Diffusion Tensor Imaging Detects Microstructural Differences of Visual Pathway in Patients With Primary Open-Angle Glaucoma and Ocular Hypertension

Objective: To study the alteration of the optic radiations in patients with primary open-angle glaucoma (POAG) by diffusion tensor imaging (DTI) and tractography, and to reveal the correlation between the DTI derived parameters and the severity of the disease. Methods: A total of 24 patients with POAG and 20 age- and gender-matched healthy controls were enrolled in this study from January 2011 to June 2013.All subjects underwent ophthalmoscopy, standard automatic perimetry, intraocular pressure measurement and MRI scanning.All the eyes of POAG patients were evaluated by Hodapp-Anderson-Parrish (HAP) system.Then the stages of bilateral eyes were added together to evaluate the disease severity.Tractography was used to measure the fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) of the optic radiations of these subjects.The results of the two groups were compared.Partial correlation was then used to reveal the correlation between these derived DTI parameters and the severity of POAG. Results: Compared with health controls, POAG patients showed significant decreased FA (t=-3.299, P=0.002) and AD (t=-2.485, P=0.013), increased RD (t=2.365, P=0.018) in optic radiation .The alteration of MD was not significant (t=0.719, P=0.454). Mean FA values of the optic radiations were negatively correlated with POAG stages (r=-0.643, P= 0.001), while mean RD values (r=0.570, P= 0.004) and mean MD values (r= 0.448, P= 0.028) were positively correlated with POAG stages.No correlation between AD values and severity of POAG was found. Conclusion: In the optic radiations of POAG patients, the FA values and AD values decrease, while RD values increase, indicating the fiber integrity changes.The alterations of FA, RD and MD are correlated with disease severity.

Glaucoma patients had a reduction in the inner annulus peripapillary choroidal microvascular density (PCMD) that became worse as the glaucoma severity progressed, which might provide new evidence supporting the vascular theory. To compare PCMD among normal tension glaucoma (NTG), primary open angle glaucoma (POAG), and healthy controls using optical coherence tomography (OCT) angiography (OCTA). The study included 40 POAG, 25 NTG, and 33 healthy controls. All subjects underwent OCT and OCTA testing. The inner annulus and outer annulus PCMD, as well as peripapillary vessel density (VD), were calculated. One-way analysis of variance was used to compare the vascular parameters of the 3 groups. Pearson correlation analysis or Spearman correlation test was used to evaluate the correlation between PCMD and glaucomatous severity factors. The spatial positional relationship between PCMD and corresponding peripapillary retinal nerve fiber layer (RNFL) thickness and visual field (VF) mean deviation (MD) was also assessed. The average and 4 quadrants of the inner annulus PCMD and peripapillary VD in the 2 glaucomatous groups were significantly lower than in normal eyes ( P <0.05). Strong correlations were found between inner annulus PCMD and VF MD, peripapillary VD, and RNFL in POAG patients. Similarly, the inner annulus PCMD in NTG patients was strongly correlated with peripapillary VD and RNFL (all r >0.5). Strong positional correlations were found between inner superior quadrantal PCMD and RNFL thickness in both POAG and NTG patients ( r =0.566 and 0.731, respectively). Likewise, inner inferior quadrantal PCMD exhibited a strong correlation with RNFL thickness in POAG patients ( r =0.608). Strong positional correlations were also found between inner superior PCMD and VF MD in both POAG and NTG patients ( r =0.589 and 0.622, respectively). Inner inferior PCMD exhibited a moderate correlation with VF MD in both POAG and NTG patients ( r =0.487 and 0.440, respectively). The study found that the inner annulus PCMD decreased to varying degrees in NTG and POAG patients. The inner annulus PCMD was closely related to the structural and visual function parameters of glaucoma in both NTG and POAG. Furthermore, inner PCMD demonstrated a spatial correlation with corresponding RNFL thickness and VF MD.

