Influence of Myopia on Size of Optic Nerve Head and Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography

PURPOSE: To investigate optic nerve head size and retinal nerve fiber layer (RNFL) thickness according to refractive status and axial length. METHODS: In a cross-sectional study, 252 eyes of 252 healthy volunteers underwent ocular biometry measurement as well as optic nerve head and RNFL imaging by spectral-domain optical coherence tomography. Correlation and linear regression analyses were performed for all subjects. The magnification effect was adjusted by the modified axial length method. RESULTS: Disc area and spherical equivalent were positively correlated (r = 0.225, r² = 0.051, p = 0.000). RNFL thickness showed significant correlations with spherical equivalent (r = 0.359, r² = 0.129, p = 0.000), axial length (r = -0.262, r² = 0.069, p = 0.000), disc radius (r = 0.359, r² = 0.129, p = 0.000), and radius of the scan circle (r = -0.262, r² = 0.069, p = 0.000). After adjustment for the magnification effect, those relationships were reversed; RNFL thickness showed negative correlation with spherical equivalent and disc radius, and positive correlation with axial length and radius of the scan circle. The distance between the disc margin and the scan circle was closely correlated with RNFL thickness (r = -0.359, r² = 0.129, p = 0.000), which showed a negative correlation with axial length (r = -0.262, r² = 0.069, p = 0.000). CONCLUSIONS: Optic disc radius and RNFL thickness decreased in more severely myopic eyes, but they increased after adjustment for magnification effect. The error due to the magnification effect and optic nerve head size difference might be factors that should be considered when interpreting optical coherence tomography results.

Analysis of Retinal Nerve Fiber Layer Thickness of Superior Segmental Optic Hypoplasia and Normal-Tension Glaucoma

PURPOSE: To analyze the peripapillary retinal nerve fiber layer (RNFL) in superior segmental optic hypoplasia (SSOH) patients and normal tension glaucoma (NTG) patients with inferior visual field defects using optical coherence tomography (OCT). METHODS: Ten eyes of 10 patients with SSOH and 10 eyes of 10 patients with NTG were evaluated. The peripapillary RNFL thickness measured by OCT was compared between the 2 groups. RESULTS: The mean RNFL thickness was not significantly different between SSOH patients (79.60 +/- 12.54 micrometer) and NTG patients (77.10 +/- 8.52 micrometer) (p = 0.089). Among the quadrant parameters, there were no significant differences between the 2 groups (p > 0.05). In a clock-hour analysis, the peripapillary RNFL thickness of the NTG group was significantly thicker than the SSOH group in 12, 1, and 2 o'clock (p = 0.029, 0.007, 0.043, respectively). In contrast, the peripapillary RNFL thickness of the SSOH group was significantly thicker than the SSOH group in 6, and 7 o'clock (p = 0.029, 0.007, respectively). CONCLUSIONS: Peripapillary RNFL thickness in patients with SSOH was thinner than in those with NTG in the superonasal region, but thicker in the inferotemporal region indicating a different retinal nerve fiber defect pattern between the 2 diseases.

A Case of Vitreous Prolapse through Iridectomy Site after Trabeculectomy

PURPOSE: To report the results of anterior vitrectomy for obstruction of the aqueous outflow shunt by prolapsed vitreous strands after trabeculectomy. CASE SUMMARY: Trabeculectomy was performed on a pseudophakic primary open angle glaucoma patient with uncontrolled intraocular pressure under maximum tolerable medical therapy. Three months after trabeculectomy, the bleb flattened and the intraocular pressure elevated. On gonioscopic examination, vitreous strands prolapsed through the iridectomy site obstructing the inner ostium. The maximum tolerable medical therapy and Nd:YAG laser vitreolysis were attempted, but the intraocular pressure was not controlled. Anterior vitrectomy was performed to remove the prolapsed vitreous strands. After anterior vitrectomy, the bleb regained filtering function and the intraocular pressure was stabilized. CONCLUSIONS: In a case with a prolapsed vitreous into the anterior chamber obstructing the outflow shunt of the aqueous humor after trabeculectomy, anterior vitrectomy showed therapeutic effects.

