Ocular Hazard from Picosecond Pulses of Nd: YAG Laser Radiation

Abstract

Seven rhesus monkeys (14 eyes) were exposed to 1064-nanometer radiation in single pulses of 25 to 35 picoseconds fromn a mode-locked Nd: YA G laser. Threshold injury resulted from single pulses with a mnean energy of 13 +/- 3 mnicrojoules. Electron microscopy of the retina revealed that damnage was highly localized in the photoreceptor and pigmented epithelial cells at the oluter retina. Membrane disruption, distorted outer segmtzents, and abnormnal melanin granules resembling fetal premelanosomnies were observed.

Visible lesion laser thresholds in Cynomolgus (Macaca fascicularis) retina with a 1064 nm 12-ns pulsed laser

“…At short distances from their origin, the magnitude of these spherically expanding waves is sufficient to induce mechanical damage (shearing forces) to the membrane and structural proteins of cells. Several authors have presented results in the rhesus model with similar laser parameters as used in this study [12][13][14]. There is significant spread in the published data with the lowest threshold value reported from previous work completed by this laboratory (HEDO) [12].…”

“…Pulse Duration 24 hour MVL ED50 [13] 15 ns 68 lJ [14] 4 ns 158 AJ [15] 20 ns 99 t] [12] 7 ns 19 1 J This report, the first in a planned series of reports, compares retinal photomechanical damage induced in the cynomolgus monkey using single 12-ns, 1064-nm exposures, with historical data from rhesus monkey. The experimental configuration utilized in this study is substantially equivalent to that employed by Cain et al with rhesus monkey.…”

Lightless cataract surgery using a near-infrared operating microscope

“…In the human eye, wavelengths between 400 nm and 1400 nm are transmitted through the ocular media to the retina. 23 There are 3 mechanismsdmechanical, 24 thermal, 25 and photochemical 26 dthat cause retinal damage within the 400 to 1400 nm wavelength.…”

Functional impairment with minimal macular damage in femtosecond laser plasma injury: case report

“…Thermal and mechanical processes require absorption of large amounts of energy in a very short period of time, which is not consistent with the case described here (3,13) . Also, mechanical processes cause more extensively visible disruption of the surrounding tissues and immediate noticeable changes in vision (3,4,14) . Thermal processes are also expected to cause extensive damage because heat spreads away from the primary site of absorption damaging over a large area around it (13) .…”