To investigate the diagnostic ability of retinal superficial vasculature evaluation by optic coherence tomography angiography (OCTA) combined with visual field (VF) testing for early primary open-angle glaucoma (POAG). In this cross-sectional study, 84 participants were included, including 11 in the ocular hypertension (OHT) group, 11 in the preperimetric POAG (pre-POAG) group, 29 in the early POAG group and 33 in the control group. All participants underwent 6 × 6 mm2 scans of macula and optic nerved head by optic coherence tomography (OCT) and OCTA, along with white-on-white and blue-on-yellow VF testing by static automated perimetry. The ability of diagnosing early glaucoma by either various examinations separately or combination of examinations in both terms of function and structure was studied using the receiver operating characteristic (ROC) curve and the area under the curve (AUC). The superficial retinal vessel densities (VD) in peri-nasal, para-temporal, peri-temporal and peri-inferior regions around the macula, as well as vessel area densities (VAD) in all peripapillary regions, were significantly different among the four groups, with lower VD or VAD in the early POAG patients compared to the normal individuals. The diagnostic ability of peripapillary superficial retinal VAD alone or VF testing alone was limited for early POAG only. However, the combination of these two was more effective in distinguishing normal individuals from OHT subjects or pre-POAG patients without VF defects, with better performance than the combination of peripapillary retinal nerve fiber layer (RNFL) thickness and VF indicators. Peripapillary retinal vessel densities were generally lower in early POAG patients compared to normal individuals. The combination of peripapillary superficial retinal VAD by OCTA with white-on-white VF testing improved the ability to distinguish POAG patients at early stage without function impairment, which may help in providing reference and guidance for the following-up and treatment of suspected POAG patients.

To investigate the diffusion characteristics of water of optic nerve and optic radiation in healthy adults and its related factors by diffusion tensor imaging (DTI) at 3T. A total of 107 healthy volunteers performed head conventional MRI and bilateral optic nerve and optic radiation DTI. The primary data of DTI was processed by post-processing software of DTI studio 2.3, obtaining fractional anisotropy value, mean diffusivity value, principal engine value, orthogonal engine value by measuring, and analyzed by the SPSS13.0 statistical software. The bilateral optic nerve and optic radiation fibers presented green color in directional encoded color (DEC) maps and presented high signal in fractional anisotropy (FA) maps. The FA value of the left optic nerve was 0.598±0.069 and the right was 0.593±0.065; the mean diffusivity (MD) value of the left optic nerve was (1.324±0.349)×10(-3)mm(2)/s and the right was (1.312±0.350)×10(-3)mm(2)/s; the principal engine value (λ‖) of the left optic nerve was (2.297±0.522)×10(-3)mm(2)/s and the right was (2.277±0.526)×10(-3)mm(2)/s; the orthogonal engine value (λ⊥) of the left optic nerve was (0.838±0.285)×10(-3)mm(2)/s and the right was (0.830±0.280)×10(-3)mm(2)/s; the FA value of the left optic radiation was 0.636±0.057 and the right was 0.628±0.056; the mean diffusivity (MD) value of the left optic radiation was (0.907±0.103)×10(-3)mm(2)/s and the right was (0.889±0.125)×10(-3)mm(2)/s; the principal eigenvalue (λ‖) of the left optic radiation was (1.655±0.210)×10(-3)mm(2)/s and the right was (1.614±0.171)×10(-3)mm(2)/s; the orthogonal enginvalue (λ⊥) of the left optic radiation was (0.531±0.103)×10(-3)mm(2)/s and the right was (0.524±0.152)×10(-3)mm(2)/s. There was no obvious difference between the FA, MD, λ‖, λ⊥ of the bilateral optic radiation and the bilateral optic nerve (P>0.05) and no obvious difference between male and female group. The FA, MD, λ‖, λ⊥ of the bilateral optic radiation and the bilateral optic nerve had no obvious correlations to the age. DTI is sensitive to the optic nerve and radiation and the relevant DTI parameters of the optic nerve and radiation are established preliminarily in this study.

Diffusion tensor imaging (DTI) parameters in the corpus callosum have been suggested to be a biomarker for prognostic outcomes in individuals with diffuse axonal injury (DAI). However, differences between the DTI parameters on moderate and severe trauma in DAI over time are still unclear. A secondary goal was to study the association between the changes in the DTI parameters, anxiety, and depressive scores in DAI over time. Twenty subjects were recruited from a neurological outpatient clinic and evaluated at 2, 6, and 12months after the brain injury and compared to matched age and sex healthy controls regarding the DTI parameters in the corpus callosum. State-Trace Anxiety Inventory and Beck Depression Inventory were used to assess psychiatric outcomes in the TBI group over time. Differences were observed in the fractional anisotropy and mean diffusivity of the genu, body, and splenium of the corpus callosum between DAI and controls (p < 0.02). Differences in both parameters in the genu of the corpus callosum were also detected between patients with moderate and severe DAI (p < 0.05). There was an increase in the mean diffusivity values and the fractional anisotropy decrease in the DAI group over time (p < 0.02). There was no significant correlation between changes in the fractional anisotropy and mean diffusivity across the study and psychiatric outcomes in DAI. DTI parameters, specifically the mean diffusivity in the corpus callosum, may provide reliable characterization and quantification of differences determined by the brain injury severity. No correlation was observed with DAI parameters and the psychiatric outcome scores.

