Abstract
Purpose: :
To investigate the impact of intraocular pressure (IOP) reduction on the ocular circulation in the patients with the acute ocular hypertension (OH).
Methods: :
Thirteen patients (age: 53.7±16.1, male:female = 16:10) with OH (16 eyes with OH, 10 eyes with normal ocular tension), who were needed the immediate reduction of IOP, were treated by the intravenous administration of 20% D-mannitol. The retinal circulation was accessed by the mean bluer rates (MBRs) of laser speckle flowgraphy (LSFG) at the optic disc, retinal artery, vein, and choroid. The MBR, IOP, the systolic blood pressure (SBP), and diastolic blood pressure (DBP) were retrospectively recorded before and an hour after the treatment. The ocular perfusion pressure (OPP) was calculated as OPP = 2/3[1/3SBP + 2/3DBP] - IOP. These parameters were compared with Wilcoxon signed-rank test and the statistical significance was set at p<0.05. Spearman correlation coefficients were used to determine the significance of an association between the OPP and the MBRs.
Results: :
After an intravenous administration of mannitol, IOPs in eyes with OH (before: 40.5±8.9mmHg, after: 28.6±11.0mmHg, p=0.0004) and the contralateral control eyes (before: 15.2±4.4mmHg, after: 11.9±2.7mmHg, p=0.01) were significantly reduced and the OPP with OH was significantly increased (before: 25.9±13.8mmHg, after: 37.1±13.5mmHg p=0.0005). There were significant differences in the MBRs of optic nerve head, retinal artery and vein, and choroid between before and after the intravenous drip. The increased ratio of OPP and MBRs were significantly correlated in the retinal artery (r=0.47, p=0.02), vein (r=0.48, p=0.018), choroid (r=0.70, p=0.0001) and the optic disc area (r=0.53, p=0.007).
Conclusions: :
The immediate reduction of IOP in acute OH eyes resulted in the increased ocular circulation in the retina.
Keywords: intraocular pressure • blood supply • optic flow