Water-drinking Test in Normal Tension Glaucoma Patients with and without High Myopia

This prospective study aims to evaluate the correlation between myopic severity and normal tension glaucoma (NTG) by investigating IOP changes following water-drinking test (WDT). We reviewed 61 patients with NTG during an interval of three years, of which 31 were highly myopic (HM) and 30 were non-highly myopic (NHM). Basic characteristics such as age, gender, spherical equivalence, baseline IOP, visual field parameters, and average retinal nerve fiber layer thickness were compared between NTG patients with and without high myopia. The IOP parameters obtained following WDT were then compared between the HM and NHM NTG groups. Intragroup analysis revealed significant IOP elevation following WDT within the 45-minute duration in both groups. However, no significant differences in IOP parameters were observed between the HM and NHM NTG groups. In conclusion, although the pattern of IOP fluctuations was different, the extent of IOP fluctuations and peak IOP following WDT was similar between the HM and NHM NTG groups, suggesting that myopic severity probably has a limited role in NTG. Lastly, WDT was an effective tool for eliciting IOP peaks when 24-hour IOP monitoring is not available.

Choroidal Thickness in Advanced Glaucoma Patients

Purpose: We investigated choroidal thickness according to the classification of glaucoma and related factors in patients with advanced glaucoma.Methods: The present study included 133 eyes of 133 advanced glaucoma patients with a mean deviation of <-12 dB. Patients were classified into primary open angle glaucoma (POAG) and normal-tension glaucoma (NTG) groups. Factors related to the subfoveal and peripapillary choroidal thickness were analyzed using linear regression analysis.Results: The mean peripapillary choroid thickness was 99.20 ± 46.85 µm in the NTG group, which was significantly thinner than in the POAG group (121.85 ± 45.39 µm, p = 0.006). Additionally, in the sectoral comparison, the NTG group had thinner choroids than the POAG group in all areas (p < 0.05 for all). In the linear regression analysis, glaucoma class (p = 0.007), age (p = 0.005), and intraocular pressure (IOP) (p = 0.024) significantly affected the peripapillary choroid thickness. Moreover, age (p = 0.029) and macular thickness (p = 0.002) were significantly associated with subfoveal choroid thickness.Conclusions: In advanced glaucoma, low baseline IOP, NTG, and old age were significantly associated with a thin peripapillary choroid, suggesting an association between thin peripapillary choroid and the etiology of NTG. Further studies are needed to clarify the significance of a thin choroid in the pathogenesis of glaucoma.

Comparison of optical coherence tomography angiography metrics in primary angle-closure glaucoma and normal-tension glaucoma

To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCT-A). One or both eyes of each subject were imaged for a 3 × 3 mm peripapillary region by swept-source OCT-A (DRI-OCT Triton, Topcon, Japan) and assessed by an automated MATLAB program. OCT-A metrics including circumpapillary vessel density (cpVD) and fractal dimension (cpFD) were compared. Their association with visual field (VF) parameters and retinal nerve fiber layer (RNFL) thickness were determined. Sixty-eight eyes of 51 PACG, 68 eyes of 48 NTG, and 68 eyes of 49 control subjects were cross-sectionally analyzed. NTG eyes had significantly lower global cpVD (52.369 ± 0.781%) compared with PACG eyes (55.389 ± 0.721%, P = 0.004) that had comparable disease severity and average RNFL thickness. Multivariable analysis revealed that, for PACG and NTG eyes, decreased cpVD ([PACG] β = −4.242; CI: −8.120, −0.363 vs [NTG] β = −5.531; CI: −9.472, −1.590) and cpFD ([PACG] β = −8.894;CI: −11.925, −5.864 vs [NTG] β = −12.064; CI: −17.095, −6.932) were associated with decreased RNFL thickness (all P ≤ 0.032); with a stronger association between decrease cpFD and decreased RNFL thickness in NTG eyes (P = 0.028). Decreased cpVD was associated with decrease mean deviation (MD) in NTG eyes (β = −0.707; CI: −1.090, −0.324; P ≤ 0.001) and not associated with the visual field parameters in PACG eyes. Early NTG had lower global cpVD compared with early PACG, despite similar disease severity and average RNFL thickness.

