Table 1.
Characteristics of HRA2 SLO reflectance and angiography operating modes and sub-modes.
| Reflection Mode (Dark field) | ||||
|---|---|---|---|---|
| Mode Channels | Channel (abbrev.) | Laser Illumination Wavelength (nm) | Reflected Wavelength Collection (nm) | Source of Reflected Signal |
| Infrared | IRDF | 815 | 815 | reflected/scattered light (altered by tissue birefringence) |
| Red Free* | RFDF | 488 | 488 | |
| Angiography Mode | ||||
|---|---|---|---|---|
| Mode Channels | Channel (abbrev.) | Laser Excitation Wavelength (nm) | Emission Collection Range (nm) | Source of Emission Signal |
| Sodium Fluorescein | FA | 488 | 500–680 | NaF fluorescence or native autofluorescence |
| Indocyanine Green | ICGA | 790 | >800 | ICG fluorescence or native autofluorescence |
| Infrared† | IR | 815 | 815 | reflected/scattered light |
*
Red Free channel does not operate as a true dark field channel when used with the 55° Wide-field objective lens since the 488nm laser excitation beam emerging from the instrument is not 100% linearly polarized.
†
Infrared channel is not used as an angiography channel but falls into this category because of instrument design. This is an “open” channel that lacks any optical filtering to eliminate the illumination laser wavelength @ 815nm. Light collected with this channel is autoreflected from ocular tissue constituents.