Endothelin-1 concentration is increased in the aqueous humour of patients with exfoliation syndrome

Emerging roles of oxidative stress in the pathogenesis of pseudoexfoliation syndrome (Review)

Pseudoexfoliation syndrome (PEXS) is a systemic disease caused by defects in the extracellular matrix (ECM) remodelling process leading to the chronic deposition of extracellular, fibrillary, white flaky pseudoexfoliation material (PEXM) throughout the body. Specifically, PEXM deposits on the lens capsule cause open-angle glaucoma, cataracts and blindness in patients with PEXS. Several gene single nucleotide polymorphisms are linked to the development of PEXS in humans, including lysyl oxidase-like 1 gene, clusterin and fibulin-5. The exact reason for the PEXM generation and its resulting pathogenesis is not well understood. However, defective ECM remodelling and oxidative stress (OS) have been hypothesized as significant events leading to the PEXM. Specifically, the link between OS and PEXS has been well studied, although the investigation is still ongoing. The present review explored recent advances in various aspects of PEXS and the involvement of OS in the eye for PEXS development.

Elevated endothelin-1 levels as risk factor for an impaired ocular blood flow measured by OCT-A in glaucoma

The purpose of this study was to ascertain whether a correlation exists between glaucoma-associated alteration of ocular vascular haemodynamics and endothelin-1 (ET-1) levels exist. Eyes of patients with cataract (n = 30) or glaucoma (n = 68) were examined with optical coherence tomography (OCT) and OCT-angiography (OCT-A; AngioVue™-RTVue-XR; Optovue, Fremont, California, USA). The peripapillary and the macular vessel density (VD) values were measured. Inferior and superior retinal nerve fibre layer (RNFL) thickness loss was used for further OCT staging. Aqueous humour of the examined eye and plasma were sampled during cataract or glaucoma surgery and analysed by means of ELISA to determine their ET-1 level. Glaucoma eyes are characterised by reductions in RNFL thickness and VD that correlate significantly with the OCT GSS score. Peripheral and ocular ET-1 level were significantly elevated in patients with glaucoma and correlate positively with the OCT-GSS score of the entire study population. Peripapillary and macula VD of glaucoma patients correlates negatively with plasma ET-1 levels. Multivariable analysis showed a subordinate role of intraocular pressure predictive factor for impaired retinal blood flow compared with plasma ET-1 level in glaucoma. Peripheral ET-1 level serves as risk factor for detection of ocular blood flow changes in the optic nerve head region of glaucomatous eyes.

The correlation between pseudoexfoliation syndrome and the Triglyceride-Glucose index

PURPOSE

Pseudoexfoliation (PEX) syndrome is an age-related disease characterized by the accumulation of extracellular material in many ocular structures, skin and internal organs. Recent studies have shown that the Triglyceride-Glucose (TyG) index has clinical importance for the evaluation of vascular damage. The purpose of this study was to determine the relationship between PEX syndrome and TyG index, and to detect the risk in terms of vascular diseases.

METHODS

In the present study, 50 patients with PEX syndrome who were admitted to the ophthalmology outpatient clinic were evaluated along with 50 others who made up the control group. The Triglyceride-Glucose index was calculated with fasting plasma glucose and triglyceride values.

RESULTS

The mean age was 68.2 ± 1.2 years and 61.0% of the patients were male. There was no statistically significant difference between the two groups in terms of blood sugar and lipid profile (except triglyceride) (p > 0.05). The TyG index value was 8.9 ± 0.5 in the PEX group and 8.6 ± 0.6 in the control group. This difference was statistically significant (p = 0.003). In univariate regression analysis, TyG index (OR = 2.81; CI: 1.37-5.75; p = 0.005) was found to be correlated with PEX. In multivariate logistic regression analysis, this correlation remained statistically significant when adjusted for age and sex (OR = 2.89; CI: 1.35-6.18; p = 0.006).

CONCLUSION

Results showed that the TyG index was high in patients diagnosed with PEX. The risk of vascular diseases can be determined by examining the TyG index in patients with PEX, and this predetermination would have significant consequences for public health.

Comparison of long-term results of trabeculectomy and phacotrabeculectomy in patients with pseudoexfoliation glaucoma and primary open-angle glaucoma: a single-center study

PURPOSE

To evaluate long-term surgical success and complications in pseudoexfoliation glaucoma (PEXG) and primary open-angle glaucoma (POAG) after trabeculectomy or phacotrabeculectomy.

METHODS

96 PEXG eyes and 114 POAG eyes who underwent primary trabeculectomy and phacotrabeculectomy were retrospectively evaluated considering intraocular pressure (IOP), the number of glaucoma medications, surgical success, and rate of complications. Two success criteria were used: Complete success comprised IOP of 5-18 mmHg and 20% reduction of baseline IOP without medication. Qualified success comprised IOP of 5-18 mmHg and 20% reduction of baseline IOP irrespective of medication. Success rates in PEXG and POAG groups, trabeculectomy and phacotrabeculectomy groups, and four groups divided according to surgery and etiology were analyzed via Kaplan-Meier survival analysis.

RESULTS

The complete and qualified success were not different between PEXG and POAG groups. The qualified success curves show a similar pattern among the four groups throughout the follow-up of 1,2,3,5,7 and 9 years. Baseline IOP and the number of medications were similar in all four groups (p = 0.275 and p = 0.209, respectively). IOP levels and the number of medications were not statistically different between the four groups during the follow-up of 2,5 and 7 years. The total number of complications and interventions were similar between PEXG and POAG groups (p = 0.258).

CONCLUSIONS

Phacotrabeculectomy is an effective procedure as trabeculectomy with similar surgical success rates and few surgical complications when it comes to treating PAOG and PEXG patients. Both approaches resulted in similar postoperative IOP levels and medication numbers in both groups.

