Exfoliation syndrome: a disease with an environmental component

Risk factors for exfoliation glaucoma - Current evidence and perspectives

Exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) represent a complex matrix of ocular age-related neurodegenerative changes. Numerous decades of research on this disease entity have highlighted the unique clinical features of ocular protein-complex aggregates, which lead to tissue dysfunction of the ocular outflow channels, leading to irreversible optic nerve damage and glaucoma. While genetic studies have reported several genes associated with XFS and XFG, numerous studies have shown their association with common systemic diseases such as ischemic heart disease, cerebrovascular accidents, and hypertension. Environmental factors are also reported to play a role in the disease pathogenesis by epigenetic control of gene expression and partly explain the difference in the prevalence rates of the disease process. Despite the identification of possible triggers for the disease onset or for the development of glaucoma, the exact mechanisms or the role of several reported risk factors in disease pathogenesis remain a mystery. This review comprehensively evaluated the several risk factors in XFS and XFG while discussing the interactive interplay between the risk factors that determine the disease onset or phenotype in XFS and XFG.

Former smoking as a risk factor for visual field progression in exfoliation glaucoma patients in Sweden

PURPOSE

The present study aimed to identify whether former smoking was a risk factor for visual field progression in exfoliation glaucoma patients.

METHODS

Prospective nonrandomised cohort study. The study included patients diagnosed with exfoliation glaucoma. All included patients were followed for three years (± three months) with reliable visual fields. At least five reliable visual fields needed to be included in the study. Exfoliation glaucoma was defined using the European Glaucoma Society Guidelines. The visual fields were tested using the 24-2 test strategy of the Humphrey Field Analyzer. Smoking was assessed through questionnaires. Outcomes: Visual field progression. Three different approaches were used: difference in mean deviation (MD), rate of progression (ROP), and guided progression analysis (GPA).

RESULTS

In total, n = 113 patients were included; among them, n = 57 were smokers. Smoking was a significant predictor for visual field progression in the three models (MD/ROP/GPA) studied (p = 0.01/p = 0.001/p ≤ 0.001), even adjusting for intraocular pressure (IOP). Other predictors were included in the MD model: IOP at diagnosis (p = 0.04) and selective laser trabeculoplasty (SLT) treatment (p = 0.01). Other predictors were in the ROP model: Visual field index (p = 0.005), number of medications (p = 0.001) and SLT treatment (p = 0.001). The number of medications was another predictor in the GPA model (p = 0.002).

CONCLUSIONS

Former smoking induced visual field deterioration in all models studied. Smoking status should be considered when establishing the glaucoma diagnosis. Increased glaucoma care should be provided to former smokers to slow the progression of the disease.

Secondary glaucoma: Toward interventions based on molecular underpinnings

Glaucoma is a heterogeneous group of progressive diseases that leads to irreversible blindness. Secondary glaucoma refers to glaucoma caused by a known underlying condition. Pseudoexfoliation and pigment dispersion syndromes are common causes of secondary glaucoma. Their respective deposits may obstruct the trabecular meshwork, leading to aqueous humor outflow resistance, ocular hypertension, and optic neuropathy. There are no disease-specific interventions available for either. Pseudoexfoliation syndrome is characterized by fibrillar deposits (pseudoexfoliative material) on anterior segment structures. Over a decade of multiomics analyses taken together with the current knowledge on pseudoexfoliative glaucoma warrant a re-think of mechanistic possibilities. We propose that the presence of nucleation centers (e.g., vitamin D binding protein), crosslinking enzymes (e.g., transglutaminase 2), aberrant extracellular matrix, flawed endocytosis, and abnormal aqueous-blood barrier contribute to the formation of proteolytically resistant pseudoexfoliative material. Pigment dispersion syndrome is characterized by abnormal iridolenticular contact that disrupts iris pigment epithelium and liberates melanin granules. Iris melanogenesis is aberrant in this condition. Cytotoxic melanogenesis intermediates leak out of melanosomes and cause iris melanocyte and pigment epithelium cell death. Targeting melanogenesis can likely decrease the risk of pigmentary glaucoma. Skin and melanoma research provides insights into potential therapeutics. We propose that specific prostanoid agonists and fenofibrates may reduce melanogenesis by inhibiting cholesterol internalization and de novo synthesis. Additionally, melatonin is a potent melanogenesis suppressor, antioxidant, and hypotensive agent, rendering it a valuable agent for pigmentary glaucoma. In pseudoexfoliative glaucoma, where environmental insults drive pseudoexfoliative material formation, melatonin's antioxidant and hypotensive properties may offer adjunct therapeutic benefits. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology.

