Disturbed oxidant/antioxidant balance in aqueous humour of patients with exfoliation syndrome

The Role of Oxidative Status in the Pathogenesis of Primary Open-Angle Glaucoma, Pseudoexfolyation Syndrome and Glaucoma

PURPOSE

To investigate the role of oxidative stress and antioxidant system in the etiopathogenesis of pseudoexfoliation and progression of pseudoexfoliation syndrome to glaucoma.

MATERIAL AND METHOD

A total of 20 patients with pseudoexfoliation syndrome, 20 with pseudoexfoliation glaucoma, 20 with primary open-angle glaucoma, and 20 without pseudoexfoliation and glaucoma as a control group, who underwent cataract or glaucoma surgery between December 2020 and March 2021 in the Health Sciences University Beyoğlu Eye Training and Research Hospital, 80 patients were included in the study. Best corrected visual acuity (BCVA), intraocular pressure with applanation tonometry, detailed anterior and posterior segment examinations with biomicroscopy were performed in all patients included in the study. Approximately 0.1 cc of anterior chamber fluid was taken from all patients at the beginning of surgery. Total Oxidant Status (TOS) and Total Antioxidant Status (TAS) levels were measured by keeping the samples taken in the deep freezer of the cornea bank at -80 degrees, transferring them with cold chain transport rules, and examining them with automatic measurement method in the laboratories of the Medical Biochemistry Department of the University of Health Sciences. Oxidative Stress Index (OSI) value was calculated to measure the degree of oxidative stress.

RESULTS

TAS averages of the control and POAG groups were found to be statistically significantly higher than the PES and PEG groups (p = 0.0001, p = 0.0001). No significant difference was observed between the other groups (p > 0.05). The TOS averages of the control and POAG groups were found to be statistically significantly lower than the PES and PEG groups (p = 0.003, p = 0.0001; p = 0.01, p = 0.001), no statistically significant difference was observed between the other groups (p > 0.05). The OSI mean of the control and POAG groups was found to be statistically significantly lower than the PES and PEG groups (p = 0.001, p = 0.0001; p = 0.002, p = 0.0001), no statistically significant difference was observed between the other groups (p > 0.05).

CONCLUSION

Increased TOS and OSI and decreased TAS levels in the aqueous humour of patients with PES and PEG suggest that increased oxidative stress and decreased antioxidative defense system play a role in the etiopathogenesis of the disease.

Pseudoexfoliation syndrome: The critical role of the extracellular matrix in pathogenesis and treatment

Pseudoexfoliation syndrome (PEXS) is an age-related condition manifesting mainly in ocular tissues. PEXS is manifested through excess aggregation of fibrillary extracellular material at the anterior part of the eye that consists of a plethora of biomolecules, such as different proteoglycans (PGs) and glycosaminoglycans. PEXS is often linked to increased intraocular pressure, and can also lead to pseudoexfoliation glaucoma with very poor prognosis. Various stimuli are known to affect PEXS, including oxidation stress (OS), UV radiation and osmotic pressure. OS, is prominently involved on the progression of the syndrome as it promotes fibrogenesis, possibly via the induction of transforming growth factor-β (TGF-β) and other biomolecular effectors. In addition, PEXS initiation is tightly connected with the dysregulation of extracellular matrix (ECM) homeostasis since aberrant expression of ECM molecules is linked to both the accumulation and low degradation of pseudoexfoliation material. This article aims at uncovering the crucial role of various ECM effectors such as lysyl oxidase-like proteins, matrix metalloproteinases, and TGF-β1, as well as the biochemical pathways involved in the development and the progression of the PEXS.

