Cy Kim

Influence of cataract on time domain and spectral domain optical coherence tomography retinal nerve fiber layer measurements.

PurposeTo assess and compare the influence of cataract on measurements of retinal nerve fiber layer (RNFL) thickness by time domain (TD) optical coherence tomography (OCT) and spectral domain (SD) OCT. MethodsPatients who underwent uncomplicated cataract surgery were consecutively enrolled in this study. The peripapillary RNFL thickness was measured before and 8 weeks after cataract surgery using TD-OCT and SD-OCT during the same visit. Changes in the RNFL thickness measurement and signal strength (SS) after cataract surgery were evaluated. ResultsA total of 54 patients (54 eyes) were included. After excluding 19 eyes owing to poor imaging or low SS (<5), scans of 35 eyes were included in the final analysis. A significant difference was identified between the preoperative and postoperative SS values using SD-OCT, but not TD-OCT (P=0.002 and 0.789, respectively). The changes in RNFL thickness after cataract surgery were more prominent and frequent for SD-OCT than TD-OCT. There was a significant correlation between change in preoperative RNFL thickness and SS changes for both TD-OCT (r2=0.410, P<0.001) and SD-OCT (r2=0.246, P=0.002). ConclusionsThe presence of cataract significantly affects RNFL thickness measurements by SD-OCT and TD-OCT. SD-OCT, which demonstrated more consistent change of RNFL measurements after cataract extraction, is not necessarily associated with lower RNFL thickness measurement performance in cataract cases, as more participants with cataract were excluded because of poor image quality or low SS, which was more associated with TD-OCT than SD-OCT.

Enhanced expression of transglutaminase 2 in anterior polar cataracts and its induction by TGF-β in vitro

Background/aims: Transglutaminase activity has long been implicated in the cataract formation. However, the precise mechanism of how it is produced and involved in this process remains unclear. Here the authors sought to examine whether transglutaminase 2 (TGase 2) is expressed in lens epithelial cells from patients with anterior polar cataracts, to determine whether TGase 2 expression is induced by transforming growth factor (TGF-β) in cultured lens epithelial cells, and to determine whether TGase 2 participates in the crosslinking of fibronectin in lens epithelial cells in vitro. Methods: Lens epithelial cells from anterior polar cataracts, nuclear cataracts, and non-cataractous clear lenses were examined for the expression of TGase 2 using reverse transcription-polymerase chain reaction, western blot analysis, and immunohistochemical analysis. The modulation of extracellular TGase 2 activity by TGF-β was measured by the formation of fibronectin polymers and the incorporation of fluorescein cadaverine into extracellular matrix proteins. The effect of TGase 2 overexpression was analysed by immunofluorescence staining and western blot analysis of human lens epithelial (HLE) B-3 cells transiently transfected with TGase 2 gene. Results: The expression of TGase 2 mRNA and its protein was markedly enhanced in lens epithelial cells from patients with anterior polar cataracts. Treatment of HLE B-3 cells with TGF-β caused an increase in TGase 2 protein, its extracellular activity, and the crosslinking of fibronectin. Transient transfection of HLE B-3 cells with the TGase 2 gene led to the increased production of fibronectin monomers and polymers. Conclusions: This study shows that TGase 2 is overexpressed in lens epithelial cells from anterior polar cataracts and that TGF-β may be a causative factor in the induction of TGase 2. The enhanced expression of TGase 2 might cause the accumulation and crosslinking of the extracellular matrix proteins and might play a part in anterior polar cataract development.

