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Featured researches published by Yoon Hyung Kwon.


Korean Journal of Ophthalmology | 2014

Predictive findings of visual outcome in spectral domain optical coherence tomography after ranibizumab treatment in age-related macular degeneration.

Yoon Hyung Kwon; Dong Kyu Lee; Hyung Eun Kim; Oh Woong Kwon

Purpose To investigate which spectral domain optical coherence tomography (SD-OCT) findings predict visual outcome after anti-vascular endothelial growth factor (VEGF) treatment in neovascular age-related macular degeneration (NV-AMD). Methods We reviewed the medical records of patients with treatment-naïve NV-AMD who underwent three or more consecutive anti-VEGF injections. The patients were divided into three groups according to their changes of visual acuity (VA); improved (group I), static (group S), or worsened (group W). We assessed the incidences and values of all available SD-OCT findings of these groups, compared these findings between the three groups and compared the initial values with the post-treatment values. Results Better initial VA and longer external limiting membrane (ELM) length were associated with less change in VA after anti-VEGF treatment. The initial VA was mildly correlated with initial photoreceptor inner and outer segment junction (IS/OS) length and initial ELM length. The final VA was also mildly correlated with the final IS/OS length and the final ELM length. VA was significantly changed after anti-VEGF treatment in groups W and I. With regard to incidence, disruption of the IS/OS (IS/OS-D), disruption of the ELM (ELM-D) and ELM length differed significantly between the three groups, particularly ELM-D. The incidences of IS/OS-D and ELM-D in group I were significantly lower than those in groups S and W, and those in group S were also lower than those in group W. The ELM length in group I was significantly longer than it was in groups S and W, and the ELM length in group S was longer than that for group W. However, these three findings did not change after the anti-VEGF treatment. Conclusions Initial IS/OS-D, ELM length and particularly ELM-D can be useful predictors of the visual outcome after anti-VEGF treatment in NV-AMD patients.


Korean Journal of Ophthalmology | 2014

The short-term efficacy of subthreshold Micropulse yellow (577-nm) laser photocoagulation for diabetic macular edema.

Yoon Hyung Kwon; Dong Kyu Lee; Oh Woong Kwon

Purpose This pilot study aimed to evaluate the efficacy and safety of subthreshold micropulse yellow (577-nm) laser photocoagulation (SMYLP) in the treatment of diabetic macular edema (DME). Methods We reviewed 14 eyes of 12 patients with DME who underwent SMYLP with a 15% duty cycle at an energy level immediately below that of the test burn. The laser exposure time was 20 ms and the spot diameter was 100 µm. Laser pulses were administered in a confluent, repetitive manner with a 3 × 3 pattern mode. Results The mean follow-up time was 7.9 ± 1.6 months. The baseline-corrected visual acuity was 0.51 ± 0.42 logarithm of the minimum angle of resolution (logMAR), which was improved to 0.40 ± 0.35 logMAR (p = 0.025) at the final follow-up. The central macular thickness at baseline was 385.0 ± 111.0 µm; this value changed to 327.0 ± 87.7 µm (p = 0.055) at the final follow-up. Conclusions SMYLP showed short-term efficacy in the treatment of DME and did not result in retinal damage. However, prospective, comparative studies are needed to better evaluate the efficacy and safety of this treatment.


Journal of Ophthalmology | 2014

The Clinical Characteristics and Surgical Outcomes of Epiblepharon in Korean Children: A 9-Year Experience

Jong Soo Kim; Sang Wook Jin; Mun Chong Hur; Yoon Hyung Kwon; Won Yeol Ryu; Woo Jin Jeong; Hee Bae Ahn