An Assessment of Cataract Severity Based on Antioxidant Status and Ascorbic Acid Levels in Aqueous Humor

Cataract is the leading cause of blindness throughout the world. Currently, the cataract severity evaluation is based on the subjective LOCS III guideline. To ameliorate the evaluation system and develop an objective and quantitative analysis, we investigated the relationships among aqueous humor total antioxidant capacity (AqTAC), ascorbic acid (AqAA) concentration, and cataract severity. In this study, we enrolled 130 cataract patients who underwent phacoemulsification between April 2019 and March 2020. The AqTAC and AqAA were measured by our own developed TAC assay and commercially available kit. Cataract severity was recorded by nuclear opalescence (NO) and cortical cataract (CC) degree according to LOCS III. Cumulative dissipated energy (CDE) during phacoemulsification was recorded to verify the severity of the cataract. As a result, we found a moderate correlation between AqTAC and CDE (p < 0.001). In addition, we found AqTAC independently associated with the CDE when analyzed by multivariate linear regression (p < 0.001). AqTAC also negatively correlated to cataract severity when measured by NO and CC (p = 0.012 in NO grade 3 vs. grade 1; p = 0.012 in CC grade 2 vs. grade 1; p < 0.001 in CC grade 3 vs. grade 1). We further found AqAA provided 71.9 ± 13.5% of AqTAC, and showed a high correlation (rho = 0.79, p < 0.001). In conclusion, we found a significant correlation between AqTAC/AqAA and cataract severity measured by CDE. The correlation was superior to the correlation between LOCS III and CDE. Aqueous humor TAC owns the potential to assess cataracts in an objective and quantitative way.

Sectorwise analysis of peripapillary vessel density and retinal nerve fiber layer thickness in exfoliation syndrome

PURPOSE

This cross-sectional study compared the peripapillary vessel density and retinal nerve fiber layer (RNFL) thickness in patients with exfoliation syndrome (XFS) and healthy controls for evaluation of the early structural and vascular alterations in XFS.

METHODS

One eye was included from 75 patients with XFS and 54 healthy controls. The patients with XFS were matched the controls for age, intraocular pressure and axial length. The vascular density of the radial peripapillary capillaries (RPCs) and the peripapillary RNFL thickness were evaluated with optical coherence tomography angiography.

RESULTS

The mean peripapillary RNFL thicknesses of the groups were similar in all sectors (p > 0.05 for all). However, eyes with XFS demonstrated lower mean peripapillary vessel densities in all areas (p < 0.05 for all) except for the nasal sector (p = 0.68) compared to the controls. The gradual age correlated decline in the peripapillary RNFL thickness and the RPC vessel density observed in the healthy eyes was absent in XFS (r = - 0.14 p = 0.65 and r = - 0.23 p = 0.05).

CONCLUSIONS

Alterations in the peripapillary vascular density despite a preserved RNFL thickness in XFS supports the hypothesis that vascular alterations may precede structural alterations and have an important role in the pathogenesis of XFS. XFS may have different effects on the microvasculature of different peripapillary areas, with the nasal sector being mostly preserved.

Homeostatic alterations related to total antioxidant capacity, elemental concentrations and isotopic compositions in aqueous humor of glaucoma patients

Glaucoma is a multifactorial eye disease, characterized by progressive optic neurodegeneration. Elevation of the intraocular pressure is the main risk factor for glaucoma and is a consequence of an imbalance in the aqueous humor hydrodynamics, the physiology of which is influenced by the homeostatic equilibrium of essential elements, oxidative stress, and antioxidants. The aim of this work was to study local alterations in glaucomatous patients from two different, but connected, points of view: (i) the total antioxidant capacity (as an indicator of oxidative damage) and (ii) the concentration of mineral elements and their isotopic composition. Such objective was pursued using aqueous humor from patients diagnosed with pseudoexfoliation glaucoma (PEXG, n = 17) and primary open-angle glaucoma (POAG, n = 5) and age-matched control subjects (n = 16). The total antioxidant capacity (TAC) was examined in both aqueous humor and 60 serum samples (n = 20 controls, n = 20 for PEXG, and n = 20 for POAG), both showing higher TAC for the glaucoma population. The concentrations of the essential mineral elements (Cu, Fe, Mg, Na, P, and Zn) and the isotopic compositions of Cu and Zn were determined in aqueous humor using single-collector and multi-collector inductively coupled plasma–mass spectrometry, respectively. Significant differences were established for Mg and P levels when comparing the results for glaucomatous patients with those for the control population (p < 0.01 and p < 0.05 for Mg and P respectively, ANOVA and Kruskal-Wallis). The Zn isotopic composition was significantly shifted from that for the control population for PEXG patients. A significant difference in the isotopic composition of Zn was also established between the PEXG and POAG glaucoma cohorts.

