Jaehong Ahn

Ajou University, Seoul, Seoul, South Korea

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Publications (7)11.37 Total impact

  • Marvin Lee, Hosung Jin, Jaehong Ahn
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    ABSTRACT: To investigate the relationship between ocular geometric factors, including temporal disc margin to fovea distance (DFD) measured by optic disc stereophotography (ODP) and central visual field (VF) defect, in normal-tension glaucoma (NTG) patients. This retrospective, single-center, cross-sectional study included 88 eyes of 88 NTG patients with mild VF defects (MD > -6.0 dB). NTG patients were divided into two groups according to VF tests: central VF-invading and central VF-sparing groups. Optic nerve head (ONH) parameters including disc dimensions, peripapillary atrophy (PPA), and DFD were obtained by ODP, and retinal nerve fiber layer (RNFL) thickness was measured by Stratus optical coherence tomography (OCT). In the invading group, DFD was shorter (3.642 ± 0.401 mm) than in the sparing group (3.877 ± 0.278 mm; p = 0.002). The sparing group had more vertically oval ONH (p = 0.023) and wider temporal PPA width (p = 0.031). The RNFL thickness in the invading group was thinner in the temporal and inferior quadrants, but thicker in the superior quadrant than that of the sparing group. In a multiple linear regression analysis, DFD was the only geometric factor associated with degree of central VF involvement (p = 0.002). DFD was positively correlated with temporal RNFL thickness in the sparing group (r = 0.484, p < 0.001) but not in the invading group (r = -0.080, p = 0.631). Eyes with a shorter DFD should be monitored carefully because central VF involvement appears to be related to shorter DFD in NTG patients with mild VF defects.
    Albrecht von Graæes Archiv für Ophthalmologie 11/2013; · 1.93 Impact Factor
  • Marvin Lee, Hyungyu Yoo, Jaehong Ahn
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    ABSTRACT: Abstract Purpose: To compare optic nerve head (ONH) parameters obtained by semi-automated disc analysis of stereo optic-disc photography (ODP) with those by spectral domain optical coherence tomography (SD-OCT) regarding their reproducibility, agreement and relationship with the retinal nerve fiber layer (RNFL) thickness. Patients and methods: In this cross-sectional retrospective study, 91 eyes (50 normal and 41 with open angle glaucoma) from 47 patients were examined. ONH parameters were obtained by ODP and SD-OCT. Agreement and reproducibility were assessed by intra-class correlation coefficients (ICCs). Inter-device agreement and precision were also evaluated. The structural factors related to the ONH measurements by both instruments and the disparity between the measurements were evaluated by the generalized estimating equation model. Results: ODP showed good intra-reader and inter-reader reproducibility, comparable to that of SD-OCT (ICC: >0.970). Disc area (DA) (ICC: 0.950) showed better inter-device agreement than rim area (RA) (ICC: 0.859). RNFL thickness was correlated with RA, but not with DA, for both devices. SD-OCT RA showed significant correlation with RNFL thickness in both the normal and glaucoma groups, whereas ODP RA correlated with RNFL only in the glaucoma group. The measurement disparity between the devices was influenced by the DA in both groups. The inter-device difference in RA was not correlated with RA, but instead with the RNFL thickness in the glaucoma group. Conclusion: ONH parameters obtained by semi-automated algorithms of ODP showed excellent reproducibility and good agreement with those measured by SD-OCT. SD-OCT RA was a better indicator of RNFL thickness, compared with ODP RA for both normal patients and glaucoma patients; however, the inter-device disparity of the RA was less in glaucoma patients who had a thinner RNFL.
    Current eye research 02/2013; · 1.51 Impact Factor
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    ABSTRACT: Background/Aims: To compare event-based methods for estimating the incidence of glaucoma progression using optical coherence tomography (OCT) and automated perimetry and to assess agreement between structural and functional tests for detecting glaucoma progression. Methods: Functional progression of glaucoma was estimated by guided progression analysis (GPA) using a Humphrey field analyzer (HFA), and structural progression was assessed by OCT and defined as the decrease in retinal nerve fiber layer thickness based on test-retest variability data of previous reports on clock-hour and quadrant maps. The level of agreement between structural and functional progression was evaluated using kappa statistics. Results: Fifty eyes of 50 patients with open-angle glaucoma were enrolled in this retrospective study. The incidence of visual field progression estimated by GPA was 18%. The occurrence of structural progression assessed by OCT ranged from 18 to 68%. The more stringent OCT progression criterion using a quadrant map showed the best agreement with HFA GPA (ĸ = 0.423) and detected perimetric progression with high specificity, while the less stringent OCT criterion considering any clock hour showed the lowest agreement with functional progression (ĸ = 0.098). Conclusion: OCT progression criteria based on test-retest variability showed moderate agreement with perimetric progression, and more stringent criteria showed better agreement with functional progression than less stringent ones.
