Jong Chul Han

The Characteristics of Lamina Cribrosa Defects in Myopic Eyes With and Without Open-Angle Glaucoma

PURPOSE We investigated the lamina cribrosa (LC) structural characteristics of myopic eyes with and without open-angle glaucoma (OAG) using enhanced depth imaging spectral-domain optical coherence tomography (EDI SD-OCT). METHODS Defects in the LC in myopic eyes with and without OAG and normal eyes without myopia were evaluated using EDI SD-OCT. Among the two types of LC defects, disinsertion type and hole type, the associations among disinsertion type LC defects, myopia-related parameters of axial length (AL), maximal γ-zone peripapillary atrophy (PPA) length, disc tilt angle, and the presence of glaucoma were evaluated. In addition, disinsertion type LC defects were divided into two subtypes, complete detachment type and triangular wedge type, and the numbers of the subtypes in myopic eyes with and without OAG were investigated. RESULTS Defects in the LC were found more in myopic eyes with than without OAG (65.7% vs. 27.8%, P < 0.001). Of LC defects, disinsertion-type LC defects were found at the location of the γ-zone PPA (R = 0.71, P < 0.001), while the location of hole-type LC defects did not correlate with the location of the γ-zone PPA (R = 0.07, P = 0.73). Of disinsertion-type LC defects, complete detachment-type defects predominated in myopic eyes with OAG, while triangular wedge-type defects were the most common in myopic eyes without OAG (P < 0.001; P < 0.001, respectively). In multivariate logistic regression analysis, disinsertion-type LC defects in myopic eyes were associated with AL, maximal PPA length, and disc tilt angle, as well as the presence of glaucoma. CONCLUSIONS Given the strong correlation of disinsertion type LC defects with glaucoma and parameters related to myopia, such defects should be considered as biomarkers of glaucoma in myopic eyes.

Cross-Modal and Intra-Modal Characteristics of Visual Function and Speech Perception Performance in Postlingually Deafened, Cochlear Implant Users

Evidence of visual-auditory cross-modal plasticity in deaf individuals has been widely reported. Superior visual abilities of deaf individuals have been shown to result in enhanced reactivity to visual events and/or enhanced peripheral spatial attention. The goal of this study was to investigate the association between visual-auditory cross-modal plasticity and speech perception in post-lingually deafened, adult cochlear implant (CI) users. Post-lingually deafened adults with CIs (N = 14) and a group of normal hearing, adult controls (N = 12) participated in this study. The CI participants were divided into a good performer group (good CI, N = 7) and a poor performer group (poor CI, N = 7) based on word recognition scores. Visual evoked potentials (VEP) were recorded from the temporal and occipital cortex to assess reactivity. Visual field (VF) testing was used to assess spatial attention and Goldmann perimetry measures were analyzed to identify differences across groups in the VF. The association of the amplitude of the P1 VEP response over the right temporal or occipital cortex among three groups (control, good CI, poor CI) was analyzed. In addition, the association between VF by different stimuli and word perception score was evaluated. The P1 VEP amplitude recorded from the right temporal cortex was larger in the group of poorly performing CI users than the group of good performers. The P1 amplitude recorded from electrodes near the occipital cortex was smaller for the poor performing group. P1 VEP amplitude in right temporal lobe was negatively correlated with speech perception outcomes for the CI participants (r = -0.736, P = 0.003). However, P1 VEP amplitude measures recorded from near the occipital cortex had a positive correlation with speech perception outcome in the CI participants (r = 0.775, P = 0.001). In VF analysis, CI users showed narrowed central VF (VF to low intensity stimuli). However, their far peripheral VF (VF to high intensity stimuli) was not different from the controls. In addition, the extent of their central VF was positively correlated with speech perception outcome (r = 0.669, P = 0.009). Persistent visual activation in right temporal cortex even after CI causes negative effect on outcome in post-lingual deaf adults. We interpret these results to suggest that insufficient intra-modal (visual) compensation by the occipital cortex may cause negative effects on outcome. Based on our results, it appears that a narrowed central VF could help identify CI users with poor outcomes with their device.