Effects of French maritime pine bark/bilberry fruit extracts on intraocular pressure for primary open-angle glaucoma

We tested oral French maritime pine bark (40 mg)/bilberry fruit extract (90 mg) supplements for intraocular pressure-lowering effects in Japanese subjects with primary open-angle glaucoma. Eighteen subjects (29 eyes) were recruited with intraocular pressure of ≥15 mmHg who used one to three bottles of antiglaucoma medications. After a 2-week observation (period 1), subjects ingested a tablet/day of Sante^® Glagenox for 4 weeks (period 2). The mean intraocular pressure (17.2 ± 2.3 mmHg) decreased significantly to 15.7 ± 1.9 mmHg (8.7% reduction) at week 4 (p = 0.0046). The mean morning intraocular pressure (14.1 ± 3.1 mmHg) self-measured using the iCare HOME tonometer during period 1 decreased significantly to 13.3 ± 2.9 mmHg (5.7% reduction) during period 2 (p = 0.0291). Blood redox parameters, diacron reactive oxygen metabolites, biologic antioxidant potential, and sulfhydryl tests were unchanged after 4-week supplementation. Intra-subject comparisons, compared to period 1, showed pooled, self-measured, period-2 intraocular pressures was significantly lower in nine subjects (50%), unchanged in six subjects (33%), and elevated in three subjects (17%), suggesting some non-responders. Four-week supplementation with French maritime pine bark/bilberry fruit extracts can further reduce intraocular pressure even in Japanese patients with controlled primary open-angle glaucoma. Further study should confirm the intraocular pressure-lowering effects and mechanisms of this supplement in glaucoma management. The study was registered in UMIN (ID: UMIN000033200).

Electrolyte, Nitric Oxide and Oxidative Stress Levels of Aqueous Humor in Patients with Retinal Detachment and Silicone Oil Tamponade

Purpose: To enlighten the pathogenesis of silicone oil (SiO)-related complications via measuring aqueous humor levels of electrolytes, nitric oxide (NO), and oxidative stress in SiO, retinal detachment (RD), and control groups. Materials and Methods: In this prospective study, 56 patients were grouped as SiO (n = 29), RD (n = 12), and control (n = 15). The results of pre- and post-operative ophthalmological examinations, aqueous humor electrolyte and NO levels, total antioxidant and oxidant status (TAS, TOS) and oxidative stress index (OSI) were analyzed. Results: SiO group had a higher mean Na⁺ level compared to controls (144.77 ± 11.48 vs 137.56 ± 6.57 mmol/kg, p = .02). Also, the mean Na⁺ and Cl^- levels of RD group were higher than controls (149.04 ± 12.05 vs. 137.56 ± 6.57 mmol/kg, p = .02, 115.2 ± 7.79 vs 106.23 ± 8.99 mmol/kg, p = .031 for Na⁺ and Cl^-, respectively). The mean NO level of RD group was higher than that of SiO group (51.07 ± 19.56 vs. 34.07 ± 13.84 μM, p = .009). The mean TAS and TOS were lower in SiO group compared to controls (1.92 ± 0.64 vs. 2.49 ± 0.56 μmolTroloxEqv./L, p = .021, 34.98 ± 26.55 vs. 61.46 ± 22.69 μmolH₂O₂Eqv./L, p = .004 for TAS and TOS, respectively). Intraocular retention time of SiO demonstrated positive correlation with post-operative visual acuity (logMAR) and negative correlation with TOS. Conclusions: Elevated aqueous humor Na⁺ and Cl^- in RD patients might reflect abolished function of ion channels on detached retina. Increased Na⁺ and lack of NO response to elevated intraocular pressure in SiO-filled eyes might contribute to secondary cataract and glaucoma formation. SiO is associated with low levels of oxidative stress in aqueous humor; however, increased intraocular retention time of SiO is related to a poor visual outcome.