Cardiovascular Manifestations of Pseudoexfoliation Syndrome: A Narrative Review

Pseudoexfoliation syndrome (PEX) is a long-term, age-related extracellular matrix condition that causes aberrant fibrillary pseudoexfoliative material (PXM) to accumulate in various body tissues. The anterior portion of the eye is where this disorder most frequently presents. It affects the entire body. Most frequently, it is seen in older people, usually those over 50. Fibrillar deposits are a symptom of the pseudoexfoliation syndrome and are found in the anterior part of the eye. Deposition of fibrillary white flaky material is seen. The lens capsule, cornea, ciliary epithelium, lens epithelium, iris pigment epithelium, zonules, orbital soft tissues, trabecular meshwork, iris blood vessels, and iris stroma have all been reported to show such depositions. The skin, heart, lungs, liver, kidneys, and other organs have also been reported to contain these deposits. Asymmetrical and bilateral illnesses are both possible. Myocardial infarction, cerebrovascular accidents, and systemic hypertension have all been linked to it. The pseudoexfoliative condition was first reported with the characteristic findings of white or grey flakes on the anterior lens capsule, the prevalence of glaucoma rising with age, and its presence in about 50% of eyes. A few decades later, the term pseudoexfoliation was given to differentiate it from the true exfoliation syndrome. True exfoliation syndrome is characterized by lamellar delamination of the lens capsule and is caused by exposure to infrared radiation. It is commonly seen in glassblowers. Age is a risk factor for PEX once a person reaches 70. Symptoms of PEX include elevated intraocular pressure, peripapillary transillumination deficiencies, potential glaucomatous optic nerve damage, poor dilatation, Sampaolesi line, and fibrillar white flaky deposits along the pupillary border. Meanwhile, fibrillar white flaky deposits on the anterior lens capsule (Hoarfrost Ring) and pigment dispersion syndrome are not pathognomonic.

Prediagnostic Plasma Metabolomics and the Risk of Exfoliation Glaucoma

Purpose

The etiology of exfoliation glaucoma (XFG) is poorly understood. We aimed to identify a prediagnostic plasma metabolomic signature associated with XFG.

Methods

We conducted a 1:1 matched case-control study nested within the Nurses' Health Study and Health Professionals Follow-up Study. We collected blood samples in 1989-1990 (Nurses' Health Study) and 1993-1995 (Health Professionals Follow-up Study). We identified 205 incident XFG cases through 2016 (average time to diagnosis from blood draw = 11.8 years) who self-reported glaucoma and were confirmed as XFG cases with medical records. We profiled plasma metabolites using liquid chromatography-mass spectrometry. We evaluated 379 known metabolites (transformed for normality using probit scores) using multiple conditional logistic models. Metabolite set enrichment analysis was used to identify metabolite classes associated with XFG. To adjust for multiple comparisons, we used number of effective tests (NEF) and the false discovery rate (FDR).

