Morphological and functional differences between normal-tension and high-tension glaucoma

Phenotypic expressions of the optic disc in primary open-angle glaucoma

BACKGROUND

Which phenotypes are we able to recognize in the optic nerve of patients with primary open angle glaucoma?

METHODS

Retrospective interventional case series. 885 eyes from 885 patients at an outpatient tertiary care centre who met specified criteria for POAG were included. Disc photographs were classified by three glaucoma specialists into the following phenotypes according to their predominant characteristics: (1) concentric rim thinning, (2) focal rim thinning, (3) acquired pit of the optic nerve (APON), (4) tilted, (5) extensive peripapillary atrophy (PPA), and (6) broad rim thinning. Demographic, medical, and ocular data were collected. Kruskal-Wallis was used as a non-parametric test and pairwise comparison was performed by using Wilcoxon rank sum test corrected.

RESULTS

Phenotypic distribution was as follows: 398(45%) focal thinning, 153(18%) concentric thinning, 153(17%) broad thinning, 109(12%) tilted, 47(5%) extensive PPA and 25(3%) APON. Phenotypic traits of interest included a higher proportion of female patients with the focal thinning phenotype (p = 0.015); myopia (p = 0.000), Asian race (OR: 8.8, p = 0.000), and younger age (p = 0.000) were associated with the tilted phenotype; the concentric thinning patients had thicker RNFL (p = 0.000), higher MD (p = 0.008) and lower PSD (p = 0.043) than broad thinning, despite no difference in disc sizes (p = 0.849). The focal thinning group had a localized VF pattern with high PSD compared to concentric thinning (p = 0.005).

CONCLUSION

We report six phenotypic classifications of POAG patients with demographic and ocular differences between phenotypes. Future refinement of phenotypes should allow enhanced identification of genetic associations and improved individualization of patient care.

Visualising structural and functional characteristics distinguishing between newly diagnosed high-tension and low-tension glaucoma patients

PURPOSE

To determine whether there are quantifiable structural or functional differences that can distinguish between high-tension glaucoma (HTG; intraocular pressure [IOP] > 21 mm Hg) and low-tension glaucoma (LTG; IOP ≤ 21 mm Hg) at diagnosis.

METHOD

This was a retrospective, cross-sectional study. Clinical results of one eye from 90 newly diagnosed HTG and 319 newly diagnosed LTG patients (117 with very-low-tension glaucoma [vLTG; ≤15 mm Hg] and 202 with middling LTG [mLTG; >15 mm Hg, ≤21 mm Hg]) were extracted, which included relevant demographic covariates of glaucoma, quantitative optical coherence tomography (including the optic nerve head, retinal nerve fibre layer and ganglion cell-inner plexiform layer) measurements and standard automated perimetry global metrics. We used binary logistic regression analysis to identify statistically significant clinical parameters distinguishing between phenotypic groups for inclusion in principal component (PC) (factor) analysis (PCA). The separability between each centroid for each cohort was calculated using the Euclidean distance (d(x,y)).

RESULTS

The binary logistic regression comparing HTG and all LTG identified eight statistically significant clinical parameters. Subsequent PCA results included three PCs with an eigenvalue >1. PCs 1 and 2 accounted for 21.2% and 20.2% of the model, respectively, with a d(x,y) = 0.468, indicating low separability between HTG and LTG. The analysis comparing vLTG, mLTG and HTG identified 15 significant clinical parameters, which were subsequently grouped into five PCs. PCs 1 and 2 accounted for 24.1% and 17.8%, respectively. The largest separation was observed between vLTG and HTG (d(x,y) = 0.581), followed by vLTG and mLTG (d(x,y) = 0.435) and lastly mLTG and HTG (d(x,y) = 0.210).

CONCLUSION

Conventional quantitative structural or functional parameters could not distinguish between pressure-defined glaucoma phenotypes at the point of diagnosis and are therefore not contributory to separating cohorts. The overlap in findings highlights the heterogeneity of the primary open-angle glaucoma clinical presentations among pressure-defined groups at the cohort level.

