Homocysteine and nitric oxide levels in plasma of patients with pseudoexfoliation syndrome, pseudoexfoliation glaucoma, and primary open-angle glaucoma

Aging of the skin in pseudoexfoliation syndrome

BACKGROUND

It was reported that pseudoexfoliative material deteriorates iris, brain, heart and lung functions. This material is also found in the skin.

AIMS

The purpose of this study was to investigate the possible effects of pseudoexfoliation material on the aging of the facial skin.

STUDY DESIGN

Cross-sectional study.

METHODS

Forty pseudoexfoliation syndrome (PES) cases and 40 age- and gender-matched controls were evaluated. Job, cigarette use and the presence of any systemic diseases as well as the duration of sun exposure for all the cases were recorded. All of the cases underwent facial skin examination with Wrinkle Assessment Scale as per Lemperle G et al. and Pinch Test.

RESULTS

Wrinkle Assessment Scale scores of the groups also were compared for all 8 facial locations. There were statistically significant differences found between Wrinkle Assessment Scale scores in PES and Control Group for all 8 locations. Mean Wrinkle Assessment Scale scores of women were 4.12 ± 0.74 in Control Group and 4.75 ± 0.37 in PES group (p = 0.0001). For men, mean Wrinkle Assessment Scale scores were 3.77 ± 0.72 in Control group and 4.54 ± 0.36 in PES group (p = 0.002).

CONCLUSION

These results implies that there is quicker progression in aging of facial skin in PES than normals.

Evaluating the impact of ocular UV exposure for the development for pseudoexfoliation syndrome in a South Indian population

CLINICAL RELEVANCE

Pathophysiology of pseudoexfoliation syndrome (XFS) can be influenced by environmental factors such as solar exposure/occupational factors and genetic factors.

BACKGROUND

The study aims to assess the association of lifetime ocular UV exposure and its impact on the risk of development of XFS.

METHODS

All eligible subjects underwent a comprehensive ocular examination. XFS was defined as precipitates on the pupillary border, cornea, and angle of anterior chamber or lens in at least one eye without any clinical signs of glaucoma. A standardised questionnaire was administered to assess the lifetime UV exposure. Conjunctival ultraviolet autofluorescence (CUVAF) photography was taken to detect the conjunctival changes with exposure to UV radiation. Ascorbic acid concentration in the aqueous humour was measured.

RESULTS

A total of 404 subjects of which 274 (controls) and 130 (XFS cases) were studied. There were 204 males (50.5%) and 200 females (49.5%).Lifetime UV exposure (OR: 1.14, 95% CI: 1.02-1.30, p: 0.032), CUVAF damage (OR: 1.03, 95% CI: 1.01-1.06, p: 0.008) and outdoor worker (OR: 1.87, 95% CI: 1.18-3.00, p: 0.008) were positively associated with XFS. Usage of spectacles (OR: 0.63, 95% CI: 0.39-0.95, p: 0.030) and ascorbic acid concentration in aqueous (OR: 0.47, 95% CI: 0.23-0.99, p: 0.038) were found to be protective against XFS.

CONCLUSION

Besides genetic factors, environmental factors such as lifetime ocular UV exposure and outdoor work are significantly associated with the risk of XFS. CUVAF can be used as a non-invasive tool to detect preclinical sun damage in outdoor workers.

Homocysteine and Glaucoma

Elevated levels of homocysteine (Hcy), a non-proteinogenic amino acid, may lead to a host of manifestations across the biological systems, particularly the nervous system. Defects in Hcy metabolism have been associated with many neurodegenerative diseases including glaucoma, i.e., the leading cause of blindness. However, the pathophysiology of elevated Hcy and its eligibility as a risk factor for glaucoma remain unclear. We aimed to provide a comprehensive review of the relationship between elevated Hcy levels and glaucoma. Through a systemic search of the PubMed and Google Scholar databases, we found that elevated Hcy might play an important role in the pathogenesis of glaucoma. Further research will be necessary to help clarify the specific contribution of elevated Hcy in the pathogenesis of glaucoma. A discovery and conceptual understanding of Hcy-associated glaucoma could be the keys to providing better therapeutic treatment, if not prophylactic treatment, for this disease.

Nutritional supplementation in the prevention and treatment of Glaucoma

Glaucoma is a chronic optic neuropathy that creates a significant burden on public health. Oxidative stress is hypothesised to play a role to glaucoma progression, and its reduction is being analysed as a therapeutic target. Dietary antioxidants play a crucial role in helping provide insight into this hypothesis. We reviewed 71 trials, interventional, I -vivo and I -vitro, including 11 randomised controlled trials, to determine if adjunctive nutritional supplementation could lead to a reduction in oxidative stress and prevent glaucomatous progression. Many laboratory findings show that vitamins and natural compounds contain an abundance of intrinsic antioxidative, neuroprotective and vasoprotective properties that show promise in the treatment and prevention of glaucoma. Although there is encouraging early evidence, most clincial findings are inconclusive. The group of B vitamins appear to have the greatest amount of evidence. Other compounds such as flavonoids, carotenoids, curcumin, saffron, CoQ10, Ggngko Biloba and Resveratrol however warrant further investigation in glaucoma patients. Studies of these antioxidants and other nutrients could create adjunctive or alternative preventative and treatment modalities for glaucoma to those currently available.

Evaluation of the optic nerve head vessel density in the patients with asymmetric pseudoexfoliative glaucoma: an OCT angiography study

PURPOSE

To evaluate vascular microcirculation changes of the optic nerve head (ONH) in the patients with asymmetric pseudoexfoliative glaucoma (XFG) using optical coherence tomography angiography (OCTA) and to compare vessel density (VD) results with healthy individuals.

METHODS

This prospective study enrolled 120 eyes in total. The eyes were divided into 3 groups: 40 glaucomatous and 40 non-glaucomatous fellow eyes without clinically pseudoexfoliation material (XFM) of patients with asymmetric XFG, and 40 healthy eyes as controls. The optic disc region was evaluated with OCTA (Optovue, Inc., Fremont, CA). VD was assessed as the ratio of the area formed by the vessels in 3 different regions: (1) inside disc; (2) in the peripapillary area defined as a 1-mm wide elliptical annulus around the disc; and (3) in the whole image defined as a 4-mm wide papillary region.

RESULTS

There were significant decreases in VD values of all regions in XFG eyes compared to fellow and control eyes (p < 0.05 for all comparisons). The mean VD values of peripapillary area and whole image were lower in the non-glaucomatous fellow eyes compared with control eyes (p = 0.011 and p = 0.015, respectively). The receiver operating characteristic analysis for differentiating fellow eyes from healthy eyes had highest area under the curve and sensitivity at 90% specificity for superior-hemi (0.811, 65.2%), followed by ppVD (0.775, 61.8%) and whole image (0.743, 55.9%).

CONCLUSIONS

OCTA as a novel imaging may be a valuable structural test in diagnosis and follow-up of glaucoma.