Microvascular Compromise Develops Following Nerve Fiber Layer Damage in Normal-tension Glaucoma Without Choroidal Vasculature Involvement

Purpose: To investigate capillary densities in patients with unilateral normal-tension glaucoma (NTG) and normal controls using optical coherence tomography-angiography. Materials and Methods: We recruited 13 patients with unilateral NTG and 13 healthy controls. Optical coherence tomography-angiography was performed and pure peripapillary retinal capillary density was calculated after manually excluding large vessels and the optic disc. Paired comparison of capillary densities was performed among 3 categories of eye: NTG eye, fellow eye, and normal eye. Through vascular layer stratification we investigated differences in the retinal and choroidal circulation. Results: In total, 33 eyes of 11 unilateral NTG patients and 11 controls were analyzed. Capillary densities of NTG eyes were significantly lower than those of fellow eyes or control eyes (both P=0.013). No significant differences were found between fellow eyes and control eyes (P=0.328). Area of capillary compromise was identical to the area of retinal nerve fiber layer (RNFL) defect in all 11 eyes. In layer analysis, a decrease in capillary plexus was demonstrated only in the inner retina and no definite changes were found in the outer retina and choroid. Optic nerve head microvasculature did not show areas of capillary dropout. Conclusions: In patients with unilateral NTG, we could observe significant retinal capillary compromise in the area of RNFL defect. No changes were demonstrated in the choroid and optic disc area. We speculated on a possibility of secondary microvascular changes in the retina to nerve damage from the wedge-shaped but not geographic shaped capillary compromise corresponding to RNFL defect area. Further studies on the optic nerve head microvasculature and blood flow are warranted to assess their relationship to glaucoma pathogenesis.

Factors affecting near vision after monofocal intraocular lens implantation.

PURPOSE To identify factors that influence near vision after monofocal intraocular lens (IOL) implantation for distance vision. METHODS A retrospective review was conducted of patients who underwent cataract surgery with monofocal IOL implantation from October 2009 to April 2010 at Samsung Medical Center. Eyes were classified as having good (⩾ J4) or poor (< J4) near vision. Factors analyzed included age, sex, intraocular lens (IOL) movement, axial length, pupil size, degree and type of astigmatism, IOL type, total aberration, and higher-order aberrations. Binary logistic regression and odds ratios with 95% confidence intervals were determined. RESULTS This retrospective study involved 84 eyes of 84 patients. Thirty-four eyes were classified as having good near vision and 50 eyes as having poor near vision. All groups had a postoperative uncorrected visual acuity greater than 0.2 logMAR (Snellen 20/32) and a refractive error within ± 0.5 diopter of spherical equivalent. Pupil size and axial length were inversely associated with good near vision (P = .034 and .039, respectively). A pupil size smaller than 2.6 mm and an axial length less than 23.0 mm resulted in better near vision than larger measurements after monofocal IOL implantation for distant target. CONCLUSIONS Among the factors analyzed, small pupil size and short axial length predicted good near vision after phacoemulsification and monofocal IOL implantation.

A novel hypothesis for the pathogenesis of glaucomatous disc hemorrhage

ABSTRACT Disc hemorrhage is known to be associated with glaucoma development and progression. Several hypotheses have been proposed to explain the pathogenesis of disc hemorrhage in glaucoma, including mechanical and ischemic theories. However, no theory has yet provided a clear explanation of cellular‐level events and related histologic findings. Moreover, research has yet to elucidate why glaucomatous disc hemorrhage occurs around the optic disc and at the margin of the retinal nerve fiber layer defect. Understanding the pathogenic mechanism of disc hemorrhage will facilitate interpretation of its clinical importance, and provide better insight into clinical practice. In this review, we sought to provide a plausible hypothesis for the development of glaucomatous disc hemorrhage that could explain the aforementioned characteristic features. We suggest a new and detailed mechanism for disc hemorrhage. Critical microscopic events are also discussed in relation to reactive gliosis in glaucoma. With proliferative reactive gliosis, fibrous glial scar forms, and we suggest that the traction force induced by glial scar formation might disrupt capillary at the border between the healthy and damaged retinal nerve fiber layer, and develop splinter‐shaped peripapillary hemorrhage. In addition to glial scar formation, remodeling and deformation of lamina cribrosa beams would insult the capillary surrounding the pore of the lamina cribrosa, and lead to development of round blotch‐shaped cup hemorrhage. Histopathologic confirmation of these findings should be explored in future investigations. HIGHLIGHTSMechanical disruption of capillaries associated with axonal degeneration may be the source of glaucomatous disc hemorrhage.Reactive gliosis in glaucoma forms gliotic scar, which can contract and generate tractional forces on the capillaries.A subset of disc hemorrhage may be related to deformation of lamina cribrosa pores in glaucoma.

