Jin A. Choi

Low Serum 25-Hydroxyvitamin D Is Associated With Myopia in Korean Adolescents

Purposes: To assess the relationship between serum level of 25-hydroxyvitamin D (25(OH)D) and refractive error in Korean adolescents. Methods: A total of 2,038 adolescent aged 13-18 years, who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2011 underwent refractive examination using an autorefractor. Serum 25(OH)D concentration and other potential risk factors were examined. Multivariate regression analysis was performed to investigate the association between serum 25(OH)D and spherical equivalent (SE). Results: Among the participants, 80.1% had myopia (-0.5 D or more myopic) and 8.9% had high myopia (-6.0D or more myopia). The age-adjusted distribution of SE according to serum 25(OH)D concentration showed a positive relationship (r = 0.067, P = 0.012).The myopia group had a significant positive relationship between SE and serum 25(OH)D tertile concentration (P = 0.020), whereas the non-myopia group did not have any significant relationship (P = 0.599).In multiple linear regression analyses, SE was significantly associated with low serum 25(OH)D concentration after adjustment for area of residence, parental income, total energy intake, dietary Ca intake, milk consumption and smoking experience (P=0.047). The prevalence of high myopia was significantly associated with the lowest tertile of serum 25(OH)D concentration after adjustment for the confounding factors (P=0.017). Smoking experience showed inverse associations with both SE and the prevalence of high myopia (P = 0.001 and 0.036) Conclusions: Low serum 25(OH)D concentration was associated with myopia prevalence in Korean adolescents. This relationship was particularly notable in adolescents with high myopia.

Optic disc tilt direction determines the location of initial glaucomatous damage.

PURPOSE To explore differences in optic disc tilt and torsion between normal control and glaucoma subjects, and to determine whether the direction of optic disc tilt is consistent with the initial location of glaucomatous visual field (VF) defect. METHODS Glaucoma patients with isolated superior or inferior hemifield loss (n = 136) and normal controls (n = 99) were analyzed. Disc ovality index and torsion degree were measured on retinal photographs. Imaging of optic disc was obtained using Heidelberg retinal tomography (HRT) III and Cirrus spectral-domain optical coherence tomography (OCT). The degree of temporal disc tilt was assessed using horizontal topographic images and vertical (upward or downward) disc tilt using vertical topographic images, respectively. RESULTS In all subjects, disc ovality was significantly associated with HRT- and OCT-measured temporal disc tilt and axial length (AL) (all P < 0.001), whereas disc torsion degree was associated with HRT- and OCT-measured vertical disc tilt and AL (all P < 0.05). Association of AL with disc ovality and torsion became more evident as the mean deviation increased. When data on glaucoma patients with superior and inferior hemifield defects were compared, the vertical disc tilt (HRT- and OCT-assessed, P < 0.001 and 0.030, respectively) and the torsion degree (P = 0.002) differed significantly. Upon multivariate logistic regression analysis, the HRT-measured vertical disc tilt was an independent factor determining initial location of the VF defect (P = 0.012). CONCLUSIONS Measurement of vertical disc tilt may give valuable information about the superior versus inferior regional susceptibilities of glaucoma.

The foveal position relative to the optic disc and the retinal nerve fiber layer thickness profile in myopia.

PURPOSE To evaluate retinal nerve fiber layer (RNFL) thickness profiles according to the foveal position relative to the optic disc in myopia METHODS In 164 eyes of 164 healthy myopic subjects, the disc-foveal angle was defined as the angle between a horizontal line through the disc center and the line connecting the fovea and disc center in fundus photographs overlaid on Cirrus-HD optical coherence tomography (OCT) images. The quadrant/clock-hour based peripapillary RNFL thickness and differences between the inferior and superior (I-S) quadrant RNFL thicknesses were measured with OCT. RNFL thickness profiles were determined according to the disc-foveal angle and axial length (AL). RESULTS As the disc-foveal angle increased (i.e., the fovea becomes more inferior to the optic disc), the superior RNFL decreased significantly (P = 0.003), whereas the inferior RNFL and I-S difference increased (P = 0.010 and P < 0.001, respectively). As the AL increased, the average and temporal RNFLs increased significantly (P = 0.013 and P < 0.001, respectively), and I-S difference was not affected (P = 0.231). The disc-foveal angle was significantly decreased with the distance between the fovea and the optic disc (P = 0.033). In multiple linear regression analysis, the disc-foveal angle was found to be a significant factor related to I-S differences, superior and inferior RNFL (all, P < 0.05) after adjusting for age, disc area, and AL. CONCLUSIONS The intrinsic foveal position relative to the optic disc was an essential determinant of normal RNFL thickness in myopia. In particular, it was associated with the vertical asymmetry of RNFL distribution.