Mechanisms and Treatment of Light-Induced Retinal Degeneration-Associated Inflammation: Insights from Biochemical Profiling of the Aqueous Humor

Ocular inflammation contributes to the pathogenesis of blind-causing retinal degenerative diseases, such as age-related macular degeneration (AMD) or photic maculopathy. Here, we report on inflammatory mechanisms that are associated with retinal degeneration induced by bright visible light, which were revealed while using a rabbit model. Histologically and electrophysiologically noticeable degeneration of the retina is preceded and accompanied by oxidative stress and inflammation, as evidenced by granulocyte infiltration and edema in this tissue, as well as the upregulation of total protein, pro-inflammatory cytokines, and oxidative stress markers in aqueous humor (AH). Consistently, quantitative lipidomic studies of AH elucidated increase in the concentration of arachidonic (AA) and docosahexaenoic (DHA) acids and lyso-platelet activating factor (lyso-PAF), together with pronounced oxidative and inflammatory alterations in content of lipid mediators oxylipins. These alterations include long-term elevation of prostaglandins, which are synthesized from AA via cyclooxygenase-dependent pathways, as well as a short burst of linoleic acid derivatives that can be produced by both enzymatic and non-enzymatic free radical-dependent mechanisms. The upregulation of all oxylipins is inhibited by the premedication of the eyes while using mitochondria-targeted antioxidant SkQ1, whereas the accumulation of prostaglandins and lyso-PAF can be specifically suppressed by topical treatment with cyclooxygenase inhibitor Nepafenac. Interestingly, the most prominent antioxidant and anti-inflammatory benefits and overall retinal protective effects are achieved by simultaneous administrating of both drugs indicating their synergistic action. Taken together, these findings provide a rationale for using a combination of mitochondria-targeted antioxidant and cyclooxygenase inhibitor for the treatment of inflammatory components of retinal degenerative diseases.

Oxidative Stress Indexes for Diagnosis of Health or Disease in Humans

Oxidative stress (OS) is the imbalance between oxidant and antioxidant molecules, in favor of oxidants, that causes aging and disease. Many studies have been published that demonstrate the relationship between OS and human health and disease; however, the following questions arise: (i) how are we sure that the OS is present in a biological process? (ii) Is the OS reported in the different investigations equivalent? (iii) What are the best oxidant and antioxidant markers for OS diagnosis? (iv) Can we establish the types and the intensity of the OS? (v) Does OS index could be useful for research and/or application in clinical medicine? In this regard, several indexes have been proposed to measure OS in humans relative to the state of health and disease, among which the following can be highlighted: Oxidative Stress Index (OSI), Tiol Ratios (-SH/TT, -SS/-SH, and-SS/TT), Glutathione Ratio (GSSG/GSH), Oxidative Stress Score (OSS), and OXY-index. Therefore, the aim of this review is to present the state of the art of knowledge about OS indexes for diagnosis of health or disease in humans. We searched for articles in English or Spanish in the PubMed/MEDLINE and Scopus electronic databases published up until May 2019. The keywords used were “oxidative stress,” “index,” and “oxidative stress index.” It was identified 11479 records in both databases, and 490 articles were analyzed. Our review suggests that all indexes analyzed allow diagnose and differentiate the OS related to human health and disease. Also, the studies on OSI, Oxy-score, and OSS indexes have proven to be reliable, practical, and with clinical utility. However, it is necessary to continue with longitudinal studies, especially assess the usefulness of the indexes in the clinical prognosis, and make comparative studies between the different indexes.

The Association of Serum Vitamin D Levels with Pseudoexfoliation Glaucoma/Syndrome

Results:

PEX glaucoma group consisted of 17 males and 14 females, PEX syndrome group of 27 males and 7 females, and the control group of 27 males and 16 females. The mean age was 70.9±8.9 years, 72.1±7.3 years, and 67.9±9.1 years in PEX glaucoma, syndrome and control group, respectively. Mean vitamin D levels were 9.4±7.7 ng/mL, 7.9±6,1 ng/mL, 11.5±14.2 ng/mL in PEX glaucoma, syndrome and control group, respectively (p>0.05). The mean serum vitamin D level was 8.04±4.7 ng/mL in those who underwent glaucoma surgery and 10.1±8.7 ng/mL in those who didn't undergo glaucoma surgery in PEX glaucoma group (p>0.05). No difference was found between the PEX glaucoma subgroups in terms of the mean deviation when classified according to vitamin D levels (<10 ng/mL, ≥10 ng/mL) (p>0.05).

