Safety Aspects of Laser Scanning Ophthalmoscopes

Abstract

Safety standards such as American National Standards Institute Z-136.1 do not give clear light-level limitations for laser scanning ophthalmoscopes. To have more than a rough estimation the retinal temperature rise due to intraocular scanning laser illumination was calculated on the basis of a thermal model. The predicted temperature development with time was compared with the calculated effect of other retinal illumination patterns with well-known hazard risks. The similarity of the thermal effect of retinal scanning and extended-source pulsed illumination is discussed and used to give maximum permissible light-level recommendations for the safe use of laser scanning ophthalmoscopes.

Eye safety for scanning laser projection systems

“…Thus, a more appropriate evaluation of laser projection systems is possible, taking into account the vertical scan movement. Klingbeil [21] suggests a reduction in the MPE of 20 % . At the same time the third pulse criterion has to be analyzed in detail.…”

“…Scanned laser beams are already used in the entertainment industry for light shows and audience scanning [10,31] , in ophthalmoscopes [21,25] and for retinal scanning displays [34,41] . In the case of entertainment systems, persons in the audience are always several meters away from the light source.…”

Imaging a Child's Fundus Without Dilation Using a Handheld Confocal Scanning Laser Ophthalmoscope

“…The exposure levels of both lasers were lower than the standard maximum-permissible levels according to the American National Standards Institute and well within the safety range for a 1000-second continuous exposure time. 19 The laser beams were combined and relayed into a handheld module via an optical fiber. The hand-held module enclosed an X-Y scanning mirror system and optics that directed the scanned beam into the entrance pupil of the subject's eye.…”

Confocal Scanning Ophthalmoscopy: Applying Laser Scanning Technology to Retinal Imaging

“…Model cal culations for the temperature rise of the retina caused by laser scanning (Klingbeil, 1986) showed that the situation can be approximated by a repeatedly pulsed area illumination. However, the case of scanning illumination, which is a combination of continuous and pulsed exposure, is not considered by ANSI.…”