IOL PRE-WARMING

Pre-injection IOL warming may be a simple solution for enabling high-power foldable lenses to be safely delivered using a cartridge injector system designed for microincision cataract surgery, according to research presented by investigators from New York University School of Medicine at the annual meeting of the Association for Research in Vision and Ophthalmology. Jonathan B Kahn MD and Jack M Dodick MD, reported the findings from a small feasibility study in which they evaluated the IOL optic for surface damage after lens delivery using the Monarch III handpiece and D cartridge (Alcon Laboratories), designed for use with a 2.2mm incision.

Pre-warming lens

They assessed four pairs of single-piece acrylic multifocal IOLs (AcrySof IQ ReSTOR SN6AD3, Alcon) with powers of 26.0, 27.0, 28.5, and 29.5 D. One lens of each pair was pre-warmed in a 45o C water bath for 10 minutes and the other lens was injected after being taken from storage at 23o C. The temperature for pre-warming represents the manufacturer’s recommended maximum temperature for lens storage. The cartridges were filled with viscoelastic prior to IOL loading, and the lenses were rinsed thoroughly with balanced salt solution after they were delivered. Photomicrographs taken from light microscopy inspection revealed abnormalities of the optic surface on four IOLs, of which three were in the control group (26.0, 27.0 and 28.5 D) and one was pre-warmed (27.0 D). The findings included debris, microscratches, and/or microcracks.

“Phacoemulsification has advanced from a larger incision procedure to microincision surgery using a 2.2mm incision, and IOL delivery systems have been introduced that can preserve the advantage of the microincision. However, according to the manufacturer, use of the D cartridge should be limited to single-piece AcrySof IOLs with powers up to 27.0 D,†said Dr Dodick. “We are encouraged by the findings from this study and hope to continue our research with a larger investigation in order to determine more definitively if IOL pre-warming can allow the advantages of small cartridges for high powered lenses. There is value for any incremental advance in cataract surgery, and we think lens warming may offer an incremental improvement in insertion technique.†Dr Kahn, senior resident, Department of Ophthalmology, New York University School of Medicine, noted that the multifocal IOLs were used in this study because they were provided as samples by the manufacturer.

However, in addition to investigating larger numbers of IOLs, a future study might also be done with monofocal IOLs. Dr Dodick said he came up with the idea of lens prewarming by extrapolating from his experience using warming as a technique to facilitate IOL folding. “When IOLs were being inserted using folders, a lens that was fairly rigid at room temperature would develop a gummy bear-like consistency and become more pliable and easier to fold if it was warmed by placing it on top of the steriliser,†he explained. Dr Dodick reasoned that if a potential for optic surface damage was related to contact between the lens and the cartridge, the risk could be mitigated by warming the lens to modify its pliability.