Correlation between choroidal thickness and intraocular pressure after 23-gauge vitrectomy for idiopathic epiretinal membrane

AIM： To determine the relationship between the subfoveal choroidal thickness（CT） and intraocular pressure（IOP） following idiopathic epiretinal membrane（ERM） surgery.METHODS： Retrospective observational case series of patients who had undergone 23-gauge vitrectomy for an ERM. The measurements of CT and IOP were done at the baseline and 1 d, 1 wk, 1, 3, 6, and 12 mo after the surgery.RESULTS： Forty-four eyes of 43 patients with a mean age of 69.8±9.5 y were studied. The CT was 200.8±86.3 μm at the baseline, 210.1±83.5 μm at 1 d, 213.2±85.4 μm at 1 wk, 203.1±84.0 μm at 1 mo, 197.5±85.5 μm at 3 mo, 197.7±84.0 μm at 6 mo, and 191.2±86.8 μm at 12 mo after surgery. The CT on day 1 and week 1 after the surgery was significantly thicker than that at the baseline CT（P=0.0023 and P〈0.0001）. The CT at 12 mo after surgery was significantly thinner than the baseline（P=0.0062）. The IOP on day 1 and week 1 were significantly lower than the baseline（P〈0.0001 and P=0.0042）. The IOP at 1, 3, 6, and 12 mo after surgery were significantly higher than the baseline IOP（P=0.0087, P=0.0023, P〈0.00051, and P〈0.0001）. The rates of changes in the CT between baseline and day 1 and week 1 were significantly and negatively correlated with the rates of change in the IOP（P〈0.0001 and P=0.046）. In the group with the IOP change rate of-30% or less at 1 d postoperatively, the change rate of CT was-21.1% to 31.2%（9.8%±12.4%） and in the group of-29% or more, it was-8.9% to 28.0%（2.6%±8.9%）. The change rate of CT in the group with the IOP change rate of-30% or less was significantly higher than the group of-29% or more（P=0.016）.CONCLUSION： CT increases soon after the ERM surgery which is probably due to the transient hypotony, showing that IOP may be a significant confounding factor for CT.

Control of Secondary Flow in a Low Solidity Circular Cascade Diffuser

According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the pres-sure recovery was improved further by the LSD with a tandem cascade in comparison with the LSD with a sin-gle-row cascade. In the present study, the flow behavior in the LSD with the tandem cascade has been analyzed numerically by using the commercial CFD code of ANSYS-CFX12. It was shown clearly that the higher pressure recovery was achieved by applying the LSD with the tandem cascade, and the high pressure recovery is based on the high pressure rise in the vaneless space upstream of the LSD and the high blade loading of the front blade of the LSD. The high pressure recovery in the LSD could be achieved by controlling the flow separation on the suc-tion surface of the front blade and also on that of the rear blade due to formation of the favorable secondary flow and due to increase in mass flow passing through the slit section between the front and rear blades.

Noise Characteristics of Centrifugal Blower with Low Solidity Cascade Diffuser(Noise Reduction by means of Small Groove Located at LSD Blade Leading Tip)

This paper deals with the effect of the blade tip-groove of the low solidity cascade diffuser (LSD) on the blowercharacteristic and the noise generated by the LSD. The small grooves were set up at the root and/or tip near theleading edge of the LSD blade. In order to clarify the mechanism of noise increase due to LSD and also to reducethe noise, the relationships between the noise increase based on the LSD, the LSD performance and the secondaryflow formed additionally by the tip-groove were investigated experimentally as well as numerically, especiallyanalyzing flow behaviors in the LSD in view points of flow separation on the suction surface of the LSD bladeand the secondary flow on the side walls. By reducing the stagnation region smaller near the root and/or tip of theLSD blade leading edge, the secondary flow behavior changes remarkably around the LSD blade, as a result, thenoise level and the blower characteristics vary. It can be concluded that, by means of a small tip-groove locatedonly at the shroud side near the LSD blade leading edge, the noise generated by the LSD can be reduced withoutdeteriorations of the LSD performance and the blower characteristics as well.

Measurement of droplet size distribution in core region of high-speed spray by micro-probe L2F

In order to investigate the distribution of droplet sizes in the core region of diesel fuel spray, instantaneous measurement of droplet sizes was conducted by an advanced laser 2-focus velocimeter （L2F）. The micro-scale probe of the L2F is made up of two foci and the distance between them is 36 lain. The tested nozzle had a 0.2 mm diameter single-hole. The measurements of injection pressure, needle lift, and crank angle were synchronized with the measurement by the L2F at the position 10 mm downstream from the nozzle exit. It is clearly shown that the droplet near the spray axis is larger than that in the off-axis region under the needle full lift condition and that the spatial distribution of droplet sizes varies temporally. It is found that the probability density distribution of droplet sizes in the spray core region can be fitted m the Nukiyama-Tanasawa distribution in most injection periods.

Velocity and Size of Droplets in Dense Region of Diesel Fuel Spray on Transient Needle Opening Condition

In order to investigate the effect of transient needle opening on early stage of spray behavior, simultaneous measurements of velocity and size of droplet were conducted by a newly developed laser 2-focus velocimeter (L2F). The micro-scale probe of the L2F was consisted of two foci with a distance of 36μm. The tested nozzle had a single hole with a diameter of 0.2 mm. The measurements of injection pressure, needle lift, and crank angle were synchronized with the spray measurement by the L2F at the position 10 mm downstream from the nozzle exit. It has been clearly shown that the velocity and size of droplet increase with needle valve opening and that the probability density distribution of droplet size can be fitted to the Nukiyama-Tanasawa distribution under the transient needle opening condition.