Negative refraction power causes underestimation of peripapillary retinal nerve fibre layer thickness in spectral-domain optical coherence tomography

Background/aims Although studies using optical coherence tomography (OCT) reported that the retinal nerve fibre layer (RNFL) thickness of myopic eyes was thinner than those of normal controls, it was unclear if this finding indicated the difference in actual structural thickness or that created by sources affecting accuracy of OCT measurement. This studys aim was to evaluate the effect of refraction power on the measurement of the RNFL thickness using spectral-domain OCT. Methods OCT scans to measure RNFL thickness were repeated in 15 cycloplegic eyes of 15 participants, while different refraction powers were induced by wearing soft contact lenses of eight different dioptres (−6 to +8). Results Measured RNFL thicknesses decreased significantly with soft contact lenses of higher plus dioptres and increased with those of more minus dioptres. This finding was consistent with or without controlling factors including the signal strength and test–retest variability of the machine. Measurement of peripapillary RNFL thicknesses was not varied between scans performed with and without plano contact lenses. Conclusions In spectral-domain OCT, RNFL thickness was underestimated in eyes with increasing negative refraction power and overestimated with increasing positive refraction power.

Protective mechanism of agmatine pretreatment on RGC-5 cells injured by oxidative stress

Agmatine has neuroprotective effects on retinal ganglion cells (RGCs) as well as cortical and spinal neurons. It protects RGCs from oxidative stress even when it is not present at the time of injury. As agmatine has high affinity for various cellular receptors, we assessed protective mechanisms of agmatine using transformed RGCs (RGC-5 cell line). Differentiated RGC-5 cells were pretreated with 100 muM agmatine and consecutively exposed to 1.0 mM hydrogen peroxide (H2O2). Cell viability was determined by measuring lactate dehydrogenase (LDH), and the effects of selective alpha 2-adrenergic receptor antagonist yohimbine (0-500 nM) and N-methyl-D-aspartic acid (NMDA) receptor agonist NMDA (0-100 microM) were evaluated. Agmatines protective effect was compared to a selective NMDA receptor antagonist MK-801. After a 16-h exposure to H2O2, the LDH assay showed cell loss greater than 50%, which was reduced to about 30% when agmatine was pretreated before injury. Yohimbine almost completely inhibited agmatines protective effect, but NMDA did not. In addition, MK-801 (0-100 microM) did not significantly attenuate the H2O2-induced cytotoxicity. Our results suggest that neuroprotective effects of agmatine on RGCs under oxidative stress may be mainly attributed to the alpha 2-adrenergic receptor signaling pathway.

Clinical experience of e-PTFE membrane implant surgery for refractory glaucoma

Aims: To evaluate the clinical efficacy of membrane tube implant made of expanded polytetrafluoroethylene (e-PTFE, Gore-Tex) membrane and silicone tube in treating refractory glaucoma. Methods: A retrospective chart review was performed on 43 eyes of 40 patients who underwent glaucoma tube shunt implant surgery using double layered e-PTFE membrane and silicone tube to treat refractory glaucoma. The surgeries were performed from May 1991 to September 1995, and the subjects were patients with terminal glaucoma without useful vision on the study eye. Results: The mean follow up period was 32.9 months. The Kaplan-Meier survival for intraocular pressure (IOP) control (IOP between 6 and 21mm Hg without significant complication) was 80.9% at 1 year, 73.9% at 2 years, and 62.2% at 3 years after surgery. After excluding three eyes of three patients who were dropped within 3 months after surgery and did not have any serious complication or problem in IOP control, the average preoperative IOP was 42.5 (SD 14.6) mm Hg and IOP on the last visit was 17.3 (10.2) mm Hg (p = 0.000, n = 40). The number of antiglaucoma medications before surgery (2.2 (0.6)) was reduced to 0.5 (0.8) on the last visit (p = 0.000). The IOP was controlled within the range of 6–21 mm Hg in 26 eyes (65.0%). In the remaining 14 eyes (35%), we could not control the IOP or additional surgery was needed to control the IOP or to treat severe complications. Two cases of endophthalmitis and three of phthisis were found as serious complications. The other complications were similar to those of other commercially available glaucoma implants. Conclusion: A comparable clinical result was obtained with this new implant as with the other commercially available implants. This implant with a thin and non-rigid reservoir has a potential to reduce some complications associated with the large volume and rigid consistency of the other implants, although it is not yet proved. This membrane tube implant may be considered as another substitute in the surgery of refractory glaucoma.

