The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma.
© Springer-Verlag 2003 tioning, but others will still maintain function. Any RGC subtype that is functioning in the area of damage can, and most likely will, detect the standard perimetry target. This reduces the sensitivity of SAP to early loss of visual function. On the other hand, visual function specific perimetry tests are designed to target primarily one of the three RGC subtypes . In humans, we call these three subtypes (1) the magnocellular cells and (2) the parvocellular cells, because their axons project to these layers of the LGN, respectively, and(3) the small bistratified (blue–yellow) ganglion cells, whose axons most likely project to the interlaminar koniocellular layers of the LGN [2, 7]. Magnocellular ganglion cells prefer low spatial and high temporal frequencies. They are good at following motion and fast flicker. For this reason, we think that flicker perimetry, various forms of motion perimetry and frequency doubling technology perimetry (FDT) most likely are assessing this sub-population of RGC. For example, FDT presents a low spatial frequency grating (0.25 cycles per degree) that is counter-phase flickered at a high temporal frequency (25 Hz). Parvocellular cells, on the other hand, prefer high spatial frequencies and low temporal frequencies. They handle foveal acuity, processing of fine detail, and red–green color vision. High-pass resolution Graefe’s Arch Clin Exp Ophthalmol (2003) 241:168–169