Chungkwon Yoo

Myopic optic disc tilt and the characteristics of peripapillary retinal nerve fiber layer thickness measured by spectral-domain optical coherence tomography.

PurposeTo investigate the correlation between myopic optic disc tilt and the characteristics of peripapillary retinal nerve fiber layer (RNFL) thickness measured by Cirrus HD spectral-domain optical coherence tomography (Cirrus HD OCT; Carl Zeiss Meditec, Dublin, CA). MethodsA total of 255 eyes of 255 healthy young male participants with various degrees of refractive errors (mean spherical equivalent, −3.17±2.40 D; range, −11.00 to 0.00 D) underwent ophthalmic examinations, including refractive error, axial length, and optic disc area measurement. The degree of horizontal/vertical optic disc tilt was evaluated by cross-sectional images obtained by the Cirrus HD OCT. The average, superior, nasal, inferior, and temporal quadrant thickness and superior/inferior peak locations of the peripapillary RNFL were also measured with the Cirrus HD OCT. ResultsOn the univariate analysis, eyes with more temporally tilted optic discs (horizontal tilt) had higher myopia, greater axial length, a thinner average, superior, nasal, and inferior RNFL, thicker temporal RNFL, and more temporally positioned superior/inferior peak locations (all P values <0.001). The degree of inferior optic disc tilt (vertical tilt) was associated with high myopia and a more temporally positioned inferior peak location (all P values <0.05). On multivariate analysis, eyes with more temporally tilted optic discs had a thicker temporal RNFL and more temporally positioned superior/inferior peak locations. ConclusionsThe characteristics of the peripapillary RNFL thickness were associated with the degree of myopic optic disc tilt, especially in the temporal area. The degree of myopic optic disc tilt should be considered when interpreting the RNFL thickness measured by the Cirrus HD OCT.

Characteristics of peripapillary retinal nerve fiber layer thickness in eyes with myopic optic disc tilt and rotation.

Purpose:The purpose of the study was to investigate the effects of myopic optic disc tilt and rotation on peripapillary retinal nerve fiber layer (RNFL) thickness characteristics measured by Cirrus HD spectral-domain optical coherence tomography (Cirrus HD OCT). Methods:A total of 93 right eyes from 93 healthy young male individuals with myopia underwent ophthalmic examinations, including refractive error, axial length, and optic disc area measurements. The superior/inferior peak locations, RNFL thickness, and horizontal/vertical optic disc tilt were evaluated using the Cirrus HD OCT. The optic disc rotation was assessed by the angle between the long axis of the optic disc and the vertical meridian. The patients were divided into the tilted group and the non-tilted group; the tilted group was further divided into the rotated group and the nonrotated group. Results:The eyes in the tilted group (n=47) had a greater axial length and thicker temporal RNFL and more temporally positioned superior/inferior peak locations than the non-tilted group (n=46) (all P <0.05). Among the eyes in the tilted group, the eyes in the rotated group (n=23) had a thicker temporal RNFL and a more temporally positioned superior peak location than the eyes in the nonrotated group (n=24) (all P <0.05). Conclusions:The eyes with a myopic temporal optic disc tilt and counterclockwise rotation had a thicker temporal RNFL and more temporally positioned superior peak location. The characteristics of the RNFL thickness in eyes with myopic optic disc tilt and rotation should be considered when interpreting the RNFL thickness measured by the Cirrus HD OCT.

The effect of lateral decubitus position on intraocular pressure in healthy young subjects

Purpose:  To investigate the effect of change of body posture from supine to lateral decubitus position (LDP) on intraocular pressure (IOP) in healthy young subjects.

Retinal vessel diameter, retinal nerve fiber layer thickness, and intraocular pressure in Korean patients with normal-tension glaucoma

PURPOSE To investigate the retinal vessel diameter and evaluate the relationship of the retinal nerve fiber layer (RNFL) thickness with retinal vessel diameter and intraocular pressure (IOP) in patients with normal-tension glaucoma (NTG). DESIGN A prospective, cross-sectional study. METHODS This study included 60 previously untreated patients with NTG (60 eyes) and 45 age- and sex-matched healthy controls (45 eyes) that had no history of systemic vascular disease at a single institution. The diameters of the central retinal arteries and veins were measured on retinal photographs. The central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were calculated using the revised Parr-Hubbard formula. The RNFL thickness was measured using Stratus optical coherence tomography. RESULTS The mean central retinal arteriolar (P = .000) and venular (P = .000) diameters were significantly smaller in the eyes with NTG than in the normal eyes. Multivariate linear regression analysis demonstrated a significant positive correlation between the RNFL thickness and CRAE (P = .014), and a negative correlation between the RNFL thickness and IOP (P = .005) in the eyes with NTG. However, there was no significant correlation between the RNFL thickness and the independent variables in the control group (P = .112). CONCLUSION The patients with NTG had smaller diameters of the central retinal vessels than the normal subjects. Both IOP and CRAE were significantly associated with RNFL thickness in the patients with NTG. Our results suggest that narrower retinal vessels and higher IOP may be related to the thinning of the RNFL in patients with NTG.

