Use of Optical Coherence Tomography to Evaluate Visual Acuity and Visual Field Changes in Dengue Fever

이택관,한정일 대한안과학회 2014 Korean Journal of Ophthalmology Vol.28 No.1

Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases,dengue fever can cause visual impairment, which usually occurs within 1 month after contracting denguefever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fevercan be detected through angiography, retinography, optical coherence tomography (OCT) imaging,electroretinography, event electroencephalography (visually evoked potentials), and visual field analysis. The purpose of this study is to report changes in the eye captured using fluorescein angiography,indocyanine green, and OCT in 3 cases of dengue fever visual impairment associated with consistent visualsymptoms and similar retinochoroidopathic changes. The OCT results of the three patients with denguefever showed thinning of the outer retinal layer and disruption of the inner segment/outer segment (IS/OS)junction. While thinning of the retina outer layer is an irreversible process, disruption of IS/OS junction isreported to be reversible. Follow-up examination of individuals with dengue fever and associated visualimpairment should involve the use of OCT to evaluate visual acuity and visual field changes in patients withacute choroidal ischemia.

황반전막환자에서 빛간섭단층촬영 형태에 따른 수술결과

서상진,이수정,박정민,Sang Jin Seo,Soo Jung Lee,Jung Min Park 대한안과학회 2013 대한안과학회지 Vol.54 No.5

Purpose: To determine the influence of morphologic classification based on optical coherence tomography (OCT) on epiretinal membrane (ERM) surgery outcomes. Methods: We retrospectively reviewed the medical records of 77 eyes with ERM treated by vitrectomy with ERM peeling. By using OCT, the preoperative ERM was classified into four types: diffuse (DIF), cystoids macular edema (CME), pseudolamellar hole (PLH), and vitreomacular traction (VMT). The postoperative changes of central macular thickness (CMT) and best-corrected visual acuity (BCVA) were compared. Results: Approximately six months postoperatively, the DIF type had the best BCVA for both idiopathic and secondary ERM, followed by the PLH, CME, and VMT types. On the other hand, regarding the mean BCVA improvement, the VMT type was the best, followed by the DIF, PLH, and CME types. When comparing the difference in BCVA improvement by each type, idiopathic ERM showed a clearer distinction when the inner segment/outer segment (IS/OS) junction was not disrupted. Conclusions: BCVA improvement was significantly different depending on the morphologic classification of ERM by using OCT. Especially in cases of ERM with an intact IS/OS junction, the morphologic classification can help predict surgical outcomes. J Korean Ophthalmol

고압전기 스파크 조사 후 발생한 양안 황반병증 1예

허현도(Hyoun Do Huh),한용섭(Yong Seop Han),정인영(In Young Chung),서성욱(Seong Wook Seo),박종문(Jong Moon Park) 대한안과학회 2016 대한안과학회지 Vol.57 No.1

Purpose: To report a case of maculopathy after exposure to a high-voltage spark. Case summary: A 40-year-old male patient visited our clinic complaining of visual disturbance in both eyes 1 day after exposure to a high voltage arc discharge. His best corrected visual acuity was 4/20 in both eyes. On fundus examination, a yellowish retinal scar was observed at the foveal area. The spectral domain optical coherence tomography (SD-OCT) showed inner segment/outer segment line disruption. The best corrected visual acuity was 4/20 in both eyes and SD-OCT showed a remaining inner segment/outer segment line disruption after 3 years. Conclusions: Maculopathy can result from exposure to a high voltage arc discharge exposure.

