Assessment of the retinal nerve fiber layer in clinical trials of glaucoma neuroprotection.

Assessment of the retinal nerve fiber layer (RNFL) is appealing for use in clinical trials of glaucoma neuroprotection, as it is directly correlated with loss of ganglion cells, which is assumed to be a primary event in glaucomatous damage. Qualitative assessment of the RNFL includes ophthalmoscopy, color stereophotography, and red-free monochromatic photography. In contrast, confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (GDx), optical coherence tomography (OCT), and retinal thickness analysis (RTA) objectively and quantitatively measure the RNFL thickness. These latter techniques are still in evolution. Continuing meticulous objective validation is necessary to assess the usefulness and limitations of these powerful tools. Nevertheless, there are excellent prospects for using longitudinal assessment of the RNFL in clinical trials of glaucoma neuroprotection.