Retinal protective effects of topically administered agmatine on ischemic ocular injury caused by transient occlusion of the ophthalmic artery

Agmatine, an endogenous polyamine and putative neuromodulator, is known to have neuroprotective effects on various neurons in the central nervous system. We determined whether or not topically administered agmatine could reduce ischemic retinal injury. Transient ocular ischemia was achieved by intraluminal occlusion of the middle cerebral artery of ddY mice (30-35 g) for 2 h, which is known to also induce occlusion of the ophthalmic artery. In the agmatine group (N = 6), a 1.0 mM agmatine-containing ophthalmic solution was administered four times daily for 2 weeks before occlusion. In the control group (N = 6), a 0.1% hyaluronic acid ophthalmic solution was instilled at the same times. At 22 h after reperfusion, the eyeballs were enucleated and the retinal sections were stained by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Transient ocular ischemia induced apoptosis of retinal cells in the entire retinal layer, and topically administered agmatine can significantly reduce this ischemic retinal injury. The proportion of apoptotic cells was definitely decreased (P < 0.001; Kruskal-Wallis test). Overall, we determined that topical agmatine application effectively decreases retinal damage in an in vivo ocular ischemic injury model. This implies that agmatine is a good candidate as a direct neuroprotective agent for eyes with ocular ischemic diseases.

Amniotic membrane transplantation for necrotising conjunctival ulceration following subconjunctival atropine injection

Conjunctival necrosis has been previously reported after subconjunctival injection of several antimicrobial agents and corticosteroids.1–3 Atropine is used widely as a form of eyedrops for mydriasis, cycloplegia, and pain and inflammation control. We describe a patient who developed severe conjunctival necrosis associated with scleral melting after subconjunctival atropine injection and which was treated by amniotic membrane transplantation. A 30 year old male patient visited our clinic because of severe pain and redness in his left eye for a day. He had recently been diagnosed with uveitis associated with circular posterior synechiae in his left eye, and which was managed by his previous physician with a subconjunctival injection of 0.4 ml …

EPH-ephrin signaling in hyperoxia induced lunginjury.

EPH-ephrin interactions have important roles in cell adhesion-based process during inflammation such as the disruption of endothelial-epithelial barriers and adhesion of leukocytes to endothelial cells allowing leukocyte egress into the extracellular space and increasing the leakiness of the endothelial barrier. This is a similar phenomenon with hyeroxia-induced toxicity which is a common complication of critical care practices involving supplemental oxygen therapy. However, little is known about the role of the EPH-ephrin pathway in hyperoxic acute lung injury.

HE3 ANALYSIS OF AN AFFORDABLE PRICE FOR PERFORMANCE-BASED RISK SHARING SCHEME: OMALIZUMAB ADAPTATION IN KOREA

14.50 and 69.07 ± 8.28 years, and average length of stay for 9.41 ± 4.45 and 9.17 ± 4.55 days, respectively. Most procedures were conducted at medical centers (45.52% and 37.57%). The most frequent diagnoses for THR are avascular necrosis (45.22%) and osteoarthritis (44.05%); while for TKR is osteoarthritis (96.42%). Only 40 THR (3.90%) and 160 TKR (6.66%) had ever been prescribed antithrombotic agents after surgeries, and mostly used aspirin alone (18 THR and 95 TKR). CONCLUSIONS: According to this nationwide individual patient dataset, antithrombotic agents are not commonly used after THR and TKR in Taiwan, but aspirin is the most frequently prescribed of all. These fi ndings deviate from the recommendations of current international guidelines. To establish Taiwanese own guidance, it is necessary to further investigate the effectiveness and safety of prophylactic antithrombotic agents after THR and TKR, and explore the infl uences of reimbursement policy and genetic factors on these outcomes.