Conclusion:

Although we found no statistically significant difference between the PEX syndrome/ glaucoma, and control group in terms of serum vitamin D levels, serum vitamin D levels were lower in PEX syndrome and glaucoma group than control group. Our results indicate that serum vitamin D levels have no effect on the development of PEX glaucoma/syndrome or the control of the disorder in cases with PEX glaucoma. However, these results need to be supported with further studies on a larger number of patients and with longer follow-up.

The Association of Oxidative Stress Status with Open-Angle Glaucoma and Exfoliation Glaucoma: A Systematic Review and Meta-Analysis

Purpose

To systematically evaluate the associations between oxidative stress status and different types of glaucoma.

Design

Systematic review and meta-analysis.

Methods

We searched PubMed, EMBASE, and the Web of Science for randomized controlled trials written in the English language between January 1, 1990, and November 30, 2016. A random effects model was used to estimate oxidative stress status along with weighted mean differences and 95% confidence intervals (CIs). A funnel plot analysis and Egger's test were performed to assess potential publication bias.

Main outcome measures

Oxidative stress status was abnormal and different in patients with OAG (open-angle glaucoma) and EXG (exfoliation glaucoma).

Results

Blood TAS (total antioxidant status) was lower in the OAG group than in the control group, with a mean difference of 0.580 mmol/L (p < 0.0001, 95% CI = −0.668 to −0.492). The aqueous humor SOD (superoxide dismutase), GPX (glutathione peroxidase), and CAT (catalase) levels were higher in the OAG group than in the control group, with mean differences of 17.989 U/mL (p < 0.0001, 95% CI = 14.579–21.298), 12.441 U/mL (p < 0.0001, 95% CI = 10.423–14.459), and 1.229 fmol/mL (p=0.042, 95% CI = 0.043–2.414), respectively. Blood TAS was lower in the EXG group than in the control group, with a mean difference of 0.262 mmol/L (p < 0.0001, 95% CI = −0.393 to −0.132). However, there were no differences in blood TOS and aqueous humor TOS between the EXG group and the control group.

Conclusions

This meta-analysis indicates that OAG patients had a lower TAS in the blood and higher levels of SOD, GPX, and CAT in the aqueous humor, while EXG patients only had a decreased TAS in the blood.

The Evaluation of Ophthalmic Findings in Women Patients With Iron and Vitamin B12 Deficiency Anemia

Purpose

To determine whether there are differences in the central corneal thickness (CCT), retinal nerve fiber layer (RNFL), and ganglion cell-inner plexiform layer (GC-IPL) in women with iron deficiency anemia (IDA) and vitamin B12 deficiency anemia (B12DA).

Methods

The patients were divided and evaluated in three groups as IDA (group 1), combined IDA-B12DA (group 2), and healthy females (group 3). Each group constituted 35 subjects. CCT, endothelial cell density (CD), the coefficient of variation (CV), and hexagonality (HEX) values were evaluated. Superior, nasal, inferior, and temporal retinal nerve fiber analysis were done, and mean thickness of GC-IPL complex was also evaluated.

Results

CCT was found to be less (thin CCT) in group 2 as compared to group 1 and group 3 (P = 0.016 and P = 0.013, respectively). While CD measurements did not vary significantly between the groups, CV value was found to be lower in the control group as compared to that in the other groups (P = 0.001 and P = 0.002, respectively). HEX and the thicknesses of all RNFL and GC-IPL were lower in both the anemic groups as compared to the control group (P = 0.012 and P = 0.013, respectively); however, no significant difference was determined between the anemia groups.

Conclusions

It should be noted that anemia is a common clinical picture particularly seen in women, and there may be a tendency toward corneal and retinal disorders in these patients. The present study found that presence in the patients with IDA and with combined IDA-B12DA may have influenced endothelial functions; also the patients with anemia had significantly thinner CCT than healthy controls.

Translational Relevance

Optical coherence tomography and specular microscopy measurements may provide important data for early diagnosis and treatment of both corneal and retinal diseases according to the type of anemia in anemic women.

