canning laer polarimetry of the normal human retinal nerve fiber layer: a quantitative analyi

PURPOE: To provide a quantitative comparion of retardation value obtained with the canning laer polarimeter (Nerve Fiber Layer Analyzer; Laer Dignotic Technologie, an Diego, California) in normal ubject, with the known hitologic propertie of the human retinal nerve fiber layer. METHOD: canning laer polarimetry wa performed on 48 normal ubject. The retardation value obtained from each eye were proceed to remove reflection from the optic nerve head vaculature and to derive peripapillary polar retardation profile. The location of the maximum and minimum retardation value uperior and inferior to the dik wa determined. Retardation value were alo determined along line running radially from the center of the optic dik to through the point of maximal retardation. REULT: Retardation value were greater in the uperior and inferior quadrant of the peripapillary retinal nerve fiber layer compared with the naal and temporal quadrant. uperiorly, peak retardation value were naal to the vertical meridian by 22.9 degree (D, 17.5) in right eye and by 15.7 degree (D, 17.7) in left eye. Inferiorly, the peak howed a cloer correpondence with the vertical meridian, lying naal to thi by 0.8 degree (D, 14.9) in right eye and temporal to thi by 2.8 degree (D, 15.4) in left eye. Radial analyi howed that the peak retardation occurred approximately (0.5 to 0.7 dik diameter from the optic dik margin) at the uperior and inferior apect of the dik. The degree of modulation of retardation around the optic dik wa le than would be expected from the variation in peripapillary nerve fiber layer thickne een hitologically. CONCLUION: The location of the peak retardation value how reaonable agreement with the angular location of the peak value of nerve fiber layer thickne publihed for human. By contrat, the modulation of retardation value around the dik and the change with eccentricity from the optic dik center differ from the anatomic data. The Nerve Fiber Layer Analyzer appear to meaure a correlate of nerve fiber layer thickne, but it i important that any dicrepancie between the retardation and anatomic data are recognized in the clinical interpretation of polarimetric data.