Comparison of the retinal nerve fiber layer and ganglion cell complex thickness in Korean patients with unilateral exfoliation syndrome and healthy subjects

Purpose

To compare retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness in patients with unilateral exfoliation syndrome (XFS) and age-matched controls using spectral domain-optical coherence tomography (SD-OCT).

Materials and methods

This prospective case–control study included 54 eyes (the XFS-affected and the fellow eyes) of 27 unilateral XFS patients and 27 eyes of 27 age-matched control subjects. The RNFL and GCC thicknesses were measured using SD-OCT (RT-Vue 100, Optovue, Fremont, CA) after pupillary dilation. RNFL and GCC thicknesses were compared between case and control groups.

Results

The mean age of XFS patients was 73.3 years and that of age-matched controls was 74.3 years. Both groups demonstrated a male preponderance. Superior RNFL thickness of XFS-affected eyes were significantly thinner than those of the healthy age-matched controls (P = 0.002 by ANOVA). There were no statistically significant differences in the RNFL thickness between both eyes of unilateral XFS patients. Moreover, superior GCC thickness of both eyes in unilateral XFS patients were thinner than those in controls (P = 0.002 by ANOVA).

Conclusions

Thinner RNFL and GCC thicknesses were observed in unilateral XFS patients without visual field defects. These findings imply that XFS itself might be a risk factor for development of glaucomatous optic disc and RNFL damage.

Role of Oxidative Stress in Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma

Objectives

To investigate the role of oxidative stress on pseudoexfoliation formation and progression from pseudoexfoliation syndrome (XFS) to pseudoexfoliation glaucoma (XFG).

Materials and Methods

This study investigated oxidative stress biomarkers in blood samples from 58 patients with XFG, 47 patients with XFS, and 134 healthy age- and sex-matched controls.

Results

The highest serum malondialdehyde (MDA) levels were measured in XFG patients (p<0.001), and MDA level was higher in XFS patients than controls (p<0.001). Superoxide dismutase (SOD) and catalase (CAT) enzyme activities were significantly lower in XFS and XFG patients than in the control group, whereas a significant increase was observed in glutathione (GSH) levels (p<0.001 for all). However, levels of these three biomarkers did not differ significantly between XFS and XFG patients (p=0.188, p=0.185, and p=0.733, respectively). Nitric oxide (NO) concentration was significantly lower in XFG patients compared to XFS patients and controls (p<0.001) but did not differ between XFS patients and controls (p=0.476).

Conclusion

Elevated MDA levels suggest that lipid peroxidation is important in XFS and XFG development and progression from XFS to XFG. In addition, reduction in SOD and CAT enzyme activities is considered a deficiency in the enzymatic antioxidant protection system. Furthermore, GSH values may be evaluated as a compensatory response to oxidative stress in XFS and XFG. Alterations in NO indicate the role of a vascular regulatory factor in the progression from XFS to glaucoma.

Homocysteine Levels in Plasma and Sensorineural Hearing Loss in Patients with Pseudoexfoliation Syndrome

PURPOSE

To determine the incidence and severity of hearing loss in different frequencies in patients with pseudoexfoliation. Furthermore, possible links between homocysteine and pseudoexfoliation were evaluated.

METHODS

Seventy-five consecutive patients with pseudoexfoliation and 75 sex- and age-matched subjects without pseudoexfoliation as control group were included in this prospective case-control study. Pure-tone audiometry was obtained in all subjects in both groups. Blood samples were obtained from 70 patients with pseudoexfoliation after overnight fasting for levels of homocysteine and analyzed by routine laboratory measurements.

RESULTS

Fifty-two (69%) patients with pseudoexfoliation and 39 (52%) controls had sensorineural hearing loss in speech frequencies. The difference between pseudoexfoliation and control group with regard to the frequency of sensorineural hearing loss in speech frequencies was statistically significant (p=0.03). No relationship was found between the degree of glaucomatous damage and hearing threshold variables in the patients with pseudoexfoliation glaucoma. Plasma homocysteine levels showed no significant difference when patients with pseudoexfoliation and hearing loss were compared with patients with pseudoexfoliation and normal hearing threshold (p=0.5). Hyperhomocysteinemia was found in 58% (29/50) of pseudoexfoliation patients with hearing loss, and 55 % (11/20) of pseudoexfoliation patients with normal hearing threshold (p=0.8). No statistically significant correlation was found between plasma homocysteine and hearing loss in patients with pseudoexfoliation.

CONCLUSIONS

These findings suggest an association between sensorineural hearing loss and pseudoexfoliation in patients with pseudoexfoliation and glaucoma. The severity of hearing loss was not correlated with the degree of glaucomatous damage. There is no association between increased homocysteine levels and hearing loss in patients with pseudoexfoliation.

[Pseudoexfoliation syndrome and pseudoexfoliation glaucoma]

Pseudoexfoliation syndrome is an age-related systemic disease that mainly affects the anterior structures of the eye. Despite a worldwide distribution, reported incidence and prevalence of this syndrome vary widely between ethnicities and geographical areas. The exfoliative material is composed mainly of abnormal cross-linked fibrils that accumulate progressively in some organs such as the heart, blood vessels, lungs or meninges, and particularly in the anterior structures of the eye. The exact pathophysiological process still remains unclear but the association of genetic and environmental factors are thought to play a role in the development and progressive extracellular accumulation of exfoliative material. Hence, LOXL1 gene polymorphisms, responsible for metabolism of some components of elastic fibers and extracellular matrix, and increased natural exposure to ambient ultraviolet or caffeine consumption have been associated with pseudoexfoliation syndrome. Ophthalmological manifestations are commonly bilateral with an asymmetric presentation and can lead to severe visual impairment and blindness more frequently than in the general population, mainly related to glaucoma and cataract. Pseudoexfoliation glaucoma is a major complication of pseudoexfoliation syndrome and represents the main cause of identifiable glaucoma worldwide. Visual field progression is more rapid than that observed in primary open angle glaucoma, and filtering surgery is more frequently required. Nuclear cataract is more frequent and occurs earlier than in the general population. Owing to poorer pupil dilation and increased zonular instability, cataract surgery with pseudoexfoliation is associated with a 5- to 10-fold increase in surgical complications compared to cataract surgery without pseudoexfoliation. Some specific treatments targeting production, formation or accumulation of exfoliative material could improve the prognosis of this syndrome.

Ocular Pseudoexfoliation Syndrome Linkage to Cardiovascular Disease

PURPOSE OF REVIEW

Pseudoexfoliation syndrome (PEX) is a common cause of open-angle glaucoma that is characterized by stress-induced elastic microfibrillopathy related to an accumulation of matrix metalloproteinases. The accumulation of matrix metalloproteinases increases deposition of protein substance within ocular structures and other organs including the heart. Many studies have associated the presence of cardiovascular disease with pseudoexfoliation syndrome, but much debate exists between studies in terms of significant relationships. The following meta-analysis aims to relate pseudoexfoliation syndrome with certain cardiovascular events and disorders. A thorough literature review was performed to acquire information concerning PEX patients with certain cardiovascular disorders. Diseases considered included myocardial infarction, ischemic heart disease, angina, congestive heart failure, cardiomyopathy, aortic aneurysm, hypertension, and homocystinuria. Patients without evidence of pseudoexfoliation disease were the controls of our study. Multiple forest plots were created to compile and analyze collected data for statistical comparison.

