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IOLs too stiff? Pop them in the microwave!
WARMING acrylic IOLs is a well-known method for increasing the flexibility of foldable IOLs that need to be folded manually for small incision cataract surgery. A simple and effective way to accomplish this is with a microwave oven, say Czech researchers who reported their findings at the XXI Congress of the ESCRS. For lenses that need to be unpacked and then rolled along their longer axis, manufacturers sometimes recommend warming up the lens from the average operating room temperature (19° to 22° C). For the lens used in this particular study (UltraChoice 1.0 – ThinOptX), the manufacturer's recommendation was warming the lens to 40° C. He therefore decided to evaluate the use of a microwave oven (Whirlpool VIP 27) to warm up foldable lenses in order to facilitate their handling. The investigator first determined the best microwave settings (power and time) required to achieve optimal warming temperature. He placed each lens in the microwave inside its vial in its original box, just before unpacking for implantation. Immediately after unpacking the lens he measured the temperature of the liquid in the lens vial using a digital thermometer (Omron). After The mean temperature of the lens storage liquid was 42.1° C. Rolling and implanting of the warmed lenses was easy in all 20 cases. The lens unfolded easily in 15 eyes. The other five IOLs required some manipulation with a spatula to help with the unrolling. Dr Stodulka concluded that the use of a microwave to warm the lens shortens the time that the lens is exposed, and therefore reduces the risk of contamination.
Pavel Stodulka MD, PhD |
However, Pavel Stodulka MD, PhD from the Bata Hospital in Zlin , Czech Republic found that heating lenses using autoclaves or special heating devices was time-consuming, and sometimes required the lens to be unpacked before warming.
preliminary experiments, he determined that an energy level of 90 mW applied for 20 seconds would achieve the desired 40° C. He evaluated this approach with 20 IOLs just before implantation. The lenses were manually rolled with forceps into an injector (Grieshaber injector system) and implanted into the eye. The lenses were implanted via 1.7 mm incisions. 
He noted that using a standard microwave oven for warming the lenses is fast and reliable. Although new injectors have been developed that allow lenses to be folded at room temperature, warming of foldable IOLs may still be necessary when working with less advanced injectors or with manually handled IOLs, he added.