Oxidative Stress in Optic Neuropathies

Increasing evidence indicates that changes in the redox system may contribute to the pathogenesis of multiple optic neuropathies. Optic neuropathies are characterized by the neurodegeneration of the inner-most retinal neurons, the retinal ganglion cells (RGCs), and their axons, which form the optic nerve. Often, optic neuropathies are asymptomatic until advanced stages, when visual impairment or blindness is unavoidable despite existing treatments. In this review, we describe systemic and, whenever possible, ocular redox dysregulations observed in patients with glaucoma, ischemic optic neuropathy, optic neuritis, hereditary optic neuropathies (i.e., Leber's hereditary optic neuropathy and autosomal dominant optic atrophy), nutritional and toxic optic neuropathies, and optic disc drusen. We discuss aspects related to anti/oxidative stress biomarkers that need further investigation and features related to study design that should be optimized to generate more valuable and comparable results. Understanding the role of oxidative stress in optic neuropathies can serve to develop therapeutic strategies directed at the redox system to arrest the neurodegenerative processes in the retina and RGCs and ultimately prevent vision loss.

Reduced 25-hydroxyvitamin D concentration in the aqueous humor of cataract patients with open-angle glaucoma

Previous epidemiological studies have demonstrated that the lower serum concentration of vitamin D was associated with elevated risk of open-angle glaucoma (OAG). However, few studies have examined the association between aqueous humor vitamin D concentrations and OAG. Hence, we investigated the relationship between 25-hydroxyvitamin D (25(OH)D) concentrations in aqueous humor and OAG. We measured 25(OH)D concentrations in aqueous humor and serum of 126 patients who underwent cataract surgery. 36 were patients with OAG and 90 were control patients. The 25(OH)D concentrations were measured using Elecsys Vitamin D Total Kits with the Cobas e602 module (Roche Diagnostics, Mannheim, Germany), an electrochemiluminescence assay. Multiple linear regression analysis was performed to investigate factors associated with serum and aqueous humor 25(OH)D concentrations. Patients with OAG had significantly lower 25(OH)D concentrations in aqueous humor than control patients. Serum 25(OH)D concentrations were higher in patients with OAG than in the control, but this was not statistically significant. 25(OH)D concentrations in aqueous humor of patients with OAG were significantly associated with axial length but not with glaucoma severity, which was determined by the retinal nerve fiber layer thickness or mean deviation. Vitamin D concentrations in aqueous humor of patients with OAG were significantly lower than those in patients without OAG.

Early-onset Exfoliation Syndrome: A Literature Synthesis

PRECIS

We conducted a literature review of younger patients with exfoliation syndrome (XFS) in an attempt to identify case similarities and better understand disease etiology.

PURPOSE

XFS that predisposes to secondary glaucoma is a strongly age-related condition. We performed a literature review of XFS and exfoliation glaucoma (XFG) in patients aged younger than 40 years to examine potential common characteristics and gain clues to its etiology.

METHODS

We conducted a broad literature search with appropriate keywords and manually extracted key demographic and ocular features on younger XFS and XFG cases. Articles that did not provide past ocular history on early-onset XFS/XFG were excluded.

RESULTS

We identified 12 cases of XFS and XFG in patients from 13 to 40 years old (8 females; 11 White; 5 from Iran). All had past ocular history remarkable for intraocular surgery for other glaucoma conditions (7 cases), other ocular diseases (3 cases), or ocular trauma (2 cases).

CONCLUSIONS

All reported early-onset XFS and XFG cases arise in the setting of events that produced a significant disruption of the blood-aqueous barrier. Understanding the metabolic alterations of aqueous humor from such cases could provide clues regarding how exfoliation material forms.

Automated Evaluation of Parapapillary Choroidal Microvasculature in Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma

OBJECTIVE

To determine whether parapapillary choroidal microvasculature (PPCMv) density as measured by optical coherence tomography angiography differs between pseudoexfoliation syndrome (PXS) and pseudoexfoliation glaucoma (PXG).

DESIGN

Cross-sectional study.

METHODS

One hundred ninety-two eyes of 120 subjects from 2 academic referral institutions were enrolled. Automated PPCMv density was calculated using custom Matlab software in inner and outer annuli around the optic nerve region in addition to peripapillary superficial vasculature. Linear modeling was used to compare vessel densities among groups.

RESULTS

Data from 64 eyes with PXS, 84 eyes with PXG, and 44 eyes healthy control subjects were analyzed. The differences of visual field mean deviation and peripapillary retinal nerve fiber layer thickness among study groups were statistically significant with lower values in PXG eyes compared with the PXS and control groups. Peripapillary superficial retinal vessel densities were significantly reduced in patients with PXG compared with patients with PXS and normal control subjects (all P < .001) without a difference between PXS and control eyes. Customized outer annular PPCMv density in the PXG group with a value of 11.1% (SD 5.1%) was lower than that in PXS with a value of 13.2% (SD 5.3%; P = .001). Similarly, PXS values were lower than those of control eyes with a value of 18.6% (SD 5.1%; P < .001).

CONCLUSION

A progressive decrease in outer PPCMv from the control group to those with PXS without glaucoma to those with PXS and glaucoma (PXG) showed deep peripapillary vasculopathy in pseudoexfoliation syndrome. Choroidal vessel density may be affected early in the course of pseudoexfoliation before glaucoma develops.

Serum Apelin and Asymmetric Dimethylarginine Levels in Patients With Exfoliation Syndrome or Exfoliative Glaucoma

PRéCIS:: Apelin and asymmetric dimethylarginine (ADMA) concentrations, affecting the nitric oxide pathway, were different in the patient group compared with the control subjects. These 2 molecules may have potential effects in vascular pathologies and their possible role in predisposition to vascular comorbidities in exfoliation syndrome (XFS) or exfoliative glaucoma (XFG).

PURPOSE

To evaluate apelin and ADMA levels in serum samples from patients with XFS or XFG compared with healthy control subjects.

METHODS

Serum ADMA and apelin concentrations were evaluated from 36 and 32 XFS patients; 27 and 24 XFG patients; and 34 and 30 healthy controls, respectively. Subjects without systemic disease (including diabetes mellitus, hypertension, coronary artery disease, obesity) were included in the study and body mass index was calculated in all participants. An enzyme-linked immunosorbent assay and high-performance liquid chromatography were used to determine serum apelin and ADMA concentrations. Independent sample t test, χ test, analysis of variance test, and Pearson test were used for statistical analysis.

