EXTENDED REPORT Association between lower optic nerve laser Doppler blood volume measurements and glaucomatous visual field progression

Aim: To perform a preliminary assessment of the relation between optic nerve circulatory parameters and glaucomatous visual field progression. Methods: This study included 29 eyes of 23 patients with open angle glaucoma that had typical glaucomatous nerve fibre bundle visual field defects and increased cup to disc ratios. Laser Doppler flowmetry (Oculix) was used to measure relative optic nerve blood volume (Vol), velocity (Vel) and flow in the superior temporal (ST) and inferior temporal (IT) neuroretinal rim of the optic nerve. After blood flow measurements patients were followed for 6–62 months (mean 33 (SD 17) months) and 2–11 Humphrey visual fields (4.7 (2.6) fields) were obtained. Progression of glaucoma was assessed by the slope of the corrected pattern standard deviation (CPSD) values versus time, which was calculated manually for each eye using regression analysis. Results: A significant negative correlation was observed between Vol in the IT rim and the CPSD slope (r =20.56, p = 0.002); patients with lower Vol tended to show faster progression of glaucomatous field damage than those with higher Vol. When the eyes were arbitrarily divided into two groups according to lower Vol (0.32 (0.06) arbitrary units, AU, n = 15) or higher Vol (0.49 (0.06) AU, n = 14), those with lower Vol had significantly worse mean CPSD slopes (0.50 (0.48) dB/year) than those with higher Vol (20.67 (1.38) dB/year; Student’s t test, p = 0.009). Conclusions: In the IT rim, the area most prone to develop glaucomatous field damage, lower Vol is associated with subsequently faster CPSD progression. These measurements suggest that circulatory abnormalities may have a role in the development of glaucoma.