Cataract Surgery Feature Story

JULY/AUGUST 2011 CATARACT & REFRACTIVE SURGERY TODAY EUROPE 29 H ydrogels, which mimic living tissue more than any other synthetic biomaterial because of their high water content and tensile strength, have numerous clinical applications in ophthalmology. Their soft, rubbery consistency can minimize friction with surrounding cells and tissue,1 and their degree of flexibility is similar to the eye’s natural tissues. Polyethylene glycol (PEG), the main component in many hydrogels, is commonly found in drugs, implants, and injectables. Use of hydrogels also avoids the risks associated with medical technologies based on biological components such as human thrombin materials. Currently, two ocular bandages made from PEG hydrogels are commercially available in Europe: the ReSure Adherent Ocular Bandage (Ocular Therapeutix, Inc., Bedford, Massachusetts) and OcuSeal Liquid Ocular Bandage (Roundtable Healthcare Partners, Lake Forest, Illinois). I have used both products, but I prefer ReSure for the following reasons: • Its foam-tipped applicator enables accurate placement over the incision; • Up to four transfers of material can be obtained from each mixture before it polymerizes, which is particularly useful when applications are made at different stages of the procedure; and • A visualization aid (FD&C Blue No. 1) helps determine thickness and placement of the application, especially on a transparent surface such as the cornea. The dye thereafter diffuses from the hydrogel and leaves behind a transparent material within 1 or 2 hours. The PEG component of the hydrogel is supplied as a powder that, when mixed with a diluant, forms a blue precursor (Figure 1). I recommend mixing these components approximately 5 minutes before the surgeon is ready to use the hydrogel. First, a drop of the blue precursor and a drop of an accelerator solution (buffered sodium phosphate tetraborate decahydrate) are placed on a hydrophobic foil pouch (Figure 2). Once the blue precursor and accelerator are mixed, they react to form the hydrogel in approximately 30 seconds. APPLICATION TIPS Tip No. 1: The ocular surface at the site of application must be dry to achieve appropriate adhesion. If applied to a wet surface, the hydrogel will migrate with the fluid before it has time to polymerize over the wound. I have found the best method for application is to place a cellulose spear or surgical sponge over the wound with one hand until the hydrogel is applied with the other hand. Improving Clear Corneal Wound Integrity