EyeWorld India March 2013 Issue

51 EWAP DEVICES March 2013 When it comes to choosing instrumentation to make incisions, variables between disposable and reusable blades make a difference D isposable or reusable? Diamond, sapphire, metal, or silicone? Depending on the type of surgery, the amount of surgical expertise, or the physical location of the operating room, different blades have different advantages. Generally speaking, diamond and sapphire blades are reusable and more expensive than their metal or silicone disposable counterparts. For some surgeons, the location of the surgery is the determining factor about which blade to use. “In my own practice, I used to use diamond blades. But at the surgery center, where there are multiple users of a single diamond blade, I started noticing a significant difference in sharpness from one day to the next,” said Ayman Naseri, MD , chief, Ophthalmology Surgical Service, San Francisco Veteran’s Affairs Medical Center, and associate professor of clinical ophthalmology, University of California-San Francisco, Calif., USA. The inconsistent quality of the diamond tip “got frustrating,” he said, as he was forced to change how he constructed a wound and the amount of pressure he would use in a split second. Although Uday Devgan, MD , in private practice, Los Not all blades serve all purposes by Michelle Dalton EyeWorld Contributing Editor continued on page 52 Angeles, Calif., USA, and chief of ophthalmology, Olive View– UCLA Medical Center, uses both a diamond blade and the newer femtosecond lasers in his practice, when he’s teaching residents he prefers they use a steel blade, and cost is not the main reason. “With a steel blade, no matter how sharp it is, there’s a tactile feedback that is beneficial to residents,” he said. “No matter how sharp the blade is, the incision will be slower and have more resistance than with a diamond blade.” Steel blades “require more effort to enter the eye,” Dr. Devgan said. Deciding on blade type Diamond blades can be too sharp for a particular incision, said Steven G. Safran, MD , in private practice, Lawrenceville, NJ, USA. He uses a diamond blade for the paracentesis, when he needs to use iris hooks, or when he makes a groove incision for scleral flaps. For his main incision, however (which ranges from 2.2 to 2.8 mm depending upon which machine This phaco incision intentionally nicks the limbal vessels to provide better long-term healing. It was created with a femtosecond laser in an anatomic pattern that is difficult to replicate with a manual blade. Source: Uday Devgan, MD A diamond keratome is used to make a corneal incision. Note the line across the tip of the blade that represents the piercing of Descemet’s membrane. The incision is nearly square with dimensions that ensure optimal sealing, minimal induced astigmatism, and adequate access to the anterior segment during surgery. While this blade is made of a gem- quality diamond, its thinness causes it to be somewhat brittle, and care must be taken during handling. With proper care, these blades can undergo 1,000 or more uses between maintenance. he’s using), he prefers metal blades. “I think it’s easier to make a well-constructed incision with a metal blade because diamonds are actually too sharp,” he said, and can cut the flap on the side. He prefers a technique of making a little groove, paralleling the cornea, and then bevelling down. At the surgery center, the staff are “much better at handling the diamond blades than they are at the hospital—in the hospital, often break and are more likely to be dropped,” Dr. Safran said, adding those reasons to why he opts for disposable blades in hospital settings. The variability in diamond blade sharpness at the VA hospital was also a problem for Dr. Naseri in training residents. In Dr. Naseri’s opinion, steel blades offer more consistency with their sharpness, and diamond blades can be inconsistent. The last diamond blade he used was trapezoidal, which presented issues with side- cutting elements in creating a multiplanar incision. “Uniplanar incisions that cut in the same plane don’t pose a problem for blades with side- cutting features, but multiplanar incisions change the plane of the cut in the cornea,” Dr. Naseri said, and this can lead to specific wound flaws. In resident cases, he has changed from a multiplanar incision created with a diamond blade to a single-plane incision created with a metal blade. Dr. Naseri found that the residents were forced to push too hard with a dull diamond blade, yet the same amount of force was problematic if they were using a sharp diamond blade. Dr. Naseri said the consistency of the metal blade sharpness has improved resident incision construction. Dr. Safran typically uses disposable blades for scleral flaps, but likes that a diamond blade can be used to more easily create a flap that starts at the limbus but moves away from him. Generally, however,