Simultaneous three wavelength imaging with a scanning laser ophthalmoscope

Background: Various imaging properties of scanning laser ophthalmoscopes (S LO) such as contrast or depth discrimination, are superior to those of the traditional photographic fundus camera. However, most SLO are monochromatic whereas photographic systems produce colour images, which inherently conta in information over a broad wavelength range. Methods: An SLO system has been modified to allow simultaneous three channe l imaging. Laser light sources in the risible and infrared spectrum were co ncurrently launched into the system. Using different wavelength triads, dig ital fundus images were acquired at high frame rates. Results: Favourable wavelengths combinations were established and high cont rast, true (red, green, blue) or false (red, green, infrared) colour images of the retina were recorded. The monochromatic frames which form the colou r image exhibit improved distinctness of different retinal structures such as the nerve fibre layer, the blood vessels, and the choroid. Conclusions: A multi-channel SLO combines the advantageous imaging properti es of a tunable, monochrome SLO with the benefits and convenience of colour ophthalmoscopy. The options to modify parameters such as wavelength, inten sity, gain, beam profile, aperture sizes, independently for every channel a ssign a high degree of versatility to the system. Cytometry 37: 165-170, 19 99. (C) 1999 Wiley-Liss, Inc.