Results

Mean age of cases (n = 205) at diagnosis was 71 years; 85% were women and more than 99% were Caucasian; controls (n = 205) reported eye examinations as of the matched cases' index date. Thirty-three metabolites were nominally significantly associated with XFG (P < 0.05), and 4 metabolite classes were FDR-significantly associated. We observed positive associations for lysophosphatidylcholines (FDR = 0.02) and phosphatidylethanolamine plasmalogens (FDR = 0.004) and inverse associations for triacylglycerols (FDR < 0.0001) and steroids (FDR = 0.03). In particular, the multivariable-adjusted odds ratio with each 1 standard deviation higher plasma cortisone levels was 0.49 (95% confidence interval, 0.32-0.74; NEF = 0.05).

Conclusions

In plasma from a decade before diagnosis, lysophosphatidylcholines and phosphatidylethanolamine plasmalogens were positively associated and triacylglycerols and steroids (e.g., cortisone) were inversely associated with XFG risk.

Red cell distribution width levels in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma

Purpose

The purpose of this study was to assess the levels of red cell distribution width (RDW) in patients with pseudoexfoliation syndrome (PEX) and pseudoexfoliation glaucoma (PEXG), and to compare their RDW values with healthy controls.

Methods

40 patients with PEX, 40 with PEXG, and 80 control subjects were enrolled in this study. Complete ophthalmologic examination and complete blood count measurements were performed of all subjects. Complete blood counts were performed within one hour of blood collection.

Results

RDW levels were significantly higher in patients with PEX and PEXG than in controls (P = 0.027 and P < 0.001, respectively). Furthermore, a significant difference was found in RDW values between PEXG and PEX groups (P = 0.016). RDW levels were gradually increased from control group to PEXG group (P < 0.001). Multivariate logistic regression analysis revealed that RDW was independently associated with the presence of PEX/PEXG (odds ratio 1.765, 95% confidence interval (CI) 1.095-2.867, P = 0.013).

Conclusion

We conclude that RDW may be a useful marker for predicting the presence of PEX and progression to PEXG.

Risk factors for visual field progression in newly diagnosed exfoliation glaucoma patients in Sweden

The present study aimed to identify risk factors for visual field progression in newly diagnosed exfoliation glaucoma patients. Prospective nonrandomized cohort study. The study included patients with newly diagnosed exfoliation glaucoma. All patients were followed for at least 3 years with reliable visual fields. Both risk factors at inclusion and during the 3-year follow-up were considered. For inclusion, five reliable visual fields were needed. Exfoliation glaucoma was defined based on the European Glaucoma Society guidelines. Visual field evaluation was performed using the 24–2 strategy of Humphrey field analysis. Outcomes: Visual field progression. Three different approaches were used: mean deviation, visual field index, and guided progression analysis. Independent variables were tested first in a univariate linear or regression model. The significant variables were retested in a multivariate linear or logistic regression model. The results were different for the MD, VFI and GPA models. The only variable that showed a significant association in the three models was age (p = 0.004; p = 0.006; p = 0.04). Significant variables in the two models were IOP at diagnosis (p = 0.02; p = 0.04), IOP reduction in absolute terms (p = 0.006; p = 0.003), IOP reduction in relative terms (%) (p = 0.04; p = 0.009) and number of medicines (p = 0.02; p = 0.002). Significant variables in one model were family history (p = 0.04), smoking (p = 0.03), cataract surgery (p = 0.04) and SLT treatment (p ≤ 0.001). Exfoliation glaucoma is a fast progressive glaucoma. Age at diagnosis must be considered. Significant IOP reduction must be achieved to slow down progress in exfoliation glaucoma. The use of SLT treatment should be advised in exfoliation glaucoma patients.