Measurement of Scleral Thickness using Swept-Source Optical Coherence Tomography in Patients With Open-Angle Glaucoma and Myopia

PURPOSE To use swept-source optical coherence tomography (OCT) to image the posterior sclera at the posterior pole and around the optic nerve head (ONH) and measure the subfoveal scleral thickness and laminar thickness to evaluate the relationship between the measured thicknesses and ocular parameters. DESIGN Prospective, cross-sectional design. METHODS The study included 103 patients with glaucoma and 43 controls with axial lengths more than 26 mm. Swept-source OCT images were obtained to capture the subfoveal and ONH regions. Subfoveal scleral thickness and laminar thickness were measured from obtained B-scan images. To verify the reproducibility of the measurement, intraclass correlation coefficients were calculated from selected B-scans. Scleral and laminar thicknesses in patients with normal-tension glaucoma (NTG) was compared with that in patients with primary open-angle glaucoma (POAG). A Pearson correlation was calculated to assess the relationships of scleral and laminar thicknesses with ocular parameters. RESULTS Posterior scleral thickness could be measured in 68.4% of patients, and laminar thickness could be measured in 88.6% by using swept-source OCT. Interobserver and intraobserver measurement reproducibility was moderate to excellent. The subfoveal scleral thickness was 670.84 ± 160.60 μm in the POAG group and 496.55 ± 115.20 μm in the NTG group; a significant difference between the groups was observed. Subfoveal scleral thickness (r = -0.677, P < 0.001) was negatively correlated with axial length only in patients with NTG, not in patients with POAG. CONCLUSIONS Swept-source OCT detected differences in the thicknesses of the posterior sclera between eyes with NTG and eyes with POAG. Subfoveal scleral thickness was negatively correlated with axial length only in eyes with NTG.

Clinical Course and Risk Factors of Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus in Korea

Background We investigated clinical course and risk factors for diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). Methods A total of 759 patients with T2DM without DR were included from January 2001 to December 2004. Retinopathy evaluation was performed at least annually by ophthalmologists. The severity of the DR was classified into five categories according to the International Clinical Diabetic Retinopathy Severity Scales. Results Of the 759 patients, 523 patients (68.9%) completed the follow-up evaluation. During the follow-up period, 235 patients (44.9%) developed DR, and 32 patients (13.6%) progressed to severe nonproliferative DR (NPDR) or proliferative DR (PDR). The mean duration of diabetes at the first diagnosis of mild NPDR, moderate NPDR, and severe NPDR or PDR were 14.8, 16.7, and 17.3 years, respectively. After adjusting multiple confounding factors, the significant risk factors for the incidence of DR risk in patients with T2DM were old age, longer duration of diabetes, higher mean glycosylated hemoglobin (HbA1c), and albuminuria. Even in the patients who had been diagnosed with diabetes for longer than 10 years at baseline, a decrease in HbA1c led to a significant reduction in the risk of developing DR (hazard ratio, 0.73 per 1% HbA1c decrement; 95% confidence interval, 0.58 to 0.91; P=0.005). Conclusion This prospective cohort study demonstrates that glycemic control, diabetes duration, age, and albuminuria are important risk factors for the development of DR. More aggressive retinal screening for T2DM patients diagnosed with DR should be required in order to not miss rapid progression of DR.

Optic Disc Characteristics in Patients With Glaucoma and Combined Superior and Inferior Retinal Nerve Fiber Layer Defects

