Distribution A: Approved for public release; distribution unlimited (approval given by local Public Affairs Office TSRL-PA-13-0011) 1 A CASE STUDY OF A BILATERAL FEMTOSECOND LASER INJURY Paper #904 Leon N. McLin 1 1 Air Force Research Laboratory, 711th Human Performance Wing, Optical Radiation Bioeffects Branch, Fort Sam Houston, TX, 78234, USA Abstract An Air Force laboratory student scientist sustained a bilateral laser injury from a 100 femtosecond Ti:Saph laser. The accident victim’s immediate report was small spots in his vision. His visual acuity was 20/20 acuity for each eye, but he reported he needed to fixate slightly eccentrically to read 20/20 letters. Damage was apparent centrally in both eyes with OCT. At one month after the injury, he reported that he did not see the blurry spots unless he thought about them. His visual acuity was right eye 20/15 and left eye 20/13. However, when reading the eye chart he reported the blurry spots to be about the same size as the 20/15 letters. The ocular findings of visual acuity, fundus images, and OCT are reported. In addition, the details of the accident from a laser safety officer’s perspective will be reported, including laser energy, root cause, contributing factors, and corrective measures. Ultrashort lasers have an especially low damage threshold compared to longer pulsed lasers. The plasma flash induced by a focused femtosecond laser has been reported to cause retinal injury. This case highlights that special vigilance in safety practices is necessary when working with ultrashort pulsed lasers. Introduction Laser technology continues to rapidly advance. Small handheld lasers are increasingly powerful and easily available to hobbyists and require diligent adherence to safety principles to avoid eye injury[1]. Ultrashort lasers, lasers with a pulse duration of less than a nanosecond (nsec), are increasingly available and are in widespread use by laser professionals. Titanium:sapphire lasers, or simply Ti:Saph lasers are tunable ultrashort lasers which emit red and near- infrared light in the range from 650 to 1100 nanometers (nm). These lasers are being used in scientific research because of their tunability and their ability to generate ultrashort pulses. The high peak power of these lasers and the capability of causing optical breakdown and super continuum generation make these lasers more hazardous than longer pulse duration lasers. Special vigilance in safety practices is necessary when working with ultrashort pulsed lasers. This paper reports on the case of a bilateral laser injury from a 100 femtosecond Ti:Saph laser. Case Report A 34 year old, Asian/Caucasian male graduate student, working in the Air Force laboratory sustained bilateral laser injuries while aligning an infrared (IR) TiSaph, ultrashort femtosecond laser. His initial symptoms were that he saw intense white flashes of light, and then had “tracers” in his vision, “the sort of thing if you look at a light bulb and then blink your eyes you can still see the bulb for a while.” He described what he was seeing as “like looking at the flash of an arc welder for a short amount of time, and having my eyes saturated (intensity wise) at a tiny spot in the center of my vision.” That perception persisted for a few days. He did not feel any pain. Prior to working on this laser system he was working on a visible laser and wearing the appropriate laser eye protection (LEP) for that laser system. When he moved to the IR laser, he did not change to the appropriate LEP. He was not protected from the IR laser with the LEP he was wearing. He reported that he has frequent migraine headaches, associated with an aura. He reports that he had a migraine the night before the accident, and that he was starting to get his aura a little before starting to help with the alignment. His visual acuity was 20/20 acuity for each eye, but he reported he needed to fixate slightly eccentrically to read 20/20 letters. OCT (SPECTRALIS® Tracking Laser Tomography) revealed thin columns of damage, approximately 40 μm in width, through the retinas at each fovea (Figure 1). Fundus examination and color fundus photography revealed small yellowish spots at the foveas of both eyes (Figure 2).