Multiple commercial femtosecond lasers have been cleared for use by the US Food and Drug Administration for ophthalmic surgery, including use in creating corneal flaps in LASIK surgery. The newest application of femtosecond lasers in ophthalmology is in cataract surgery. Currently there are a few lasers at or near the point of commercial release. LenSx (Alcon Laboratories Inc., Ft Worth, TX, USA) is the first one which get FDA permit and most popular one in the clinic. During normal operation, some of laser energy passes beyond the cornea and through the lens with potential effects on the retina. As a model for retinal laser exposure during OCT assisted femtosecond laser surgery, we measured the temperature rise in human cadaver retinas during direct illumination by the laser. Human cadaver retinas were irradiated with a LenSx femtosecond laser and the temperature rise was measured with an infrared thermal camera. The results showed a temperature rise of less than 0.5 degrees for realistic pulse energies. A numerical simulation was developed to quantify the temperature rise as a validation of the ex-vivo experiments. Thermal camera measurements are in agreement with the simulation. During routine femtosecond laser cataract surgery with normal clinical parameters, the temperature rise is well beneath the threshold for retina damage.
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