PURPOSE: The reflectance of the retinal nerve fiber layer (RNFL) arises from cylindrical light
scattering elements distributed throughout its thickness. To determine whether these
elements include axonal microtubules, eyecup preparations of the toad Bufo marinus were
treated with the microtubule depolymerizing agent colchicine. METHODS: Some eyecups
were incubated for various times in different colchicine concentrations and then fixed and
prepared for electron microscopy (EM). In other eyecups the reflectance of the RNFL at 440 …

purpose. The reflectance of the retinal nerve fiber layer (RNFL) arises from light scattering by
cylindrical structures oriented parallel to ganglion cell axons. In amphibian retinas, at 440
nm, microtubules (MTs) contribute about one half of RNFL reflectance. In rodent retinas, MTs
are the only structure contributing to RNFL birefringence. To increase understanding of the
anatomic basis for clinical RNFL measurements, this study was conducted to evaluate the
MT contribution to RNFL reflectance in rodent retinas by using the MT depolymerizing agent …