Abstract
Purpose: :
To evaluate whether the position of the central retinal vessel trunk is correlated with the shape of glaucomatous rim loss.
Methods: :
A cross-sectional study was carried out including glaucomatous patients without any other significant eye disease or ocular surgery. After a complete ophthalmic evaluation, all subjects underwent optic disc topographic measurements with confocal scanning laser tomography - Heidelberg Retina Tomograph III (HRTIII [Heidelberg Engineering, Dossenheim,Germany]). Three exams were performed for each eye. We determined the position of the central retinal vessel trunk exit on the lamina cribosa surface and accessed the neuroretinal rim area values measured by the HRT III. The distance between the central retinal vessel trunk exit and optic nerve center was measured and called the eccentricity of the trunk. This measure was correlated with the larger and lower rim area of the optic disc by regression analysis.
Results: :
Measurements of the neuroretinal rim, from the closest and most distant quadrants to the central retinal vessel trunk exit, revealed mean (standard deviation) values of 0.355 (0.031) mm2 and 0.158 (0.006) mm2 respectively. The paired t-test showed that the neuroretinal rim located most distant to the central retinal vessel trunk exit was significantly smaller than the closest rim (P < 1.8 x 10-13). With respect to the influence of the trunk eccentricity on the rim area, a regression analysis examined the relation of the distance between the closest rim area and the central retinal vessel trunk exit to the distance between the trunk and the optic disc center, replying this analysis to the most distant rim area. The analysis of variation (ANOVA) showed that we can not state that the closest and the most distant rim area are dependent on the distance between the central retinal vessel trunk exit and the optic disc center (p= 0,73 and 0,26, respectively).
Conclusions: :
This suggests that the central retinal vessel trunk is one factor among others that could be correlated with the regional vulnerability of the neuroretinal rim in glaucomatous patients, as the neuroretinal rim located most distant to the central retinal vessel trunk exit was significantly smaller than the closest rim. However, by the present study, we can not infer there is a correlation between the distance from the trunk exit to the center of the optic nerve and the rim area in the closest nor the most distant rim portion.
Keywords: optic nerve • lamina cribrosa • imaging/image analysis: clinical