RECENT FINDINGS

From a literature review, 18 studies were selected for our analysis. Cardiovascular disorders that had a statistically significant association (within a 95 % confidence interval) with PEX included ischemic heart disease, aortic aneurysms, and homocystinuria. The association between ischemic heart disease and PEX was statistically significant (p = 0.045). Myocardial infarction, chronic ischemic heart disease, angina, and hypertension did not show a correlation of relationship with the presence of pseudoexfoliation. Patients with PEX are prone to present with ischemic heart disease in addition to abdominal aortic aneurysms and homocystinuria. Patients that present with PEX should be screened for these detrimental cardiovascular disorders.

Nailfold capillary morphology in exfoliation syndrome

PurposeThe purpose of the study was to investigate nailfold microvascular morphology in exfoliation syndrome with or without glaucoma (XFS/XFG) compared with primary open-angle glaucoma (POAG) and control subjects using nailfold capillary videomicroscopy.Patients and methodsWe used a JH-1004 capillaroscope to perform nailfold capillary videomicroscopy on the fourth and fifth digit of the non-dominant hand. We enrolled 56 XFS/XFG patients, 87 POAG patients, and 75 control subjects. Masked observers graded the videos for hemorrhages, avascular zones ≥200 microns (μm), and degree of microvascular tortuosity on a four-point subjective scale. Multivariable odds ratios, 95% confidence intervals and P-for trends for assessing the relation between morphological changes and POAG or XFS/XFG were obtained from logistic regression analyses. We also assessed this relation with XFS/XFG compared with POAG in multivariable models.ResultsAfter adjusting for multiple covariates, nailfold hemorrhages, avascular zones ≥200 μm, and higher degree of vascular tortuosity were more common in XFS/XFG vs controls (P-for trend ≤0.0001) and in POAG vs controls (P-for trend ≤0.01). For each 100 capillaries, the number of hemorrhages was similar (P-for trend=0.91) between XFS/XFG and POAG patients; however, there were more avascular zones per 100 capillaries with borderline significance (P-for trend=0.04) in the XFS/XFG group. XFS/XFG patients had more tortuosity than POAG patients; specifically, having a tortuosity score ≥1.5 was associated with a 4.4-fold increased odds of XFS/XFG (95% confidence interval: 1.5-13.3) relative to a tortuosity score <1.0 (P-for trend=0.005).ConclusionA high degree of nailfold capillary tortuosity is a distinct non-ocular feature associated with XFS/XFG compared with either POAG or controls.

Hereditary Thrombophilic Factors in Glaucoma

PURPOSE

To evaluate the hereditary thrombophilic factors in patients with primary open-angle glaucoma, exfoliative glaucoma, and exfoliation syndrome and to compare their results with those of healthy control subjects.

MATERIALS AND METHODS

The study included 75 patients [25 patients with primary open-angle glaucoma (group I), 25 patients with exfoliative glaucoma (group II), and 25 patients with exfoliation syndrome (group III)] and 25 healthy control subjects (group IV). Well-known hereditary thrombophilic factors including methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation, prothrombin G20210A mutation, factor V Leiden mutation, activated protein C resistance, protein S, protein C, and antithrombin III activities, and homocysteine levels were measured in venous blood samples of all subjects.

RESULTS

Fifty-one males and 49 females were included in the study. The mean age of the patients was 67.8 ± 8.7 years (range, 46 to 87 y). There was no statistically significant difference with regard to the mean age (P=0.057) and distribution of sex (P=0.391) between the study groups. The difference of homocysteine, folate, vitamin B12, antithrombin III activity, protein C activity, free protein S activity, and activated protein C resistance were not statistically significant; and the number of subjects with MTHFR C677T, prothrombin G20210A, and factor V Leiden mutations were similar between the study groups.

CONCLUSION

Our results suggest that there is no significant difference between the prothrombotic inherited risk factors of glaucomatous and nonglaucomatous subjects.

Systemic Associations of Exfoliation Syndrome

Exfoliation syndrome (XFS) is an age-related disease characterized by the production, deposition, and progressive accumulation of a white, fibrillar, extracellular material in many ocular tissues, most prominent on the anterior lens surface and pupillary border. Its prevalence increases steadily with age in all populations. It is the most common identifiable cause of open-angle glaucoma worldwide and is a potentially reversible or even curable disease. First described in Finland in 1917 by Lindberg, it has long been associated with open-angle glaucoma. However, in recent years, it is being increasingly reported in conjunction with a multiplicity of both ocular and systemic disorders, and the number of these is expected to grow, particularly with investigations based on attempts to associate other diseases with those genes known to be associated with XFS. Despite the focus on XFS as a cause of open-angle glaucoma for nearly a century, in reality it is still only an ocular manifestation of a protean systemic disease. It is a unique disorder with extensive and often serious ocular and systemic manifestations and not, as it has long been termed, a "form" or "type" of glaucoma. This misconception has delayed research into the molecular and cellular processes involved in its development, and the underestimation of its overall importance and its underlying causative mechanisms have largely been long ignored. The purpose of this article is to review the systemic disorders which are becoming increasingly associated with XFS. Reviews of epidemiology, genetics, biomarkers, molecular mechanisms of development, and ocular findings may be found elsewhere.

Exfoliation syndrome: a disease with an environmental component

PURPOSE OF REVIEW

Exfoliation syndrome (XFS), the most common cause of secondary open angle glaucoma, is associated with significant ocular morbidity. Recent studies have pointed toward environmental components that may alter the risk of XFS development. This review focuses on the recent studies elucidating the role of environmental factors that play a role in the development of exfoliation syndrome.

RECENT FINDINGS

In XFS, aberrant microfibril formation emanating from the cell-extracellular matrix interface admixes with other macromolecules and is cross-linked by lysyl oxidase like 1 (LOXL1) activity. A common gene variant in the LOXL1 enzyme, an enzyme critical for enhancing the tensile strength of collagen and elastin in extracellular matrices, has been found in approximately 90% of XFS cases. However, approximately 80% of controls also have disease-associated LOXL1 gene variants. These findings point toward other nongenetic factors influencing the development of XFS. Increasing latitude, solar radiation, climatic variables and dietary factors such as high coffee consumption and low dietary folate intake are among the nongenetic factors associated with increased risk of XFS.

SUMMARY

A greater understanding of the environmental components associated with XFS may lead to lifestyle preventive strategies to ameliorate disease burden.

Plasma homocysteine and genetic variants of homocysteine metabolism enzymes in patients from central Greece with primary open-angle glaucoma and pseudoexfoliation glaucoma

BACKGROUND

The purpose of this study was to investigate plasma homocysteine levels and polymorphisms in genes encoding enzymes in the metabolic pathway of homocysteine in association with primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXFG).