RESULTS

Mean serum apelin levels of XFG, XFS, and control group were 1063.3±373.4, 1196.7±433.7, and 1343.3±405.1 ng/mL, respectively. Patients with XFG demonstrated significantly lower level of apelin versus controls (P=0.034). Mean serum ADMA concentration was significantly greater in XFS subjects (2.05±0.98 µmol/L) compared with normal controls (1.57±0.58 µmol/L) (P=0.042). No association was detected between ADMA and apelin concentrations and age, sex, and body mass index for both XFS and XFG groups.

CONCLUSIONS

Significant alterations in serum levels of apelin and ADMA may suggest potential effects in vascular pathologies and a possible role in predisposition to vascular comorbidities in XFS/XFG.

Association between Obstructive Sleep Apnea and Exfoliation Syndrome: The Utah Project on Exfoliation Syndrome

PURPOSE

Exfoliation syndrome (XFS), the most common recognizable cause of open-angle glaucoma worldwide, is a systemic disorder with genetic predisposition due to variations in lysyl oxidase-like 1 (LOXL1) function, leading to altered elastin matrices in ocular and systemic tissues. Obstructive sleep apnea (OSA) is a highly prevalent disorder also involving elastic tissue dysfunction and is associated with glaucoma. Because of the similarities between the disorders, we sought to uncover any relationship in the prevalence of these diagnoses.

DESIGN

Case-control, retrospective cohort study.

PARTICIPANTS

A cohort of 81 735 patients diagnosed with OSA at ages 50 to 90 years was identified from medical records from 1996 to 2017 in the Utah Population Database. Case subjects were matched to random controls on sex and birth year in a 4:1 ratio.

METHODS

International Classification of Diseases, Ninth Revision (ICD-9) codes or their Tenth Revision equivalent were used to define a diagnosis of OSA (ICD-9 327.23) and a diagnosis of XFS (ICD-9 365.52 and 366.11). Conditional logistic regression odds ratios (ORs) accounting for individual matching on sex and birth year were used to estimate the risk of XFS in patients with OSA. Models included adjustment for race, obesity, tobacco use, hypertension (HTN), atrial fibrillation (AF), and chronic obstructive pulmonary disease (COPD).

MAIN OUTCOME MEASURE

Whether patients with OSA have an increased risk of diagnosis of XFS compared with controls without OSA.

RESULTS

There was an increased risk of an XFS diagnosis in patients with OSA compared with non-OSA controls (OR, 1.27; 95% confidence interval [CI], 1.02-1.59; P = 0.03). In a stratification of patients by HTN diagnosis history, patients with OSA and HTN exhibited an increased risk of XFS compared with non-OSA controls with HTN (OR, 2.67; 95% CI, 2.06-3.46; P < 0.0001).

CONCLUSIONS

Patients with OSA may be at an increased risk of XFS compared with patients without OSA, particularly in patients with a history of HTN.

Relationship between homocysteine levels, anterior chamber depth, and pseudoexfoliation glaucoma in patients with pseudoexfoliation

PURPOSE

This study investigates the relationship between plasma homocysteine levels, anterior chamber depth (ACD), and pseudoexfoliation glaucoma (PEXG) in patients with pseudoexfoliation syndrome.

METHODS

Sixty patients (F:M = 35:25) with pseudoexfoliation (PEX) were divided into two groups based on their plasma homocysteine levels; group 1 (< 20 µmol/L, normal) and group 2 (≥ 20 µmol/L, high). Intraocular pressure (IOP) and ACD values as well as plasma homocysteine levels were compared between the two groups. Moreover, the mean values for ACD and IOP were compared between patients stratified according to the reference upper limit for the homocysteine level (above and below 14 μmol/L), and the prevalence of high IOP was estimated.

RESULTS

Groups 1 and 2 showed no statistically significant differences in the mean ACD (3.04 ± 0.28 vs. 3.07 ± 0.31 mm, respectively) and mean IOP (20.63 ± 10.22 vs. 21.67 ± 7.55 mmHg, respectively). Patients with PEX and homocysteine levels > 14 μmol/L had a significantly increased prevalence (P < 0.05) of high IOP (≥ 22 mmHg).

CONCLUSIONS

Patients with PEX and high homocysteine levels have an increased prevalence of high IOP. No relationship exists between plasma homocysteine levels and ACD. Thus, PEXG should be suspected in patients with PEX and high plasma homocysteine levels. Plasma homocysteine levels could be helpful for the diagnosis of PEXG, although larger sample studies are required to confirm this finding.

The Effects of Trabeculectomy on Pseudoexfoliation Glaucoma and Primary Open-Angle Glaucoma

Purpose

To compare long-term effects of trabeculectomy on pseudoexfoliation glaucoma (PXG) and primary open-angle glaucoma (POAG).

Methods

This retrospective case-control study included 53 eyes of PXG and 76 eyes of POAG. Intraocular pressure (IOP), number of antiglaucoma medications used, surgical success rate, and occurrence of complications were observed and statistically analyzed in both groups at 3 and 6 months and at 1, 3, and 5 years after trabeculectomy. Surgical success was defined according to the following 3 criteria: (1) IOP ≤ 21 mmHg; (2) IOP ≤ 18 mmHg; (3) IOP ≤ 15 mmHg. Complete success is defined as patients met these criteria without medical treatment, and qualified success is defined as patients met these criteria with medical treatment (≤3 medications). Cumulative probabilities of success were compared using the Kaplan–Meier survival analysis.

Results

For the 3 criteria, there were no statistically significant differences in complete and qualified success rates between the two groups at 3 and 6 months after trabeculectomy (P > 0.05). For criterion A, complete success rates in PXG at 3 and 5 years after surgery were lower than those in POAG; for criterion B, complete and qualified success rates in PXG at 3 and 5 years after surgery were lower than those in POAG; for criterion C, complete and qualified success rates in PXG at 1, 3, and 5 years after surgery were lower than those in POAG, the differences were statistically significant (P < 0.05).

Conclusions

The short-term success rates of both types of glaucoma were similar; however, the long-term success rate of PXG was significantly lower, and it was difficult to achieve long-term control of IOP at a low target level.

Clinical and Laboratory Biomarkers for Pseudoexfoliation Syndrome

In this review, we present an update on biomarkers (both clinical and laboratory) on the basis of recent peer-reviewed publications relating to pseudoexfoliation syndrome and pseudoexfoliation glaucoma.