Evaluation of corneal biomechanical properties using the ocular response analyzer and the dynamic Scheimpflug-Analyzer Corvis ST in high pressure and normal pressure open-angle glaucoma patients

PURPOSE

To characterize differences in corneal biomechanics in high (HPG) and normal pressure (NPG) primary open-angle glaucoma, and its association to disease severity.

METHODS

Corneal biomechanical properties were measured using the Ocular Response Analyzer (ORA) and the dynamic Scheimpflug-Analyzer Corvis ST (CST). Disease severity was functionally assessed by automated perimetry (Humphrey field analyzer) and structurally with the Heidelberg Retina Tomograph. To avoid a possible falsification by intraocular pressure, central corneal thickness and age, which strongly influence ORA and CST measurements, group matching was performed. Linear mixed models and generalized estimating equations were used to consider inter-eye correlation.

RESULTS

Following group matching, 60 eyes of 38 HPG and 103 eyes of 60 NPG patients were included. ORA measurement revealed a higher CRF in HPG than in NPG (P < 0.001). Additionally, the CST parameter integrated radius (P < 0.001) was significantly different between HPG and NPG. The parameter SSI (P < 0.001) representing corneal stiffness was higher in HPG than in NPG. Furthermore, regression analysis revealed associations between biomechanical parameters and indicators of disease severity. In HPG, SSI correlated to RNFL thickness. In NPG, dependencies between biomechanical readings and rim area, MD, and PSD were shown.

CONCLUSION

Significant differences in corneal biomechanical properties were detectable between HPG and NPG patients which might indicate different pathophysiological mechanisms underlying in both entities. Moreover, biomechanical parameters correlated to functional and structural indices of diseases severity. A reduced corneal deformation measured by dynamic methods was associated to advanced glaucomatous damage.

Serum Biomarkers for the Diagnosis of Glaucoma

Despite the importance of the early detection of glaucoma, most patients with progressive glaucoma show minimal symptoms. We aimed to evaluate biomarkers for glaucoma diagnosis in Korea. Forty-two volunteers with/without open-angle glaucoma were enrolled from January through October 2015—divided into a control or open-angle glaucoma group, which was further divided into normal-tension glaucoma (NTG) and high-tension glaucoma (HTG) groups—and underwent assessments for myelin basic protein (MBP), heat shock protein 60, anti-Sjögren’s-syndrome-related antigen A (SSA) and antigen B (SSB), anti-α-fodrin, and anti-nucleic acid. The glaucoma group showed a higher serum MBP level and lower serum anti-α-fodrin antibody level than the control group (p < 0.05). The NTG group showed higher serum anti-SSA and anti-SSB levels and lower anti-α-fodrin IgG/IgA levels than the HTG group. In the receiver operating characteristic curve analysis, the area under the curve (AUC) for serum MBP level was 0.917 in discriminating between controls and patients with glaucoma. Between the NTG and HTG groups, anti-SSA, anti-SSB, and anti-α-fodrin IgG/IgA levels showed an AUC above 0.8. Thus, these biomarkers were useful for diagnosing glaucoma and discriminating between controls and patients with glaucoma, and patients with NTG and HTG.

Structure-function relationship between Bruch's membrane opening-minimum rim width and perimetry in open-angle glaucoma subtypes

PURPOSE

To seek the threshold value of Bruch's membrane opening-minimum rim width (BMO-MRW) where visual field (VF) damage occurs in open-angle glaucoma (OAG) and explore whether there are structural differences between primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG).

METHODS

We recruited 83 healthy and 106 glaucoma (49 with POAG and 57 with NTG) subjects for this study. All subjects underwent optical coherence tomography (OCT), BMO-MRW scans, and Humphrey visual field (VF) analyzer examination. Global and sectoral BMO-MRW was correlated with the corresponding VF according to the Garway-Heath map. Using a broken-stick statistical model, the structure-function relationship of VF values and BMO-MRW, the tipping point where VF defects were associated with a reduction in BMO-MRW and the slopes above and below the tipping point were determined and compared between POAG and NTG.

RESULTS

The tipping point of global BMO-MRW for VF impairment was 234.38 μm, 228.09 μm, and 249.68 μm in the OAG, POAG, and NTG groups, respectively. The slope below the tipping point was significantly steeper than the slope above it in all quadrants of each group (p < 0.001). The tipping point in NTG in the inferotemporal and nasal quadrants was smaller than that of POAG, especially in the inferotemporal quadrant.