METHODS

A total of 156 glaucoma patients (76 with POAG and 80 with PXFG) and 135 controls matched for age and sex were enrolled in this study. Plasma homocysteine levels were measured using a commercially available enzyme-linked immunosorbent assay kit. DNA was extracted from peripheral blood leukocytes and real-time polymerase chain reaction was performed for genotyping of the samples. Patients were genotyped using predesigned TaqMan(®) single nucleotide polymorphism genotyping assays for two exon variations (rs1801131, rs1801133) in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene and one intron variation (rs8006686) in the methylenetetrahydrofolate dehydrogenase (MTHFD1) gene.

RESULTS

Homocysteine levels were slightly higher in the patient group (POAG and PXFG) compared with controls, but the difference did not reach statistical significance. The minor alleles of the MTHFR single nucleotide polymorphisms showed a protective effect for POAG and showed an increased risk for PXFG, but none of these associations reached statistical significance (P>0.05). The minor allele of MTHFD1 rs8006686 showed a trend for increased risk of both POAG and PXFG (P>0.05). No statistically significant interaction was seen between the genetic variants and homocysteine levels (P>0.05).

CONCLUSION

Our results show that neither the examined single nucleotide polymorphisms from genes involved in the pathway of homocysteine metabolism nor the measured homocysteine levels were associated with POAG or PXFG in our study cohort.

Pseudoexfoliation syndrome and cardiovascular diseases

Pseudoexfoliation (PEX) syndrome is a well-recognized late-onset disease caused by a generalized fibrillopathy. It is linked to a broad spectrum of ocular complications including glaucoma and perioperative problems during cataract surgery. Apart from the long-known intraocular manifestations, PEX deposits have been found in a variety of extraocular locations and they appear to represent a systemic process associated with increased cardiovascular and cerebrovascular morbidity. However, as published results are inconsistent, the clinical significance of the extraocular PEX deposits remains controversial. Identification of PEX deposits in the heart and the vessel wall, epidemiologic studies, as well as, similarities in pathogenetic mechanisms have led to the hypothesis of a possible relation between fibrillar material and cardiovascular disease. Recent studies suggest that PEX syndrome is frequently linked to impaired heart and blood vessels function. Systemic and ocular blood flow changes, altered parasympathetic vascular control and baroreflex sensitivity, increased vascular resistance and decreased blood flow velocity, arterial endothelial dysfunction, high levels of plasma homocysteine and arterial hypertension have all been demonstrated in PEX subjects. Common features in the pathogenesis of both atherosclerosis and PEX, like oxidative stress and inflammation and a possible higher frequency of abdominal aorta aneurysm in PEX patients, could imply that these grey-white deposits and cardiovascular disorders are related or reflect different manifestations of the same process.

A prospective study of folate, vitamin B₆, and vitamin B₁₂ intake in relation to exfoliation glaucoma or suspected exfoliation glaucoma

IMPORTANCE

Effective strategies for primary prevention are lacking for exfoliation glaucoma (EG), which is the most common type of secondary glaucoma.

OBJECTIVE

To examine the association between B vitamin intake and EG or suspected EG (EG/SEG) risk.

DESIGN, SETTING, AND PARTICIPANTS

National prospective cohort study using more than 20 years of follow-up data from the Nurses' Health Study (all female registered nurses) and the Health Professionals Follow-up Study (all male health professionals) from June 1, 1980, to May 31, 2010 (Nurses' Health Study) and January 1, 1986, to December 31, 2010 (Health Professionals Follow-up Study). We included a subset of 78,980 Nurses' Health Study women and 41,221 Health Professionals Follow-up Study men who were 40 years or older, free of glaucoma, had completed diet questionnaires, and reported eye examinations (follow-up rate, >85%).

EXPOSURES

Cumulatively updated intake of B vitamins (folate, vitamin B6, and vitamin B12) as ascertained by repeated administration of validated questionnaires.

MAIN OUTCOMES AND MEASURES

Incident cases of EG/SEG, totaling 399 (329 women and 70 men), were first identified with the questionnaires and were subsequently confirmed with medical records. Multivariable relative risks for EG/SEG were calculated in each cohort and then pooled with meta-analysis.

RESULTS

Vitamin B₆ and vitamin B₁₂ intake was not associated with EG/SEG risk in pooled analyses (P = .52 and P = .99 for linear trend, respectively). However, a suggestive trend of a reduced risk was observed with higher intake of folate: compared with the lowest quintile of cumulatively averaged updated total folate intake, the multivariable relative risk for EG/SEG for the highest quintile (≥654 μg/d) was 0.75 (95% CI, 0.54-1.04; P = .02 for linear trend). These results were not materially altered after adjustment for vitamin B₆ and vitamin B₁₂ intake. An association was observed for supplemental folate intake but not for dietary folate only (P = .03 and P = .64 for linear trend, respectively). Greater frequency of multivitamin use showed a modest suggestive inverse association (current multivitamin use of ≥6 times per week vs nonuse multivariable relative risk, 0.84; 95% CI, 0.64-1.11; P = .06 for linear trend).

CONCLUSIONS AND RELEVANCE

Higher total folate intake was associated with a suggestive lower risk for EG/SEG, supporting a possible causal role of homocysteine in EG/SEG.

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

PURPOSE

To establish the total oxidant status (TOS), total antioxidant capacity (TAC) and oxidative stress index (OSI) of the aqueous humour in patients presenting exfoliation syndrome (EXS) without glaucoma.

METHODS

The TOS, TAC and OSI of the aqueous humour of patients with EXS (group 1, n = 17) and patients without EXS (group 2, n = 25) who underwent cataract surgery were evaluated. Samples were measured spectrophotometrically using a colourimetric method. The Mann-Whitney U, independent-samples t tests, Pearson correlation and analysis of covariance tests were used in the statistical analyses.

RESULTS

The mean TOS in group 1 and 2 patients was 57.6 ± 32.4 and 30.4 ± 22.6 mmol/L, respectively, which is a statistically significant difference (p = 0.001). The mean TAC level in group 1 and 2 patients was 2.3 ± 0.7 and 2.5 ± 0.7 mmol/L, respectively, and although TAC was decreased in group 1 relative to group 2, the difference was not statistically significant (p = 0.55). The mean OSI in group 1 and 2 patients was 27.4 ± 17.1 and 12.5 ± 8.3 mmol/L, respectively, with the mean OSI level statistically higher in group 1 (p = 0.03).

CONCLUSION

Our findings provide evidence that the aqueous humour of EXS patients is characterised by increased oxidative stress and a disturbed oxidant/antioxidant balance. The increased oxidative stress and decreased levels of antioxidants in ocular fluids of EXS patients may play a significant role in the pathogenesis and complications of EXS.