A Case of Vitreous Prolapse through Iridectomy Site after Trabeculectomy

PURPOSE: To report the results of anterior vitrectomy for obstruction of the aqueous outflow shunt by prolapsed vitreous strands after trabeculectomy. CASE SUMMARY: Trabeculectomy was performed on a pseudophakic primary open angle glaucoma patient with uncontrolled intraocular pressure under maximum tolerable medical therapy. Three months after trabeculectomy, the bleb flattened and the intraocular pressure elevated. On gonioscopic examination, vitreous strands prolapsed through the iridectomy site obstructing the inner ostium. The maximum tolerable medical therapy and Nd:YAG laser vitreolysis were attempted, but the intraocular pressure was not controlled. Anterior vitrectomy was performed to remove the prolapsed vitreous strands. After anterior vitrectomy, the bleb regained filtering function and the intraocular pressure was stabilized. CONCLUSIONS: In a case with a prolapsed vitreous into the anterior chamber obstructing the outflow shunt of the aqueous humor after trabeculectomy, anterior vitrectomy showed therapeutic effects.

Analysis of Effect of Inferior Oblique Myectomy in Patients With Inferior Oblique Overaction

PURPOSE: To investigate the effect of inferior oblique (IO) myectomy by analyzing the correlation of the amount of inferior oblique overaction (IOOA), hypertropia and excyclotorsion before, between, and after IO myectomy in patients with various degrees of IOOA. METHODS: A total of 86 eyes from 59 patients with IOOA who underwent IO myectomy were enrolled in the present study. The correlation analysis was performed for the amount of IOOA, hypertropia and excyclotorsion before and after surgery, according to the preoperative amount of IOOA, hypertropia, and excyclotorsion. RESULTS: The IOOA decreased from +2.5 +/- 0.6 before surgery to -0.01 +/- 0.25 (p < 0.05) after surgery. The vertical deviation was 5.7 +/- 6.3 prism diopter (PD) and 2.3 +/- 5.2 PD (p < 0.05) postoperatively. The amount of cyclodeviation was 15.3 +/- 7.6degrees before surgery and 6.6 +/- 5.7degrees (p < 0.05) after surgery. The amount of surgical correction for IOOA and the hypertropia was significantly correlated with preoperative deviation (p < 0.05, p < 0.05). The amount of excyclotorsion before and after surgery was also positively correlated but was not statistically significant (p = 0.05). CONCLUSIONS: IO myectomy can correct any degree of IOOA, hypertropia, and related excyclotorsion.

Differences in the Histopathology and Matrix Metalloproteinase Expression in Tenon's Tissue of Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma

PURPOSE: To investigate the differences in the histopathology and matrix metalloproteinase (MMP) expression in the Tenon's tissue of primary open-angle glaucoma (POAG) patients, primary angle-closure glaucoma (PACG) patients, and non-glaucomatous patients. METHODS: POAG and PACG patients, who underwent a trabeculectomy and had no history of ocular disease except glaucoma, were enrolled. The number and instillation period of topical eye drops were reviewed. For the controls, which were patients without glaucoma or a history of ocular surgery, the Tenon's tissue was obtained in the course of retinal detachment surgery. For glaucoma patients, the Tenon's tissue was obtained during the trabeculectomy. H&E and Masson's trichrome staining and immunohistochemistry for MMP-1, MMP-2, and MMP-9 were performed. A total of six eyes of POAG, six eyes of PACG, and four control eyes were evaluated. RESULTS: The duration of topical anti-glaucoma medication and the mean number of anti-glaucoma medications were similar in the POAG and PACG groups. The levels of MMP-1 and 2 were elevated in the POAG and PACG groups compared to the control group (p=0.03, 0.01, respectively). Compared with the control group, the MMP-2 level was higher in the POAG patients (p=0.01), whereas the MMP-1 was higher in the PACG patients (p=0.04). The levels of MMP-9 in the POAG and PACG patients were not significantly different from that of the control patients (p=0.48, 0.26). The levels of MMP-2 were significantly lower in the PACG patients than in the POAG patients (p=0.02). CONCLUSIONS: The MMP expression was altered in the Tenon's tissue of glaucoma patients compared to the control group. The levels of MMP-2 were lower in the PACG patients than in the POAG patients. These results suggest that there may be histopathological differences in the Tenon's tissue of POAG and PACG patients.

