Despite Impaired Binocular Function, Binocular Disparity Integration Across the Visual Field Is Spared in Normal Aging and Glaucoma.

Retinal nerve fiber layer thickness measurements with scanning laser polarimetry predict glaucomatous visual field loss

To investigate the association of magnetic resonance imaging (MRI) of anterior optic pathway with glaucomatous visual field damage and optic disc cupping. Twenty-three healthy volunteers (controls) and 31 glaucoma patients (14 with primary open angle glaucoma and 17 with normal tension glaucoma) were enrolled. All the participants showed no abnormal signs in their intracranial space and optic tract causing optic nerve atrophy and visual field defect, as confirmed by MRI. Multislice T1-weighted spin-echo imaging was performed in the sagittal plane followed by the coronal plane. MRI enabled the evaluation of the diameter of the optic nerve located in the retro-bulb space and the height of the optic chiasm in an observer-masked fashion. The MRI data were compared with the mean deviation (MD) score of the full threshold static visual field test and the optic cup-disc ratio (C/D ratio). The optic nerve diameter was significantly smaller in glaucoma patients (2.25 +/- 0.33 mm) than in controls (2.47 +/- 0.24 mm) and the height of the optic chiasm was significantly shorter in glaucoma patients (2.12 +/- 0.37 mm) than in controls (2.77 +/- 0.36 mm). The optic nerve diameter showed significant correlation with MD score (r = 0.547, P = 0.001) and C/D ratio (r = 0.407, P = 0.009). These correlations are similar to that between MD score and C/D ratio (r = 0.490, P = 0.001). The height of the optic chiasm showed significant correlation with MD score (r = 0.503, P = 0.01) and low correlation with C/D ratio (r = 0.339, P = 0.113). Glaucoma affects the anterior visual pathway anterogradely at least up to the optic chiasm, and these morphologic changes in the anterior visual pathway are correlated with glaucomatous optic nerve damage. MRI of the anterior visual pathway may be a good tool for evaluating glaucomatous damage objectively.

The efficacy of short-wavelength automated perimetry (SWAP) and conventional automated perimetry (CAP) in detecting the progression of glaucomatous visual field loss was compared. After 3 years, CAP detected progressive visual field damage in 3 (13.6%) of 22 eyes, while SWAP detected progressive visual field damage in 8 (36.6%) of 22 eyes. Thus, SWAP was more efficient than CAP in detecting progressive visual field losses in glaucomatous patients with incipient defects.

Commentary: Rethinking 10-2 visual fields in early diagnosis of glaucoma for a glided glaucoma practice: The right choice to pick up a feeble noise?

Ocular hypertension (OHT) refers to a condition in which the intraocular pressure increases without causing glaucomatous optic nerve changes or visual field damage. The incidence rate of OHT in people over 40 years old is as high as 4% to 10%. According to the OHT Treatment Study (OHTS), the incidence of primary open angle glaucoma (POAG) among OHT patients is increasing year by year, so it is necessary to conduct long-term follow-up. This article elaborates on five major risk factors for the progression of OHT to POAG: age, intraocular pressure, vertical cup-disc ratio, pattern standard deviation of visual field, and central corneal thickness. It also summarizes other potential risk factors, such as long-term fluctuations in intraocular pressure, asymmetry of intraocular pressure and visual field between the two eyes, structural phenotypes of the optic disk, and optic disk hemorrhage. Predicting the risk of OHT progression to POAG based on risk factors, patients with different risk levels require different timing for treatment initiation and follow-up intervals. Those with higher risks should start preventive treatment earlier and have shorter follow-up intervals. Both drug therapy and selective laser trabeculoplasty can serve as initial treatment options for OHT. Combining evidence-based medicine research and individualized evaluation of treatment can enhance the clinical diagnosis and treatment level of OHT.

To characterize the circadian (24-hour) pattern of habitual-position intraocular pressure (IOP) and its association with visual field (VF) damage in eyes with normal-tension glaucoma (NTG). A total of 177 eyes with NTG were examined over a 3-year period. IOP was recorded at 8 AM, 10 AM, 12 PM, 2 PM, 4 PM, 6 PM, 8 PM, 10 PM, 12 AM, 3 AM, and 6 AM by a single, well-trained ophthalmology resident using a hand-held tonometer. The circadian pattern and peak hours of habitual-position IOP and seated IOP were analyzed in all patients. Subgroup analysis was also performed, with groups defined by the time of maximum habitual-position IOP. The relationship between 24-hour habitual-position IOP parameters and VF indices was evaluated. There were 72 men and 105 women, all of whom were Koreans. Analysis of the entire population indicated a nocturnal peak (acrophase) for habitual-position IOP. Subgroup analysis indicated that 28 (15.8%) patients had diurnal acrophase, 91 (51.4%) patients had nocturnal acrophase, and 58 (32.8%) patients had no evident acrophase. There were no correlations between various 24-hour habitual-position IOP parameters and VF indices. In the 177 NTG patients, there was a significant nighttime elevation of habitual-position IOP, and nocturnal seated IOP was significantly less than nocturnal habitual-position IOP. Subgroup analysis indicated three distinct daily patterns of peak IOP in the patients. There was no relationship between nocturnal elevation of habitual IOP and the magnitude of VF damage.