안쪽 분절과 바깥 분절의 변형 및 추가가 네온 색 확산에 미치는 효과

정우현,이일우 한국인지및생물심리학회 2010 한국심리학회지 인지 및 생물 Vol.22 No.1

Five experiments were performed to compare the effects of inner and outer segments on the neon color spreading using the modified Redies-Spillmann figure. Experiment 1 examined the effect of collinearity of inner and outer segments on neon color spreading and experiment 2 compared the effect of continuity. Experiment 3-1 and 3-2, investigated the effects of same space and length of colored segments and outer segments on neon color spreading. Experiment 4 tested how the degree of neon color spreading changed when inner and outer segments were added. The result showed that the impact of outer segments was stronger than inner segments on neon color spreading in collineartity and continuity. However, the effects of identical spaces and lengths were less important than collinearity and continuity on color spreading. In contrast with addition of inner segments, when outer segments were added color spreading were reduced significantly. These results suggest that the centrifugal color spreading is stronger than centripetal spreading and that the subjective contours and the color spreading are caused by separate mechanisms. 변형된 Redies-Spillmann 도형을 자극으로 사용하여 색 분절의 바깥쪽에 있는 분절과 안쪽에 있는 분절이 네온 색 확산에 미치는 효과를 비교해 보았다. 실험 1에서는 안쪽 분절과 바깥쪽 분절의 공선성이 네온 색 확산에 미치는 효과를 살펴보았고 실험 2에서는 연결성의 효과를 비교해 보았다. 실험 3-1과 3-2에서는 바깥쪽 분절과 색 분절의 간격의 동일성과 길이의 동일성이 네온 색 확산에 미치는 효과를 살펴보았다. 실험 4에서는 안쪽 분절과 바깥쪽 분절이 추가되었을 때 네온 색 확산의 정도가 어떻게 달라지는지 알아보았다. 실험 결과 안쪽 분절의 공선성과 연결성의 영향보다는 바깥쪽 분절의 영향이 더 큰 것으로 나타났다. 간격의 동일성과 길이의 동일성은 공선성이나 연결성에 비해 네온 색 확산에 미치는 효과가 미미했다. 안쪽 분절이 추가되었을 때는 네온 색 확산이 거의 영향을 받지 않았으나 바깥쪽 분절이 추가될 경우 네온 색 확산이 감소되는 경향이 나타났다. 이런 결과는 색 확산이 안쪽 윤곽과 바깥쪽 윤곽의 내부로 일어날 때 그 진행 방향이 동일하지 않으며 주관적 윤곽과 네온 색 확산은 별개의 기제에 의해서 만들어짐을 시사한다.

외부 하중에 따른 세그먼트 라이닝 변형과 보강용 내부 강재 라이닝의 거동 특성

이경주,송기일 사단법인 한국터널지하공간학회 2024 한국터널지하공간학회논문집 Vol.26 No.3

쉴드TBM 터널에서 단면 부족이나 큰 변형이 세그먼트 라이닝의 안정성에 우려될 경우 터널 외부에 지반 그라우팅으로 보강하거나 터널 내부에 강판 보강, 링 빔 보강, Inner double layer lining으로 보강하는 경우가 있다. 또한, 기존의 쉴드 TBM 터널의 해석은 세그먼트라이닝의 분절 특성을 고려하지 않는 연속체의 강성일체법으로 해석되어왔다. 본 연구는 내부 강재 라이닝으로 보강한 double layer 보강 단면에 대해 보강 메커니즘을 연구하였다. 본 연구는 세그먼트 라이닝에 대한 모델링을 개선하여 세그먼트 라이닝의 분절 특성을 고려한 분절체 모델링(BJM)을 적용하였고 이를 통해 세그먼트 라이닝의 변형 특성을 반영한 double layer 보강 단면을 해석하였다. 연구 결과 기존 콘크리트 세그먼트 라이닝은 하중을 일정부분 분담하는 역할이 아닌 터널 주변 지반을 보강한 것과 같은 역할을 하였다. 일반적으로, 세그먼트 라이닝의 분절을 고려한 BJM 모델과 분절을 고려하지 않는 강성일체법 모두 하중을 받은 라이닝의 변형 형상과 응력 분포가 유사하게 나타났다. 그러나 하중의 강도가 임계치를 넘는 경우 변형의 양상에 차이가 있으며 변형 특성을 보다 면밀히 검토할 수 있는 것으로 나타났다. If there are concerns about the stability of segment lining due to section deficiency or large deformation in shield TBM tunnel, reinforcement can be done through ground grouting outside the tunnel or by using steel plate reinforcement, ring beam reinforcement, or inner double layer lining inside the tunnel. Traditional analyses of shield TBM tunnels have been conducted using a continuum method that does not consider the segmented nature of segment lining. This study investigates the reinforcement mechanism for double layer reinforced sections with internal steel linings. By improving the modeling of segment lining, this study applies Break-joint mode (BJM), which considers the segmented characteristics of segment lining, to analyze the deformation characteristics of double layer reinforced sections. The results indicate that the existing concrete segment lining functioned similarly to ground reinforcement around the tunnel, rather than distribution the load. In general, both the BJM model considering the segmentation of segment lining and the continuum rigid method were similar deformation shapes and stress distributions of the lining under load. However, in termsof deformation, when the load strength exceeded the threshold, the deformation patterns of the two models differed.