Retinal and Choroidal Vascular Changes in Eyes with Pseudoexfoliation Syndrome: A Comparative Study Using Optical Coherence Tomography Angiography

Background:

Optical coherence tomography angiography allows a detailed evaluation of retinal and choroidal microvascular structures without the need for a contrast agent. Pseudoexfoliation syndrome is a condition that leads to anatomical and functional losses due to accumulation of degraded abnormal fibrillar material in the intraocular and extraocular tissues. Histopathological studies have shown that the accumulation of Pseudoexfoliation syndrome material in the vascular structures may play a role in different ocular pathologies such as retinal vein occlusion, iris hypoperfusion, anterior segment hypoxia, retinal arterial occlusion, and neovascular glaucoma.

Aims:

To evaluate and compare flow and vascular density in the retina and choroid in eyes with Pseudoexfoliation syndrome, fellow eyes without Pseudoexfoliation syndrome, and healthy eyes using optical coherence tomography angiography.

Study Design:

Case control study.

Methods:

The study included 35 eyes with Pseudoexfoliation syndrome of 35 Pseudoexfoliation syndrome patients, 32 fellow eyes without Pseudoexfoliation syndrome of 32 unilateral Pseudoexfoliation syndrome patients, and 35 eyes of healthy control subjects. Flow area and vascular density in the superficial capillary plexus and deep capillary plexus were measured by optical coherence tomography angiography as three separate parameters: total, parafoveal, and foveal. Choroidal thickness and foveal avascular zone area were measured for each patient.

Results:

There were significant differences between the Pseudoexfoliation syndrome eyes and control eyes in total, parafoveal, and foveal flow and vascular density in the superficial capillary plexus (p<0.05 for all), while there were no significant differences between these groups in any of the flow or vascular density values in the deep capillary plexus (p>0.05). None of the superficial capillary plexus and deep capillary plexus flow and vascular density values showed significant differences between Pseudoexfoliation syndrome eyes and non-Pseudoexfoliation syndrome fellow eyes or between the non-Pseudoexfoliation syndrome fellow eyes and control eyes (p>0.05). Choroidal thickness was significantly lower in Pseudoexfoliation syndrome eyes compared to control eyes. Foveal avascular zone area was significantly enlarged in Pseudoexfoliation syndrome eyes compared to control eyes in both the superficial and deep layers (p<0.05).

Conclusion:

Pseudoexfoliation syndrome eyes exhibit significant damage to the retinal and choroidal vascular structures.

Macula Vessel Density and Foveal Avascular Zone Parameters in Exfoliation Glaucoma Compared to Primary Open-Angle Glaucoma

Purpose

The purpose of this study was to explore macula vessel density and foveal avascular zone (FAZ) parameters in exfoliation glaucoma (XFG) compared to primary open-angle glaucoma (POAG) using optical coherence tomography angiography (OCTA).

Methods

This was a cross-sectional observational study. Twenty-six XFG and 28 POAG patients with comparable visual field defects on Humphrey 24-2 and 10-2 perimetries were recruited. OCTA scans (3 × 3 mm) centered on the fovea were obtained. Built-in software was used to measure superficial capillary plexus (SCP) vessel density at different quadrants of the macula. Custom software was then used to create a full-thickness image. The FAZ was manually delineated, and large vessels were removed. Vessel density in eight concentric rings with increments of 200-μm diameters from the delineated FAZ was measured. FAZ parameters were calculated using the custom software.

Results

SCP density was significantly lower in the superior (mean difference [MD] = -4.32, 95% confidence interval [CI] = -7.02, -1.61, P = 0.003) and nasal (MD = -3.00, 95% CI = 05.22, -0.77, P = 0.010) quadrants in XFG versus POAG. SCP vessel density using the concentric ring approach revealed significantly decreased values at all eight rings in XFG versus POAG. In the full-thickness analysis, density was significantly less in the XFG group in all rings except the initial 200 μm. No significant differences existed in FAZ parameters between the groups.

Conclusions

Despite the presence of comparable central visual field defects, the macula vessel density was predominately lower in XFG compared with POAG in our sample of patients. Further studies are warranted to investigate the consistency of our results.

Monitoring and management of the patient with pseudoexfoliation syndrome: current perspectives

Pseudoexfoliation syndrome (PES) is a complex and age-related systemic disorder characterized by the progressive accumulation and granular deposition of pseudoexfoliative material in various intraocular and extraocular tissues. The diagnosis of PES is so important because it is a major risk factor for complications during cataract surgery and the most frequent cause of secondary glaucoma. In addition to ocular complications, PES is related with numerous systemic abnormalities, for which the list is growing steadily. Therefore, management and monitoring of patients with PES are crucial. The aim of this paper was to review current perspectives on monitoring patients with PES and addressing management of ocular and systemic associations of this clinically important and biologically fascinating disease.

Outcomes of Trabeculectomy With and Without Mitomycin C in Pseudoexfoliative Glaucoma Compared With Mitomycin C in Primary Open Angle Glaucoma

The aim of this study was to evaluate the outcomes of trabeculectomy with mitomycin C (MMC) in patients with Pseudoexfoliative Glaucoma (PXG) and compare the results with the outcomes of trabeculectomy without MMC in PXG and with MMC in Primary Open Angle Glaucoma (POAG). Ninety eyes (76 patients) submitted to trabeculectomy were included in a one-year retrospective study. Fifty-eight eyes with PXG were divided into group 1 (28 eyes) and group 2 (30 eyes), with and without MMC application respectively. Then, the group 1 results were compared with 32 eyes with POAG that performed trabeculectomy with MMC (group 3). Main outcome measures were intraocular pressure (IOP), number of IOP lowering medications, rate of bleb failure (encapsulation, flattening and/or vascularization) and the number of eyes submitted to surgical procedures after trabeculectomy (needling, 5-fluorouracil (5FU) or 2nd trabeculectomy). Results revealed that compared to trabeculectomy with MMC in POAG and trabeculectomy with MMC in PXG, trabeculectomy without MMC in PXG leads to higher IOP (preoperative mean ± standard deviation [SD] was 28.6 ± 5.4 mmHg in group 1, 32.2 ± 8.2 mmHg in group 2 and 26.1 ± 6.5 mmHg in group 3; and after one year was 13.9 ± 3.9 mmHg in group 1, 16.1 ± 5.9 mmHg in group 2 and 12.5 ± 4.0 mmHg in group 3); higher number of IOP lowering medications (preoperative mean ± SD was 3.1 ± 0.60 in group 1, 2.8 ± 0.81 in group 2 and 3.4 ± 0.76 in group 3; and after one year was 1.1 ± 1.1 in group 1, 1.1 ± 1.0 in group 2 and 0.33 ± 0.89 in group 3); higher prevalence of bleb failure (47% in group 1, 53% in group 2, and 18% in group 3); and increased participation in surgical procedures following trabeculectomy (47% in group 1, 57% in group 2, and 6% in group 3). We concluded that trabeculectomy without MMC in PXG had the worst surgical outcome. Thus, PXG appears to be a potential risk factor for filtration bleb failure. Therefore, it could be considered in surgical protocols of MMC application.

