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Synthesis Ophthalmic Scanning Laser Systems Page 17 of 141
88292-EN, Rev D
power varying from barely visible to 1 mW maximum. The safe (Class II) exposure duration
limit at a maximum power level of 1 mW is 3.9 seconds. To protect the patient from possible
retinal damage during treatment, use the lowest practical aiming beam intensity and the
minimal required time duration.
Using any of the larger patterns while the slit lamp magnification is set to 32X, may result in
the pattern overfilling the visual field. Reduce the slit lamp magnification or adjust the pattern
size. Do not attempt treatment unless the entire pattern is visible.
Laser Safety Eyewear
Laser safety eyewear is routinely required with most lasers. When using the system, the
laser safety officer should determine the need for safety eyewear based on the Maximum
Permissible Exposure (MPE), Nominal Hazard Zone (NHZ) and the Nominal Ocular Hazard
Distance (NOHD) for each of the available laser wavelengths, as well as the wavelength
itself and the configuration of the treatment room (usually within the controlled area).
ANSI Standard Z136.1-2007 defines MPE as “the level of radiation to which a person may
be exposed without hazardous effect or adverse biological changes in the eye or skin”; the
NHZ as “the space within which the level of direct, reflected or scattered radiation during
normal operation is not expected to exceed the applicable MPE”; and the NOHD as “the
distance along the axis of the unobstructed beam from the laser to the human eye beyond
which the irradiance or radiant exposure during operation is not expected to exceed the
appropriate MPE.”
The NOHD is measured from the slit lamp and pattern generator delivery system laser
aperture. ANSI defines the controlled areas as “an area where the occupancy and activity of
those within is subject to control and supervision for the purpose of protection from radiation
hazards.”
All personnel who are within the NOHD are considered to be in the controlled area and
shall wear eye protection with the appropriate optical density. Eyewear must be
resistant to physical damage and photo-bleaching. The minimum optical density (OD)
is 4 at 532 nm or 577 nm; for countries inside Europe and that comply with EN 207, the
eyewear must have a protection class of L5 at 532 nm or L4 at 577 nm.
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