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When performing cataract surgery, it is critical to understand the properties of ophthalmic and viscosurgical devices.
When performing cataract surgery, it is critical to understand the properties of ophthalmic viscosurgical devices (OVDs), and how different flow rates and vacuums affect their performance.
OVDs may be divided into three categories: cohesives, dispersives, and the new adaptive OVDs. ProVisc (Alcon), Amvisc (Bausch & Lomb), and Healon (AMO) are classic examples of cohesives. They're great for moving tissue, and can be removed from the eye very easily. They're also great for inserting the lens.
Because it maintains an intermediate cohesive dispersive index (CDI)-neither extremely cohesive nor highly dispersive-DisCoVisc (Alcon) is classified as viscous-dispersive. DisCoVisc provides endothelial protection similar to VisCoat and space maintenance similar to ProVisc; it also stays in place during the initial stages of surgery and is easily removed at the end of surgery. Healon 5 is considered viscoadaptive: at low flow rates, it behaves as a cohesive, but at high flow rates, it becomes fracturable, and acts more like a dispersive.
Precaution must be taken, however, with Healon 5. If it is left in the eye, the patient's IOP will be high the following day, necessitating emergency surgery.
In my practice, I primarily use DisCoVisc because of its easy-to-control adaptive properties. Healon 5 is perfect when I need concrete-like space maintenance.
Postoperatively, IOPs must be monitored every 4 to 6 hours for the first 24 hours, and spikes must be treated. Cataract surgery wounds are usually self-sealing, and IOP spikes of 22 to 30 mm Hg within 4 to 6 hours aren't unusual. Occasionally, patients may complain of discomfort due to spikes of up to 38 to 40 mm Hg.
Although performing a burp of the wound immediately lowers the pressure, the pressure will eventually build back up. Therefore, use IOP-lowering agents to increase outflow and decrease inflow.
There is some fear that burping the wound may increase the risk of endophthalmitis, so it's typically reserved for those with particularly high IOP spikes.
For example, out of one day's 22 cataract surgeries, 17 of the patients had normal (12 to 21 mm Hg) postoperative IOP measurements. Three had pressures between 22 and 28 mm Hg; one had a pressure of 28 to 30 mm Hg, and another one had a pressure of 38 mm Hg.
The patient with the IOP of 38 mm Hg was the only one who received medication and the wound was also burped. The others were simply given IOP-lowering medication. All were seen 24 hours later, and no adverse events occurred.
Matching the OVD to your particular style and method of surgery can maximize the beneficial properties of the OVD and minimize the risk of dangerously high IOP spikes. When IOP spikes occur, a well-developed response protocol is key to preserving your patients' vision.
Caraco markets generic ketorolac
FROM STAFF REPORTS
Detroit-Caraco Pharmaceutical Laboratories Ltd. has launched ketorolac tromethamine ophthalmic solution 0.5% following a final approval from the FDA for Sun Pharma's abbreviated new drug application for generic Acular ophthalmic solution on the first day following patent expiration. This strength of ketorolac is therapeutically equivalent to Acular ophthalmic solution 0.5% from Allergan. Ketorolac tromethamine ophthalmic solution is indicated for temporary relief of ocular itching due to seasonal allergic conjunctivitis. Ketorolac tromethamine ophthalmic solution is also indicated for the treatment of postoperative inflammation in patients who have undergone cataract extraction. Acular ophthalmic solution has annual sales of about $40 million in the United States, according to a prepared statement from Caraco.
Alan S. Crandall, MD, is professor and senior vice chairman of ophthalmology and visual sciences, director of glaucoma and cataract, Moran Eye Center, The University of Utah, Salt Lake City. He is a consultant for Alcon Laboratories.