Structural Recovery of the Detached Macula after Retinal Detachment Repair as Assessed by Optical Coherence Tomography

조수근,김윤전,채주병,양성재,이주영,김준근,윤영희 대한안과학회 2013 Korean Journal of Ophthalmology Vol.27 No.3

Purpose: To investigate correlations between preoperative and postoperative foveal microstructures in patients with macula-off rhegmatogenous retinal detachment (RRD). Methods: We reviewed the records of 31 eyes from 31 patients with macula-off RRD who had undergone successful re-attachment surgery. We analyzed data obtained from complete ophthalmologic examinations and optical coherence tomography (OCT) before and 9 to 12 months after surgery. All postoperative OCT measurements were taken with spectral-domain OCT, but a subset of preoperative OCT measurements were taken with time-domain OCT. Results: The mean duration of macular detachment was 15.5 ± 15.2 days, and mean preoperative best-corrected visual acuity (BCVA, logarithm of the minimum angle of resolution) was 1.03 ± 0.68. Preoperative visual acuity was correlated with retinal detachment height (p < 0.001) and the existence of intraretinal separation (IRS) along with outer layer undulation (OLU) (p = 0.022), but not with macula-off duration. The final BCVA was significantly correlated with integrity of the junction between the photoreceptor inner and outer segments (IS/OS) combined with the continuity of external limiting membrane (ELM) (p = 0.025). The presence of IRS and OLU on a detached macula were highly correlated with the final postoperative integrity of the IS/OS junction and the ELM (p = 0.017). Conclusions: Eyes preoperatively exhibiting IRS and OLU showed a higher incidence of disruption to the photoreceptor IS/OS junction and the ELM at final follow-up. Such a close correlation between preoperative and postoperative structural changes may explain why ultimate visual recovery in such eyes is poor.

Association between Microperimetric Parameters and Optical Coherent Tomographic Findings in Various Macular Diseases

김동윤,양현승,국윤준,이주용 대한안과학회 2015 Korean Journal of Ophthalmology Vol.29 No.2

Purpose: To analyze the correlation between microperimetric parameters and optical coherent tomographic findings in the eyes of patients with macular diseases. Methods: A total of 64 eyes were included in this retrospective cross-sectional study. Differences in the macular integrity index and microperimetric parameters were analyzed according to types of outer retinal band defects. Correlations between average threshold values and retinal thickness in the corresponding areas were analyzed. Finally, microperimetric parameters were compared between inner and outer retinal lesions. Results: Measures of best-corrected visual acuity, macular integrity index, and average threshold values were significantly worse in eyes with defects in the ellipsoid portion of the photoreceptor inner segment (ISe), the cone outer segment tip (COST), and the external limiting membrane (ELM) than in eyes without ISe, COST, and ELM defects. Also, visual functionality is more significantly impacted by ELM defects than by other hyper- reflective band defects. There was a significant negative correlation between retinal thickness and the average threshold of the corresponding area in the Early Treatment Diabetic Retinopathy Study grid. Microperimetric parameters in the eyes of patients with inner retinal lesions were better than in the eyes of patients with outer retinal lesions. Conclusions: The macular integrity index may be a useful factor for reflecting the functional aspects of macular diseases. Specifically, ELM, ISe, and COST defects are significantly associated with poor retinal sensitivity and macular integrity index values that suggest abnormalities. Among eyes with these particular defects, the visual functionality of patients is most sensitively impacted by ELM defects. This finding suggests that microperimetric parameters are sensitive and useful for evaluating functional abnormalities in the eyes of patients with macular disease, particularly in patients with outer retinal pathology.

비선형 와류격자법을 이용한 낮은 종횡비 날개의 공력특성 계산

이태승(Taeseung Lee),박승오(Seung-O Park) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.11

본 논문에서는 새로운 비선형 와류격자법 계산 과정이 제안된다. 기존의 계산 과정은 자유와의 형태 계산을 위해 내부 반복계산 및 하향이완법을 포함한다. 하지만 본 논문에서는 유사 정상 개념에 기초한 새로운 수식을 제안하여 자유와의 형태를 계산함으로써, 계산 과정에서 내부 반복계산 및 하향이완법을 생략한다. 또한 반복계산이 진행됨에 따라 각 분절에 유도되는 유속도를 적절히 평균해 줌으로써 알고리듬의 수치적 안정성을 향상시킨다. 그리고 낮은 종횡비 날개에 대한 수치실험을 수행하여 분절의 길이, 와류중심반경, 후류영역 계산범위 등과 같은 중요 인자들의 적절한 기준을 경험적으로 결정한다. A new computational procedure for the Non-Linear Vortex Lattice Method (NLVLM) is suggested in this work. Conventional procedures suggested so far usually involves inner iteration loop to update free vortex shape and an under-relaxation based iteration loop to determine the free vortex shape. In this present work, we suggest a new formula based on quasi-steady concept to fix free vortex shape which eliminates the need for inner iteration loop. Further, the ensemble averaging of the induced velocities for a given free vortex segment evaluated at each iteration significantly improves the convergence property of the algorithm without resorting to the under-relaxation technique. Numerical experiments over several low aspect ratio wings are carried out to obtain optimal empirical parameters such as the length of the free vortex segment, the vortex core radius, and the rolled-up wake length.