Evaluation of Aqueous Endocan and Endostatin Levels in Patients With Pseudoexfoliation Syndrome

PURPOSE

The purpose of the present study was to evaluate the aqueous humor endocan and endostatin levels in patients with pseudoexfoliation (PEX) syndrome and to compare the results with healthy individuals.

MATERIALS AND METHODS

Twenty nine cataract patients with PEX syndrome (PEX group) and 32 cataract patients without PEX syndrome (control group) were enrolled in the study. Endocan and endostatin were measured in the aqueous humor of the PEX and control groups by enzyme-linked immunosorbent assay.

RESULTS

There was no difference between the PEX and control groups in terms of age (P=0.721) and sex (P=0.902). The aqueous levels of endocan in patients with PEX (26.39±5.80 pg/mL) was significantly higher than in the control group (11.42±2.44 pg/mL) (P=0.039). The aqueous levels of endostatin was 12.00±1.35 ng/mL in the PEX group and 14.22±3.31 ng/mL in the control group, however, the difference was not statistically significant (P=0.41).

CONCLUSIONS

The findings of the present study could suggest that the increased levels of aqueous endocan may be related to pathogenesis of PEX. However, levels of aqueous endostatin did not show any significant difference in PEX.

Retrobulbar hemodynamics and aqueous humor levels of endothelin-1 in exfoliation syndrome and exfoliation glaucoma

Background

Endothelin-1 (ET-1) is the most potent vasoconstrictor in the body. There are reports in the literature correlating plasma levels of ET-1 and its impact on retrobulbar hemodynamics. This study evaluates aqueous humor levels of ET-1 and retrobulbar hemodynamics in patients with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG).

Patients and methods

Patients scheduled for cataract surgery were included. Patients were allocated to non-exfoliation non-glaucoma group (controls), XFG and XFS groups. Peak systolic velocity (PSV), end diastolic velocity, and resistivity index of the ophthalmic artery (OA), short posterior ciliary arteries, and central retinal artery (CRA) were determined preoperatively using color Doppler imaging. Aqueous humor samples obtained at the beginning of cataract surgery were analyzed with enzyme-linked immunosorbent assay.

Results

Sixty-nine participants of similar age were included (controls: n=24, XFG: n=22, XFS: n=23). Multiple regression analysis showed that ET-1, OA-PSV, OA-resistivity index, CRA-PSV, and CRA-end diastolic velocity were influenced by group but not by sex or age. ET-1 for the XFG group (15.93±2.8 pg/mL) was significantly higher than for the XFS (8.92±2.7 pg/mL) and control (8.44±2.6 pg/mL) groups. The difference in ET-1 titers between the control and XFS groups was not statistically significant. All four hemodynamic parameters affected by group status significantly correlated with ET-1 levels in eyes with XFS. In eyes with XFG, two of the four hemodynamic parameters significantly correlated with ET-1 levels. In control eyes, no correlation between ET-1 and hemodynamic parameters affected by group status was detected.

Conclusion

ET-1 aqueous levels in eyes with XFG were significantly higher than those of age-matched controls. Reduced blood flow and increased vascular resistivity were detected in the OA and the CRA in eyes with XFG/XFS. ET-1 levels in eyes with XFG/XFS exhibit a significant correlation with hemodynamic parameters that indicate reduced perfusion.

Peripapillary Perfused Capillary Density in Exfoliation Syndrome and Exfoliation Glaucoma versus POAG and Healthy Controls: An OCTA Study

PURPOSE

To compare the peripapillary perfused capillary density (PCD) among eyes with exfoliation syndrome (XFS), exfoliation glaucoma (XFG), primary open-angle glaucoma (POAG), and controls.

DESIGN

Observational, cross-sectional study.

METHODS

Optical coherence tomography angiography (OCTA) images (4.5×4.5 mm) of the optic nerve head were obtained using a commercial spectral domain OCTA system (AngioVue Avanti RTVue-XR, OptoVue, Fremont, CA). Two concentric circles with 1.95-mm (inner) and 3.45-mm (outer) diameters were placed manually, producing an annulus of width 0.75 mm centered at the optic disc. PCD was calculated as the ratio of pixels associated with capillaries to the pixels in the annulus after large blood vessel removal. Continuous variables were assessed by analysis of variance and Tukey honest significant difference (HSD) test. Multiple linear regression analysis was performed to adjust for confounding factors.

RESULTS

Forty-three XFG eyes, 31 POAG eyes matched for visual field mean deviation, 33 XFS eyes, and 45 control eyes were analyzed. PCD demonstrated a progressive decrease from controls to XFS to POAG to XFG. Pairwise comparisons revealed significant differences in PCD between each pair of groups (all P<0.01) except for PCD between XFS and POAG (P = 0.08). A multivariable model adjusting for age and stage showed a more significant decrease in PCD in XFG compared with POAG (P = 0.001).

CONCLUSIONS

PCD was more significantly decreased in XFG compared with POAG eyes and in XFS compared with control eyes. OCTA provides the first quantitative evidence of the microvascular disturbance that accompanies XFS.

[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.