The role of the cytokines in the pathogenesis of pseudoexfoliation syndrome

AIM

To examine the mechanism of the development of pseudoexfoliation (PSX) syndrome via both cytokine formation and endothelial vasorelaxing and growth factors that will provide us new therapeutic insights for the treatment.

METHODS

This is a cross sectional study included two groups; Group 1: control patients with nuclear cataract (n=20, aged 51-80 years). Group 2: PSX patients with nuclear cataract (n=18, aged 50-90 years). Patients with other ophthalmic problems and systemic diseases were excluded. Vascular endothelial growth factor (VEGF), interleukin-6 (IL-6) and interleukin-1β (IL-1β) and nitrotyrosine levels were determined through serum samples by Enzyme-linked immunosorbent assay (ELISA) method. Nitrite-nitrate levels were measured with photometric endpoint determination.

RESULTS

There were no significant differences between the groups in terms of age, VEGF, IL-1β, nitrite-nitrate and nitrotyrosine. The significant results were the mean IL-6 levels that were higher in PSX group 2 (37.68±29.52 pg/mL) compared to that in control group 1 (15.32±10.08 pg/mL) (P<0.001).

CONCLUSION

Several interacting and extending biochemical pathways may lead to the promotion of VEGF and IL-6 expressions. IL-6 which is the only altered marker in our study may indirectly cause an increase of vascular permeability and neovascularization. We suggest inflammation as a factor that can be involved in etiopathogenesis of PSX.

High-sensitivity C-reactive Protein and Tumor Necrosis Factor Alpha in Pseudoexfoliation Syndrome

OBJECTIVES

The purpose of the present study was to determine the alterations in high-sensitivity C-reactive protein and Tumor Necrosis factor alpha levels in the blood serum of pseudoexfoliation syndrome cases (a disease with similar risk factors as systemic endothelial dysfunction diseases) and to compare the results with healthy individuals.

METHODS

High-sensitivity C-reactive protein and Tumor Necrosis factor alpha levels were determined in 30 cases with pseudoexfoliation syndrome and in 30 control patients of the same age and sex, by enzyme-linked immunosorbent assay.

RESULTS

The levels of high- sensitivity C-reactive protein and Tumor Necrosis factor alpha in the blood serum of patients with pseudoexfoliation syndrome (3.95±0.88 mg/l, 3.32±0.99 pg/ml, respectively) were significantly higher than in the control group (2.51±0.79mg/l, 0.43±0.15 pg/ml, respectively) p=0.001, p=0.002.

CONCLUSION

The results suggest that increased levels of high- sensitivity C-reactive protein and Tumor Necrosis factor alpha, as markers of inflammation and peripheral endothelial dysfunction in pseudoexfoliation syndrome, may be risk factors for systemic and ocular manifestations of pseudoexfoliation syndrome.

The Relationship between caffeine and coffee consumption and exfoliation glaucoma or glaucoma suspect: a prospective study in two cohorts

PURPOSE

We examined the association between caffeine and caffeinated beverage consumption in relation to the risk of exfoliation glaucoma or exfoliation glaucoma suspect (EG/EGS).

METHODS

We followed 78,977 women from the Nurses' Health Study (NHS) and 41,202 men from the Health Professionals Follow-up Study (HPFS) who were at least 40 years of age, did not have glaucoma, and reported undergoing eye examinations from 1980 (NHS) or 1986 (HPFS) to 2008. Information on consumption of caffeine-containing beverages and potential confounders were repeatedly ascertained in validated follow-up questionnaires. Confirmation with medical record review revealed 360 incident EG/EGS cases. Multivariate rate ratios (RRs) for EG/EGS were calculated in each cohort and then pooled using meta-analytic techniques.

RESULTS

Compared with participants whose cumulatively updated total caffeine consumption was <125 mg/day, participants who consumed ≥ 500 mg/day had a trend toward increased risk of EG/EGS that was not statistically significant (RR = 1.43; 95% confidence interval [CI], 0.98-2.08); P trend = 0.06). Compared to abstainers, those who drank ≥ 3 cups of caffeinated coffee daily were at increased risk of EG/EGS (RR = 1.66; 95% CI, 1.09-2.54; P trend = 0.02). These results were not materially altered after adjustment for total fluid intake. Associations were stronger among women with a family history of glaucoma (P interaction = 0.06 for coffee; P interaction = 0.03 for caffeine). We did not find associations with consumption of other caffeinated products (caffeinated soda, caffeinated tea, decaffeinated coffee or chocolate) and risk of EG/EGS (P trend ≥ 0.31).

CONCLUSIONS

We observed a positive association between heavier coffee consumption with risk of EG/EGS in this large prospective study.

Association of ocular pseudoexfoliation syndrome with ischaemic heart disease, arterial hypertension and diabetes mellitus

PURPOSE

To determine the prevalence of pseudoexfoliation syndrome (PEX) in Lithuanian urban population and its association with ischaemic heart disease (IHD), arterial hypertension (AH) and diabetes mellitus (DM).

METHODS

In this population-based study, 1065 participants aged 45-72 years were randomly drawn from the population register of Kaunas, Lithuania. They were classified as having PEX if any pseudoexfoliation material was determined by a slit-lamp examination in at least one eye. The data were acquired from questionnaire; register of myocardial infarction, electrocardiogram, biochemical blood analyses and blood pressure measurement were used to determine IHD, AH, DM and smoking habits. Poststratification weights based on Kaunas population sex and age distribution were applied.

RESULTS

Pseudoexfoliation syndrome was estimated in 9% of a population. The AH rate was higher in PEX subjects than in non-PEX subjects (p=0.017) and the rates of IHD, DM and cholesterol levels did not differ statistically significantly. Chi-square linear-by-linear association test found higher AH rate in unilateral PEX subjects and even higher AH rate in bilateral PEX subjects than in non-PEX subjects (p=0.014). Pseudoexfoliation syndrome increased odds for AH by 1.8 times (p=0.021). Median of systolic blood pressure was higher in the PEX group than in non-PEX group (p=0.04). But all associations could not be confirmed after adjusting for age. Smoking duration increased age-adjusted odds for PEX. Pseudoexfoliation syndrome did not increase risk for IHD, AH or DM.

CONCLUSIONS

Pseudoexfoliation syndrome prevalence is high in Lithuania. No clear PEX association with IHD, AH and DM was proven after controlling for effect of age.

Antioxidant status and oxidative stress in primary open angle glaucoma and pseudoexfoliative glaucoma

PURPOSE

The aim of this study was to establish the antioxidant status and oxidative stress in patients with primary open-angle glaucoma (POAG) and pseudoexfoliative glaucoma (PEG).

METHODS

Serum levels of total antioxidant capacity (TAC) and superoxide dismutase (SOD) as indicators of antioxidant status; and total oxidant status (TOS), nitric oxide (NO), protein carbonyl (PC), and malondialdehyde (MDA) as indicators of oxidative stress were measured from the blood samples of patients with POAG (n = 23), PEG (n = 24) and healthy control subjects (n = 19) by spectrophotometry.

