Eyeworld

EW CATARACT 28 December 2015 by Matt Young and Gloria D. Gamat EyeWorld Contributing Writers Understanding eyes that have undergone refractive surgery L ooking back at the early days of refractive surgery, surgeons may now have mixed feelings about the era of radial keratotomy (RK). RK not only had relatively poor predictability but also produced eyes with unstable refractive errors. The significant diurnal fluctuations and high altitude related hyperopic shifts after surgery alone were enough to give the refractive surgeon of 30 years ago considerable clinical nightmares. "Everybody wanted to do RK back then, but the minute we knew excimer laser was coming, we stopped doing them," said John D. Sheppard, MD, professor of ophthalmology, microbiology and molecular biology, and clinical director, Thomas R. Lee Center for Ocular Pharmacology, Eastern Vir- ginia Medical School, Norfolk, Va. What ray tracing can do Today, RK eyes—and an ever-in- creasing number of LASIK eyes—face cataract surgery more often. Fortu- nately, thanks to modern ophthal- mology, these patients can now benefit from technologies such as ray tracing to properly buttress their situation going into phacoemulsifi- cation. According to Dr. Sheppard, ray tracing is a helpful method to ana- lyze the problematic eyes of patients who underwent RK in the 1960s and 70s, and understand their incredible refractive abnormalities. Ray tracing, available today in wide variety, is used to determine the refractive amplitude of the eye. "The eye images are digitally gen- erated and are assessed for accuracy and repeatability," Dr. Sheppard said. Although the discipline is com- plex, ray tracing is in fact simply "a calculation method for single rays passing through an optical system," said Paul-Rolf Preussner, MD, PhD, University Eye Hospital, Mainz, Germany, in a publication presented at the 2011 European Society of Cat- aract & Refractive Surgeons (ESCRS) meeting. It can be a useful field for under- standing eyes that have undergone refractive surgery. "Eyes after corneal refractive surgery differ from normal eyes," Dr. Preussner noted in the same report. "In these eyes the high- est errors occur from keratometry measured corneal radii. The reason is that keratometers are adjusted to spherical or moderately prolate aspherical corneae. But eyes after refractive surgery often have oblate aspherical corneae [such as with RK]. The resulting errors can be avoided Ray tracing helps underpin IOL surgery Daily life: Has an active lifestyle—takes daily walks, gardens, attends weekly bridge games, goes on a yearly vacation with friends Lives on her own. Her daughter helps her from time to time Has an upbeat, independent attitude Health: She is on PGA therapy that has reduced her IOP from 26 mm Hg OU to 18 mm Hg OU for several years She takes a systemic beta-blocker for hypertension IOP status: Recently, her IOP has risen to around 22 mm Hg OU, and optic nerve damage has progressed She is cognizant of the need to work toward a target IOP and a reduction of approximately 5 mm Hg A potential candidate for SIMBRINZA ® (brinzolamide/brimonidine tartrate ophthalmic suspension) 1%/0.2% Meet Ann She has open-angle glaucoma with elevated IOP* Age: 77 years Not actual patient. *Hypothetical patient profi le. Has an active lifestyle—takes daily walks, gardens, attends weekly bridge games, goes on Lives on her own. Her daughter helps her from Has an upbeat, independent attitude She is on PGA therapy that has reduced her IOP from 26 mm Hg OU to 18 mm Hg OU for several years She takes a systemic beta-blocker for hypertension Recently, her IOP has risen to around 22 mm Hg OU, and optic nerve damage has progressed She is cognizant of the need to work toward a target She has open-angle glaucoma SIMBRINZA ® (brinzolamide/brimonidine tartrate ophthalmic suspension) 1%/0.2% is a fi xed combination indicated in the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. Dosage and Administration The recommended dose is one drop of SIMBRINZA ® Suspension in the affected eye(s) three times daily. Shake well before use. SIMBRINZA ® Suspension may be used concomitantly with other topical ophthalmic drug products to lower intraocular pressure. If more than one topical ophthalmic drug is being used, the drugs should be administered at least fi ve (5) minutes apart. IMPORTANT SAFETY INFORMATION Contraindications SIMBRINZA ® Suspension is contraindicated in patients who are hypersensitive to any component of this product and neonates and infants under the age of 2 years. Warnings and Precautions Sulfonamide Hypersensitivity Reactions—Brinzolamide is a sulfonamide, and although administered topically, is absorbed systemically. Sulfonamide attributable adverse reactions may occur. Fatalities have occurred due to severe reactions to sulfonamides. Sensitization may recur when a sulfonamide is readministered irrespective of the route of administration. If signs of serious reactions or hypersensitivity occur, discontinue the use of this preparation. Corneal Endothelium—There is an increased potential for developing corneal edema in patients with low endothelial cell counts. Severe Hepatic or Renal Impairment (CrCl <30 mL/min)— SIMBRINZA ® Suspension has not been specifi cally studied in these patients and is not recommended. Acute Angle-Closure Glaucoma—The management of patients with acute angle-closure glaucoma requires therapeutic interventions in addition to ocular hypotensive agents. SIMBRINZA ® Suspension has not been studied in patients with acute angle-closure glaucoma. Contact Lens Wear—The preservative in SIMBRINZA ® Suspension, benzalkonium chloride, may be absorbed by soft contact lenses. Contact lenses should be removed during instillation of SIMBRINZA ® Suspension but may be reinserted 15 minutes after instillation. Severe Cardiovascular Disease—Brimonidine tartrate, a component of SIMBRINZA ® Suspension, had a less than 5% mean decrease in blood pressure 2 hours after dosing in clinical studies; caution should be exercised in treating patients with severe cardiovascular disease. Potentiation of Vascular Insuffi ciency—Brimonidine tartrate, a component of SIMBRINZA ® Suspension, may potentiate syndromes associated with vascular insuffi ciency. It should be used with caution in patients with depression, cerebral or coronary insuffi ciency, Raynaud's phenomenon, orthostatic hypotension, or thromboangiitis obliterans. Contamination of Topical Ophthalmic Products After Use—There have been reports of bacterial keratitis associated with the use of multiple-dose containers of topical ophthalmic products. These containers have been inadvertently contaminated by patients who, in most cases, had a concurrent corneal disease or a disruption of the ocular epithelial surface. INDICATIONS AND USAGE

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