    Ophthalmologica 07/2012; · 1.41 Impact Factor
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    ABSTRACT: Grape seed extract (GSE) is a potent antioxidant. We examined the effect of GSE on oxidative stress-induced cell death in a transformed retinal ganglion cell line, RGC-5. Staurosporine-differentiated RGC-5 (ssdRGC-5) cells obtained by treating RGC-5 cells with 1 µM staurosporine were incubated with GSE for 2 h and then exposed to buthionine sulfoximine plus glutamate (B/G) for 24 h. Cell death was detected using the LIVE/DEAD viability assay and the type of cell death was evaluated using fluorescein isothiocyanate-conjugated Annexin-V/propidium iodide staining. To investigate the mechanism underlying cell death, we determined the caspase-3 activity and level of reactive oxygen species (ROS) formation. Treatment of ssdRGC-5 cells with B/G increased intracellular ROS and induced apoptosis (not necrosis) with increasing caspase-3 activity. GSE rescued the ssdRGC-5 cells from oxidative stress-induced cell death by inhibiting both intracellular ROS production and caspase-3 activation. GSE had a neuroprotective effect against oxidative stress-induced apoptotic death in ssdRGC-5 cells.
    Current eye research 04/2012; 37(4):339-44. · 1.51 Impact Factor
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    ABSTRACT: PURPOSE:: To investigate the relationship between central visual field (VF) defects and ocular pulse amplitude (OPA) in early normal-tension glaucoma (NTG). PATIENTS AND METHODS:: This retrospective study included 100 eyes of 100 subjects: 54 NTG patients whose mean deviations were better than -7.00 dB and 46 normal subjects. OPA was measured by dynamic contour tonometry. NTG patients were divided into 2 subgroups according to VF tests: the central VF-invading and the central VF-sparing groups. Ocular parameters including OPA, intraocular pressure (IOP), and indices of VF tests were analyzed in glaucoma patients and normal subjects. RESULTS:: There was no difference in the OPA between the NTG and normal groups. However, IOP and OPA of the central VF-invading group (14.4±2.87 and 2.9±0.78 mm Hg) were higher than those of the central VF-sparing group (12.7±2.52 and 2.0±0.80 mm Hg; P=0.025 and P<0.001, respectively). OPA, but not IOP, showed a positive correlation with the VF test indices that represented central field defects (r=0.494, P<0.001). CONCLUSIONS:: Increased OPA was related to more centrally located VF defects in NTG patients with mild VF defects.
    Journal of glaucoma 02/2012; · 1.74 Impact Factor
  • Journal of American Association for Pediatric Ophthalmology and Strabismus 02/2007; 11(1):85-86. · 0.73 Impact Factor
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    ABSTRACT: To evaluate the usefulness of infrared digital photography for determining scotopic pupil size by comparing infrared digital photography with a Colvard pupillometer (Oasis Medical). Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea. Scotopic pupil size in 50 eyes of 25 healthy individuals was measured with a Colvard pupillometer and a digital camera (DSC-F828) using infrared burst shots after 5 minutes of dark adaptation. Measurements were performed by 2 independent examiners (E1 and E2). The digital photograph images were read using the ruler function of Adobe Photoshop 7.0 by 2 independent readers (R1 and R2). Agreement and repeatability were analyzed using the comparison method described by Bland and Altman. The mean scotopic pupil diameter measured using the Colvard pupillometer was 6.69 mm +/- 0.78 (SD) (E1) and 6.70 +/- 0.71 mm (E2). The mean scotopic pupil diameter measured from the digital photograph images was 6.67 +/- 0.75 mm (E1) and 6.66 +/- 0.78 mm (E2). The mean difference between E1 and E2 with both devices was small; however, the result with the infrared digital camera was marginally smaller than with the Colvard pupillometer. The limits of agreement were -0.01 +/- 0.70 mm with the Colvard pupillometer and 0.01 +/- 0.20 mm with the digital photograph image. The digital photograph image showed better agreement. The coefficient of interrater repeatability was smaller for the digital photograph image (0.39) than for the Colvard pupillometer (0.70). Scotopic pupil measurement using an infrared digital camera with a burst shot had good agreement with the Colvard pupillometer and better repeatability. The infrared digital camera is less expensive, and pupil unrest can be overcome by taking serial images.
    Journal of Cataract and Refractive Surgery 01/2007; 32(12):2113-7. · 2.53 Impact Factor