Changes in pulse waveforms in response to intraocular pressure elevation determined by laser speckle flowgraphy in healthy subjects

Background: The influences of intraocular pressure (IOP) elevations on the pulse waveform in the optic nerve head (ONH) were evaluated using laser speckle flowgraphy (LSFG) in normal subjects. Methods: This prospective cross-sectional study was conducted at the Nagoya University Hospital. An ophthalmodynamometer was pressed on the sclera to increase the IOP by 20 mmHg or 30 mmHg for 1 min (experiment 1, 16 subjects) and by 30 mmHg for 10 min (experiment 2, 10 subjects). The mean blur rate (MBR) and the eight pulse waveform parameters determined using LSFG were measured before, immediately after and during an IOP elevation, and after the IOP returned to the baseline pressure. Results: A significant elevation in the IOP and a significant reduction in the ocular perfusion pressure (OPP) were found after applying the ophthalmodynamometer (both, P < 0.001). The blowout score (BOS) reduced significantly (P < 0.001), and the flow acceleration index (FAI; P < 0.01) and resistivity index (RI; P < 0.001) increased significantly immediately after increasing the IOP by 20 or 30 mmHg (experiment 1). The BOS reduced significantly (P < 0.001), and the FAI (P < 0.01) and RI (P < 0.001) increased significantly after the IOP elevation by 30 mmHg in both experiment 2 and 1. However, the BOS and RI recovered significantly at time 10 compared to that in time 0 (immediately after IOP elevation) during the 10-min IOP elevation (P < 0.001 and P = 0.008, respectively). Conclusions: In conclusion, the BOS, FAI, and RI of the pulse waveforms changed significantly with an acute elevation in the IOP. The change should be related to the larger difference between the maximum and minimum MBRs during the IOP elevation

Effects of photocoagulation on ocular blood flow in patients with severe non-proliferative diabetic retinopathy.

To investigate ocular blood flow and correlations between ocular blood flow and variables in patients with severe non-proliferative diabetic retinopathy (S-NPDR) following panretinal photocoagulation (PRP).In this retrospective, cross-sectional study, the blood flow on the optic nerve head (ONH) and choroid was assessed with laser speckle flowgraphy (LSFG) using the mean blur rate (MBR) in 76 eyes of 76 patients with S-NPDR who underwent PRP, 39 eyes of 39 patients with S-NPDR who did not undergo PRP, and 71 eyes of 71 normal subjects. The correlation between MBR and variables, including visual acuity (VA) and choroidal area determined by binarization method, was analyzed.The mean age was 62.9 ± 11.9 years in the S-NPDR with PRP eyes, 55.6 ± 11.4 years in the S-NPDR without PRP eyes, and 60.3 ± 11.1 years in the normal subject eyes. The ONH MBR in vessel and tissue areas and the choroidal MBR were significantly lower in the S-NDR with PRP group than in the other groups (p < 0.001, p < 0.001, and p < 0.001, respectively). The luminal and the stromal areas were significantly smaller in the S-NDR with PRP group than in the other groups (p < 0.001 and p < 0.001, respectively). LogMAR best corrected visual acuity (BCVA) exhibited significant negative correlation with the ONH MBR in vessel (r = -0.386, p < 0.001), tissue (r = -0.348, p < 0.001), and the choroid MBR (r = -0.339, p = 0.002) in the S-NDR with PRP group. Stepwise multiple regression analysis demonstrated that BCVA was a common independent factor associated with the ONH MBR in vessel, tissue, and the choroidal MBR in the S-NDR with PRP group.ONH and choroid MBR in addition to choroidal component, including the luminal area, were significantly lower in eyes of patients with S-NPDR after PRP compared with no PRP and normal subjects group. This could suggest that the significantly reduced ocular blood flow in PRP-treated S-NPDR eyes correlated with long-term decreased post-PRP luminal area and visual acuity

Changes in Blood Flow on Optic Nerve Head After Vitrectomy for Rhegmatogenous Retinal Detachment

PURPOSE. To determine the preoperative characteristics and the changes in retinal blood flow following vitrectomy in eyes with a rhegmatogenous retinal detachment (RRD). METHODS. Twenty-five-gauge vitrectomy without scleral bucking was performed on 31 eyes of 31 patients with macula-on RRD. The retinal blood flow on the optic nerve head (ONH) was assessed by laser speckle flowgraphy (LSFG), and the mean blur rate (MBR) and pulse waveform parameters before and at 10 days, 1, 2, 3, and 6 months after the surgery were examined. Eyes treated by scleral buckling, and eyes with an epiretinal membrane and cataract that underwent surgery were used as controls. RESULTS. The mean preoperative MBR-vessel on the ONH was significantly lower in eyes with RRD than in the fellow unaffected eyes (P &lt; 0.001), but it was not significantly different from the operated eye and the fellow eye in the control group. A significant increase in the mean MBR-vessel on the ONH was observed following vitrectomy in eyes affected by RRD (P &lt; 0.001), whereas no significant difference was observed in the fellow eye, the scleral buckling-treated eyes, and the control eyes. Of the eight pulse waveform parameters, only the flow acceleration index was significantly lower in eyes with a RRD than in the fellow eyes preoperatively, but then it significantly increased with time following vitrectomy. The changes in the MBR-vessel were not correlated with that of other parameters (e.g., the ocular perfusion pressure). CONCLUSIONS. These results indicate that the retinal blood flow is reduced in eyes affected by RRD preoperatively, and can recover following successful RRD repair by vitrectomy