The assessment of the condition of the retinal nerve fiber layer plays an important role for the early detection of blinding eye diseases like glaucoma. We describe the application of a scanning laser polarimeter for quantitative measurements of the retinal nerve fiber layer thickness in vivo. The measuring beam of the scanning laser polarimeter is focused on the retina and penetrates the birefringent nerve fiber layer. The retardation of the light double- passing the nerve fiber layer is proportional to its thickness and is measured at 256 by 256 positions within a field of view of 15 by 15 degrees. The measurement time is less than 1 second. During the measurement, the polarization effects of the anterior segment of the human eye are canceled by a cornea polarization compensator. The retinal retardation values are displayed as a color coded map of the retinal nerve fiber layer thickness distribution.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.