Effect of senescence on ocular blood flow in the retina, neuroretinal rim and lamina cribrosa, using scanning laser Doppler flowmetry

Abstract

Purpose: To determine the effects of age on blood flow measurements obtained using the scanning laser Doppler flowmeter (SLDF).

Method: Using SLDF (Heidelberg retina flowmeter, Heidelberg Engineering, Germany) three 10 degrees images were taken of the superior temporal retina and three further images of the superior temporal neuroretinal rim in 15 young, healthy subjects (mean age 27.9 years +/- 6.2 years) and 15 mature, healthy subjects (mean age 65.2 years +/- 13.7 years). In addition, measurements were taken of the lamina cribrosa in 12 of the volunteers from each subject group (mean age 27.1 +/- 6.3 years and 64.8 +/- 13.2 years respectively). Using a 10 x 10 pixel measurement frame, blood flow readings were obtained at a predetermined position on the retina, neuroretinal rim and lamina cribrosa. Student's two-tailed unpaired t-tests were used to compare measures of blood flow, volume and velocity between the two subject groups (P < 0.05). In addition, linear regression analysis was used to assess the relationship between age and blood flow, volume and velocity at the retina, neuroretinal rim and lamina cribrosa.

Results: Retinal blood volume measured at the retina was significantly lower in the mature compared with the young subject group (P = 0.01). Mature subjects also exhibited reduced blood flow and velocity at the neuroretinal rim (P = 0.01 for both parameters) and lamina cribrosa (P = 0.008 and P = 0.01 respectively). Regression analysis revealed negative trends for all blood flow parameters in each of the anatomical areas with advancing age. Significant negative correlations were obtained for retinal blood volume (r = -0.455, P < 0.05), neuroretinal rim blood velocity (r = -0.359, P < 0.05) and lamina cribrosa blood volume (r = -0.475, P < 0.05).

Conclusion: Capillary blood flow in the retina, neuroretinal rim and lamina cribrosa decreases with advancing age. This may be of consequence in the progression of chronic ocular diseases such as glaucoma, and should be considered in the longitudinal determination of change in disease monitoring.