Individuals with and without normal tension glaucoma exhibit comparable performance on tests of cognitive function

AIM: To evaluate aspects of cognition impacted by individuals with and without normal tension glaucoma. METHODS: Fifty normal tension glaucoma (NTG) and 50 control patients ≥50y of age were recruited from the UCSF Department of Ophthalmology. Demographic data and glaucoma parameters were extracted from electronic medical records for both groups. Tests of executive function [Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER)] and learning and memory [California Verbal Learning Test–Second Edition (CVLT-II)] were administered to both NTG and controls. Race, handedness, best-corrected visual acuity, maximum intraocular pressure, optic nerve cup-to-disc ratio, visual field and optic nerve optical coherence tomography parameters, and a measure of general health (Charlson Comorbidity Index) were compared between NTG and controls as well as within NTG subgroups. Multivariate linear regression was used to compare group performances on the EXAMINER battery and CVLT-II while controlling for age, sex, and years of education. RESULTS: NTG and controls were comparable with respect to age, sex, race, education, handedness, and the Charlson Comorbidity Index (P>0.05 for all). Performance on the EXAMINER composite score and the CVLT-II did not differ between NTG and controls (P>0.05 for both). CONCLUSION: This is the first prospective study in which the cognitive function of subject with NTG were evaluated using a comprehensive, computerized neurocognitive battery. Subjects with NTG do not perform worse than unaffected controls on tests of executive function, learning, and memory. Results do not support the hypothesis that individuals with NTG are at higher risk for cognitive dysfunction and/or dementia.

Clinical characteristics of choroidal microvasculature dropout in normal-tension glaucoma versus nonarteritic anterior ischemic optic neuropathy: an optical coherence tomography angiography study

The present study investigated the characteristics of choroidal microvasculature dropout (CMvD) in eyes with nonarteritic anterior ischemic optic neuropathy (NAION) versus those in eyes with normal-tension glaucoma (NTG). This study included 27 NAION, 27 NTG, and 27 healthy control subjects. CMvD was observed in 15 eyes (55.6%) of the NAION group and 20 (74.1%) of the NTG group. The area and angular width of CMvD were significantly greater in eyes with NAION (0.278 ± 0.172 mm2 and 86.5 ± 42.3°) than in those with NTG (0.138 ± 0.068 mm2 and 35.1 ± 16.2°, p = 0.002 and p < 0.001, respectively). CMvD in eyes with NAION were distributed in 120–250° and most frequently located at the temporal region, while CMvD in eyes with NTG showed double peaks at 220–280° and 110–140° and most frequently located at the inferotemporal region. The factors associated with the discrimination of NAION from NTG were greater area of CMvD (OR, 1.181; 95% CI, 1.021–1.366; p = 0.025) and location closer to the temporal region of the CMvD (OR, 0.904; 95% CI, 0.838–0.975; p = 0.009). The clinical characteristics of CMvD differed between eyes with NAION and those with NTG. Optical coherence tomography angiography may provide an additional approach to differentiating glaucoma from NAION.

Impact of intraocular pressure fluctuations on progression of normal tension glaucoma

AIM: To investigate short- and long-term intraocular pressure (IOP) fluctuations and further ocular and demographic parameters as predictors for normal tension glaucoma (NTG) progression. METHODS: This retrospective, longitudinal cohort study included 137 eyes of 75 patients with NTG, defined by glaucomatous optic disc or visual field defect with normal IOP (<21 mm Hg), independently from therapy regimen. IOP fluctuation, mean, and maximum were inspected with a mean follow-up of 38mo [standard deviation (SD) 18mo]. Inclusion criteria were the performance of minimum two 48-hour profiles including perimetry, Heidelberg retina tomograph (HRT) imaging, and optic disc photographs. The impact of IOP parameters, myopia, sex, cup-to-disc-ratio, and visual field results on progression of NTG were analyzed using Cox regression models. A sub-group analysis with results from optical coherence tomography (OCT) was performed. RESULTS: IOP fluctuations, average, and maximum were not risk factors for progression in NTG patients, although maximum IOP at the initial IOP profile was higher in eyes with progression than in eyes without progression (P=0.054). The 46/137 (33.5%) eyes progressed over the follow-up period. Overall progression (at least three progression confirmations) occurred in 28/137 eyes (20.4%). Most progressions were detected by perimetry (36/46). Long-term IOP mean over all pressure profiles was 12.8 mm Hg (SD 1.3 mm Hg); IOP fluctuation was 1.4 mm Hg (SD 0.8 mm Hg). The progression-free five-year rate was 58.2% (SD 6.5%). CONCLUSION: Short- and long-term IOP fluctuations do not result in progression of NTG. As functional changes are most likely to happen, NTG should be monitored with visual field testing more often than with other devices.