Abstract
Purpose: :
To assess peripheral vascular reactive response to occlusion provocation test, using two-channels laser Doppler probe in patients with normal tension glaucoma (NTG) and normal control subjects.
Methods: :
16 patients with NTG (12 women and 4 men), aged from 49 to 75 (mean 58,9 SD 7,9 ) and 15 control subjects (6 women and 4 men), aged 34-69 (mean 60,7 SD 10,9) were subjected to an occlusion test. All subjects were tested in the morning between 9 and 12 am, in a room with a constant temperature 22 ± 1ºC. In preparation for the test each subject rested in a sitting position for 10-15 minutes in a quiet room. The experiment comprised following steps: 1/ a 5-minute baseline-period 2/ a 2-minute occlusion of the left hand using a 15 cm wide cuff located directly over the elbow (the pressure in the cuff was 50 mmHg higher than the systolic pressure measured on the arm 3/ a 15- minute final recovery period after occlusion (the post-occlusive hyperemia response). Finger hyperemia was assessed by two-channels laser-Doppler flowmeter MBF-3d, Moor Instruments, Ltd. Two surface probes were attached to the pulp of the third finger (basic probe with the emitter-detector distance of 0,2 mm) and second finger (mean probe which consists of 8 detecting fibres located symmetrically around the emitting fibre in a circle of a diameter 1mm) of the left hand. The hand of the seated subjects rested comfortable on the table, at heart level. TM (time to peak flow) and MAX (maximum hyperemia response) amplitude were evaluated for both probes (TM1 and MAX1 for basic probe and TM2 and MAX2 for mean probe) and compared between two groups of patients. The Kruskal-Wallis test analysis was used to test the differences between groups.
Results: :
In NTG patients, TM1 were significantly longer comparing with healthy subjects (14,520 vs 4,984 p=0,0248) whereas MAX1 was significantly lower as compared to the control group (35,833 vs. 48,644 p=0,0017). The similar differences were noted between groups for the TM2 (16,556 vs. 5,604) and MAX2 (28,462 vs 37,493) but they were not statistically significant.
Conclusions: :
Occlusion provocation test elicits a different systemic hyperemia response in patients with NTG compared with healthy subjects. The results of evaluation using two-channel laser Doppler flowmeter depends on the volume of the measured tissue.
Keywords: vascular occlusion/vascular occlusive disease