Seungbum Kang

Prevalence and risk factors for refractive errors: Korean National Health and Nutrition Examination Survey 2008-2011.

Purpose To examine the prevalence and risk factors of refractive errors in a representative Korean population aged 20 years old or older. Methods A total of 23,392 people aged 20+ years were selected for the Korean National Health and Nutrition Survey 2008–2011, using stratified, multistage, clustered sampling. Refractive error was measured by autorefraction without cycloplegia, and interviews were performed regarding associated risk factors including gender, age, height, education level, parents education level, economic status, light exposure time, and current smoking history. Results Of 23,392 participants, refractive errors were examined in 22,562 persons, including 21,356 subjects with phakic eyes. The overall prevalences of myopia (< -0.5 D), high myopia (< -6.0 D), and hyperopia (> 0.5 D) were 48.1% (95% confidence interval [CI], 47.4–48.8), 4.0% (CI, 3.7–4.3), and 24.2% (CI, 23.6–24.8), respectively. The prevalence of myopia sharply decreased from 78.9% (CI, 77.4–80.4) in 20–29 year olds to 16.1% (CI, 14.9–17.3) in 60–69 year olds. In multivariable logistic regression analyses restricted to subjects aged 40+ years, myopia was associated with younger age (odds ratio [OR], 0.94; 95% Confidence Interval [CI], 0.93-0.94, p < 0.001), education level of university or higher (OR, 2.31; CI, 1.97–2.71, p < 0.001), and shorter sunlight exposure time (OR, 0.84; CI, 0.76–0.93, p = 0.002). Conclusions This study provides the first representative population-based data on refractive error for Korean adults. The prevalence of myopia in Korean adults in 40+ years (34.7%) was comparable to that in other Asian countries. These results show that the younger generations in Korea are much more myopic than previous generations, and that important factors associated with this increase are increased education levels and reduced sunlight exposures.

Prevalence and risk factors for diabetic retinopathy: the Korea National Health and Nutrition Examination Survey 2008-2011.

PURPOSE We evaluated the prevalence and risk factors for diabetic retinopathy (DR) in a representative Korean population. METHODS This cross-sectional study involved 16,109 subjects aged >40 years who had participated in the Korean National Health and Nutrition Survey from 2008 to 2011. Seven standard retinal fundus photographs were obtained after pupil dilatation from both eyes. The DR was graded using the modified Airlie House classification system. Risk factors for DR and vision-threatening diabetic retinopathy (VTDR) were evaluated, including age, sex, diabetes duration, glycated hemoglobin (HbA1c), hypertension, lipid profiles, and refractive error. RESULTS Of the 16,109 eligible individuals participating in the study, 14,595 (90.6%) had fasting blood glucose results available. Of these, 2023 (13.8%) were diagnosed with diabetes mellitus. Among these, gradable photographs were available for 1678 subjects (82.9%), including 1323 subjects with known diabetes mellitus (KDM) and 355 with newly diagnosed diabetes mellitus (NDM). The prevalences of any DR and VTDR were 15.8% (95% confidence interval [CI], 14.1-17.5), and 4.6% (95% CI, 3.6-5.6), respectively. Any DR was associated with a longer duration of diabetes (odds ratio [OR], 1.08; 95% CI, 1.06-1.10), higher HbA1C level (OR, 1.52; 95% CI, 1.28-1.80), higher systolic blood pressure (OR, 1.02; 95% CI, 1.01-1.03), and lower body mass index (OR, 0.91; 95% CI, 0.87-0.96) in a multivariate analysis. CONCLUSIONS We provide data on the prevalence and risk factors for DR in a representative Korean population. The prevalence of any DR and VTDR in the Korean population was lower than that reported previously. The condition of DR was associated with a longer duration of diabetes, poor glycemic control, and higher systemic blood pressure.

One-year results of intravitreal ranibizumab for neovascular age-related macular degeneration and clinical responses of various subgroups

PurposeTo report 1-year clinical outcomes of intravitreal ranibizumab treatment for choroidal neovascularization (CNV) due to age-related macular degeneration (AMD) and to identify predictive factors that may influence visual acuity (VA) outcomes in Korean patients.MethodsSixty patients (64 eyes) with subfoveal CNV were followed up over 12 months after intravitreal injection (0.5 mg) of ranibizumab at baseline and subsequent injections on an as-needed basis. The VA outcomes over 12 months were compared with baseline VA and evaluated across subgroups based on sex, age, baseline VA, CNV size, CNV type, and presence or absence of systemic disease and prior photodynamic therapy.ResultsVA improved or remained stable in 46 of 64 eyes (71.9%) at 12 months. Subgroup analysis showed that both baseline VA and CNV size influenced VA outcomes after ranibizumab treatment (P = 0.039, P = 0.042, respectively). However, the patients’ sex (P = 0.643), baseline age (P = 0.361), CNV type (P = 0.940), and the presence or absence of systemic disease (P = 0.775) and prior photodynamic therapy (P = 0.890) did not affect VA outcomes.ConclusionsIntravitreal injections of ranibizumab improve mean VA in patients with subfoveal CNV secondary to AMD, and baseline VA and CNV lesion size were predictive factors of VA outcomes after ranibizumab treatment in Korean patients.

