Chorioretinal response to intravitreal aflibercept injection in acute central serous chorioretinopathy

AIM: To evaluate chorioretinal responses to intravitreal aflibercept injection(IAI) in patients with acute central serous chorioretinopathy(CSC). METHODS: Seventy-one eyes from 71 patients with symptomatic CSC for less than six months were included. Thirty-five eyes received a single IAI and 36 eyes were observed without treatment. Best-corrected visual acuity(BCVA), central subfield foveal thickness(CSFT), and subfoveal choroidal thickness(SFCT) were assessed at baseline and at 1, 2, and 3 mo. RESULTS: The mean SFCT in the IAI group decreased at 1 mo, rebounded at 2 mo and remained stable at 3 mo compared to the baseline, while significant change was not noted in the observation group. The mean CSFT decreased significantly during the 3-month study period in both groups, and was significantly lower in the IAI group at 1 mo(P<0.001). A rebound of CSFT between 1 and 2 mo was noted in 14 eyes(40.0%) in the IAI group and in 1 eye(2.8%) in the observation group(P<0.001). The significant visual improvement was achieved from 1 mo in the IAI group, and from 2 mo in the observation group. The rate of complete absorption of subretinal fluid at 3 mo did not differ between the two groups.(45.7% vs 41.7%, P=0.813). CONCLUSION: A single IAI for acute CSC induce a transient decrease in SFCT and CSFT, which implies that IAI may have a pharmacological effect on the underlying hyperpermeable choroid in acute CSC.

The Design Improvement of High Integrity Protection System

HIPS （High Integrity Protection System） is a really important system to protect the fractionation column from overpressure and to protect any atmospheric pollution from flare stack, scrubber and VCU （vapor combustion unit）, etc. KOSHA （Korea Occupational Safety ＆ Health Agency） made criteria about HIPS inspection in 2007 to enforce HIPS inspection. HIPS is the first system which KOSHA and KGS （Korea Gas Safety Corp.） officially required to attach SIL verification report in the Process Safety Report. KOSHA and KGS uniformly require SIL3 for HIPS and require to configure the safety instrumented function to meet SIL3 requirement. The flare system with SIL3 application should have the interlocks to shut off the heat source in case of high pressure from tower, the cooling system failure and the power failure. KOSHA and KGS admit that the flare load is 0 where SIL 3 is applied to the flare system. So it is beneficial to plant because the equipment investment cost can be saved if SIL3 is applied to the flare system. By this reason, so many plants in Korea applied SIL3 to the flare system, scrubber system and VCU, etc. For SIL3 application, the redundant shutdown valve with PST （partial stroke test） should be installed with 1 out of 2 voting and the positioner for PST function should have HART communication function. There were problems caused by HART communication devices, so the system design should be cautiously done considering the operation availability and safety at the same time.