Association between Systemic Antioxidant Capacity and Retinal Vessel Diameters in Patients with Primary-Open Angle Glaucoma

Is Primary Open-Angle Glaucoma a Vascular Disease? Assessment of the Relationship between Retinal Arteriolar Morphology and Glaucoma Severity Using Adaptive Optics

BACKGROUND

Retinal vascular abnormalities may be associated with glaucomatous damage. Adaptive optics (AO) is a new technology that enables the analysis of retinal vasculature at the cellular level in vivo. The purpose of this study was to evaluate retinal arteriolar parameters using the rtx1 adaptive optics fundus camera (AO-FC) in patients with primary open-angle glaucoma (POAG) at different stages and to investigate the relationship between these parameters and changes in spectral-domain optical coherence tomography (SD-OCT) and perimetry.

METHODS

Parameters of the retinal supratemporal and infratemporal arterioles (wall thickness (WT), lumen diameter (LD), total diameter (TD), wall-to-lumen ratio (WLR), and cross-sectional area of the vascular wall (WCSA)) were analysed with the rtx1 in 111 POAG eyes, which were divided into three groups according to the severity of the disease, and 70 healthy eyes. The associations between RTX1 values and the cup-to-disk ratio, SD-OCT parameters, and visual field parameters were assessed.

RESULTS

Compared with the control group, the POAG groups showed significantly smaller TD and LD values (p < 0.05) and significantly higher WLR and WT values (p < 0.05) for the supratemporal and infratemporal arterioles. TD was significantly positively correlated with the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) (p < 0.05). LD was significantly positively correlated with the RNFL, GCC, and rim area (p < 0.05). The WLR was significantly negatively correlated with the RNFL, GCC, rim area, and MD (p < 0.05), while it was significantly positively correlated with the cup-to-disc ratio and PSD (p < 0.05).

CONCLUSIONS

The results suggest that vascular dysfunction is present in POAG, even at a very early stage of glaucoma, and increases with the severity of the disease.

Linear association between aging and decreased blood thiol antioxidant activity in patients with cataract

We comprehensively assessed the roles of systemic redox markers by including both prooxidant and antioxidant markers in 121 Japanese subjects (mean ± SD age, 70 ± 11 years; 38 men) with no ocular pathology except age-related cataract. Serum levels of lipid peroxides, ferric-reducing activity, and thiol antioxidant activity were measured using the diacron reactive oxygen metabolite (dROM), biologic antioxidant potential (BAP), and sulfhydryl (SH) tests, respectively, using a free-radical analyzer. Univariate analyses suggested that older age, higher pulse rate, worse best-corrected visual acuity (BCVA), higher intraocular pressure, and higher cataract grade were associated with a lower SH level. Scatterplots revealed virtually linear associations between age and the SH level (estimate, -4.4 μM/year). Multivariate analyses suggested that older age, higher systolic blood pressure, and worse BCVA were associated with a lower SH level. Neither the univariate nor multivariate analyses, except between female sex and higher dROM level, were associated with the dROM or BAP level. A lower serum SH level was the driver of aging itself and age-related decline in VA due to cataract. The serum SH level may be an excellent predictor of aging status in each subject.

Positive Association between Aqueous Humor Hydroxylinoleate Levels and Intraocular Pressure

We previously proposed the total assessment of hydroxylinoleates (HODEs) by LC-MS/MS after saponification and reduction of the biologic samples as biomarkers to investigate pathogenesis, disease progression, and prognosis. In this study, HODE levels were estimated in aqueous humor (AH) samples from 63 eyes (41 Japanese subjects; 15 men; mean age, 77.3 ± 6.8 years) with primary open-angle glaucoma (POAG) or cataracts. The correlations between intraocular HODE levels and background parameters, including intraocular pressure (IOP), were analyzed to assess the possible involvement of oxidative stress in glaucoma pathology. Univariate analyses showed that linoleic acid (LA) (p = 0.034) and arachidonic acid (AA) (p = 0.0041) levels were associated negatively with age; 13-(Z,E)-HODE (p = 0.018) and 13-(E,E)-HODE (p = 0.021) were associated positively with IOP; 9-(Z,E)-HODE (p = 0.039), 13-(Z,E)-HODE (p = 0.021), totally assessed-HODE (t-HODE, p = 0.023), LA (p = 0.0080), and AA (p = 0.0051) were higher in eyes with glaucoma than cataract. No gender differences were seen. A mixed-effect regression model showed that higher 13-(Z,E)-HODE (p = 0.0040) and higher t-HODE (p = 0.040) were associated with glaucoma rather than cataracts; and higher levels of 13-(Z,E)-HODE/LA (p = 0.043), 13-(E,E)-HODE/LA (p = 0.042), 13-(Z,E)-HODE (p = 0.0054), and 13-(E,E)-HODE (p = 0.027) were associated with higher IOP. Linoleate-derived oxidation products were quantified successfully in AH samples from patients with glaucoma and cataracts. A free radical oxidation mechanism can be associated with IOP elevation, while enzymatic oxidation may be involved, specifically, in the pathogenesis of POAG.

Retinal Disease and Metabolism

Retinal diseases, such as diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinopathy of prematurity (ROP), are some of the leading causes of blindness all over the world [...]