RESULTS

Mean TAC level was 0.6 ± 0.1 mmol/L in the POAG group; 0.5 ± 0.1 mmol/L in the PEG group and 1.2 ± 0.3 mmol/L in the control group (p = 0.001). Mean SOD level was 13 ± 0.5 mg/L in the POAG group, 11.6 ± 0.2 mg/L in the PEG group and 9.4 ± 0.6 mg/L in the control group (p = 0.001). Mean TOS level was 19.6 ± 2.6 μmol/L in the POAG group, 21.2 ± 4.2 μmol/L in the PEG group and 15.1 ± 7 μmol/L in the control group (p = 0.001). Mean NO level was 74.3 ± 14.4 µmol/L in the POAG group, 66.1 ± 8.1 µmol/L in the PEG group and 62.3 ± 13.5 µmol/L in the control group (p = 0.005). Mean PC level was 641.5 ± 102.5 nmol/mg in the POAG group, 988.3 ± 214.7 nmol/mg in the PEG group and 654.4 ± 150.7 nmol/mg in the control group (p = 0.001). Mean MDA level was 1.9 ± 0.2 µmol/L in the POAG group, 1.7 ± 0.4 µmol/L in the PEG group and 1.1 ± 0.2 µmol/L in the control group (p = 0.001).

CONCLUSION

The findings of the present study are potentially of significance and add to the growing body of evidence for oxidative stress in POAG and PEG. Decreased antioxidant defense and increased oxidative stress system may play an important role in the pathogenesis of POAG and PEG.

Geographic and climatic factors associated with exfoliation syndrome

OBJECTIVE

To identify geographic and climatic risk factors associated with exfoliation syndrome (ES).

METHODS

A retrospective study of 626 901 eye care recipients, dating from 2001 to 2007 from 47 US states in a managed care network. Incident ES cases-patients (N = 3367) were identified by using billing codes. We assessed the risk of ES by geographic latitude tier in the continental United States and assigned state-level climatic data (eg, ambient temperature, elevation, and sun exposure) according to patients' residential location. The hazard of ES was calculated by using multivariable-adjusted Cox proportional hazards regression models.

RESULTS

Compared with middle-tier residence, northern-tier residence (above 42°N) was associated with an increased hazard of ES (adjusted hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.94-2.35). Southern-tier (below 37°N) was associated with a reduced hazard of ES (HR, 0.83; 95% CI, 0.75-0.93). Excluding whites did not change these associations. After adjustment for joint environmental effects, for every 1° increase in July high temperature, the hazard of ES decreased by 9% (HR, 0.91; 95% CI, 0.89-0.93); for every 1° increase in January low temperature, the hazard decreased 3% (0.97; 0.96-0.98). For each additional sunny day annually, the hazard increased by 1.5% (HR, 1.02; 95% CI, 1.01-1.02) in locations with average levels of other climatic factors.

CONCLUSION

Ambient temperature and sun exposure may be important environmental triggers of ES.

Endothelin-1 and nitric oxide levels in patients with glaucoma

AIMS

To investigate the levels of endothelin-1 (ET-1) and nitric oxide (NO) in the aqueous humor and plasma of human eyes with different types of glaucoma: primary open-angle glaucoma (POAG) and chronic closed-angle glaucoma (CCAG).

METHODS

Patients were classified into 3 groups: group I comprised 35 patients with POAG, group II comprised 25 patients with CCAG, and 30 patients with senile cataract (group III) were used as a control group. Aqueous humor and corresponding plasma were analyzed for ET-1 and NO concentrations by enzyme-linked immunosorbent assay. A Bonferroni correction for multiple comparisons was performed.

RESULTS

There was no significant difference in plasma levels of either ET-1 or NO metabolites between the groups studied. ET-1 and NO were significantly elevated in the aqueous humor of patients with CCAG and POAG compared to the corresponding value in patients with cataract (p < 0.001). ET-1 and NO concentrations in the aqueous humor were more marked in CCAG than in POAG. NO levels were correlated with ET-1 in the aqueous humor of patients with glaucoma (p < 0.001).

CONCLUSIONS

Increased concentrations of ET-1 and NO in aqueous humor may be useful with POAG and CCAG. In addition, ET-1 and NO may have useful metabolite levels in the aqueous humor of POAG and CCAG patients as a result of glaucoma damage and may not be a cause of it.

Aqueous humor and plasma levels of vascular endothelial growth factor and nitric oxide in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma

PURPOSE

To investigate levels of vascular endothelial growth factor (VEGF) and nitric oxide (NO) in the aqueous humor and plasma of patients with pseudoexfoliation syndrome (PXS) and pseudoexfoliation glaucoma (PXG), compared with controls.

METHODS

This prospective study involved 37 patients with PXS, 15 with PXG, and 32 control subjects in whom cataract surgery was indicated. Aqueous humor and plasma VEGF and NO levels were measured with enzyme-linked immunosorbent assay and chemiluminescence methods, respectively.

RESULTS

Aqueous humor and plasma VEGF concentrations were higher in patients with PXS and PXG than in controls (P<0.001). Aqueous humor NO concentrations were higher in patients with PXS and PXG than in controls (P<0.05 and P=0.001, respectively). Plasma NO concentrations did not differ between the 3 groups. Aqueous humor and plasma VEGF and NO levels were not significantly different in patients with PXS versus PXG. VEGF and NO levels showed no significant correlation among the 3 groups (P>0.05).

CONCLUSIONS

Elevated aqueous humor VEGF and NO levels and plasma VEGF concentrations in eyes with PXS and PXG can be explained by the ischemic nature of these disorders. The lack of correlation between VEGF and NO levels may indicate impaired downregulation, which may have a role in the progression to PXG.

Systemic high-sensitivity C-reactive protein level in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

PURPOSE

To evaluate the systemic high sensitivity C-reactive protein (hsCRP) levels in patients with pseudoexfoliation syndrome (XFS) and pseudoexfoliation glaucoma (XFG).

MATERIALS AND METHODS

We prospectively examined 31 patients with XFS, 26 with XFG, and 25 controls. To the study patients with the exclusion of serious hypertension that do not have any cardiovascular and cerebrovascular disease and that diagnosed as XFS and XFG have been included. Each patient passed through a detailed blood sampling including hsCRP, biochemistry, and lipid profile. Plasma C-reactive protein (CRP) levels were measured with nephelometric method by using Beckman IMMAGE hsCRP reagent.

RESULTS

Each group had similar demographic parameters including age, sex, body mass index, heart rate, and blood pressure. When we compared with controls, there was no statistically significant difference in the hsCRP and biochemistry results between the 3 groups. When all patients with pseudoexfoliation (PEX) compared with controls there was no difference.

CONCLUSIONS

Our findings indicated no difference in the hsCRP level between XFS, XFG, and controls. This study suggests that CRP is not a predictive marker of inflammation and peripheral endothelial dysfunction in XFS, which is accepted as a systemic disorder.