This study aimed to assess vascular endothelial function in patients with ocular hypertension (OHT) or primary open-angle glaucoma (POAG) by measuring: (a) endothelium-dependent flow-mediated vasodilation (FMD) of the brachial artery, and (b) circulating endothelial progenitor cells, which are believed to support the integrity of the vascular endothelium. We enrolled 25 patients with OHT, 23 with POAG and 26 control subjects, all of whom were aged < 65 years and had no medical history of cardiovascular disease or cardiovascular risk factors. All subjects underwent a complete ophthalmological examination, biochemistry study, assessment of cardiovascular parameters, brachial artery ultrasound assessment of endothelium-dependent FMD, generic circulating progenitor cell (CPC) and circulating endothelial progenitor cell (EPC) count with the use of flow cytometry. Flow-mediated vasodilation values differed significantly in OHT (4.5 +/- 1.1%; p = 0.021) and POAG (4.0 +/- 0.9%; p = 0.003) patients compared with controls (7.7 +/- 0.8%). The CD34(+) KDR(+) EPC count was markedly lower in OHT (28.0 +/- 5.0; p < 0.001) and POAG (24.3 +/- 3.4; p < 0.001) patients compared with controls (73.1 +/- 8.1). Neither FMD not EPCs differed significantly between OHT and POAG patients. No significant differences in CPC count or cardiovascular parameters were found among OHT or POAG patients and controls. The levels of CD34(+) KDR(+) EPCs were directly correlated (p = 0.043) with FMD, and inversely correlated (p = 0.032) with baseline intraocular pressure in OHT and POAG patients. Both OHT and POAG patients without cardiovascular risk factors have previously unreported severely reduced circulating EPCs and reduced FMD, both of which are indicators of endothelial dysfunction and increased risk of cardiovascular events.

Differentiation of high-grade-astrocytomas from solitary-brain-metastases: Comparing diffusion kurtosis imaging and diffusion tensor imaging

The aim is to investigate whether there is a microstructural change in the white matter pathways in patients with spontaneous intracranial hypotension (SIH). Additionally, the relationship between conventional magnetic resonance imaging (MRI) findings and diffusion tensor imaging (DTI) parameters is determined. Thirty patients diagnosed with SIH and 31 control patients (between January 2019 and February 2024) were included in the case-control study. MRI findings constituting the Bern score were evaluated in contrast-enhanced brain MRI. Ten different white matter pathways were evaluated with the following DTI parameters: fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusion (AD), and radial diffusion (RD). We also examined the association between MRI findings and DTI parameters. In the cingulum, a decreased FA value (Z = -3.18, p = 0.002) was observed in patients with SIH, indicating disruption of white matter integrity and weakened synaptic transmission in this region. In the corona radiata, significant reductions were observed in both FA (Z = -5.67, p < 0.001) and AD (Z = -3.59, p < 0.001), alongside an increase in RD (Z = -4.99, p < 0.001). The concomitant increase in RD further supports the idea of potential damage to the myelin sheath, which, together with other findings, may reflect disruptions in white matter architecture that underlie the cognitive and motor deficits frequently seen in patients with SIH. In the splenium of the corpus callosum, a significant reduction in AD (Z = -3.00, p = 0.007) was also noted. In the anterior limb of the internal capsule (ALIC), both FA (Z = -4.57, p < 0.001) and AD (Z = -2.73, p = 0.012) values decreased, while RD increased (Z = -2.93, p = 0.007). These alterations suggest the involvement of motor and sensory pathways. In the posterior limb of the internal capsule (PLIC), significant reductions were found in both FA (Z = -5.59, p < 0.001) and AD (Z = -3.82, p < 0.001), along with an increase in RD (Z = -5.49, p < 0.001). In the corticospinal tract, patients with SIH exhibited a decrease in FA (Z = -4.15, p < 0.001), an increase in ADC (Z = -2.87, p = 0.008), and an increase in RD (Z = -3.73, p < 0.001). These findings represent significant microstructural changes reflecting a reduction in the integrity of motor pathways in white matter. In the middle cerebellar peduncle (MCP), patients with SIH showed increased ADC (Z = -4.78, p < 0.001) and RD (Z = -3.23, p = 0.002). Similarly, in optic radiation, there was decreased FA (Z = -4.55, p < 0.001) and AD (Z = -2.59, p = 0.018), with increased RD (Z = -2.95, p = 0.007). In the correlation analysis, positive correlations were found between suprasellar distance and AD values in both the ALIC (rs = 0.451, p = 0.012) and MCP (rs = 0.416, p = 0.022). These findings suggest that structural changes and anatomical shifts, especially in the suprasellar region, may be associated with microstructural changes in the adjacent white matter pathways. We revealed microstructural changes in white matter in SIH. The alterations in DTI parameters may suggest that the white matter microarchitecture is changed as a result of mechanical compression of the axons in the white matter pathways due to brain prolapse and venous congestion.