CONCLUSION

In OAG, BMO-MRW loss seems to occur before the onset of perimetric impairment. Compared with POAG, NTG appears to have more severe rim damage, especially in the inferotemporal quadrant at the onset of detectable VF defects.

Patterns of Retinal Nerve Fiber Layer Loss in Different Subtypes of Open Angle Glaucoma Using Spectral Domain Optical Coherence Tomography

PURPOSE OF THE STUDY

The purpose of the study was to determine whether there are different patterns of retinal nerve fiber layer (RNFL) thinning as measured by spectral domain optical coherence tomography (SD-OCT) for 4 subtypes of open angle glaucoma (OAG): primary OAG (POAG), normal tension glaucoma (NTG), pseudoexfoliation glaucoma (PXG), and pigmentary glaucoma (PDG) and to compare them with normal controls.

MATERIALS AND METHODS

SD-OCT RNFL thickness values were measured for 4 quadrants and for 4 sectors (ie, superior-nasal, superior-temporal, inferior-nasal, and inferior-temporal). Differences in RNFL thickness values between groups were analyzed using analysis of variance. Paired t tests were used for quadrant comparisons.

RESULTS

Two hundred eighty-five participants (102 POAG patients, 33 with NTG, 48 with PXG, 13 with PDG, and 89 normal patients) were included in this study. All 4 subtypes of OAG showed significant RNFL thinning in the superior, inferior, and nasal quadrants as well as the superior-temporal and inferior-temporal sectors (all P-values <0.0001) compared with normals. POAG and NTG patients had greater RNFL thinning inferiorly and inferior-temporally than superiorly (P-values: 0.002 to 0.018 and 0.006, respectively) compared with PXG patients. In contrast, PDG patients had greater RNFL thinning superiorly and superior-nasally than inferiorly compared with other OAG subtypes (ie, POAG, NTG, PXG groups, with P-values: 0.009, 0.003, 0.009, respectively). Of the 4 OAG subtypes, PXG patients exhibited the greatest degree of inter-eye RNFL asymmetry.

CONCLUSIONS

This study suggests that SD-OCT may be able to detect significant differences in patterns of RNFL thinning for different subtypes of OAG.

Posterior displacement of the lamina cribrosa in normal-tension and high-tension glaucoma

PURPOSE

To compare the in vivo lamina cribrosa position in patients with normal-tension glaucoma (NTG) and high-tension glaucoma (HTG).

METHODS

The comparative cross-sectional study included three age- and sex-matched groups: 26 eyes of 26 NTG patients, 26 eyes of 26 HTG patients and 25 eyes of 25 healthy controls. Serial horizontal B-scan images of the optic nerve head were obtained from each eye using enhanced depth imaging optical coherence tomography. Mean and maximum lamina cribrosa depths were measured in 11 equally spaced horizontal B-scans. Statistical analysis was conducted to compare lamina cribrosa depth among the three groups and to correlate lamina cribrosa depth with age, retinal nerve fibre layer (RNFL) thickness and visual field (VF) mean deviation (MD). The area under the receiver operating characteristic curve (AUC) for lamina cribrosa depth was calculated.

RESULTS

Mean and maximum lamina cribrosa depths were significantly greater in HTG than in NTG eyes, and in NTG than in normal eyes in all 11 scans (all p < 0.05). The AUCs of the averaged mean and averaged maximum lamina cribrosa depths in HTG eyes (0.977 and 0.988, respectively) were significantly greater than those in NTG eyes (0.735 and 0.765, respectively; both p < 0.01). Lamina cribrosa depth was found to have a negative correlation with age in HTG eyes; however, the same association was not found in NTG or controls. Neither RNFL thickness nor VF MD was significantly correlated with lamina cribrosa depth in each group.

CONCLUSIONS

The lamina cribrosa is more posteriorly located in HTG than in NTG eyes, as well as in NTG eyes compared with healthy controls. The lamina cribrosa depth can help differentiate HTG from normal eyes, but it does not reach a good level of diagnostic accuracy for detecting NTG.

