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    Reducing posterior capsular rupture

    Accidental perforation of the capsular membrane during surgery may cause posterior capsular rupture, leading to vitreous loss, which, in turn, may result in severe visual disability, cystoid macular oedema and retinal detachment.1 Posterior capsular rupture is thought to occur in approximately 2% of cataract surgeries performed by skilled surgeons.2 Although phacoemulsification is the standard of care in cataract surgery, it is commonly associated with posterior capsular rupture.

    Innovations in phaco tip design

    A potential risk factor for posterior capsule rupture is the design of the phaco needle. Typically, phaco needles are sharp in order to cut through the cataract. However, even the briefest encounter between phaco needle and capsule may lead to capsular rupture.3 Given the sight-threatening complications associated with this phenomenon, it is not surprising that phaco-needle manufacturers are designing tips with safety firmly in mind.

    Early examples of efforts to improve tip safety included a design by Peter Davis, MD, who in the early 1990s developed a needle that had a rounded outer edge but retained a sharp inner edge. Joseph F. Gravlee, MD, created a needle with a blunted bevel. Takayuki Akahoshi, MD, devised the “knuckle tip”, which utilised a bulbous design with round edges on all surfaces.4

    A more recent development in safe phaco-tip design is the Dewey Radius Tip (MicroSurgical Technologies, Redmond, Washington, USA), which was launched in 2006. The brainchild of Steven Dewey, MD, the Dewey Radius Tip represents considerable innovation in phaco-tip design. It incorporates radius edges on the inner and outer surfaces and is available in 

    thicknesses of 0.7 mm and 0.9 mm with a 30° bevel (Figures 1a and 1b). The inner and outer rims of the tip are rounded with exacting precision so there are no sharp edges to come into contact with the iris or the capsule, thus affording safer phacoemulsification. Dr Dewey notes that the Dewey Radius Tip behaves and functions exactly like a sharp-edged

    phaco needle and is used in the same way; that is, no further training or modification in surgical technique is required. It can also be used on any patient and with any phaco machine, although older generations of phaco equipment might not be compatible.5

    Figure 1a: 0.9 mm Dewey Straight Tip 30

    Figure 1b: 0.7 mm Dewey Straight Tip 30






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