Klotho and Endothelin-1 in Pseudoexfoliation Syndrome and Glaucoma

PURPOSE

Klotho is a newly discovered protein that presumably has an important role in the aging process. The goal of this research is to compare the levels of Klotho and Endothelin-1 (ET-1) in the serum and aqueous humor of patients with pseudoexfoliation syndrome (PES) and pseudoexfoliative glaucoma (PEG).

PATIENTS AND METHODS

Aqueous humor and serum samples were obtained at the time of cataract surgery from 15 patients with PES, 15 patients with PEG, and 15 control patients. All of the samples were analyzed using enzyme-linked immunosorbent assay to evaluate the levels of ET-1 and Klotho protein.

RESULT

Aqueous and serum levels of Klotho in PES patients (49.02±10.97, 56.32±10.25 ng/mL) and PEG patients (34.53±4.87, 50.49±2.63 ng/mL) were lower than in control patients (56.31±7.68, 65.06±12.32 ng/mL). Both aqueous and serum levels of Klotho in the PEG group were lower than in the PES group (P=0.001). Mean aqueous and serum levels of ET-1 in the PES (1.28±0.09, 1.65±0.75 pg/mL) and the PEG groups (1.45±0.07, 1.58±0.58 pg/mL) were significantly higher than that measured in the control group (1.17±0.09, 1.16±0.34 pg/mL). Aqueous levels of ET-1 in the PEG group were higher than the PES group (P=0.04), but there were no significant difference in serum levels of ET-1 between the PES and the PEG groups (P=0.83).

CONCLUSIONS

Aqueous and serum levels of Klotho decreased both in PES and PEG patients, and this decrease in the PEG group was more significant. In contrast, aqueous and serum levels of ET-1 increased in the PES and the PEG patients, and the increase in the aqueous level of ET-1 in PEG patients was more significant.

Major review: Exfoliation syndrome; advances in disease genetics, molecular biology, and epidemiology

Exfoliation syndrome (XFS) is a common age-related disorder that leads to deposition of extracellular fibrillar material throughout the body. The most recognized disease manifestation is exfoliation glaucoma (XFG), which is a common cause of blindness worldwide. Recent developments in XFS genetics, cell biology and epidemiology have greatly improved our understanding of the etiology of this complex inherited disease. This review summarizes current knowledge of XFS pathogenesis, identifies gaps in knowledge, and discusses areas for future research.

Influence of Endothelin-1 in Aqueous Humor on Intermediate-Term Trabeculectomy Outcomes

Purpose. To investigate whether increased concentrations of ET-1 in aqueous humor of glaucoma patients influences surgical outcome of standard trabeculectomy with Mitomycin C. Methods. Retrospective chart review of 36 glaucoma patients with known ET-1 concentrations who had undergone trabeculectomy with Mitomycin C. Patients were divided into two groups based on their aqueous ET-1 concentration, a below-median (low ET-1) and an above-median (high ET-1) group. Postoperative IOP development, necessity of glaucoma medication, surgical success and complications, postoperative use of antifibrotics (5-FU), and number of additional glaucoma surgeries were compared between the groups. Results. Overall surgical success of trabeculectomy was comparable to published literature (90%, 81%, 76%, and 68% absolute success at 12, 24, 36, and 48 months after surgery). There was no difference between high and low ET-1 group in the postsurgical development of IOP, surgical success rate, or complication rate. There was no difference in postoperative scarring or indirect indicators thereof (e.g., number of 5-FU injections, needlings, suture lyses, or IOP lowering medications). Conclusion. In this set of patients, ET-1 in aqueous humor does not appear to have influenced surgical outcome of trabeculectomy with Mitomycin C. There is no indication of an increased likelihood of bleb fibrosis in patients with increased ET-1 concentrations.

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.

Prediction of Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma by Using Neutrophil to Lymphocyte Ratio and Platelet to Lymphocyte Ratio

PURPOSE

To assess the levels of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) in patients with pseudoexfoliation syndrome (PEX) and to compare the NLR and PLR results of patients with PEX, PEX glaucoma (PXG), and healthy controls.

METHODS

In total, 34 patients with PEX, 29 patients with PXG, and 42 healthy subjects were enrolled in this retrospective study. Complete ophthalmologic examination and complete blood count measurements were performed of all subjects. Complete blood counts were performed within 2 h of blood collection.

RESULTS

There was a significant difference in NLR between PEX and control groups (p = 0.012) and PXG and control groups (p = 0.003). Also, a significant difference was found in PLR values between control and PXG groups (p = 0.024).

CONCLUSIONS

Our study for the first time provides evidence that PLR and NLR may be useful for predicting the prognosis of PEX patients and progression to PXG.

Ocular and systemic manifestations of exfoliation syndrome

Exfoliation syndrome is an age-related disease characterized by the production and progressive accumulation of a fibrillar extracellular material in many ocular tissues. It leads to the most common identifiable cause of open-angle glaucoma worldwide, comprising the majority of glaucoma in some countries. The material in the eye appears as white deposits on the anterior lens surface and/or pupillary border. During pupillary movement, the iris scrapes exfoliation material from the lens surface, while the material on the lens causes rupture of iris pigment epithelial cells, with concomitant pigment dispersion into the anterior chamber and its deposition on anterior chamber structures. Exfoliation material can be found in many different organs. It is an ischemic disease and is associated with elevated serum homocysteine. Systemic associations include transient ischemic attacks, hypertension, angina, myocardial infarction, cerebrovascular and cardiovascular disease, aortic aneurysm, Alzheimer disease, and hearing loss. The discovery in 2007 of nonsynonymous single nucleotide polymorphisms in the LOXL1 (lysyl oxidase-like 1) gene are expected to make a major impact not only in understanding exfoliation syndrome, but in leading to new avenues of therapy.

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.

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.

Ocular pseudoexfoliation syndrome and vascular disease: a systematic review and meta-analysis

Objective

Many studies have assessed the association between ocular pseudoexfoliation syndrome (PEX) and vascular disease and produced controversial results. We performed a meta-analysis of epidemiologic studies to evaluate this relationship.