Anthocyanins from the seed coat of black soybean reduce retinal degeneration induced by N-methyl-N-nitrosourea☆

Anthocyanins are known to have antioxidant effects and thus may play an important role in preventing various degenerative diseases. In this study, we examined the effect of anthocyanins extracted from the seed coat of black soybean on an animal model of retinal degeneration (RD), a leading cause of photoreceptor cell death resulting in blindness. RD was induced in rats by an intraperitoneal injection of N-methyl-N-nitrosourea (MNU) (50mg/kg), a DNA-methylating agent that causes photoreceptor damage. Anthocyanins extracted from black soybean seed coat (50mg/kg) were daily administered, orally, for 1, 2, and 4 weeks after MNU injection. Electroretinographic (ERG) recordings and morphological analyses were performed. In control rats with MNU-induced retinal damage, the ERG recordings showed a gradual significant time-dependent reduction in both a- and b-wave amplitudes compared with those of normal animals. In the MNU-induced RD rats given anthocyanins for 4 weeks, ERG responses were significantly increased compared with untreated RD rats, more apparently in scotopic stimulation than in the photopic condition. However, in the MNU-injected rats given anthocyanins for 1 and 2 weeks, the increase in ERG responses was not significant. Morphologically, the outer nuclear layer, where photoreceptors reside, was well preserved in the anthocyanin-treated rat retinas throughout the experimental period. In addition, retinal injury, evaluated by immunolabeling with an antibody against glial fibrillary acidic protein, was markedly reduced in anthocyanin-treated retinas. These results demonstrate that anthocyanins extracted from black soybean seeds can protect retinal neurons from MNU-induced structural and functional damages, suggesting that anthocyanins from black soybean seed coat may be used as a useful supplement to modulate RD.

Tissue response of selective retina therapy by means of a feedback-controlled energy ramping mode

The purpose of the study was to evaluate the safety and selectivity of the retinal pigment epithelium lesions by using automatic energy ramping and dosimetry technique for selective retina therapy and to investigate the healing response.

Prevalence and Risk Factors for Age-Related Macular Degeneration: Korean National Health and Nutrition Examination Survey 2008–2011

Abstract Purpose: To evaluate the prevalence of and risk factors for age-related macular degeneration (AMD) in a representative Korean population. Materials and Methods: A nationwide population-based cross-sectional study was conducted among the civilian, noninstitutionalized Korean population aged 40 and older (mean age, 55.7 years; 95% confidence interval [CI], 55.4–56.0). A total of 16,109 older (≥40 years of age) subjects participated in the Korean National Health and Nutrition Survey 2008–2011. All participants underwent standardized interviews and comprehensive ophthalmic examinations. Using physiologic mydriasis, a 45° digital fundus photograph was taken of both eyes of each participant. All fundus photographs were graded according to an international classification and grading system. Main outcome measures consisted of prevalence of early- and late-AMD. Results: Of the 16,109 subjects, fundus photographs were gradable for 14,352 (89.1%). The prevalence of early- and late-AMD in the Korean population was 6.0 and 0.6%, respectively. The prevalence of early-AMD increased from 1.5% in those aged 40–49 years to 16.2% in those aged ≥70 years. After adjusting for confounders, the prevalence of early-AMD increased with increasing age (odds ratio [OR], 1.08; CI, 1.06–1.09). For late-AMD, old age (OR, 1.09; CI, 1.04–1.14), male gender (OR, 2.45; CI, 1.11–5.37), high systolic blood pressure (OR, 1.03; CI, 1.00–1.06) and high fasting glucose level (OR, 0.97; CI, 0.94–0.99) were significant risk factors. Smoking was not associated with either early- or late-AMD in this Korean population. Conclusions: The present study provides the first population-based data on the prevalence of and risk factors for AMD in a representative Korean population. The prevalences of early- and late-AMD in this population were 6.0 and 0.6%, respectively. The prevalence of AMD in Koreans is higher than for those in other Asian countries and similar to that of Caucasians in Western countries.