Purpose. To examine the demographic characteristics, clinical features, surgical outcomes, and long-term prognoses of epiblepharon in Korean children. Methods. Epiblepharon patients who were followed for ≥ 6 month following surgical correction between January 2005 and December 2013. The patient demographics, clinical features, concomitant disorders, surgical outcomes, and complications were retrospectively reviewed. Results. A total of 768 epiblepharon records were included in the analysis. The mean patient age was 6.55 ± 2.37 years. At presentation, 712 patients (92.8%) complained of typical epiblepharon symptoms. The mean patient age at surgery was 6.95 ± 2.52 years, with 629 patients (81.9%) on the lower lid and 72 patients (9.4%) on the upper lid and 82 patients (10.7%) undergoing surgery on both lids. The eyelid was well everted with no recurrence in 740 patients (96.4%). Conclusion. Epiblepharon frequently occurs in Korean children and is correctable with a simple surgery. Recurrence and serious complications do not occur often, and any suspicions of epiblepharon should be investigated. A thorough ocular examination can lead to a correct diagnosis and timely corrective surgery. Most procedures are successful and prevent secondary complications that often occur with uncorrected epiblepharon.


Ophthalmic Plastic and Reconstructive Surgery | 2013

Efficacy of temperature-sensitive Guardix-SG for adhesiolysis in experimentally induced eyelid adhesion in rabbits.

Eun Jung Sohn; Hee Bae Ahn; Mi Sook Roh; Won Yeol Ryu; Yoon Hyung Kwon

Purpose: To determine the efficacy of a temperature-sensitive poloxamer/alginate mixture (Guardix-SG) for reducing adhesions after blepharoplasty in rabbit models. Methods: Thirty-six intact eyes of 18 rabbits were randomly designated to 2 groups, and primary blepharoplasty was performed on both the upper eyelids of the 18 rabbits. Sterile cotton soaked in 1 N NaOH was used to produce chemical tissue damage to experimentally induce eyelid adhesion, which was followed by adhesiolysis in 2 weeks. During adhesiolysis, Guardix-SG was applied to the OD of rabbits in the experimental group, while adhesiolysis alone was performed on the OS of rabbits in the control group. Both sides were compared by gross examination 1 day, 1 week, and 4 weeks after surgery, and the degrees of inflammation and fibrosis were examined with hematoxylin-eosin (H&E) and Masson’s trichrome (MT) stains. The expression of &agr;-smooth muscle actin (&agr;-SMA) antibody was also immunohistochemically examined. Results: The gross examinations performed after adhesiolysis yielded results that were not significantly different between the experimental and the control groups, and no prevalent complications, such as eyelid traction or distorted eyelids, were observed. One day (p = 0.028), 1 week (p = 0.028), and 4 weeks (p = 0.028) after surgery, the experimental group had a lower infiltration rate of inflammatory cells than the control group, as shown by H&E staining. The MT staining and &agr;-SMA staining also showed that the collagen deposition and fibrosis (1 week, p = 0.059; 4 weeks, p = 0.034) and the degree of myofibroblast differentiation were significantly lower in the experimental group than in the controls (1 week, p = 0.027; 4 weeks, p = 0.024). Conclusions: The temperature-sensitive poloxamer/alginate mixture (Guardix-SG) decreased inflammation and fibrosis after blepharoplasty and histopathologically prevented the readhesion of secondary blepharoplasty in rabbit models. Therefore, additional clinical studies are needed for other ophthalmic surgeries that could benefit from preventing postoperative adhesions.


Blood Research | 2015

Intraocular lymphoma in Korea: the Consortium for Improving Survival of Lymphoma (CISL) study.

Seul Lee; Moon Jin Kim; Jin Seok Kim; Sung Yong Oh; Seok Jin Kim; Yoon Hyung Kwon; In Young Chung; Jung Hun Kang; Deok Hwan Yang; Hye Jin Kang; Dok Hyun Yoon; Won Seog Kim; Hyo Jin Kim; Cheolwon Suh

