1. Color, where the retina is illuminated by white light and examined in full color.
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| retinal color photography |
2. Red-free, where the imaging light is filtered to remove red colors, improving contrast of vessels and other structures.
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| red free |
3. Angiography, where the vessels are brought into high contrast by intravenous injection of a fluorescent dye. The retina is illuminated with an excitation color which fluoresces light of another color where the dye is present. By filtering to exclude the excitation color and pass the fluorescent color, a very high-contrast image of the vessels is produced. Shooting a timed sequence of photographs of the progression of the dye into the vessels reveals the flow dynamics and related pathologies. Specific methods include sodium fluorescein angiography.
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| angiography |