IMPORTANCE Eyes with initial bihemifield defects show faster progression compared with eyes with initial single-hemifield involvement, suggesting greater optic nerve susceptibility to glaucomatous damage. We hypothesized that certain disc phenotypes may exist in patients with glaucoma who have bihemispheric structural damage at the initial stage of the disease. OBJECTIVE To identify the optic disc characteristics related to bihemispheric retinal nerve fiber layer (RNFL) defects in early-stage glaucoma. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study of 136 patients with early-stage primary open-angle glaucoma from a glaucoma referral practice. Eyes were divided into those with RNFL defects in the superior or the inferior hemisphere (group 1) and those with bihemispheric RNFL defects (group 2). We measured the degree of horizontal tilt angle and RNFL thickness using spectral-domain optical coherence tomography. We performed multivariate logistic regression analysis to determine potential risk factors related to the bihemispheric RNFL defects. EXPOSURES Bihemispheric RNFL defects. MAIN OUTCOMES AND MEASURES Disc ovality (defined as the ratio between the longest and shortest diameters of the optic disc), the degree of horizontal tilt angle, and the presence of bihemispheric RNFL defects. Asymmetry in RNFL thickness between hemispheres was defined as the difference between the superior and inferior mean RNFL thickness. RESULTS Disc ovality (mean [SD], 1.09 [0.12] in group 1 vs 1.18 [0.18] in group 2; difference, -0.09; 95% CI, -0.14 to -0.03), proportion of tilted discs (5.3% vs 17.5%, respectively; difference, -12.2; 95% CI, -13.0 to -11.4), and horizontal tilt angle (mean [SD], 4.17° [4.13°] vs 5.93° [4.84°], respectively; difference, -1.76; 95% CI, -3.47 to -0.03) were significantly different between groups 1 and 2 (P = .001, P = .03, and P = .045, respectively). The asymmetry in RNFL thickness decreased with increased disc ovality (exponentiation of the B coefficient, 1.67; 95% CI, 1.10-2.55; P = .02), although associations were not identified with spherical equivalent, axial length, or the angle between the temporal retinal veins. In multivariate logistic analysis, disc ovality was suggested to be an independent risk factor for bihemispheric RNFL defects, after controlling for mean deviation, age, axial length, and disc area (P = .02). CONCLUSIONS AND RELEVANCE Optic disc tilt appears to be associated with bihemispheric RNFL defects in patients with early glaucoma, regardless of their refractive status. These data suggest that disc tilt, associated with bihemispheric structural damages, is a risk factor for glaucoma progression.

Retinal nerve fiber layer loss is associated with urinary albumin excretion in patients with type 2 diabetes.

OBJECTIVES To identify the factors associated with retinal nerve fiber layer (RNFL) loss in patients with type 2 diabetes. DESIGN Cross-sectional study. PARTICIPANTS Ninety-six nonglaucomatous patients with type 2 diabetes without renal impairment (estimated glomerular filtration rate, ≥60 ml/minute per 1.73 m(2)). METHODS Eyes were divided into 2 groups based on the presence or absence of RNFL defects detected by red-free retinal fundus photography. All participants underwent an eye fundus examination, and the urinary albumin-to-creatinine ratio (ACR) was determined. A cardiovascular autonomic function test was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to the Valsalva maneuver, and standing. Multiple logistic regression analyses were performed to determine potential risk factors related to the presence of RNFL defects in these patients. MAIN OUTCOMES AND MEASURES The association between RNFL defects and diabetic complications. RESULTS Among the patients, 43 (44.8%) had localized RNFL defects (group 1), whereas the others (55.2%) did not (group 2). The RNFL defects occurred more frequently on the superior side (75.6% and 71.0% in right and left eyes, respectively) compared with the inferior side (13.8% and 0.0% in right and left eyes, respectively). Patients with RNFL defects (group 1) had significantly higher rates of diabetic retinopathy (60.5%) compared with those without RNFL defects (group 2; 32.1%; P = 0.007). The urinary ACR was significantly higher in patients with RNFL defects than in those without defects (45.3±72.1 μg/mg vs. 15.4±17.3 μg/mg creatinine, respectively; P = 0.015), whereas autonomic function test grading was similar between the groups. The urinary ACR was the only factor related to visual field defect location in both univariate (P = 0.021) and multivariate (P = 0.036) logistic regression analyses after adjusting for age; gender; presence of diabetic retinopathy; diabetes duration; smoking; statin use; and antiplatelet, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker treatment. CONCLUSIONS Urinary albumin excretion was associated with nerve fiber layer loss in patients with type 2 diabetes. Careful examination of the optic nerve head may be necessary, particularly in patients with type 2 diabetes exhibiting albuminuria.

