGA study-group treatment consisted of either travoprost, latanoprost, or bimatoprost. † Treatment difference (mm Hg) and P-value at Week 6 was -3.7, P<0.0001. Reference: 1. Data on fi le, 2014. Study Design: A prospective, randomized, multicenter, double-blind, parallel-group study of 189 patients with open-angle glaucoma and/or ocular hypertension receiving treatment with a PGA. PGA treatment consisted of either travoprost, latanoprost, or bimatoprost. Patients in the study were randomized to adjunctive treatment with SIMBRINZA ® Suspension (N=88) or vehicle (N=94). The primary effi cacy endpoint was mean diurnal IOP (IOP averaged over all daily time points) at Week 6 between treatment groups. Key secondary endpoints included IOP at Week 6 for each daily time point (8 AM, 10 AM, 3 PM, and 5 PM) and mean diurnal IOP change from baseline to Week 6 between treatment groups. 1 IOP Time Points (mm Hg) 1‡ Treatment Arm 8 AM 10 AM 3 PM 5 PM PGA + SIMBRINZA ® Suspension (N=83) Baseline § 24.5 22.9 21.7 21.6 Week 6 19.4 15.8 17.2 15.6 PGA + Vehicle (N=92) Baseline § 24.3 22.6 21.3 21.2 Week 6 21.5 20.3 20.0 20.1 ‡ Least squares means at each Week 6 time point. Treatment differences (mm Hg) and P-values at Week 6 time points between treatment groups were: -2.14, P=0.0002; -4.56, P<0.0001; -2.84, P<0.0001; -4.42, P<0.0001. § Baseline (PGA Monotherapy). Mean Diurnal IOP (mm Hg) 1|| Treatment Arm PGA + SIMBRINZA ® Suspension (N=83) Baseline ¶ 22.7 Week 6 17.1 PGA + Vehicle (N=92) Baseline ¶ 22.4 Week 6 20.5 ll Treatment difference (mm Hg) and P-value at Week 6 was -3.4, P<0.0001. ¶ Baseline (PGA Monotherapy). Learn more at myalcon.com/simbrinza Up to 7.1 mm Hg additional IOP reduction from baseline when added to a PGA 1 5.6 † mm Hg additional mean diurnal IOP lowering observed from baseline when added to a PGA 1 EYEWORLD 09.01.15 90714 continued on page 30

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