Dysregulated Retinoic Acid Signaling in the Pathogenesis of Pseudoexfoliation Syndrome

Pseudoexfoliation (PEX) syndrome, a stress-induced fibrotic matrix process, is the most common recognizable cause of open-angle glaucoma worldwide. The recent identification of PEX-associated gene variants uncovered the vitamin A metabolic pathway as a factor influencing the risk of disease. In this study, we analyzed the role of the retinoic acid (RA) signaling pathway in the PEX-associated matrix metabolism and evaluated its targeting as a potential candidate for an anti-fibrotic intervention. We provided evidence that decreased expression levels of RA pathway components and diminished RA signaling activity occur in an antagonistic crosstalk with TGF-β1/Smad signaling in ocular tissues and cells from PEX patients when compared with age-matched controls. Genetic and pharmacologic modes of RA pathway inhibition induced the expression and production of PEX-associated matrix components by disease-relevant cell culture models in vitro. Conversely, RA signaling pathway activation by natural and synthetic retinoids was able to suppress PEX-associated matrix production and formation of microfibrillar networks via antagonization of Smad-dependent TGF-β1 signaling. The findings indicate that deficient RA signaling in conjunction with hyperactivated TGF-β1/Smad signaling is a driver of PEX-associated fibrosis, and that restoration of RA signaling may be a promising strategy for anti-fibrotic intervention in patients with PEX syndrome and glaucoma.

The genetic basis for adult onset glaucoma: Recent advances and future directions

Glaucoma, a diverse group of eye disorders that results in the degeneration of retinal ganglion cells, is the world's leading cause of irreversible blindness. Apart from age and ancestry, the major risk factor for glaucoma is increased intraocular pressure (IOP). In primary open-angle glaucoma (POAG), the anterior chamber angle is open but there is resistance to aqueous outflow. In primary angle-closure glaucoma (PACG), crowding of the anterior chamber angle due to anatomical alterations impede aqueous drainage through the angle. In exfoliation syndrome and exfoliation glaucoma, deposition of white flaky material throughout the anterior chamber directly interfere with aqueous outflow. Observational studies have established that there is a strong hereditable component for glaucoma onset and progression. Indeed, a succession of genome wide association studies (GWAS) that were centered upon single nucleotide polymorphisms (SNP) have yielded more than a hundred genetic markers associated with glaucoma risk. However, a shortcoming of GWAS studies is the difficulty in identifying the actual effector genes responsible for disease pathogenesis. Building on the foundation laid by GWAS studies, research groups have recently begun to perform whole exome-sequencing to evaluate the contribution of protein-changing, coding sequence genetic variants to glaucoma risk. The adoption of this technology in both large population-based studies as well as family studies are revealing the presence of novel, protein-changing genetic variants that could enrich our understanding of the pathogenesis of glaucoma. This review will cover recent advances in the genetics of primary open-angle glaucoma, primary angle-closure glaucoma and exfoliation glaucoma, which collectively make up the vast majority of all glaucoma cases in the world today. We will discuss how recent advances in research methodology have uncovered new risk genes, and how follow up biological investigations could be undertaken in order to define how the risk encoded by a genetic sequence variant comes into play in patients. We will also hypothesise how data arising from characterising these genetic variants could be utilized to predict glaucoma risk and the manner in which new therapeutic strategies might be informed.

Exfoliation Syndrome in Baja Verapaz Guatemala: A Cross-Sectional Study and Review of the Literature

There are little epidemiologic data on exfoliation syndrome (XFS) or exfoliation glaucoma (XFG) in Guatemala, especially in the underserved Baja Verapaz region. This observational study assessing XFS/XFG and demographic factors of this region aims to better understand unique exogenous and endogenous risk factors associated with XFS/XFG in Guatemala. During Moran Eye Center's global outreach medical eye camps from 2016-2017, 181 patients age 15 years and older presented for complete eye exams. These individuals were screened for eye disease and evaluated for possible surgical interventions that could occur during the camps to improve eyesight. During the dilated exams, XFS was noted as missing or present. Of those 181, 10 had insufficient data and 18 lacked a definitive diagnosis of XFS or XFG, resulting in 153 evaluable patients; 46 XFS and 9 XFG were identified. Age, gender, hometown, ancestry (languages spoken by parents and grandparents), past medical history, family medical history, and occupational data (only 2017 trip) were obtained for each patient. The most common occupations of these individuals were farming and housekeeping. Higher rates of XFS/XFG were noted in individuals of rural compared to urban settings and Mayan speaking people compared with Spanish speakers. Based on this subset of patients, with various ocular pathologies being evaluated during medical eye outreach camps, the prevalence of XFS/XFG appeared to be 36%, a high prevalence compared to other world populations. Location and higher altitude, along with a farming occupation, may contribute to XFS development and subsequent progression to XFG. To our knowledge, this is the largest study looking at the epidemiology of XFS/XFG in the Baja Verapaz region of Guatemala for those over the age of 15 years seeking eye exams and interventions.