Levels of plasma homocysteine in pseudoexfoliation glaucoma

BACKGROUND

To examine levels of serum homocysteine (Hcy), vitamin B12 and folic acid in patients with pseudoexfoliation glaucoma (PEXG), primary open-angle glaucoma (POAG), and healthy control subjects.

METHODS

This study included 36 patients with PEXG, 40 with POAG, and 40 age-matched healthy subjects. Fasting plasma Hcy concentrations and levels of serum vitamin B12 and folic acid were measured using competitive chemiluminescent enzyme immunoassay; values exceeding 14 μm/l were considered elevated.

RESULTS

Mean plasma Hcy was significantly higher in PEXG (16.55 ± 7.23 μm/l) compared with POAG (13.91 ± 3.61 μm/l) and controls (13.12 ± 5.13 μm/l) (p = 0.03 and p = 0.0007 respectively). There were no statistical differences in serum vitamin B12 and folic acid levels among PEXG, POAG and control subjects (p > 0.05). A moderate, although statistically significant, relationship between Hcy and folic acid levels was found in the PEXG group (R(2) = 0.23, p = 0.003). Hcy levels were found not to be related with folic acid or vitamin B12 in either POAG or control subjects.

CONCLUSIONS

In this study, plasma Hcy is significantly higher in PEXG group than the POAG and control groups. Hyper-Hcy might play a role in the pathogenesis of PEXG. Hyper-Hcy may be an independent factor stressing vasculopathy in addition to pseudoexfoliation, so might be a modifiable risk factor for PEXG.

Levels of circulating homocysteine, vitamin B6, vitamin B12, and folate in different types of open-angle glaucoma

OBJECTIVE

To compare the levels of plasma homocysteine (Hcy), vitamin B6 (vit-B6), serum vitamin B12 (vit-B12), and folate in healthy individuals and in patients with normal tension glaucoma (NTG), pseudoexfoliative glaucoma (PXG), or primary open-angle glaucoma (POAG).

STUDY DESIGN

A prospective controlled trial.

PARTICIPANTS AND METHODS

Forty healthy subjects, 48 patients with NTG, 38 patients with PXG, and 34 patients with POAG were included in the study. Those who used vitamin supplements or medications affecting Hcy and vitamin levels were excluded from the study. The levels of Hcy and vit-B6 were measured by High Performance Liquid Chromatography (HPLC). The levels of serum vit-B12 and folic acid were measured by competitive chemiluminescent enzyme immunoassay (CEI). One-way analysis if variance (ANOVA), analysis of covariance (ANCOVA), and the Tukey honestly significant difference test were used for statistical analysis.

RESULTS

The mean Hcy level of the PXG group was 15.46+/-9.27 micromol/L which was significantly higher (P=0.03) than that of the control group. There were no statistical differences in serum vit-B12 and folate levels among control subjects and NTG, PXG and POAG groups (P>0.05). It was found that the mean plasma vit-B6 level was significantly higher in subjects with NTG (P=0.03) and POAG (P=0.025) versus controls. Mean vit-B6 levels in NTG and POAG were 30.50+/-11.29 microg/L and 30+/-12.15 microg/L, respectively.

CONCLUSIONS

The plasma level of Hcy was found to be increased only in PXG patients and the plasma levels of vit-B6 were found to increase in the NTG and POAG sample groups. Using homocysteine and vit-B6 levels as the determinants of hyperhomocysteinemia still needs further research.

Association of exfoliation syndrome and central retinal vein occlusion: an ultrastructural analysis

PURPOSE

To evaluate prospectively the frequency with which exfoliation syndrome (XFS) occurs in patients with central retinal vein occlusion (CRVO) by clinical examination and ultrastructural examination of conjunctival biopsy specimens.

METHODS

Prospective observational case series. Thirty-six eyes of 36 consecutive patients with CRVO were investigated for XFS by slit-lamp examination and conjunctival biopsy when XFS was not clinically visible on examination.

RESULTS

A clinical diagnosis of XFS or a positive biopsy result for exfoliation material (XFM) was present in 22 of the 36 patients (61%; 95% confidence interval 45-75%). Twelve of these 22 patients (54%) had a clinical diagnosis of XFS. Aggregates of XFM were identified ultrastructurally in the biopsy specimens in 10 of 24 patients with no clinical signs of XFS (42%). Patients with and without XFS had similar distribution of age, gender, race and prevalence of systemic disorders. Twelve of the 22 (54%) XFS patients had neither glaucoma nor ocular hypertension prior to the CRVO.

CONCLUSION

In accordance with previous retrospective and histological studies, this prospective, in vivo study suggests that CRVO is commonly associated with XFS.

Epidemiology of exfoliation syndrome in the Reykjavik Eye Study

Exfoliation syndrome (XFS) is a major risk factor for glaucoma. It is characterized by a pathological accumulation of polymorphic fibrillar material in the anterior segment of the eye. It is likely that the increase in intraocular pressure (IOP) seen in XFS patients is at least in part because of flakes of material clogging up the trabecular meshwork, and thereby increasing the resistance to outflow and increasing IOP. XFS glaucoma progresses more rapidly, is more resistant to medical treatment and has worse prognosis than other glaucomas. The prevalence of XFS has been found to vary greatly between different studies, raising the possibility of racial and/or environmental modulators. XFS has also been linked to other changes in ophthalmological structures such as; changes in central corneal thickness (CCT), steeper corneal curvature (CC) and nuclear lens opacifications. Some studies have found XFS to be associated with systemic diseases, mostly cardiovascular and cerebrovascular. Exposure to ultra-violet (UV) light has also been investigated as a possible culprit, along with several other plausible factors. The aim of the present study was to determine the prevalence and 5-year incidence of XFS, to establish possible risk factors and/or concomitant symptoms and finally to investigate the relationship between XFS and glaucomatous changes. The Reykjavík Eye Study (RES) is a prospective study based on a random sample from the Icelandic national population sample. The baseline examination was performed in the autumn of 1996, when 1045 persons older than 50 years participated. Of these, 846 (88.2% of survivors) participated in a follow-up 5 years later. All participants went through a standard examination protocol, and answered a comprehensive questionnaire on health and life style. In the prevalence study, XFS was found in 10.7% of subjects, more frequently in women and older persons. Five years later, a further 5.2% of those that participated in the follow-up study and had no signs of XFS at baseline were diagnosed having XFS. We found a strong correlation between IOP and XFS. No difference was found in the anterior segment parameters measured, but there was a significant loss of neural tissue in the XFS as demonstrated by measurements of cup/disk ratio. In conclusion, we find XFS to be frequent among Icelanders, increasing with age and more in women. Our diagnostic criteria are reliable over time. We have also identified possible risk factors that point to a role of antioxidants in the development of XFS. We find changes in corneal curvature and thickness more related to age than XFS.

