Early detection of glaucomatous damage is critical for successful treatment. Glaucoma is associated with ganglion cell and Nerve Fiber Layer (NFL) loss. Today we know that up to 50% of the total number of ganglion cells are located in the macula. The loss of these two layers is directly reflected in retinal thickness  ^(1,2).

None of the other automated imaging tools have emerged as a new gold standard for early glaucoma diagnosis and monitoring. The RTA, however, in addition to imaging the optic disc cupping, identifies and quantifies the anatomical damage in the macula and the peripapillary region before symptoms appear ^(3,4).

The RTA is the only tool that provides objective assessment of all three key components of glaucoma-associated changes in the fundus of the eye: macula, peripapillary region and disc area.
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Reference

1.	Quigley HA, Addicks EM, Green WR. Optic nerve damage in human glaucoma. III. Quantitative correlation of nerve fiber loss and visual field defect in glaucoma, ischemic neuropathy, papilledema, and toxic neuropathy. Arch Ophthalmol 1982;100(1):135-46.
2.	Curcio CA, Allen KA. Topography of ganglion cells in human retina. J Comp Neurol 1990;300:5-25.
3.	Zeimer R, Asrani S, Zou S, et al. Quantitative detection of glaucomatous damage at the posterior pole by retinal thickness mapping. A pilot study. Ophthalmology 1998;105(2):224-31.
4.	Brusini P, Tosoni C, Miani F. Quantitative mapping of the retinal thickness at the posterior pole in chronic open angle glaucoma. Acta Ophthalmol Scand Suppl 2000;78(232):42-4.