The Role of Diet in Glaucoma: A Review of the Current Evidence

Intraocular pressure (IOP) reduction by medications, laser, or surgery remains the mainstay of treatment in glaucoma. However, the role of complementary and alternative medicine (CAM) in glaucoma has received great interest from both patients and ophthalmologists. Previous evidence suggests that diet, a major domain of CAM, can influence an individual's IOP level. Furthermore, certain dietary components have been linked to the incidence and progression of glaucoma. In this review, we aim to provide a summary of the current evidence regarding the role of obesity, certain dietary components, and dietary supplements in glaucoma.

Association between systemic oxidative stress and visual field damage in open-angle glaucoma

Local and systemic oxidative stress in intraocular pressure (IOP) elevation and optic nerve damage may be involved in the pathogenesis of glaucoma. We reported previously that a lower level of systemic antioxidative capacity is associated with IOP elevation in open-angle glaucoma (OAG). We assessed the correlation between the visual field sensitivity value, i.e., mean deviation (MD), and systemic levels of prooxidants and antioxidants by analyzing the blood biochemistry in 202 patients with glaucoma. Serum levels of lipid peroxides, ferric-reducing activity, and thiol antioxidant activity were measured using the diacron reactive oxygen metabolite (dROM), biological antioxidant potential (BAP), and sulfhydryl (SH) tests, respectively, using a free-radical analyzer. Univariate and multivariate analyses suggested a positive correlation between MD and BAP (R = 0.005 and P = 0.0442 by a multiple regression model adjusted for seven demographic parameters), but no significant associations between the MD and the dROM (R = 0.002 and P = 0.8556) and SH tests (R = −0.001 and P = 0.8280). Use of more antiglaucoma medication and primary OAG rather than normal tension glaucoma also were associated significantly with worse visual field damage. This large and comprehensive assessment of the association between systemic redox status and visual field damage in OAG suggests that lower systemic antioxidant capacity measured by ferric-reducing activity is associated with more severe visual field damage in OAG that partly explained its roles in IOP elevation.

Oxidant/antioxidant balance in the aqueous humor of patients with glaucoma

AIM

To evaluate total antioxidant status (TAS), total oxidant status (TOS), and the oxidative stress index (OSI) of the aqueous humor (AH) in patients with glaucoma.

METHODS

The prospective study was composed of a study group (n=31) and a control group (n=31). Fifteen patients in the study group were diagnosed with primary open angle glaucoma (POAG), and 16 patients were diagnosed with pseudoexfoliation glaucoma (PEG). The control group was composed of non-glaucomatous patients with cataracts. AH samples were collected and analyzed for TAS, TOS, and OSI levels.

RESULTS

Mean AH TAS level was significantly higher in patients with glaucoma than that in the control group (P<0.01). Mean TOS and OSI levels tended to increase in patients with glaucoma. No significant differences in TAS, TOS, or OSI levels were observed between patients with POAG and PEG.

CONCLUSION

High levels of TAS were observed in patients with glaucoma, which was likely a response to the increased oxidative stress observed in these patients.

Correlation between Systemic Oxidative Stress and Intraocular Pressure Level

BACKGROUND

The involvement of local and systemic oxidative stress in intraocular pressure (IOP) elevation and optic nerve damage has been hypothesized in the pathogenesis of glaucoma. We reported previously that the level of systemic antioxidative capacity is lower in patients with open-angle glaucoma than controls without glaucoma. Here, we assessed the correlation between IOP and systemic levels of prooxidants and antioxidants by analyzing the blood biochemistry in patients with glaucoma.

METHODS

Peripheral blood samples were collected from Japanese patients with primary open-angle glaucoma (n = 206), exfoliation syndrome (n = 199), and controls (n = 126). Serum levels of lipid peroxides, ferric-reducing activity, and thiol antioxidant activity were measured by diacron reactive oxygen metabolite (dROM), biological antioxidant potential (BAP), and sulfhydryl (SH) tests, respectively, using a free radical analyzer. To test the possible effect of oxidative stress on IOP levels, the patients were classified into one of four groups (Q1, Q2, Q3, and Q4, with Q1 having the lowest IOP) based on the quartile value of IOP. For this classification, the known highest IOP value in both the right and left eyes was regarded as each subject's IOP. For comparisons among the IOP groups, the differences were calculated using one-way analysis of variance followed by post-hoc unpaired t-tests. To adjust for differences in demographic characteristic distributions, the dROM, BAP, and SH test values were compared among the IOP groups using multiple logistic regression analysis; the odds ratio (OR) of each variable was calculated with the Q1 group as the reference.

