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Guillaume Besombes, Franck Grunewald, Nassima Ramdane, Julia Salleron, Pierre Labalette, Jean-François Rouland; Position of the central retinal vessel trunk and location of visual field and parapapillary nerve fibers damage in early to moderate glaucoma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):950. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To address the question of whether the position of the central retinal vessel trunk (CRVT) exit in the optic disc has a spatial relationship with glaucomatous damage
This clinical observational study included patients with early to moderate primary open-angle glaucoma. The position of the CRVT exit on the lamina cribrosa was evaluated on optic disc photographs. The papillary region was divided into a superotemporal (ST), an inferotemporal (IT), a superonasal (SN) and an inferonasal (IN) quadrant (figure 1). In addition, the distance between the CRVT and the nasal disc border was calculated as the ratio of the distance between the CRVT and the nasal disc border (figure 2.A) divided by the horizontal disc diameter (figure 2.B). Humphrey visual field tests and retinal nerve fibers layer (RNFL) thicknesses, as measured by spectral-domain optical coherence tomography, were evaluated.
The study included 65 eyes with a CRVT mostly decentered into the SN quadrant (44.6%), followed by the IN quadrant (41.5%), and the temporal quadrant (13.9%). Comparing measurements between the opposite disc quadrants indicated that the RNFL thickness was significantly thinner in the inferotemporal quadrant when the CRVT was located in the superonasal quadrant compared with an exit in the inferonasal (p=0.0183) or temporal (p=0.0039) quadrant. The distance from the CRVT to the nasal disc border was significantly smaller and correlated positively with the occurrence of RNFL abnormality in the temporal region (p=0.0334). Visual field defect incidence was higher in the superonasal quadrant of the pattern deviation plot when the CRVT was located in the superonasal quadrant compared with an exit in the inferonasal quadrant (p<0.0003). Temporal visual field abnormalities occurred more often when the CRVT exit was located in the temporal part of the optic disc than when the CRVT exit was located in the nasal half (p=0.008).
Many factors are associated with the pattern of glaucomatous damage. These results may suggest that the local glaucoma damage susceptibility within the optic nerve head depends also on the position of the CRVT, which can act as a stabilizing element against the deformation of the lamina cribrosa. In eyes with an abnormal position of the CRVT, the glaucomatous damage may display an abnormal pattern related to this location.
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