Background Intraocular lymphoma (IOL) is a rare malignant lymphoma that most closely resembles a diffuse large B-cell lymphoma, and it is a subtype of primary central nervous system lymphoma (PCNSL). IOL is located inside the eye in the retina, uvea, and/or optic nerve. We retrospectively analyzed IOL patient data to identify treatment patterns and survival rates in Korea. Methods Cytological confirmation for a diagnosis of IOL was performed for all patients. The clinical data collected from medical records included Ann Arbor stage, International Prognostic Index, performance status, date of diagnosis, treatment modality and response, date of relapse, and date of last follow-up. Results Twenty patients who were diagnosed with IOL, between December 2007 and June 2014 at multiple centers in Korea, were included in the analysis. Four patients were diagnosed with IOL alone, not involving the CNS. Two patients with isolated IOL later developed PCNSL. Nine patients developed CNS lesions before the onset of ocular lymphoma. Five patients had simultaneous onset in the eye and CNS. Twelve patients were treated by intravitreal injection of methotrexate for IOL. The median progression-free survival (PFS) for patients was 19.7 months (95% CI, 8.7-30.7 mo). The estimated 3-year overall survival (OS) for all patients was 75.1%. Conclusion Treatment for IOL patients included radiotherapy and intraocular chemotherapy. IOL patients showed favorable PFS and OS. These patients would require long-term follow-up to identify relapse and adverse effects of radiotherapy or intraocular chemotherapy.


Journal of Aapos | 2014

Herpes zoster ophthalmicus with isolated trochlear nerve palsy in an otherwise healthy 13-year-old girl

Won Yeol Ryu; Nam Yeong Kim; Yoon Hyung Kwon; Hee Bae Ahn

Herpes zoster ophthalmicus is rare in healthy children. It is occasionally associated with extraocular muscle palsies and rarely with isolated trochlear nerve palsy. We report a case of unilateral isolated trochlear nerve palsy associated with herpes zoster ophthalmicus in an immunocompetent 13-year-old girl who presented with diplopia and blurred vision in her right eye. The right cornea had multiple subepithelial opacities. Ocular motility returned to normal and diplopia and corneal opacification resolved with steroid therapy. To our knowledge, this is the first such case involving the troclear nerve in a child.


Journal of Aapos | 2013

The effect of a temperature-sensitive poloxamer-alginate-CaCl2 mixture after strabismus surgery in a rabbit model

Won Yeol Ryu; Hye Mi Jung; Mee Sook Roh; Yoon Hyung Kwon; Woo Jin Jeung; Woo Chan Park; Sae Heun Rho; Hee Bae Ahn

PURPOSE To determine the efficacy of a temperature-sensitive poloxamer-alginate mixture in reducing adhesions after strabismus surgery in a rabbit model. METHODS The superior rectus muscle was recessed in each of 36 eyes from 18 rabbits. One randomly assigned eye in each rabbit was treated with a poloxamer-alginate mixture (PA group); the other eye was treated with a subconjunctival injection of saline (control group). The adhesions between the superior rectus muscle, sclera, and conjunctiva were clinically evaluated by a masked observer at 1 day, 1 week, and 4 weeks after surgery. Inflammation was analyzed by hematoxylin and eosin staining and anti-CD11b staining. Late fibrosis was assessed by the Masson trichrome and α-smooth muscle actin staining. Adhesion, inflammation, and fibrosis were graded on a scale of 0-4. RESULTS There was no significant between-group difference in the degree of adhesion at 1 day and 4 weeks after surgery. However, the degree of adhesion in the PA group was lower than that in the control group at postoperative week 1 (P < 0.05). Acute inflammation was similar between the groups (P > 0.05). At postoperative week 4, inflammatory cell infiltration was reduced in the PA group (P = 0.046). A significant between-group difference in late fibrosis at postoperative week 4 was observed through the Masson trichrome (P = 0.024) and α-smooth muscle actin staining (P = 0.025). CONCLUSIONS The poloxamer-alginate mixture significantly decreased adhesion after strabismus surgery in a rabbit model. Additional studies are warranted to evaluate the use of this mixture in preventing postoperative adhesions.