Effects of Different Sleeping Postures on Intraocular Pressure and Ocular Perfusion Pressure in Healthy Young Subjects

OBJECTIVE To investigate the effects of different sleeping positions of head and body on intraocular pressure (IOP) and ocular perfusion pressure (OPP) in healthy, young subjects. DESIGN Prospective, comparative case series. PARTICIPANTS Twenty healthy young Korean subjects. METHODS We measured IOP and blood pressure (BP) with the subjects seated and recumbent, including supine, right lateral decubitus, left lateral decubitus, prone with right head turn, and prone with left head turn positions. We measured IOP using an Icare tonometer in both eyes 5 minutes after assuming each position in a randomized sequence. We calculated the OPP using the formulas based on the mean BP adjusted for the height of the eye over the heart. The eye on the lower side in the lateral decubitus or prone with head turn position was termed the dependent eye. MAIN OUTCOME MEASURES Difference in IOP and OPP of the dependent and nondependent eyes during changes of sleeping positions of body and head. RESULTS Mean IOP of right and left eyes while sitting was significantly lower than that measured in each recumbent position (all P<0.001). The OPPs in both eyes were significantly higher in all recumbent positions than in a sitting position (all P<0.001). Mean IOP of the dependent eyes was higher than that of the nondependent eyes in the lateral decubitus positions and in the prone positions with head turns (all P<0.001). No significant intereye difference in OPP was found for any position. Among IOPs measured in the recumbent positions, mean IOP of the dependent eye in the lateral decubitus position or in the prone position with head turn was significantly higher than that of the ipsilateral eye in the supine position (all P<0.0001). CONCLUSIONS All sleeping positions of head and body resulted in an elevation of IOP and an increase in the calculated OPP compared with the sitting position in healthy, young subjects. The postural change from supine to lateral decubitus or prone with head turn position increased the IOP of the dependent eyes without significant alteration in OPP in healthy awake subjects. Further research is needed under nocturnal conditions in a sleep laboratory. FINANCIAL DISCLOSURES The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Simplified method to measure the peripapillary choroidal thickness using three-dimensional optical coherence tomography.

Purpose To evaluate a simplified method to measure peripapillary choroidal thickness using commercially available, three-dimensional optical coherence tomography (3D-OCT). Methods 3D-OCT images of normal eyes were consecutively obtained from the 3D-OCT database of Korea University Medical Center On the peripapillary images for retinal nerve fiber layer (RNFL) analysis, choroidal thickness was measured by adjusting the segmentation line for the retinal pigment epithelium to the chorioscleral junction using the modification tool built into the 3D-OCT image viewer program. Variations of choroidal thickness at 12 sectors of the peripapillary area were evaluated. Results We were able to measure the peripapillary choroidal thickness in 40 eyes of our 40 participants, who had a mean age of 41.2 years (range, 15 to 84 years). Choroidal thickness measurements had strong inter-observer correlation at each sector (r = 0.901 to 0.991, p < 0.001). The mean choroidal thickness was 191 ± 62 µm. Choroidal thickness was greatest at the temporal quadrant (mean ± SD, 210 ± 78 µm), followed by the superior (202 ± 66 µm), nasal (187 ± 64 µm), and inferior quadrants (152 ± 59 µm). Conclusions The measurement of choroidal thickness on peripapillary circle scan images for RNFL analysis using the 3D-OCT viewing program was highly reliable and efficient.

Astigmatism and optical coherence tomography measurements

BackgroundTo evaluate the effect of astigmatism change on measurement of retinal nerve fiber layer (RNFL) and macular thickness by Cirrus HD spectral-domain optical coherence tomography (Cirrus HD OCT; Carl Zeiss Meditec, Dublin, CA, USA).MethodsA total of 30 right eyes from 30 healthy young subjects underwent RNFL and macular thickness measurements using Cirrus HD OCT. Measurements were performed at the baseline state and induced with-the-rule (WTR) and against-the-rule (ATR) astigmatism states by wearing toric soft contact lenses (+1.50 −3.25 diopter × 90° and +1.50 −3.25 diopter × 180° respectively). Dfferences in RNFL and macular thickness between the baseline state and induced astigmatism states were analyzed.ResultsWearing toric soft contact lenses induced a mean 2.92 diopter WTR and 3.18 diopter ATR astigmatism respectively. After signal strength change adjustment, RNFL thicknesses of average, superior quadrant, 12 and 6 o’clock hour sectors decreased after induction of a WTR astigmatism (mean difference range, 1.58 to 6.88 μm); RNFL thicknesses of average, nasal, temporal quadrants, 2, 3, and 9 o’clock hour sectors decreased after induction of an ATR astigmatism (mean difference range, 0.75 to 5.11 μm) (all P values <0.05). Macular thickness was not significantly affected by astigmatism changes (all P values ≥ 0.250).ConclusionAlthough the amount of change was not substantial, RNFL thickness measured by Cirrus HD OCT was affected by astigmatism changes induced by contact lenses. It may be warranted to consider the effect of astigmatism on RNFL thickness measured by OCT in eyes with higher degrees of astigmatism.