Methods

Eligible studies that reported the incidence of vascular disease among PEX and control groups were identified via computer searches and reviewing the reference lists of the key articles. The summary odds ratio (OR) and 95% confidence interval (CI) were pooled using a random-effects model. Meta-regression to assess heterogeneity by several covariates and a subgroup analysis on study design and population were performed. Publication bias was tested by Begg's funnel plot and Egger's regression test.

Results

Sixteen eligible studies involving 8,533 PEX patients and 135,720 control patients were included in the meta-analysis. All studies were performed primarily in whites with a mean age between 54.7 and 77.1 years. The overall combined ORs for patients with PEX compared with the reference group were 1.72 (95% CI: 1.31 to 2.26) for any vascular disease, 1.61 (95% CI: 1.22 to 2.14) for coronary heart disease, 1.59 (95% CI: 1.12 to 2.23) for cerebrovascular disease, and 2.48 (95% CI: 1.30 to 4.72) for aortic aneurysm. There was evidence of statistical heterogeneity; however, subgroup and sensitivity analyses showed this result to be robust. No evidence of publication bias was observed.

Conclusions

The overall current literature suggests that PEX was associated with increased risk of vascular disease. Because of the limitations of the included studies and meta-analysis, the findings need to be confirmed in future research via well-designed cohort studies.

Endothelin B receptors contribute to retinal ganglion cell loss in a rat model of glaucoma

Glaucoma is an optic neuropathy, commonly associated with elevated intraocular pressure (IOP) characterized by optic nerve degeneration, cupping of the optic disc, and loss of retinal ganglion cells which could lead to loss of vision. Endothelin-1 (ET-1) is a 21-amino acid vasoactive peptide that plays a key role in the pathogenesis of glaucoma; however, the receptors mediating these effects have not been defined. In the current study, endothelin B (ET_B) receptor expression was assessed in vivo, in the Morrison's ocular hypertension model of glaucoma in rats. Elevation of IOP in Brown Norway rats produced increased expression of ET_B receptors in the retina, mainly in retinal ganglion cells (RGCs), nerve fiber layer (NFL), and also in the inner plexiform layer (IPL) and inner nuclear layer (INL). To determine the role of ET_B receptors in neurodegeneration, Wistar-Kyoto wild type (WT) and ET_B receptor-deficient (KO) rats were subjected to retrograde labeling with Fluoro-Gold (FG), following which IOP was elevated in one eye while the contralateral eye served as control. IOP elevation for 4 weeks in WT rats caused an appreciable loss of RGCs, which was significantly attenuated in KO rats. In addition, degenerative changes in the optic nerve were greatly reduced in KO rats compared to those in WT rats. Taken together, elevated intraocular pressure mediated increase in ET_B receptor expression and its activation may contribute to a decrease in RGC survival as seen in glaucoma. These findings raise the possibility of using endothelin receptor antagonists as neuroprotective agents for the treatment of glaucoma.

Endothelin antagonism as an active principle for glaucoma therapy

Endothelin, the most potent vasoactive peptide known to date, has been suggested to play a potential role in the pathogenesis of open-angle glaucoma. Open-angle glaucoma is the most common optic nerve head neuropathy and is associated with a loss of retinal ganglion cells and visual field damage. Although an increased intraocular pressure is a major risk factor for glaucomatous optic neuropathy, other factors such as a reduced ocular blood flow play an important role for appearance of the disease. Thus, treatment of glaucoma is focused on lowering of intraocular pressure and preventing the occurrence or progression of glaucomatous optic neuropathy. Endothelin participates in the regulation of intraocular pressure by an effect on trabecular outflow, the main route for aqueous humour outflow from the eye. Trabecular outflow is modulated by trabecular meshwork contractility which is affected by endothelin. In addition to the effects of endothelin in the anterior part of the eye, the vasoconstrictor causes a decrease in ocular blood flow followed by pathological changes in the retina and the optic nerve head which is assumed to contribute to the degeneration of retinal ganglion cells. In sum, inhibition of endothelin signalling leads to lowering of intraocular pressure and exerts neuroprotective effects. Thus, endothelin antagonism in the eye represents a promising approach for pharmacological treatment of glaucoma.

Effect of SPP 301, an endothelin antagonist, on intraocular pressure in glaucomatous monkey eyes

PURPOSE

To evaluate the effect of topical application of avosentan (SPP 301), endothelin receptor type A antagonist, on intraocular pressure (IOP) in monkey eyes with laser-induced unilateral glaucoma.

MATERIALS AND METHODS

A multiple-dose study was performed in eight glaucomatous monkey eyes that were topically treated with SPP 301 by applying a 50 µl drop (25 µl × 2) at 9:30 a.m. and 3:30 p.m. for 5 consecutive days at three concentrations (0.003%, 0.03%, or 0.3%). IOP was measured hourly for 6 hrs on each day of the study beginning at 9:30 a.m. for one baseline day, one vehicle-treated day, and treatment days 1, 3, and 5.

RESULTS

Twice daily administration of each of the three concentrations of SPP 301 for 5 days significantly (p < 0.05) reduced IOP. The maximum reduction in IOP occurred 2 or 3 hrs after morning dosing and was 1.8 ± 0.8 (mean ± SEM) mmHg (6%) for 0.003% SPP 301, 4.1 ± 0.7 mmHg (13%) for 0.03% SPP 301, and 7.1 ± 1.3 mmHg (21%) for 0.3% SPP 301. The longest duration of IOP reduction was for 2 hrs with 0.003% SPP 301, and was for at least 6 hrs with 0.03% and 0.3% concentrations. Compared to 0.03% or 0.003% concentrations, 0.3% SPP 301 produced a greater (p < 0.05) IOP reduction. IOP was reduced in fellow untreated normal eyes 2 hr after morning dosing with 0.3% SPP 301, maximum reduction in IOP (11%) occurred on day 1. Of the eyes treated with 0.3% SPP 301, one eye demonstrated mild conjunctival discharge and one eye was closed for 5 min after dosing.

CONCLUSION

Topically applied SPP 301, an endothelin antagonist, reduced IOP in glaucomatous monkey eyes in a dose-dependent manner. Endothelin antagonists, a novel class of compound, may have potential for the treatment of glaucoma.

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.