Risk Factors in Normal-Tension Glaucoma and High-Tension Glaucoma in relation to Polymorphisms of Endothelin-1 Gene and Endothelin-1 Receptor Type A Gene

The aim of the research is to analyse the influence of polymorphisms of endothelin-1 gene and endothelin-1 receptor type A gene on the clinical condition of patients with primary open angle glaucoma. Methods. 285 Polish patients took part in the research (160 normal-tension glaucoma and 125 high-tension glaucoma). DNA was isolated by standard methods and genotype distributions of four polymorphisms in genes encoding endothelin-1 (K198N) and endothelin-1 receptor type A polymorphisms (C1222T, C70G, and G231A) were determined. Genotype distributions were compared between NTG and HTG groups. The clinical condition of participants was examined for association with polymorphisms. Results. A similar frequency of occurrence of the polymorphic varieties of the studied genes was observed in patients with NTG and HTG. There is no relation between NTG risk factors and examined polymorphisms. NTG patients with TT genotype of K198N polymorphism presented with the lowest intraocular pressure in comparison to GG + GT genotype (p = 0.03). In NTG patients with CC genotype of C1222T polymorphism (p = 0.028) and GG of C70G polymorphism (p = 0.03) the lowest values of mean blood pressure were observed. Conclusions. The studied polymorphic varieties (K198N, C1222T) do have an influence on intraocular pressure as well as arterial blood pressure in NTG patients.

Retinal Thickness and the Structure/Function Relationship in the Eyes of Older Adults with Glaucoma

Glaucoma is common and shows high prevalence in older adults. However, there are few studies on the structure/function relationship in older adults with glaucoma. This prospective, cross-sectional study (conducted between February and August 2014), enrolled 102 eyes of 102 subjects aged over 75 years, including 57 eyes with primary open angle glaucoma (POAG), 15 eyes with pseudoexfoliation glaucoma (PXG), and 30 healthy eyes. Multiple regression analysis was used to determine the correlation of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular parameters to mean deviation (MD) to and standard automated perimetry (SAP)-measured sensitivity, assessed with the 30–2 and 10–2 programs. In each 10–2 SAP test point, Spearman’s rank correlation coefficient was used to compare macular retinal nerve fiber layer thickness (mRNFLT), macular ganglion cell-inner plexiform layer thickness (GCIPLT), and mRNFL+GCIPL thickness (GCCT) with sensitivity after adjusting for retinal ganglion cell (RGC) displacement. In eyes with POAG and PXG, cpRNFLT was significantly correlated with 30–2 MD and 30–2 sensitivity. Multiple regression analysis revealed that the POAG had significantly lower cpRNFLT, mRNFLT, GCIPLT, and GCCT according to the severity of disease than control eyes after adjusting for sensitivity, age, sex, and axial length. The PXG eyes had significantly lower cpRNFLT, mRNFLT, and GCCT when compared with the early to moderate POAG eyes. GCCT was significantly correlated with 10–2 sensitivity, except in one juxtafoveal point, (r = 0.338–0.778) in the POAG eyes. The periphery of the central 10° area showed a good correlation between sensitivity and mRNFLT, while the central 5.8° showed a good correlation between sensitivity and GCIPLT. The correlation between structure and function was significant, and objective and quantitative method with OCT assessing glaucoma that does not require patient ability could be a possible parameter to assess diagnosis and progression in older patients with glaucoma.

Optic disc topography in Malay patients with normal-tension glaucoma and primary open-angle glaucoma

Background

There are limited data concerning the optic disc topography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) patients living in Southeast Asian countries. This study aims to compare optic disc parameters in patients with NTG and POAG in Malaysia and to discuss the results in comparison with studies of NTG and POAG in other Asian countries.

Methods

This prospective cross-sectional study was performed in two hospitals with glaucoma service in Malaysia from 2010 to 2012. Seventy-seven patients of Malay ethnicity were enrolled in this study, including 32 NTG patients and 45 POAG patients. Using the Heidelberg Retinal Tomograph III, we measured optic disc area, cup area, rim area, cup volume, rim volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area.

