Intraocular lens damage from Nd:YAG laser pulses focused in the vitreous. Part I: Q-switched lasers

The damage resulting from laser-induced optical breakdown and plasma formation on or near an intraocular lens (IOL) has been well described, but there is another form of damage, not associated with optical breakdown, that can harm an IOL. The parameters that lead to this damage were investigated. Polymethylmethacrylate IOLs were irradiated by a Q-switched Nd:YAG laser beam focused so that plasmas were formed well clear of the IOL. Damage was induced in the volume of plastic through which the laser beam passed and was cumulative, not being visible until several laser pulses had passed through the lens. The number of pulses required to produce damage varied inversely with the distance between the IOL and the site of plasma formation. This damage is most likely to occur clinically when vitreous structures are targeted in the pseudophakic eye.