Differences in the Histopathology and Matrix Metalloproteinase Expression in Tenon's Tissue of Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma

PURPOSE: To investigate the differences in the histopathology and matrix metalloproteinase (MMP) expression in the Tenon's tissue of primary open-angle glaucoma (POAG) patients, primary angle-closure glaucoma (PACG) patients, and non-glaucomatous patients. METHODS: POAG and PACG patients, who underwent a trabeculectomy and had no history of ocular disease except glaucoma, were enrolled. The number and instillation period of topical eye drops were reviewed. For the controls, which were patients without glaucoma or a history of ocular surgery, the Tenon's tissue was obtained in the course of retinal detachment surgery. For glaucoma patients, the Tenon's tissue was obtained during the trabeculectomy. H&E and Masson's trichrome staining and immunohistochemistry for MMP-1, MMP-2, and MMP-9 were performed. A total of six eyes of POAG, six eyes of PACG, and four control eyes were evaluated. RESULTS: The duration of topical anti-glaucoma medication and the mean number of anti-glaucoma medications were similar in the POAG and PACG groups. The levels of MMP-1 and 2 were elevated in the POAG and PACG groups compared to the control group (p=0.03, 0.01, respectively). Compared with the control group, the MMP-2 level was higher in the POAG patients (p=0.01), whereas the MMP-1 was higher in the PACG patients (p=0.04). The levels of MMP-9 in the POAG and PACG patients were not significantly different from that of the control patients (p=0.48, 0.26). The levels of MMP-2 were significantly lower in the PACG patients than in the POAG patients (p=0.02). CONCLUSIONS: The MMP expression was altered in the Tenon's tissue of glaucoma patients compared to the control group. The levels of MMP-2 were lower in the PACG patients than in the POAG patients. These results suggest that there may be histopathological differences in the Tenon's tissue of POAG and PACG patients.

The Clinical Usefulness of the Hong's Grading Method

PURPOSE: To compare the Hong's grading method, utilized for slit-lamp grading of the mid-peripheral angle, with other conventional grading methods. Actual angle was measured by ultrasound biomicroscopy (UBM) for comparison. METHODS: Fifteen eyes with narrow angles and eighteen eyes with wide angles were studied. The average age of thirty-three subjects was 46.8+/-19.2, and the male to female ratio was 1:3.7. The mid-peripheral angle was graded by Hong's, van Herick's and Spaeth's grading system. The actual anterior chamber angle was evaluated by UBM and the correlation between each grading system and actual angle was investigated. RESULTS: The results from the Hong's grading (r=0.802, R2=0.643, p<0.01), Spaeth's grading (r=0.728, R2=0.530, p<0.01) and van Herick's grading (r=0.618, R2=0.382, p<0.01) methods correlated significantly with the actual angles. CONCLUSIONS: The Hong's grading method was an easy and effective tool to evaluate anterior chamber angle. In addition, the results of the Hong's grading method were closer to the actual angle than the other methods.

Prevalence of Myopia in 19-year-old Korean Males: The Relationship between the Prevalence and Education or Urbanization

PURPOSE: To study the relationship between the prevalence of myopia and both urbanization and increased education level. METHODS: We performed noncycloplegic autorefraction in 12, 207 nineteen-year-old Korean conscripts. In order to analyze the relationship between prevalence of myopia and urbanization, we divided the subjects into two groups: urban and rural. To analyze the relationship between the prevalence of myopia and the level of education, we categorized the subjects into three groups: college education (>or=13 years), high school education (10-12 years), and primary education (