RESULTS

The dROM and the SH levels did not differ significantly (p = 0.6704 and p = 0.6376, respectively) among the four IOP groups. The BAP levels differed significantly (p = 0.0115) among the four IOP groups; the value was significantly lower in the Q4 group (1,932 μmol/L) compared with the Q1 (2,023 μmol/L, p = 0.0042) and Q2 (2,003 μmol/L, p = 0.0302) groups and significantly lower in the Q3 group (1,948 μmol/L) than the Q1 (p = 0.0174) group. After adjustment for differences in various demographic characteristics, lower BAP values were significantly associated with the classification into higher IOP groups (Q3 group, p = 0.0261 and OR = 0.06/range; Q4 group, p = 0.0018 and OR = 0.04/range). The dROM and SH values did not reach significance in any comparisons.

CONCLUSIONS

Lower systemic antioxidant capacity measured by ferric-reducing activity is involved in the pathogenesis of open-angle glaucoma via its roles in IOP elevation.

Update on pseudoexfoliation syndrome pathogenesis and associations with intraocular pressure, glaucoma and systemic diseases

PURPOSE OF REVIEW

Pseudoexfoliation (PEX) syndrome is a common age-related disorder affecting intraocular and extraocular tissues. This review focuses on recent publications related with the pathogenesis and associations of PEX syndrome with intraocular pressure (IOP), glaucoma and systemic diseases.

RECENT FINDINGS

In PEX tissues, expression of lysyl oxidase-like 1 (LOXL1) was found to be markedly dysregulated. This may adversely affect elastin metabolism and lead to elastotic alteration in tissues such as lamina cribrosa. There is increasing evidence that cellular stress conditions and low-grade chronic inflammatory processes are involved in the pathogenesis of PEX. Although there is an increased risk for glaucoma development in patients with PEX and ocular hypertension as compared with non-PEX patients with ocular hypertension, LOXL1 single nucleotide polymorphisms were not associated with intraocular pressure (IOP) differences. Lack of association of PEX with all-cause mortality or dementia has been reported recently. The association with vascular diseases is not consistent among different studies.

SUMMARY

Despite the high prevalence of the LOXL1 variants in the general population, a much lower proportion of the population develops PEX, suggesting that in addition to LOXL1, other genetic, epigenetic and environmental factors may contribute to the development of PEX. Also, LOXL1 cannot help to identify those with PEX at increased risk for glaucoma development. Increased risk for glaucoma development in PEX patients who present with increased IOP may be related to other factors beyond IOP, contributing to increased vulnerability of the optic nerve to glaucoma development in the presence of PEX.

Oxidative stress in dry age-related macular degeneration and exfoliation syndrome

Oxidative stress refers to cellular or molecular damage caused by reactive oxygen species, which especially occurs in age-related conditions as a result of an imbalance between the production of reactive oxygen species and the antioxidant defense response. Dry age-related macular degeneration (AMD) and exfoliation syndrome (XFS) are two common and complex age-related conditions that can cause irreversible vision loss. Two subtypes of AMD, which is the leading cause of blindness in the Western world, exist: the most prevalent dry type and the most severe wet type. Early dry AMD is characterized by formation of drusen, which are sub-retinal deposits, in the macular area and may progress to geographic atrophy with more dramatic manifestation. XFS is a systemic disorder of the extracellular matrix characterized by the accumulation of elastic fibrils that leads, in most cases, to glaucoma development with progressive and irreversible vision loss. Due to the aging population, the prevalence of these already-widespread conditions is increasing and is resulting in significant economic and psychological costs for individuals and for society. The exact composition of the abnormal drusen and XFS material as well as the mechanisms responsible for their production and accumulation still remain elusive, and consequently treatment for both diseases is lacking. However, recent epidemiologic, genetic and molecular studies support a major role for oxidative stress in both dry AMD and XFS development. Understanding the early molecular events in their pathogenesis and the exact role of oxidative stress may provide novel opportunities for therapeutic intervention for the prevention of progression to advanced disease.