Publications by authors named "Kwang Eon Choi"

Purpose: To investigate the impact of the distance from the most-anterior surface of the optic to the principal object plane (POP) and from the foremost haptic to the principal object plane (H-POP) on the intraocular lens (IOL) power calculation.

Setting: A tertiary hospital.

Design: Optical simulation and retrospective cross-sectional study.

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Objective: The purpose of this experiment was to evaluate the functional and histologic changes in the upper eyelid muscles after injection of triamcinolone acetonide (TA) alone or TA combined with botulinum toxin A (Botox or BTXA) in the cynomolgus monkey model.

Methods: Twenty eyes of 10 cynomolgus monkeys were divided into 4 groups: 3 experimental groups (1, 2, and 3) and the control group (group 4) based on the injection type. In group 1, 0.

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Purpose: To investigate the imaging and clinical features of polypoidal choroidal vasculopathy (PCV) with pulsation.

Methods: The PCV eyes were classified into pulsatile and nonpulsatile PCV groups according to the pulsation on indocyanine green angiography. Imaging features including the dye filling time of the polyp and clinical features were compared.

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Background: Obesity is known to increase the risk and severity of age-related macular degeneration (AMD). Increased inflamed metabolic activity of visceral adipose tissue (VAT) is considered as a crucial underlying mechanism for the harmful effects of obesity. In this study, we aimed to investigate the inflamed metabolic activity of VAT with F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and their association with AMD.

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Purpose: To evaluate anatomical changes in the low-stage partial attachment-type idiopathic epiretinal membrane (iERM) over 2 years.

Methods: Data from patients with low-stage partial attachment-type iERM (stage 2) were analyzed. The main outcome measures were anatomical changes, including changes in the foveal avascular zone (FAZ) area, vessel density (VD) in the vascular plexus, and thickness of retinal sublayers during the follow-up period.

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Article Synopsis
  • This study investigates how effective electrical stimulation is on retinal ganglion cell (RGC) responses in normal versus degenerate retinas using a specific primate model of retinitis pigmentosa (RP).
  • It was found that the charge needed to stimulate these RGCs was significantly higher in the degenerate retinas compared to healthy ones, indicating different stimulation requirements.
  • The research suggests that optimizing the electrical pulse strategy, especially by focusing on pulse amplitude rather than duration, could improve the development of retinal prosthetics for those suffering from outer retinal degeneration.
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Polyglactin 910 (Vicryl) and polypropylene (Prolene) are common suture materials used in ophthalmic surgical procedures. However, there are limited studies assessing tissue reactions to different sutures in eyelid areas. In this study, these suture materials were used subcutaneously in 10 lateral canthi of 5 pigs.

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The main objective of this study was to induce and evaluate drug-dose-dependent outer retinal degeneration in cynomolgus monkeys by application of N-methyl-N-nitrosourea (MNU).Intravitreal temporary tamponade induced outer retinal degeneration with MNU solutions (2-3 mg ml) after vitrectomy in five cynomolgus monkeys. Optical coherence tomography (OCT), fundus autofluorescence (FAF), full-field electroretinography (ffERG), and visual evoked potentials (VEP) were performed at baseline and weeks 2, 6, and 12 postoperatively.

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Article Synopsis
  • The study examined how different types of 3D microelectrodes affected the retinal structure in mini pigs after subretinal implantation.
  • The 75-μm-high electrodes caused significant retinal penetration and fibrous reactions, while the sloped substrates with smaller electrodes showed better tissue preservation.
  • Results indicated that smaller electrodes and sloped substrates are more compatible with retinal tissue, minimizing adverse effects compared to larger electrodes.
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The purpose of this study was to investigate the characteristics of blowout fractures caused by baseball trauma. The authors reviewed 337 cases of blowout fracture surgeries and included 330 eyes of 330 patients who underwent blowout fracture reconstruction between January 2017 and December 2020, in the Department of Ophthalmology at Korea university Hospital.Medical records including patient demography, trauma etiology, accompanied ocular disease, and preoperative computed tomography images were evaluated.

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The purpose of this study was to investigate the distribution of blowout fracture sites among age groups and compare clinical factors that can affect the fracture site. The authors reviewed 330 cases of blowout fracture surgeries and included 226 eyes of 226 patients aged between 20 and 29 years and between 50 and 59 years who underwent blowout fracture reconstruction between January 2017 and December 2020, in the Department of Ophthalmology at Korea University Hospital.Medical records including patient demography, trauma etiology, and preoperative computed tomography image were evaluated.

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A single-center retrospective observational case series was conducted. This case series enrolled patients who showed ophthalmic manifestations within one week after COVID-19 vaccination at Korea University Guro Hospital in Seoul, Korea, from May 2021 to January 2022. The medical records of patients who complained of ocular symptoms and showed ophthalmic adverse events within one week after COVID-19 vaccination were reviewed.

