Abstract
Purpose::
The purpose of this study is to compare the vascular pulsatility of the Choroidal vessels in normal subjects, versus treated and non-treated glaucoma groups.
Methods::
11 normal subjects mean ages 57± 12.8 years and mean IOP 16.5±3.9 mmHg and 62 glaucoma subjects in four categories based on IOP: Low IOP: 5 to 10 mmHg (n=8); Moderate IOP: 11 to 19 mmHg( n=13); High IOP 20 to 29 (n=16) and very High IOP: >30 mmHg(mean 37.3± 7.6 mmHg, n=17) were recruited. Subjects were monitored with a single point Laser Doppler Flowmeter to measure pulsatility for 60 seconds. The probing laser, emitting at 785 nm, was focused on the subfoveal area and monitored with an infrared CCD camera to visualize the fundus structures. We determined the pulsatility of flow as a unitless coefficient from 0 to 1 according to the formula: Pulsatility = Fmax-Fmin/Fmax
Results::
We measured the choroidal pulsatility in all five groups. The result of the ANOVA statistical test analysis for all groups revealed a p value of 0.0007. The normal group showed a mean of 0.352± 0.16 .The mean values among glaucoma patients was: Low IOP: 0.346 ± 0.109; Moderate IOP: 0.331 ± 0.10; High IOP: 0.389 ± 0.12 and Very High IOP: 0.540±0.16The Low and Moderate IOP groups were not significantly different when compared to normal (p=0.83 and 0.94 respectively).The Very High IOP groups, showed a statistically significant difference from normals (p=0.0008 ) and also a significant difference when compared to all other groups.
Conclusions::
The pulsatility of blood flow in the choroidal subfoveal area was significantly different when comparing the Very High IOP patients to any other group . In general, this pulsatility appears to be greater at IOP’s greater than 30mmHg and there was no significant difference in Flow pulsatility between normals and glaucoma patients with IOP’s below 30 mmHg. The mechanisms by which this increased pulsatile blood flow may contribute to neuroretinal and optic nerve damage will be discussed.
Keywords: blood supply • choroid • optic flow