This study investigated correlations between American Spinal Injury Association (ASIA) clinical injury motor scores in patients with traumatic cervical cord injury and magnetic resonance (MR) diffusion tensor imaging (DTI) parameters. Conventional imaging and DTI were performed to evaluate 25 patients (age, 39.7±13.9 years; 4 women, 21 men) with blunt spinal cord injury and 11 volunteers (age, 31.5±10.7 years; 3 women, 8 men). Cord contusions were hemorrhagic (HC) in 13 and non-hemorrhagic (NHC) in 12 patients. The spinal cord was divided into three regions to account for spatial and pathological variation in DTI parameters. Comparisons of regional and injury site mean diffusivity (MD), fractional anisotropy (FA), radial diffusivity ( λ(⊥)), and longitudinal diffusivity ( λ(‖)) were made with control subjects. ASIA motor scores were correlated with DTI using linear regression analysis. HC and NHC patients showed significant reduction (p<0.001) in MD and λ(‖) in all three regions. At the injury site, significant decreases in FA and λ(‖) were seen for both injury groups (p<0.001). λ(⊥) values were significantly increased only for patients with NHC (p<0.05). Significant reduction in FA and λ(‖) (p<0.0001) was observed at the whole cord level between the injured (NH and NHC) and control groups. Within the NHC group, strong correlations were observed between ASIA motor scores and average MD, FA, λ(⊥), and λ(‖) at the injury site. However, no correlation was observed within the HC group between any of the DTI parameters and ASIA motor scores. DTI parameters reflect the severity of spinal cord injury and correlate well with ASIA motor scores in patients with NHC.

Purpose: To compare the plasma levels of hydrogen sulfide (H2S), homocysteine (Hcy), and L-cysteine (Cys) among primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), ocular hypertension (OHT), and normal individuals. To explore associated factors and evaluate their diagnostic abilities in glaucoma. Methods: POAG, NTG, OHT, and normal subjects were recruited from Ruijin Hospital between December 2016 and December 2018. All subjects underwent thorough ophthalmological examinations, and fasting venous blood was taken to determine the concentrations of H2S, Hcy, and Cys. Results: Forty-two POAG, 20 NTG, 52 OHT, and 78 controls were enrolled. The H2S levels in POAG group were significantly lower than those in OHT group (P = 0.036) and normal group (P < 0.001), while the Hcy and Cys levels in POAG and NTG groups were significantly higher (P = 0.007-0.043). The concentrations of H2S, Hcy, and Cys in glaucoma patients with different stages were not significantly different (all P > 0.05). POAG patients with longer duration of diagnosis had lower concentrations (P = 0.026, P = 0.001, P < 0.001), but no significant differences in NTG patients (all P > 0.05). The Hcy and Cys levels in NTG patients showed negative but weak correlations with mean deviation (r = -0.450, P = 0.047; r = -0.478, P = 0.033). All these concentrations showed significant but poor diagnostic values in POAG-Normal group [area under curve (AUC) = 0.642-0.721, P < 0.05]. The H2S level showed poor diagnostic power in POAG-OHT group (AUC = 0.657, P < 0.01). Conclusion: Decreased levels of H2S and increased levels of Hcy and Cys may be associated with glaucoma, especially in POAG. However, the H2S/Hcy metabolic pathway is not sufficiently sensitive to be used as a reliable biomarker in glaucoma.