Anisometropia and degree of optic nerve damage in chronic open-angle glaucoma

To develop and evaluate a method to map glaucomatous visual field (VF) damage by allocating additional test points to the standard 6° interval VF test pattern, considering the distribution of VF scotomata. Subjects comprised 22 glaucomatous patients. Gradients of sensitivity were calculated for "squares" of test points in a patient's 24-2/30-2 VF results, so that the edges of scotomata could be identified where gradients were steep. Next, 10 new VF points were placed in these locations for each patient. Each patient's VF was then measured using this novel test grid (52 standard 24-2 test points and 10 additional points examined concurrently) on two separate occasions. The absolute difference between the measured sensitivity at each new additional test point and the average of the sensitivities of its surrounding four test points was calculated (Δave). The intra- and intervisit reproducibility of the additional test points' thresholds was calculated. Finally, fluctuation of overall VF damage was estimated using the intraclass correlation coefficient (ICC) and the coefficient of variation (CV). The average of the sensitivities (Δave) increased as the gradient of the plane steepened, whereas the reproducibility of the additional test points' thresholds remained stable. ICC was significantly higher and CV was significantly lower for the novel test grid compared with the standard 24-2 test pattern. It may be advantageous to increase the density of VF test points where there are large local differences in VF sensitivity. These additional measurements may result in more reproducible and well-defined estimates of scotomata.

Oxidative stress has been implicated as a risk factor at several levels in the pathophysiology of glaucoma (Ferreira et al., 2004, 2009, 2010) as well as neurodegenerative diseases (Famulari et al., 1996); growing evidence supports the role of oxidative stress in glaucomatous neurodegeneration (Tezel, 2006). Reactive oxygen species are involved in signalling pathways during retinal ganglion cells death by acting as second messengers and/or modulating protein functions (Neufeld et al., 1999). Evidence of oxidative and nitrative processes was found in glaucoma in terms of activity of antioxidant enzymes, levels of low-molecular weight antioxidants and markers of lipid peroxidation (Aslan et al., 2008). Moreover it has been reported that nitric oxide may be an important mediator in retinal ganglion cells death in glaucoma (Neufeld et al., 1997). In the glaucoma eye, an altered oxidant/antioxidant balance may result in a number of molecular changes that contribute to the development of this ocular disease. Glaucoma is a disease characterized by a specific pattern of optic nerve head and visual field damage in which if it is not controlled may lead to blindness. Although it has been traditionally associated with high intraocular pressure (IOP), glaucoma is now considered as a multifactorial disease. In this context, IOP is the most important known risk factor for the development of glaucomatous optic nerve damage. Even in normal-pressure glaucoma, reducing IOP can be beneficial in terms of halting visual field damage progression. However, lowering IOP may not be enough in every case, since different mechanisms that may or may not depend on the IOP level could contribute to this damage. Proposed mechanisms include ischemia (Lander, 1982), obstruction of axoplasmic flow (Anderson & Hendrickson 1974) and deprivation of one or more trophic factors (Quigley et al., 1995), excitoxicity (Vorwerk et al., 1997) and oxidative stress damage (Ferreira et al., 2004, 2009, 2010). IOP is not elevated in all the eyes that exhibit characteristics of glaucomatous neurodegeneration but experimental elevation of IOP induces oxidative stress in the retina. Aqueous humor is known to contain several active oxidative agents such as hydrogen peroxide and superoxide anion. Low molecular weight antioxidants, such as glutathione (GSH), and ascorbate, together with molecules with free radicals scavenging properties like cysteine and tyrosine, have been identified in the aqueous. Ascorbate is present at high concentrations in it (1-2 mM) (Richer & Rose, 1998) and antioxidant enzymes such as

Effect of Trabeculectomy on Visual Field in Progressive Normal-Tension Glaucoma

Comparing Five Criteria for Evaluating Glaucomatous Visual Fields

To evaluate relationships between the macular visual field (VF) mean sensitivity and the ganglion cell and inner plexiform layer (GCA) thicknesses. Seventy-one glaucoma patients and 29 healthy subjects were included in this cross-sectional study. At each visit, GCA thicknesses were measured by Cirrus HD-OCT and static threshold perimetry was performed using Macular Integrity Assessment (MAIA). The relationship between the VF sensitivity and GCA thickness was examined globally, and in the superior hemiretina, inferior hemiretina, and six VF sectors with both VF and optical coherence tomography (OCT) in retinal view. Regression analysis was used to investigate the relationship between the GCA thickness and macular sensitivity. Macular VF sensitivity (dB) and GCA thickness relationships were statistically significant in each sector (R = 0.365-0.706, all P < 0.001). The highest correlation observed was between the inferotemporal average mean sensitivity and the inferotemporal average GCA thickness (R = 0.706) with both VF and OCT in retinal view. Strength of the structure-function relationship for each of the corresponding inferior sectors was higher than those for the corresponding superior sectors. The strength of the structure-function relationship of the temporal sector was higher than that of the nasal sector. GCA thickness measured by Cirrus HD-OCT showed statistically significant structure-function associations with central VF. Inferotemporal central VF had the strongest association.