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Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient's visual acuity is at best less than 20/420. Reduced visual acuity may be explained by a decrease in the signal-to-noise ratio due to the spontaneous hyperactivity of retinal ganglion cells (RGCs) found in degenerate retinas.

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Article Synopsis
  • Retinal prosthesis aims to restore vision in blind individuals by electrically stimulating surviving neurons in the retina, especially after photoreceptor loss due to retinal degeneration (RD).
  • This study used an N-methyl-N-nitrosourea (MNU)-induced porcine model of RD to explore the retinal response to electrical stimulation by recording retinal ganglion cell (RGC) spikes.
  • Results showed that degenerative retinas required higher stimulation intensity to produce RGC spikes compared to normal retinas, indicating that early stages of RD allow for easier electrical activation, but severe degeneration presents challenges for vision recovery.
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Purpose: To present normative data of optical coherence tomography (OCT) parameters, electrophysiological tests, and optical biometry conducted for cynomolgus monkeys.

Methods: Multimodal examinations were performed for 11 adult cynomolgus monkeys (Macaca fascicularis, weighing 2.6-7.

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Purpose: To evaluate the morphologic features of macular neovascularization (MNV) trunks at different layers using optical coherence tomography angiography.

Methods: Type 1 MNV trunks in age-related macular degeneration were retrospectively evaluated at the subretinal pigment epithelium and sub-Bruch membrane (subBM) layers. The detectability and location of the trunks were compared.

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Purpose: The purpose of this study was to present normative data of optical coherence tomography (OCT), electrophysiological, and ocular biometry parameters and their correlation in minipigs.

Methods: Eighty-eight eyes of 44 minipigs underwent full-field electroretinogram (ERG) recording and ocular biometry. However, 10 eyes of 6 minipigs were excluded because of poor OCT image quality.

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We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of MNU, the vitreous cavity of each eye was filled with 4, 8, 10, 12, or 16 mg/mL MNU for 10 min, which was then replaced with a balanced salt solution. Multimodal examinations including spectral-domain optical coherence tomography (OCT) images and full-field electroretinography (ffERG) were obtained at baseline and week 2, week 6, and week 12.

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We sought to describe the surgical techniques required in the ab-interno method to implant subretinal prostheses in mini-pigs and suggest tips to facilitate optimal outcomes. During vitrectomy, the use of valved trocar cannulas was essential to stabilize the detached retina and implanted chip. As a first step in retinal detachment, a 23-gauge cannula with very small amount of viscoelastic material was used to establish the retinal hole and promote retinal detachment.

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We aimed to investigate the clinical implication of suspended scattering particles in motion (SSPiM) using optical coherence tomography angiography (OCTA) among branch retinal vein occlusion disease (BRVO) cases with macular edema (ME). Medical records of BRVO patients were reviewed. Central retinal thickness (CRT), ME type, and cyst size on optical coherence tomography images were evaluated before and after intravitreal bevacizumab injection.

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We aimed to evaluate the relationship between the capillary abnormalities including nonperfusion area (NPA) in optical coherence tomography angiography (OCTA) images and the recurrence of macular edema (ME) secondary to branch retinal vein occlusion (BRVO) after intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF; bevacizumab). The records of 40 patients who underwent intravitreal bevacizumab injection for ME secondary to BRVO and had at least six months of follow-up were reviewed. Central retinal thickness (CRT; μm) and macular edema type were evaluated prior to treatment.

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Purpose: To evaluate the immediate effect of 3% diquafosol ophthalmic solution on tear MUC5AC concentration, periodic acid-Schiff (PAS)-positive goblet cells, and tear film stability in normal and keratoconjunctivitis sicca (KCS) rat models.

Methods: Rats were divided into normal and KCS groups. 3% of diquafosol solution was instilled into the right eye and normal saline into the left eye in both groups.

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Purpose: To evaluate the effect of photobleaching on fundus autofluorescence (FAF) images in acute central serous chorioretinopathy.

Methods: We obtained prephotobleaching and postphotobleaching images using an Optomap 200Tx, and photobleaching was induced with a Heidelberg Retina Angiograph 2. Degrees of photobleaching were assessed as grayscale values in Optomap images.

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Background: The purpose of this study was to investigate peripapillary choroidal thickness (CT) in eyes with neovascular age-related macular degeneration (AMD) and to assess whether peripapillary CT is affected by intravitreal injection of ranibizumab (IVR) in eyes with neovascular AMD.

Methods: Peripapillary and subfoveal CT were measured in spectral domain optical coherence tomography images from 39 eyes of neovascular AMD patients and 39 eyes of age-matched controls retrospectively. The patients were treated with 0.

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Purpose: To evaluate the type and cause of orbital blowout fractures in Korea.

Design: Retrospective, observational case series.

Methods: Patients who underwent reconstruction for blowout fracture from March 2004 to April 2013 at Korea University Guro and Ansan Hospitals were included in this study.

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