INFRARED IMAGING OF SUBRETINAL STRUCTURES IN THE HUMAN OCULAR FUNDUS

The interaction of infrared light with the human ocular fundus, partic ularly sub-retinal structures, was studied in vivo. Visible and infra- red wavelengths and a scanning laser ophthalmoscope were used to acqui re digital images of the human fundus. The contrast and reflectance of selected retinal and sub-retinal features were computed for a series of wavelengths or modes of imaging. Near infrared light provides bette r visibility than visible light for sub-retinal features. Sub-retinal deposits appear light and thickened; the optic nerve head, retinal ves sels, and choroidal vessels appear dark. Contrast and visibility of fe atures increases with increasing wavelength from 795 to 895 nm. Optimi zing the mode of imaging improves the visibility of some structures. T his new quantitative basis for near infrared imaging techniques can be applied to a wide range of imaging modalities for the study of pathop hysiology and treatment in diseases affecting the retinal pigment epit helium and Bruch's membrane, such as age-related macular degeneration.