The Effect of Diurnal Fluctuation in Intraocular Pressure on the Evaluation of Risk Factors of Progression in Normal Tension Glaucoma

Purpose To investigate whether diurnal fluctuation in intraocular pressure (IOP) can influence the result of the correlations between IOP-related factors and progression of normal tension glaucoma (NTG). Methods Glaucoma progression was defined as visual field (VF) progression and changes in the optic disc and/or retinal nerve fiber layer (RNFL). Two different methods were used to evaluate the impact of the diurnal fluctuation in IOP. ‘Conventional method’ used in previous studies included all IOP measurements during the follow up time. ‘Time adjusted method’ was used to adjust diurnal fluctuation in IOP with the preferred time. Mean IOP, long term IOP fluctuation and the difference between the lowest and highest IOP were calculated using both methods. Cox regression analyses were performed to evaluate the association between IOP-related factors and NTG progression. Results One hundred and forty eyes of 140 patients with NTG were included in this study. 41% (58 of 140 eyes) of eyes underwent NTG progression. Long term IOP variation calculated by conventional method was not a significant risk factor for NTG progression (hazard ratio[HR], 0.311; 95% confidence interval[CI], 0.056–1.717; P = 0.180). Long term IOP variation calculated by time adjusted method, however, was related to progression, with an HR of 5.260 (95% CI,1.191–23.232; P = 0.029). Conclusion Although having the same IOP-related factors, if diurnal fluctuation is included, different results may be found on the relationship between IOP-related factors and NTG progression. Based on our results, diurnal fluctuation in IOP should be considered when IOP-related factors are studied in the future.

Optic Disc Characteristics and Visual Field Progression in Normal Tension Glaucoma Patients With Tilted Optic Discs.

Purpose of the Study:The purpose of the study was to evaluate the optic disc characteristics associated with visual field (VF) progression in normal tension glaucoma (NTG) eyes with tilted optic discs. Methods:Sixty-six eyes of 66 NTG patients with tilted optic disc were included in this cross-sectional study, who were examined by at least 5 Humphrey 30-2 VFs. Glaucomatous VF progression was evaluated using pointwise linear regression. Optic nerve heads were scanned with enhanced-depth imaging optical coherence tomography (EDI-OCT), and evaluated for the focal lamina cribrosa (LC) defects and LC thicknesses. Optic disc torsion degrees and tilt ratios were measured from disc photographs. Logistic regression analyses were used to identify the risk factors for VF progression and focal LC defects. Results:Multivariate analysis showed that VF progression was associated with the presence of focal LC defects and greater number of VFs. The eyes with focal LC defects were associated with greater torsion degree and tilt ratio in multivariate analysis. The VF mean deviation slopes and localized VF progression rates in eyes with focal LC defects were greater than those without defects. Conclusions:The greater optic disc tilt and torsion in NTG eyes with tilted optic disc were associated with focal LC defects, but not with VF progression. The focal LC defects were associated with VF progression. This study suggests that the focal LC defects in NTG patients with tilted optic disc may be an independent risk factor for glaucomatous VF progression, and the development of focal LC defects could be influenced by optic disc torsion or tilt.

Long-term outcomes of argon laser photocoagulation in small size cyclodialysis cleft

BackgroundTo evaluate the long-term outcomes of Argon laser photocoagulation compared to surgical direct cyclopexy in small-size cyclodialysis cleft patients.MethodsThis is a retrospective study. Small-size cyclodialysis cleft patients who underwent Argon laser photocoagulation and surgical direct cyclopexy were reviewed. The mean follow-up period were 82.4 (range, 61 – 145) months and 99.9 (range, 62 – 184) months in both groups. The comparison of best corrected visual acuity (BCVA), intraocular pressure (IOP), postoperative peak IOP and time to normalization of IOP before and after the treatment.ResultsThe causes of all included 15 cyclodialysis cleft cases were blunt trauma. seven patients underwent Argon laser photocoagulation and eight patients underwent surgical direct cyclopexy. The mean age of included patients was not significantly different (p = 0.38). Preoperatively, the mean logMAR BCVA (standard deviation, SD) was 0.7 (0.2) and 1.1 (0.9) and mean IOP was 4.4 (2.4) mmHg and 3.0 (1.5) mmHg in Argon laser group and surgical direct cyclopexy group (p = 0.24 and p = 0.18, respectively). The extension of cyclodialysis and duration of cyclodialysis cleft were not significantly different between the two groups (p = 0.08 and p = 0.24, respectively). The mean follow-up period were 82.4 (range, 61 – 145) months and 99.9 (range, 62 – 184) months in both groups (p = 0.41). Postoperatively, the mean logMAR BCVA was 0.0 (0.1) and 0.2 (0.3) and mean IOP was 14.5 (3.1) mmHg and 16.8 (2.5) mmHg (p = 0.15 and p = 0.16, respectively). Postoperative peak IOP and time to normalization of IOP were not different between the two groups (p = 0.75 and p = 0.91, respectively).DiscussionIt is necessary to use invasive treatment such as cryotherapy or surgical direct cyclopexy in cyclodialysis cleft with hypotonic maculopathy. In the present study, Argon laser photocoagulation showed good prognosis in a small-size cyclodialysis cleft below 1.5 clock-hours. Considering possible complications and cost of surgical direct cyclopexy, Argon laser can be more beneficial than surgical direct cyclopexy in small-size cyclodialysis cleft below 1.5 clock-hours.ConclusionsThe clinical ourcome of Argon laser photocoagulation seems to be as good as surgical direct cyclopexy in small-size cyclodialysis cleft below 1.5 clock-hours.