The role of endothelin in the pathophysiology of glaucoma

IMPORTANCE OF THE FIELD

Glaucoma is the second leading cause of blindness worldwide. To date, treatment of glaucoma has focused on lowering intraocular pressure (IOP) though there are other mechanisms that might damage the optic nerve, leading to characteristic visual field loss. Endothelin, a potent vasoconstrictor, is believed to play a role in the pathogenesis of glaucomatous optic neuropathy.

AREAS COVERED IN THIS REVIEW

We review the evidence from the last 20 years exploring the action of endothelin in the eye, its association with the pathophysiology of glaucoma, as well as the potential therapeutic role of targeting the endothelin pathway to affect disease progression in glaucomatous eyes.

WHAT THE READER WILL GAIN

The goal of this paper is to inform readers about endothelin structure, actions, and role in ocular pathology, pharmacology, and potential areas of future research.

TAKE HOME MESSAGE

Overall, we believe that the body of evidence supports the following conclusions; i) endothelin is a potent vasoconstrictor that plays a role in ocular physiology, ii) endothelin may play a role in the pathophysiology of glaucoma and iii) modulation of the endothelin system with newly discovered potent antagonists holds promise in treating glaucoma through both pressure-dependent and pressure-independent pathways.

Aqueous humor endothelin-1 (Et-1), vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) levels in Mexican glaucomatous patients

PURPOSE

To evaluate the concentration of endothelin-1, vascular endothelial growth factor, and cyclooxygenase-2 in aqueous humor from normal and glaucomatous human patients.

MATERIAL AND METHODS

Concentrations of these proteins were measured using ELISA kits in 83 patients (30 presenting for cataract surgery and 53 with glaucoma).

RESULTS

Endothelin-1, vascular endothelial growth factor, and cyclooxygenase-2 were detected in all samples. The ages of the patients with glaucoma (64.51 +/- 17.51 years) and cataracts subjects (59.30 +/- 19.15 years) were similar. The endothelin-1 concentration in cataracts patients (48.55 +/- 9.50 pg/ml) was statistically different when compared to endothelin-1 concentration in aqueous humor from primary open-angle glaucoma (107.94 +/- 12.20 pg/ml) and neovascular glaucoma (114.68 +/- 25.50 pg/ml) (p < 0.05). No statistical difference was observed in normal tension glaucoma group (69.14 +/- 52.80 pg/ml) (p > 0.05). Vascular endothelial growth factor concentration was higher in neovascular glaucoma (81.84 +/- 6.40 pg/ml), being the difference statistically significant when compared with the other groups (p < 0.0001). Cyclooxygenase-2 levels showed no statistical difference between cataract groups and any other glaucoma group (p > 0.05). No effect of age, gender, or previously medication of aqueous humor concentration of these proteins could be detected (p > 0.05).

CONCLUSION

In this study we observed increased levels of endothelin-1 in aqueous humor from patients with primary open-angle glaucoma and neovascular glaucoma, and increased levels of vascular endothelial growth factor only in neovascular glaucoma patients, raising a possible connection between endothelin-1 and vascular endothelial growth factor in the role of some types of glaucoma. Regarding cyclooxygenase-2 levels detected, perhaps indicate that low values of cyclooxygenase-2 are necessary for normal functions of the eye.

Effects of endothelin-1 on the cytoskeleton protein F-actin of human trabecular meshwork cells in vitro

AIM

To observe the effect of endothelin-1 (ET-1) on the cytoskeleton protein F-actin of cultured human trabecular meshwork (HTM) cells.

METHODS

CULTURED HTM CELLS WERE RANDOMLY DIVIDED INTO FOUR GROUPS: control group, low-dose ET-1 (10(-9) mol/L) treatment group, middle-dose ET-1 (10(-8) mol/L) treatment group, and high-dose ET-1(10(-7) mol/L) treatment group. After treated with ET-1, the expression of cytoskeleton protein F-actin in trabecular meshwork was analyzed with Western-blot and the distribution of F-actin was detected with FITC-Phalloidin probe.

RESULTS

ET-1 dose-dependently and significantly increased F-actin in trabecular meshwork cells (P<0.05). The F-actin stress fiber and periphery actin fiber highly increased and manifested mild reorganization after treated with ET-1; and there were much more cell-to-cell and cell-to-extracellular matrix attachments formation in ET-1 treated HTM cells than that in the untreated HTM cells.

CONCLUSION

ET-1 promotes the expression of cytoske- leton protein F-actin and induced the trabecular meshwork actin cytoskeleton reorganization.

Ascorbic acid concentration is reduced in the secondary aqueous humour of glaucomatous patients

BACKGROUND

We aimed to evaluate the ascorbic acid concentration in secondary aqueous humour (AH) from glaucomatous patients and to compare it with primary AH from primary open-angle glaucoma patients and non-glaucomatous patients.

METHODS

Primary AH samples were prospectively obtained from clinically uncontrolled primary open-angle glaucoma patients and senile cataract patients (controls) prior to trabeculectomy and cataract surgery. Secondary AH samples were obtained from eyes with previous intraocular surgery, prior to trabeculectomy or cataract surgery. AH (0.1 mL) was aspirated by inserting a 26-gauge needle into the anterior chamber just before surgery and then immediately stored at -80 degrees C. The ascorbic acid concentration was determined in a masked fashion by high-pressure liquid chromatography.

RESULTS

A total of 18 patients with senile cataract, 16 glaucomatous patients with primary AH (no previous intraocular surgery) and 11 glaucomatous patients with secondary AH (previous intraocular surgery) were included. There was no difference in mean age between groups (P = 0.15). The mean +/- standard deviation concentration of ascorbic acid in the secondary AH from glaucomatous patients (504 +/- 213 micromol/L [95% confidence interval {CI}, 383-624]) was significantly lower than the concentration of ascorbic acid found in the primary aqueous of primary open-angle glaucoma (919 +/- 427 micromol/L [95% CI, 709-1128]) and control patients (1049 +/- 433 micromol/L [95% CI, 848-1249]; P < 0.01, Kruskal-Wallis test).

CONCLUSIONS

The ascorbic acid concentration in secondary AH of glaucomatous patients was approximately twofold lower in comparison with primary AH of glaucomatous and cataract patients. The implications of a reduced concentration of ascorbic acid in the secondary AH deserve further investigation.