Plasma homocysteine, MTHFR gene mutation, and open-angle glaucoma

OBJECTIVE

Elevated plasma homocysteine has been associated with an increased risk of cardiovascular disease. The association between open-angle glaucoma and cardiovascular disease has recently stimulated interest in the role of homocysteine in the pathogenesis of glaucoma. Some studies report elevated plasma homocysteine in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma (PXFG), but have not found this association consistently in other types of open-angle glaucoma. In this study, we have measured plasma homocysteine and C677T methylenetetrahydrofolate reductase (MTHFR) mutation, the commonest genetic cause of elevated plasma homocysteine, in patients with PXFG, primary open-angle glaucoma (POAG), and normal tension glaucoma (NTG).

DESIGN

Prospective cross-sectional cohort study.

PARTICIPANTS

Forty-eight patients with PXFG, 36 patients with POAG, 34 patients with NTG, and 42 controls without glaucoma.

METHODS

Fasting venous blood samples from each participant were analyzed for plasma homocysteine and the C677T MTHFR gene mutation. MAIN OUTCOME OF INTEREST: Mean plasma homocysteine levels, number of individuals with homocysteine above the reference range, and percentage of individuals with heterozygous or homozygous C677T MTHFR gene mutations.

RESULTS

Mean plasma homocysteine was significantly higher in PXFG (11.77+/-4.18 micromol/L), POAG (11.21+/-2.84 micromol/L), and NTG (11.74+/-3.79 micromol/L) compared with control (9.82+/-1.75 micromol/L). Hyperhomocysteinemia was found in 27.1% of PXFG patients, 30.6% of POAG patients, and 29.4% of NTG patients. There was no significant difference in frequency of MTHFR C677T gene mutation between groups.

CONCLUSIONS

Plasma homocysteine was elevated in PXFG, POAG, and NTG. Elevated plasma homocysteine seems to be associated with glaucoma in these patients.

Is exfoliation syndrome a sign of systemic vascular disease?

Exfoliation syndrome (ES) is an age-related disorder in which greyish-white flakes accumulate in different tissues in the anterior eye. Its pathogenesis is not completely known, but it results in electron-dense microfibrils. The finding that these can be seen outside the eye in many visceral organs inspired the theory that ES might be a part of a generalized disorder. It was postulated that ES might contribute to increased morbidity, mainly of systemic vascular diseases. This review is a summary of the existing knowledge. The prevalence of arterial hypertension (AHT) in elderly populations is > 30%. No differences have been found in the frequency of AHT among patients with ES or exfoliative glaucoma (EG) compared with those with primary open-angle glaucoma (POAG) or no ES. There are conflicting reports of frequencies of ischaemic heart disease (IHD). A recent registry-based study that used uniform criteria for IHD found no difference in the rate of IHD between patients with EG and those with POAG. However, findings of elevated homocysteine levels in the plasma and aqueous humour of patients with ES or EG suggest an increased vascular risk. No studies have yet been conducted to assess possible links between ES and systemic vascular diseases. In a single-blind study, ES was associated with abdominal aortic aneurysm, but this was not found in a large, cross-sectional investigation. The frequency of ES in patients with diabetes mellitus (DM) is only about half of that when compared in patients with no ES or with POAG. This finding warrants further studies. Molecular genetics research has found no common denominator for ES and the vascular diseases. There is no evidence that ES or EG are related to increased mortality for cardiovascular diseases. Further large-scale, randomized clinical studies are required. At present there are no known medical indications that infer an increased systemic vascular risk or imply a need for the complete internal medical examination of a symptom-free patient with newly diagnosed ES in the eye.

Decreased cardiovagal regulation in exfoliation syndrome

PURPOSE

To investigate the parasympathetic cardiovascular regulation, baroreflex sensitivity (BRS), and pulse wave velocity (PWV) in exfoliation syndrome (XFS).

METHODS

Heart rate variability indices [standard deviation of all RR intervals (SDNN); the mean of absolute successive differences (RMSSD); the percentage of intervals differing by >50 ms from the preceding interval (pNN50); low frequency power, and high frequency power], as well as BRS and PWV, were determined on 27 consecutive white XFS patients and 20 white control subjects under standard circumstances, with controlled breath rate of 0.25 Hz. The paired t test, the Mann-Whitney U test, and the Fisher exact test were used for comparisons.

RESULTS

There was no significant difference between the XFS and control groups in sex distribution, age, heart rate, blood pressure, body mass index, systemic diseases, or medication. But in XFS patients, SDNN (mean+/-SD, 24+/-7.3 vs. 49+/-16.5 ms), RMSSD (17+/-7.3 vs. 45+/-29.1 ms), pNN50 (1.6%+/-2.5% vs. 17.7%+/-25.9%), high frequency (112+/-109 vs. 479+/-554 ms), and BRS (4.64+/-2.12 vs. 9.49+/-4.76 ms/mm Hg for BRS+ and 5.28+/-2.16 vs. 10.29+/-4.62 ms/mm Hg for BRS-) were all significantly lower than in the control group (P<0.01 for each parameter). Low frequency was also reduced in XFS (72+/-55 vs. 253+/-241 ms) (P=0.027). In XFS, PWV was significantly increased compared with the control group (11.6+/-4.1 vs. 9.3+/-2.2 m/s) (P=0.023).

DISCUSSION

Our results suggest a clinically and statistically significant impairment of cardiovagal regulation and impairment of conduit artery function in XFS patients.

The management of exfoliative glaucoma

Exfoliation syndrome (XFS) is an age-related, generalized disorder of the extracellular matrix characterized by the production and progressive accumulation of a fibrillar extracellular material in many ocular tissues and is the most common identifiable cause of open-angle glaucoma worldwide. XFS plays an etiologic role in open-angle glaucoma, angle-closure glaucoma, cataract, and retinal vein occlusion. It is accompanied by an increase in serious complications at the time of cataract extraction, such as zonular dialysis, capsular rupture, and vitreous loss. It is associated systemically with an increasing number of vascular disorders, hearing loss, and Alzheimer's disease. XFS appears to be a disease of elastic tissue microfibrils. The characteristic fibrils, composed of microfibrillar subunits surrounded by an amorphous matrix comprising various glycoconjugates, contain predominantly epitopes of elastic fibers, such as elastin, tropoelastin, amyloid P, vitronectin, and components of elastic microfibrils, such as fibrillin-1, fibulin-2, vitronectin, microfibril-associated glycoprotein (MAGP-1), and latent TGF-beta binding proteins (LTBP-1 and LTBP-2), the proteoglycans syndecan and versican, the extracellular chaperone clusterin, the cross-linking enzyme lysyl oxidase, and other proteins. A recent milestone study showed that two common single nucleotide polymorphisms in the coding region of the lysyl oxidase-like 1 (LOXL1) gene located on chromosome 15 were specifically associated with XFS and XFG. LOXL1 is a member of the lysyl oxidase family of enzymes, which are essential for the formation, stabilization, maintenance, and remodeling of elastic fibers and prevent age-related loss of elasticity of tissues. LOXL1 protein is a major component of exfoliation deposits and appears to play a role in its accumulation and in concomitant elastotic processes in intra- and extraocular tissues of XFS patients. This discovery should open the way to new approaches and directions of therapy for this protein disorder.