Age-Related Association of Refractive Error with Intraocular Pressure in the Korea National Health and Nutrition Examination Survey

Background To investigate the distribution of intraocular pressure (IOP) and refractive errors according to age group in a representative sample of non-glaucomatous Korean adults. Methods A total of 7,277 adults (≥19 years) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2011 underwent ophthalmic examination were divided into three groups according to age: the young- (19–39 years), middle- (40–59 years), and old- (≥60 years) age groups. Simple and multiple regression analyses between IOP and various parameters (including the refractive error) were conducted. Results The mean IOP of the total population was 14.0±0.1 mmHg [young: 13.9±0.1 mmHg; middle: 14.1±0.1 mmHg; old: 13.8±0.2 mmHg (P for trend = 0.085)]. Myopia and high myopia were more prevalent in the young- (70.8% and 16.1%, respectively), compared to the middle- (44.6% and 10.9%) and old- (8.9% and 2.2%) age groups. Univariate analysis in the total population showed that higher IOP was associated with myopic refractive error, the female gender, higher body mass index (BMI), diabetes, hypertension, and hypercholesterolemia (all P<0.05). In the young- and middle-age groups, higher IOP was associated with myopic refractive error, the female gender, higher BMI, hypercholesterolemia and diabetes (all P<0.05). In the old-age group, the association between IOP and refractive error was not significant (P = 0.828). In multiple linear regression analysis, similar significant relationships between the refractive error and IOP were found in the young- and middle-age groups (beta = −0.08 and −0.12; P = 0.002 and <0.001 for young- and middle-age group, respectively), but not in the old-age group (beta = 0.03; P = 0.728), after adjusting for age, gender, BMI, region of habitation, diabetes, hypertension, and hypercholesterolemia. Conclusions Myopic refractive error was an independent predictor of higher IOP in non- glaucomatous eyes, and the association between refractive error and IOP differed according to age.

Retinal nerve fiber layer thickness profiles associated with ocular laterality and dominance.

Although human anatomy is arranged symmetrically based on a central vertical axis, the majority of persons will use one side of their body more readily than the other. Interestingly, these lateral body dominances including ocular dominance are all rightward. The asymmetry in retinal nerve fiber layer (RNFL) thickness between the right and left eyes in healthy subjects has been reported in several studies, and the reason for this structural difference between right and left eyes is unclear. In the manuscript, we hypothesized that the characteristics of ocular dominance are reflected in the RNFL profile and may be related to inter-ocular structural differences between right and left eyes. In this study, ocular dominance occurred mostly in right eyes (right vs. left: 78.77% vs. 21.22%; P<0.001). According to ocular dominance and laterality, different relationships between the inferior and superior RNFLs were observed. The right eyes had a thicker RNFL, except in the superior quadrant, than the left eyes. Regardless of laterality, inferior RNFL was thicker than superior RNFL in the dominant eyes. To our knowledge, this paper is the first report demonstrating the RNFL characteristics associated with ocular dominance.

Lipoprotein(a) predicts the development of diabetic retinopathy in people with type 2 diabetes mellitus

BACKGROUND Lipoprotein(a) [Lp(a)] has mainly been considered to be a predictor of the incidence of cardiovascular disease. In addition, previous studies have shown potential linkage between Lp(a) and diabetic microvascular complications. OBJECTIVES We investigated the incidence and risk factors for the development of diabetic retinopathy (DR) in patients with type 2 diabetes. METHODS A total of 787 patients with type 2 diabetes without DR were consecutively enrolled and followed up prospectively. Retinopathy evaluation was annually performed by ophthalmologists. The main outcome was new onset of DR. RESULTS The median follow-up time was 11.1 years. Patients in the DR group had a longer duration of diabetes (P < .001), higher baseline HbA1c (P < .001), higher albuminuria level (P = .033), and higher level of Lp(a) (P = .005). After adjusting for sex, age, diabetes duration, presence of hypertension, renal function, LDL cholesterol, mean HbA1c, and medications, the development of DR was significantly associated with the serum Lp(a) level (HR 1.57, 95% confidence interval [1.11-2.24]; P = .012, comparing the 4th vs 1st quartile of Lp(a)). The patient group with the highest quartile range of Lp(a) and mean HbA1c levels ≥7.0% had an HR of 5.09 (95% confidence interval [2.63-9.84]; P < .001) for developing DR compared with patients with lower levels of both factors. CONCLUSIONS In this prospective cohort study, we demonstrated that the DR was independently associated with the serum Lp(a) level in patients with type 2 diabetes.