Results

The eyes for NTG patients had significantly larger optic disc areas (2.65 [standard deviation, 0.41] vs 2.40 [standard deviation, 0.36] mm², respectively; P=0.006) and cup areas (1.54 [standard deviation, 0.43] vs 1.32 [standard deviation, 0.40] mm², respectively; P=0.027) compared with the eyes of POAG patients. Comparison of the other parameters between the two groups revealed no significant difference (P>0.050). The moderate and severe NTG patients showed significantly deeper cups and larger disc and cup areas when compared with the moderate and severe POAG patients (P<0.050).

Conclusion

The NTG patients in this study have notably larger optic disc and cup areas than the POAG patients. Our observations are consistent with those reported in studies of NTG and POAG patients in Korea. The deeper cups and larger disc and cup areas may serve as indicators of severity when comparing NTG with POAG. However, these findings require verification with IOP and visual field results.

Severity-dependent association between ganglion cell inner plexiform layer thickness and macular mean sensitivity in open-angle glaucoma

PURPOSE

To evaluate the structure-function relationship between macular mean sensitivity (mMS) and ganglion cell inner plexiform layer thickness (GCIPLT) according to glaucoma severity and to compare it with that between mMS and peripapillary retinal nerve fibre layer thickness (pRNFLT), using spectral-domain (Cirrus) optical coherence tomography (OCT).

METHODS

Three hundred and sixty-two eyes of 362 patients with open-angle glaucoma of differing severity (preperimetric, early, moderate, and advanced) together with 130 eyes of 130 healthy controls, all of whom underwent Cirrus OCT imaging and 30-2 standard automated perimetry (SAP), were included in the study. The mMS was assessed by calculating the average of sensitivities at 12 central SAP points. The relationships between mMS and the various GCIPLT (average, minimum, superior, and inferior) parameters obtained by Cirrus OCT were evaluated according to disease severity using a linear regression model and were then compared with those between pRNFLT parameters and mMS.

RESULTS

The mMS and GCIPLT showed stronger relationships with the increase in glaucoma severity, but this was not the case with the pRNFLT parameters. In preperimetric glaucoma, the associations between mMS and both GCIPLT and pRNFLT were not significant. In moderate and advanced glaucoma, all GCIPLT parameters showed a statistically significant relationship with mMS. However, pRNFLT showed a moderate association in early and moderate glaucoma and none at all in advanced glaucoma.

CONCLUSIONS

GCIPLT showed a stronger structure-function relationship with mMS in more advanced stages of glaucoma compared to pRNFLT. GCIPLT reflected macular functional damage better than pRNFLT in advanced glaucoma.

Phase III safety and efficacy study of long-term brinzolamide/timolol fixed combination in Japanese patients with open-angle glaucoma or ocular hypertension

BACKGROUND

The purpose of this study was to evaluate the safety and efficacy of a long-term, twice-daily brinzolamide 1%/timolol 0.5% fixed combination ophthalmic suspension (BRINZ/TIM-FC) in Japanese patients with open-angle glaucoma (primary open-angle, normal-tension, exfoliation, or pigmentary) or ocular hypertension.

METHODS

This was a prospective, nonrandomized, multicenter, open-label, Phase III study of Japanese patients aged ≥20 years with diagnoses of open-angle glaucoma or ocular hypertension. Patients were treated with topical BRINZ/TIM-FC twice daily for 52 weeks. The primary endpoint was mean reduction from baseline in intraocular pressure. Data were analyzed using repeated-measures analysis of variance and t-tests. Adverse events and ophthalmic, physiologic, and laboratory parameters were measured throughout the study as safety endpoints. A total of 126 patients (mean ± SD age, 63±12 years) were enrolled, and 125 received BRINZ/TIM-FC.

RESULTS

Mean intraocular pressure was significantly reduced from baseline at weeks 4 through 52, with changes ranging from -4.1 mmHg to -5.7 mmHg (P<0.0001, all time points). Adverse events related to BRINZ/TIM-FC treatment were observed in 22% of patients. No substantial changes from baseline were observed in ophthalmic, physiologic, or laboratory variables.

CONCLUSION

Long-term, twice-daily BRINZ/TIM-FC therapy produced and maintained significant intraocular pressure reductions and was generally well tolerated in Japanese patients with open-angle glaucoma or ocular hypertension.