Comparison of peripapillary vessel density between preperimetric and perimetric glaucoma evaluated by OCT-angiography

Purpose To determine peripapillary vessel density in eyes with perimetric glaucoma (PG) or preperimetric glaucoma (PPG) compared to normal controls using optical coherence tomography-angiography (OCT-A). Methods We recruited 13 patients with unilateral perimetric normal-tension glaucoma (NTG) and fellow preperimetric NTG showing only inferotemporal retinal nerve fiber layer (RNFL) defect in red-free RNFL photography in both eyes. We also enrolled 9 healthy controls. Using OCT-A, radial peripapillary capillary densities at inferotemporal and superotemporal regions were evaluated. Paired comparison of peripapillary vessel density was performed for PG eye, PPG eye, and normal eye. Results A total of 26 eyes of the 13 patients with unilateral PG and fellow PPG eyes and 18 eyes of 9 normal controls were analyzed. Vessel densities at the whole peripapillary region and inferotemporal region in PG eyes were significantly lower than those in PPG eyes (P = 0.001, P<0.001, respectively). Comparison between PPG and normal eyes showed no significant difference in the whole peripapillary region or the inferotemporal region (P = 0.654, P = 0.174, respectively). There was no significant (P = 0.288) difference in vessel density at superotemporal region among the three types of eyes (PG eye, PPG eye, and normal eye). Conclusion PPG eyes and normal eyes were found to have the similar densities of peripapillary microvasculature at the area with nerve fiber layer defect, whereas in PG eye, there was a significant decrease in vessel density at the area of RNFL thinning. This provides evidence that microvascular compromise in the retina might be a secondary change to nerve fiber layer degeneration in the pathogenesis of NTG.

The Characteristics of Deep Optic Nerve Head Morphology in Myopic Normal Tension Glaucoma

Purpose To investigate the relationship between axial length (AL) and deep optic nerve head (ONH) structure and to evaluate the characteristics of deep ONH structures in myopic normal tension glaucoma (NTG). Methods The following parameters were assessed using spectral-domain optical coherence tomography (SD-OCT): externally oblique border tissue (EOBT) length, ONH tilt angle, optic canal (OC) obliqueness, and β-zone peripapillary atrophy (PPA). In addition, the angular location of the maximal value of each parameter and retinal nerve fiber layer (RNFL) defect were measured using infrared and red-free photos. Results A total of 74 myopic NTG eyes and 67 myopic control eyes with a spherical equivalent < -0.5 diopters from 141 subjects were included. AL was correlated with the maximal values of EOBT length, ONH tilt angle, OC obliqueness, and β-zone PPA (P < 0.001, P = 0.003, P < 0.001, and P < 0.001, respectively). Multivariate logistic regression analysis revealed that temporally located maximal values of EOBT length, ONH tilt angle, and OC obliqueness were associated with the presence of myopic NTG (P = 0.014, P = 0.016, and P = 0.030, respectively). In myopic NTGs, RNFL defect locations were consistent with the locations of maximal values of EOBT length, ONH tilt angle, OC obliqueness, and β-zone PPA (P < 0.001, P < 0.001, P < 0.001, and P = 0.003, respectively). Conclusions Temporalized angular locations of deep ONH parameters were associated with the presence of NTG in myopia. In myopic NTGs, the locations of deep ONH parameters were consistent with the locations of RNFL defect.