Polymorphism rs3742330 in microRNA Biogenesis Gene DICER1 Is Associated with Pseudoexfoliation Glaucoma in Saudi Cohort

We investigated the association between DICER1 (rs3742330) and DROSHA (rs10719) polymorphisms and pseudoexfoliation glaucoma (PXG) and related clinical phenotypes in a Saudi cohort. In a retrospective case-control study, TaqMan real-time, PCR-based genotyping was performed in 340 participants with 246 controls and 94 PXG cases. The minor (G) allele frequency of rs3742330 in PXG (0.03) was significantly different from that in the controls (0.08) and protective against PXG (odds ratio (OR) = 0.38, 95% confidence interval (CI) = 0.16–0.92), p = 0.017). Similarly, the rs3742330 genotypes showed a significant protective association with PXG in dominant (p = 0.019, OR = 0.38, 95% CI = 0.15–0.92), over-dominant (p = 0.024, OR = 0.39, 95% CI = 0.16–0.95), and log-additive models (p = 0.017, OR = 0.38, 95% CI = 0.16–0.92). However, none remained significant after an adjustment for age, sex, and multiple testing. Rs10719 in DROSHA did not show any significant allelic or genotype association with PXG. However, a protective effect of the GA haplotype in DICER1 and DROSHA and PXG (p = 0.034) was observed. Both polymorphisms showed no significant effect on intraocular pressure and the cup–disk ratio. In conclusion, we report a significant genetic association between variant rs3742330 in DICER1, a gene involved in miRNA biogenesis, and PXG. Further investigation in a larger group of patients of different ethnicities and functional studies are warranted to replicate and validate its potential role in PXG.

Alternate Causes for Pathogenesis of Exfoliation Glaucoma, a Multifactorial Elastotic Disorder: A Literature Review

Exfoliation glaucoma (XFG) is the most recognizable form of secondary open-angle glaucoma associated with a high risk of blindness. This disease is characterized by white flaky granular deposits in the anterior chamber that leads to the elevation of intraocular pressure (IOP) and subsequent glaucomatous optic nerve damage. Conventionally, XFG is known to respond poorly to medical therapy, and surgical intervention is the only management option in most cases. Various genetic and nongenetic factors are known to be linked to the development of XFG. Despite decades of research on the genetic factors in exfoliation syndrome (XFS) by study groups and global consortia involving different ethnic populations, the pathogenesis of XFS and the mechanism of onset of glaucoma still remains an unsolved mystery. The key lies in understanding how the function of a gene (or set of genes) is altered by environmental triggers, along with other molecular events that underlie the key disease attributes, namely, oxidative stress and the disruption of the blood–aqueous barrier (BAB). It remains a challenge to evolve a theory encompassing all factions of molecular events occurring independently or parallelly that determine the disease manifestation (phenotype) or the stage of the disease in the eye (or in any tissue) in exfoliation. Our enhanced understanding of the underlying molecular pathophysiology of XFG, beyond the known genes or polymorphisms involved in the disease, will lead to improved diagnosis and management and the ability to recognize how the environment influences these key events that lead to the disease phenotype or disease progression. This review summarizes the recent observations and discoveries of four key factors that may hold the answers to the non-lysyl oxidase-like 1 (LOXL1) mechanisms behind XFG pathogenesis, namely, the epigenetic factor miRNA, disordered autophagy along with the potential involvement of mitochondrial mutations, and a compromised aqueous–blood barrier.