Relation Between Grade II Hypertensive Retinopathy and Coronary Artery Disease in Treated Essential Hypertensives

It is known that in advanced hypertensive retinopathy, which changes advanced hypertensive retinopathy (Grade III or IV), there is a strong relation between retinal microvascular lesions and cardiac and macrovascular markers of target organ damage (TOD). The prevalence of grade II hypertensive retinopathy and its relationship to cardiovascular risk factors remain controversial. The subjects, a total of 437 hypertensive patients, were divided into three groups according to modified Keith, Wagener, and Barker (KWB) classification by two ophthalmologists: Grade 0 with normal retinal change (N = 169, 38.7%), Grade I with arteriolar narrowing (N = 215, 49.1%), Grade II with arteriovenous crossings (N = 49, 11.2%). The prevalence of Grade I and Grade II hypertensive retinopathy was significantly higher than that of advanced hypertensive retinopathy. The grade of hypertensive retinopathy was related to age, duration of hypertension, coronary artery disease (CAD), and left ventricular hypertrophy (LVH). The prevalence of LVH and CAD in Grade II was significantly higher than in Grade I and Grade 0. The hypertensive retinopathy Grade II was significantly correlated with LVH (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.21–4.44, p < 0.05) and CAD (OR 4.2, 95% CI 1.97–8.95, p-<-0.001). Grade I and Grade II hypertensive retinopathy are frequently observed in hypertensive patients compared to Grade III and IV patients. We concluded that Grade II hypertensive retinopathy is closely related to CAD and should therefore not be ignored.

Comparison of posterior capsular opacification in heparin-surface-modified hydrophilic acrylic and hydrophobic acrylic intraocular lenses

PurposeTo compare posterior capsular opacification (PCO) in a heparin-surface-modified (HSM) hydrophilic acrylic intraocular lens (IOL) and a hydrophobic acrylic IOL.MethodsSeventy-eight patients with simple cataract were randomized to receive either the BioVue 3 HSM hydrophilic acrylic IOL (Ophthalmic Innovations International, Ontario, CA, USA) (n = 38) or the Sensar AR40e hydrophobic acrylic IOL (AMO, Santa Ana, CA, USA) (n = 40). Another 99 patients with complicated cataract received either the BioVue 3 (n = 49) or the Sensar AR40e IOL (n = 50). Twelve months after surgery, POCOman software was used to analyze digital retroillumination photographs of the PCO.ResultsIn the simple cataract group, the respective PCO areas, expressed as a percentage and PCO severity scores at 12 months were 6.12% and 0.081 in the BioVue 3 group and 5.91% and 0.075 in the Sensar AR40e group. There was no statistically significant difference in the PCO area or the PCO severity score between the two IOLs (P = 0.631, P = 0.495, respectively). In the complicated cataract group, the respective PCO areas and PCO severity scores were 35.80% and 0.181 in the BioVue 3 group and 27.17% and 0.110 in the Sensar AR40e group. There was no statistically significant difference between the two IOLs (P = 0.147, P = 0.162).ConclusionThere was no difference in the degree or severity of PCO between the HSM hydrophilic acrylic IOL and the hydrophobic acrylic IOL groups.

Antiangiogenic Effects of Axitinib, an Inhibitor of Vascular Endothelial Growth Factor Receptor Tyrosine Kinase, on Laser-Induced Choroidal Neovascularization in Mice

Purpose: To investigate the effects of axitinib, an inhibitor of vascular endothelial growth factor receptors, on choroidal neovascularization (CNV) in an animal model of neovascular age-related macular degeneration (AMD). Methods: Experimental CNV lesions were induced in C57BL/6 mice by laser photocoagulation. Beginning 1 day after CNV induction, mice were treated with axitinib (5 mg/kg/day) or vehicle for 2 weeks. In other groups of mice, axitinib or vehicle treatment was started 7 days after the laser application to determine the effect of the drug on established CNV. Untreated mice were used as a baseline group. Two weeks after laser injury, the extent of CNV was assessed from choroidal flat mounts perfused with fluorescein-labeled dextran. Immunofluorescence staining with isolectin IB4 was also used to quantify the CNV lesions. Results: Orally administered axitinib inhibited CNV growth in the laser-induced CNV model. Axitinib caused a 70.1% inhibition of CNV lesions compared to vehicle-treatment (p < 0.001). Axitinib also caused a significant regression of established CNV, reducing the area by 71.1% compared to vehicle treatment (p < 0.001). Moreover, immunofluorescence staining showed that the area of isolectin IB4 labeled vessels was smaller in the axitinib-treated group compared to the vehicle-treated group (p < 0.001). Conclusions: Axitinib effectively inhibits the progression of CNV in an experimental animal model. These results suggest that axitinib could constitute a therapeutic alternative for the treatment of neovascular AMD.

Effect of cediranib, an inhibitor of vascular endothelial growth factor receptor tyrosine kinase, in a mouse model of choroidal neovascularization

Background:  This study was conducted to evaluate the effect of cediranib, an inhibitor of vascular endothelial growth factor receptor tyrosine kinase, in a mouse model of laser‐induced choroidal neovascularization.