Central corneal thickness and anterior scleral thickness in korean patients with open-angle glaucoma: An anterior segment optical coherence tomography study

PurposeTo assess the correlation between central corneal thickness (CCT) and anterior scleral thickness (AST) in Korean patients with normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). Patients and MethodsConsecutive patients with POAG, NTG, and normal individuals were recruited. Anterior segment optical coherence tomography (AS-OCT, Visante) was used to measure CCT and AST. The AST was measured 2 mm posterior to the scleral spur in the temporal meridian. Statistical analysis of the data included ANOVA and Pearson correlation analysis. ResultsOne hundred and eight participants (36 with NTG, 35 with POAG, and 37 normal individuals) were enrolled. The CCT (NTG 514.81±25.03 &mgr;m; POAG 534.43±34.79 &mgr;m; controls 536.70±32.11 &mgr;m) was found to be thinner in patients with NTG compared with POAG and the control eyes (P=0.023; P=0.009). The AST (NTG 738.53±53.63 &mgr;m; POAG 771.86±53.75 &mgr;m; controls 783.62±57.03 &mgr;m) was thinner in the patients with NTG compared with POAG and the normal controls (P=0.032; P=0.002). No significant difference in AST was found among the POAG and control eyes (P=0.636). A correlation between CCT and AST was found only among the patients with NTG (r=0.469, P=0.004). However, no correlation was observed between CCT and AST in patients with POAG and controls. ConclusionsAnterior scleral thickness was correlated with CCT in the NTG group, but this correlation was not observed among the POAG or control groups.

Peripheral Anterior Synechiae and Ultrasound Biomicroscopic Parameters in Angle-Closure Glaucoma Suspects

Purpose To investigate the correlation between peripheral anterior synechia (PAS) and the quantitative anterior chamber angle parameters measured by ultrasound microscopy (UBM) in angle-closure glaucoma suspect (ACGS) eyes. Methods Eyes were defined ACGS as having occludable angles and intraocular pressure less than 21 mm Hg without glaucomatous optic nerve head. The gonioscopic criteria for ACGS were the trabecular meshwork invisible in 3 or more quadrants of the entire angle and the angular width less than 20 degrees by Shaffer classification. Twenty-seven eyes of 20 patients underwent anterior chamber angle and ciliary body imaging with UBM. Angle opening distance (AOD500), angle recess area (ARA), trabecular-ciliary process distance (TCPD) and trabecular-iris angle (TIA) were measured from the UBM images at each quadrant. Results The AOD500, ARA, and TIA were not significantly different between the eyes with PAS (9 eyes)and without PAS (18 eyes) at each quadrant. However, the TCPD was significantly shorter in the superior quadrant when compared with the eyes without PAS (mean: 405.3±70.9 µm vs 536.4±140.5 µm) (p<0.05). Conclusions The results suggest that the shorter distance from trabecular meshwork to ciliary body or the anterior placement of ciliary process may play a role in the development of PAS in ACGS eyes.

Atypical acute syphilitic posterior placoid chorioretinitis.

A 48-year-old man presented with visual dimness in the right eye that had developed 2 weeks previously. Dilated fundus examination showed few vitreous cells and numerous yellow, placoid lesions in both eyes. His right eye had more severe serous retinal detachment involving the macula. Fluorescein angiography demonstrated early irregular hypofluorescence with late staining in the areas of the yellow placoid lesions. He started a regimen of 60 mg of oral prednisone daily. Two weeks later, a serologic fluorescent treponemal antigen absorption test was positive for Ig G and Ig M. He was referred to an infectious disease specialist for antibiotic therapy. A week later, he returned, having stayed on prednisone only and not having taken the internists antibiotic prescription. Meanwhile, the chorioretinitis in his right eye, which had initially been at a more advanced stage, was resolved with the use of steroids. The chorioretinitis in his left eye, which was aggravated at an earlier stage, ultimately recovered. Our case had atypical courses such that one eye improved and the other worsened during the same steroid treatment period. This result was inconsistent with that of previous reports showing that oral steroid influences the clinical course of acute syphilitic posterior placoid chorioretinitis.