International Journal of Ophthalmology | 2013

Efficacy of Seprafilm® graft with adhesiolysis in experimentally induced lid adhesion in rabbits

Sang Wook Jin; Hee Bae Ahn; Mi Sook Roh; Yoon Hyung Kwon; Won Yeol Ryu

AIM To evaluate the efficacy of Seprafilm(®) transplantation following adhesiolysis for preventing postoperative readhesion and improving surgical outcomes. METHODS Primary blepharoplasty was carried out on both eyelids of 18 albino rabbits. After 2 weeks, a new skin incision was made, and adhesiolysis was performed on both eyelids. The rabbits were categorized into two groups, one with adhesiolysis alone in the left eyelid (control group), and the other with adhesiolysis with a Seprafilm(®) graft in the right eyelid (Seprafilm(®) group). The degrees of inflammation and fibrosis were examined with hematoxylin-eosin (HE) and Massons trichrome stains. Expression of α-smooth muscle actin (α-SMA) was also immunohistochemically examined. RESULTS Eyelid examination immediately after the operation revealed mild swelling and hemorrhage in both groups, but these symptoms resolved after 1 week-2 weeks, and eyelid shape had recovered completely in both groups. Microscopic assessments demonstrated that the Seprafilm(®) group showed less inflammation and fibrosis than the control group. The Seprafilm(®) group also exhibited fewer α-SMA-positive cells than the control group. CONCLUSION Based on these findings, we conclude that Seprafilm(®) graft with adhesiolysis is an effective method for preventing postoperative readhesions after eyelid surgery.


Retinal Cases & Brief Reports | 2012

Subretinal tenecteplase injection in a submacular hemorrhage from polypoidal choroidal vasculopathy: a case report.

Yoon Hyung Kwon; Su J. Lim; Woo Jin Jeung; Yong S. You; Soon Hyun Kim; Oh Woong Kwon

PURPOSE The purpose of this report was to describe a case with a thick submacular hemorrhage (SMH) resulting from polypoidal choroidal vasculopathy that was successfully treated with a subretinal tenecteplase injection. METHODS A retrospective case report. RESULTS A 63-year-old man with acute SMH secondary to polypoidal choroidal vasculopathy underwent a partial posterior vitrectomy, a subretinal tenecteplase (100 μg/0.1 mL) injection with air/fluid exchange, and an intravitreal injection of bevacizumab (2.5 mg/0.1 mL). His preoperative corrected visual acuity was 20/30, but the SMH threatened the fovea. The SMH was displaced inferiorly and absorbed completely at 1 month postoperative. His visual acuity decreased to 20/40 1 week postoperative but recovered to 20/20 2 months after surgery. The electroretinogram showed no distinct elongation of implicit time and slightly decreased amplitude of a-wave and b-wave at 3 months postoperative; optical coherence tomography presented disruption of the inner segment/outer segment line at the onset of SMH but recovered completely at 3 months postoperative. CONCLUSION Subretinal tenecteplase was found to have sufficient hemolytic function and no retinal toxicity and could represent a feasible treatment option for the management of SMH.


Seminars in Ophthalmology | 2014

Acute Disseminated Encephalomyelitis Without Optic Neuritis Followed by Optic Neuritis in a Child Due to the Sudden Cessation of Steroid Therapy

Won Yeol Ryu; Eun Jung Sohn; Yoon Hyung Kwon; Woo Jin Jeung; Hee Bae Ahn; Woo Chan Park; Sae Heun Rho

Abstract Acute disseminated encephalitis (ADEM) is an autoimmune demyelinating disorder of the central nervous system that usually occurs in children after viral infection or vaccination. It is not uncommon for ADEM to be accompanied by optic neuritis. However, ADEM followed by optic neuritis is a rare. We report the case of a 6-year-old girl who initially presented with ADEM (without optic neuritis) due to a live measles, mumps, and rubella vaccine and was treated with intravenous high-dose corticosteroids. After steroid therapy, she recovered neurologically and was not prescribed any medication, including an oral steroid taper, for use after discharge. Three weeks later, she developed unilateral optic neuritis and was again treated with steroid therapy. This is a rare case of ADEM without optic neuritis in a child, followed by optic neuritis due to the sudden cessation of steroid therapy. Further studies and follow-ups are needed to determine whether ADEM followed by optic neuritis can be considered a specific clinical form of this disorder.

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