In this work, we aim to assess the significance of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameters in grading gliomas. Retrospective studies were performed on 53 subjects with gliomas belonging to WHO grade II (n=19), grade III (n=20) and grade IV (n=14). Expert marked regions of interest (ROIs) covering the tumour on T2-weighted images. Statistical texture measures such as entropy and busyness calculated over ROIs on diffusion parametric maps were used to assess the tumour heterogeneity. Additionally, we propose a volume heterogeneity index derived from cross correlation (CC) analysis as a tool for grading gliomas. The texture measures were compared between grades by performing the Mann-Whitney test followed by receiver operating characteristic (ROC) analysis for evaluating diagnostic accuracy. Entropy, busyness and volume heterogeneity index for all diffusion parameters except fractional anisotropy and anisotropy of kurtosis showed significant differences between grades. The Mann-Whitney test on mean diffusivity (MD), among DTI parameters, resulted in the highest discriminability with values of P=0.029 (0.0421) for grade II vs. III and P=0.0312 (0.0415) for III vs. IV for entropy (busyness). In DKI, mean kurtosis (MK) showed the highest discriminability, P=0.018 (0.038) for grade II vs. III and P=0.022 (0.04) for III vs. IV for entropy (busyness). Results of CC analysis illustrate the existence of homogeneity in volume (uniformity across slices) for lower grades, as compared to higher grades. Hypothesis testing performed on volume heterogeneity index showed P values of 0.0002 (0.0001) and 0.0003 (0.0003) between grades II vs. III and III vs. IV, respectively, for MD (MK). In summary, the studies demonstrated great potential towards automating grading gliomas by employing tumour heterogeneity measures on DTI and DKI parameters.

To evaluate the results of short wavelength perimetry (SWAP) of ocular hypertensive (OHT) patients and correlate these findings with central corneal thickness (CCT) measurements. Thirty-seven OHT patients with a mean age of 50.2+/-8.2 (SD) years and 30 control subjects with a mean age of 50.3+/-8.5 (SD) years were included in this study. A questionnaire was applied to patients to evaluate the demographic risk factors that may predict glaucoma development. After a detailed ophthalmologic examination, achromatic and short wavelength perimetries and ultrasonic pachymetry were performed and the results were compared between the two groups with Student t test and Mann-Whitney U test. A p value<0.05 is considered as statistically significant. Mean CCT was higher in the OHT group (right eye; 558.13+/-28.39 microm and left eye; 558.94+/-27.30 microm) when compared with the control subjects (524.66+/-30.53 microm and 525.86+/-30.46 microm, respectively) (p<0.01). A significant positive correlation was found between CCT measurements and intraocular pressure (r=0.5, p<0.001). Four right eyes (10.8%) and five left eyes (13.5%) of OHT patients had defects in SWAP. OHT patients with SWAP abnormalities had significantly lower CCT measurements in right (527.25+/-17.34 microm) and left eye (528.80+/-13.60 microm) when compared with OHT patients without SWAP defects (561.87+/-27.29 microm and 563.65+/-25.92 microm, respectively) (p<0.05). Significant correlations were found between CCT and SWAP MD, PSD, and CPSD (p<0.05). OHT patients with SWAP abnormalities had significantly lower CCT measurements than those without. CCT is considered as a risk factor for the development of glaucomatous damage in OHT patients.

The purpose of the study was to compare radial peripapillary capillary (RPC) density between normal subjects and patients with early primary open-angle glaucoma (POAG) using optical coherence tomography angiography (OCT-A). A total of 24 patients with early POAG and age-matched 52 normal subjects underwent scanning with OCT-A imaging (RTVue XR-100, Avanti OCT). The enface angioflow images obtained were analyzed qualitatively for the RPC network, and RPC capillary density (CD) was measured in 8 sectors within a 3.45-mm-diameter circle around the optic disc, using the Bar-Selective Combination of Shifted Filter Responses (B-COSFIRE) method. CD and retinal nerve fiber layer (RNFL) thickness were compared between corresponding sectors with the Mann-Whitney U test. Correlations between CD and Humphrey visual field parameters and optic disc structural parameters were calculated by linear regression analysis. In the normal eyes, RPC bed was clearly visible on OCT-A as a dense microvascular network around the optic disc, whereas in POAG patients it was focally attenuated. RPC CD was lower in the inferotemporal (P=0.002) and superotemporal (P=0.008) sectors with corresponding focal RNFL defect in POAG patients when compared with normal controls. The average CD correlated with visual field mean deviation (P=0.01) and pattern standard deviation (P=0.02) in glaucomatous eyes. OCT-A demonstrated reproducible, focal loss of RPCs in patients with early POAG when compared with normal controls. The results of our study suggest that the RPC density measurements may have a value in the diagnosis and monitoring of glaucoma.