Remote contrast sensitivity (CS) testing through a free downloadable home test correlates with glaucomatous macular damage measured by 10-2 visual field (VF) testing. To assess the feasibility and validity of home CS monitoring as a measure of glaucomatous damage using a free downloadable smartphone application. Twenty-six participants were asked to remotely use the Berkeley Contrast Squares (BCS) application, a free downloadable tool that records the user's CS for varying degrees of visual acuity. An instructional video detailing how to download and use the application was sent to the participants. Subjects were asked to send logarithmic CS results with a minimum 8-week test-retest window, and test-retest reliability was measured. Results were validated against office-based CS testing that was collected within the previous 6 months. Validity analysis was also carried out to determine whether CS as measured by BCS is a good predictor of 10-2 and 24-2 VF mean deviation (MD). There was a high BCS test-retest reliability with an intraclass correlation coefficient score of 0.91 and a significant correlation between repeat test results and baseline test scores (Pearson, 0.86, P < 0.0001). There was significant agreement between unilateral CS scores as measured by BCS and office-based CS testing ( b = 0.94, P < 0.0001, 95% CI: 0.61 to 1.27). Unilateral CS as measured by BCS was significantly associated with 10-2 VF MD ( r2 = 0.27, P = 0.006, 95% CI: 3.7 to 20.6), but not with 24-2 VF MD ( P = 0.151). This study suggests that a free, rapid home CS test correlates with glaucomatous macular damage as measured by 10-2 VF.

The purpose of this study is to test the hypothesis that the relationship between baseline visual field damage and the rate of progression depends upon the use of logarithmic (dB) versus linear (1/Lambert) scale. A total of 60 eyes (60 patients) with treated, established glaucoma and at least 5 reliable 24-2 visual fields were included. Baseline visual field mean deviation (MD) in dB was transformed to 1/Lambert using standard equation. Mixed effects linear regression was used to calculate the slopes (MD rates of progression over time) with linear and nonlinear scales. We tested the relationship between baseline MD and MD slopes for each scale of measure. In dB scale, worse baseline visual field loss was associated with faster MD slopes (P=0.037), whereas the opposite effect was seen in 1/Lambert (P=0.001). For a similar rate of progression in dB/y, eyes with mild visual field damage lost more linear sensitivity over a given period of time than those with more severe baseline damage. There is a significant relationship between baseline visual field severity and rates of MD progression, although the direction of this association depends on the scale sensitivity is measured. The definition of fast versus slow visual field progression should be revised and take into account that sensitivity in linear scales show a better correlation with structural loss than when conventionally measured in nonlinear scale.

To investigate and compare the relationships between glaucomatous visual field loss and intraocular pressure (IOP) as measured by both Pascal dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT). All primary open-angle glaucoma and normal tension glaucoma patients seen between July 2005 and June 2006 with at least 2 sets of good-quality, bilateral DCT and GAT measurements were retrospectively identified. Additional inclusion criteria required that all subjects had repeatable, asymmetric glaucomatous visual field loss that corresponded with asymmetric glaucomatous optic neuropathy. After mean IOP values were computed and visual fields were scored using Advanced Glaucoma Intervention Study (AGIS) criteria, paired-eye comparisons were conducted using right versus left eyes and higher versus lower AGIS-score eyes. Sixty-seven (42 primary open-angle glaucoma, 25 normal tension glaucoma) subjects met all criteria for study inclusion. Per paired t test, mean DCT-IOP was significantly higher in the higher AGIS-score eyes compared with the lower AGIS-score eyes (16.3 vs. 15.5 mm Hg, P=0.004), whereas GAT-IOP was not significantly different in these same eyes (14.5 vs. 14.4 mm Hg, P=0.56). Mean IOP difference between the 2 methods was significantly larger in higher versus lower AGIS-score eyes (P<0.001), and 72% of the subjects demonstrated larger intermethod IOP differences in their higher AGIS-score eye compared with their lower AGIS-score eye (P<0.001; 95% confidence interval: 0.59-0.82). Multivariate linear regression analysis revealed that AGIS-score differences between eyes were independently associated with both intermethod IOP differences between eyes (P=0.004) and central corneal thickness (CCT) differences between eyes (P=0.04). CCT, however, was not associated with intermethod IOP differences within or between eyes. These findings suggest that DCT-IOP is correlated with glaucomatous damage, and moreover, DCT-IOP is more closely related to extent of glaucoma damage than is GAT-IOP. The most likely explanation for these results is that GAT-IOP systematically underestimates IOP compared with DCT-IOP. Our findings also support the hypothesis that corneal biomechanical factors other than CCT are major confounders of applanation tonometry measurements.