Purpose To evaluate platelet parameters in primary open-angle glaucoma (POAG) patients and to explore the association between platelet parameters and POAG severity. Methods A total of 402 consecutive POAG patients and 408 healthy control subjects from the Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Fudan University, were consecutively recruited between January 2016 and October 2018. Detailed ophthalmological and systematic examinations were performed. Blood samples for platelet parameters, including platelet count (PLT), platelet distribution width (PDW), plateletcrit (PCT), mean platelet volume (MPV), and platelet large cell ratio (P-LCR), were analyzed using an automated hematology analyzer in the department of clinical laboratory science of the hospital. The POAG subgroups were classified according to age (<50, ≥50), gender, and visual field mean deviation (MD): mild (MD ≤ 6 dB), moderate (6 dB < MD ≤ 12 dB), and severe (MD > 12 dB). Results In POAG patients, PLT counts (207.08 ± 54.70 ∗ 109/L) were significantly lower (p=0.001) than those of the control group (220.46 ± 55.85 ∗ 109/L). In the POAG group, PDW (13.76 ± 3.16 fL) and MPV (10.46 ± 1.32 fL) values were significantly higher (all p < 0.001) than those of the control group (PDW 11.82 ± 2.44 fL, MPV 10.13 ± 1.10 fL). PDW and MPV values were highest in the severe POAG group (PDW 14.49 ± 2.99 fL; MPV 10.74 ± 1.39 fL), followed by the moderate group (PDW 12.50 ± 3.14 fL; MPV 10.02 ± 1.08 fL) and then the mild group (PDW 11.82 ± 2.44 fL; MPV 9.92 ± 0.76 fL), with statistically significant differences observed between mild-severe POAG and moderate-severe POAG groups by LSD post hoc test. Multiple linear regression analyses showed a significant association between PDW and MD (β = 0.430, p < 0.001) and MPV and MD (β = 0.363, p=0.001). Logistic regression analyses revealed that PDW (OR = 1.297, 95% CI = 1.011–1.663) was associated with the severity of POAG. Conclusions PDW and MPV values were significantly elevated in POAG patients, and PDW was positively associated with disease severity, which suggested the possibility that platelet activation be involved in pathomechanisms of POAG.

To observe the diurnal variations of intraocular pressure (IOP) measured with dynamic contour tonometer (DCT) in primary open angle glaucoma (POAG) patients, normal tension glaucoma (NTG) patients, and healthy controls, and to compare the differences of diurnal variation curves between the two eyes of each subject and define the distribution of the peak of IOP; to analyze the diurnal variation range of ocular pulse amplitude (OPA) and compare the differences among the POAG and NTG patients and healthy controls. DCT was used to measure the diurnal variations of IOP and OPA in the two eyes of 18 POAG patients, 17 NTG patients and 30 normal controls at 5:00, 7:00, 10:00, 14:00, 18:00, and 22:00 and the distribution of the peak IOP was observed. The range of the diurnal variation of OPA was identified. The diurnal variation curves of IOP were different among the POAG patients, NTG patients, and normal people, and also between the two eyes of each subject. Four right eyes (13.3%) and 6 left eyes (20.0%) of the healthy controls, 4 right eyes (23.5%) and 5 left eyes (29.4%) of the NTG patients, and 5 right eyes (27.8%) and 4 left eyes (22.2%) of the POAG patients reached the peak IOP values in out-office period. Diurnal variation of OPA was detected in both the patients and controls, and the variation curves were different within different groups sampled and between the two eyes of each subject. The diurnal OPA range of the right and left eyes of the POAG group were (2.1 +/- 1.3) mm Hg, and (2.4 +/- 1.9) mm Hg respectively, significantly larger than those of the normal controls [(1.1 +/- 0.5) mm Hg and 1.2 +/- 0.5) mm Hg respectively], and those of the NTG group [(1.1 +/- 0.8) mm Hg and (1.0 +/- 0.5) mm Hg) respectively] (all P < 0.01). OPA has diurnal variation. The diurnal variation of the POAG patients is the largest. NTG patients and normal controls have asymmetric IOP and OPA diurnal variations. The two eyes of the same individual cannot always be treated as the same. The value of IOP measured in the office-time cannot completely represents the 1 d IOP.