A global genetic epidemiological review of pseudoexfoliation syndrome

Pseudoexfoliation (PXF) syndrome is an important public health concern requiring individual population level analysis. Disease prevalence differs by geographic location and ethnicity, and has environmental, demographic, genetic, and molecular risk factors have been demonstrated. Epidemiological factors that have been associated with PXF include age, sex, environmental factors, and diet. Genetic and molecular components have also been identified that are associated with PXF. Underserved populations are often understudied within scientific research, including research about eye disease such as PXF, contributing to the persistence of health disparities within these populations. In each population, PXF needs may be different, and by having research that identifies individual population needs about PXF, the resources in that population can be more efficiently utilized. Otherwise, PXF intervention and care management based only on the broadest level of understanding may continue to exacerbate health disparities in populations disproportionally burdened by PXF.

Association of Single Nucleotide Polymorphisms Located in LOXL1 with Exfoliation Glaucoma in Southwestern Sweden

Introduction: Glaucoma is an optic neuropathy that leads to visual field defects. Genetic mechanisms seem to be involved in glaucoma development. Lysyl Oxidase Like 1 (LOXL1) has been described in previous studies as a predictor factor for exfoliation glaucoma. The present article studied the association between three single nucleotide polymorphisms (SNPs) in the LOXL1 gene and the presence of exfoliation glaucoma in Southwestern Sweden. Methods: Case-control study for genetic association. In total, 136 patients and 1011 controls were included in the study. Patients with exfoliation glaucoma were recruited at the Eye Department of Sahlgrenska University Hospital and Skaraborgs Hospital, Sweden. Controls were recruited from the Gothenburg H70 Birth Cohort Study. Three different SNPs were genotyped: LOXL1_rs3825942, LOXL1_rs2165241 and LOXL1_rs1048661. Results: The distribution of allele frequencies was significantly different between controls and glaucoma patients; for rs3825942 (p = 2 × 10⁻¹²), for rs2165241 (p = 3 × 10⁻¹⁶) and for rs1048661 (p = 2 × 10⁻⁶). Logistic regression analyses using an additive genetic model, adjusted for sex and age, also showed associations between the studied SNPs and glaucoma (p = 9 × 10⁻⁶; p = 2 × 10⁻¹⁴; p = 1 × 10⁻⁴). Conclusion: A strong association was found between allele frequencies of three different SNPs (LOXL1_rs3825942, LOXL1_rs2165241, and LOXL1_rs1048661) and the presence of exfoliation glaucoma in a Southwestern Swedish population.

The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome

LOXL1 (lysyl oxidase-like 1) has been identified as the major effect locus in pseudoexfoliation (PEX) syndrome, a fibrotic disorder of the extracellular matrix and frequent cause of chronic open-angle glaucoma. However, all known PEX-associated common variants show allele effect reversal in populations of different ancestry, casting doubt on their biological significance. Based on extensive LOXL1 deep sequencing, we report here the identification of a common non-coding sequence variant, rs7173049A>G, located downstream of LOXL1, consistently associated with a decrease in PEX risk (odds ratio, OR = 0.63; P = 6.33 × 10⁻³¹) in nine different ethnic populations. We provide experimental evidence for a functional enhancer-like regulatory activity of the genomic region surrounding rs7173049 influencing expression levels of ISLR2 (immunoglobulin superfamily containing leucine-rich repeat protein 2) and STRA6 [stimulated by retinoic acid (RA) receptor 6], apparently mediated by allele-specific binding of the transcription factor thyroid hormone receptor beta. We further show that the protective rs7173049-G allele correlates with increased tissue expression levels of ISLR2 and STRA6 and that both genes are significantly downregulated in tissues of PEX patients together with other key components of the STRA6 receptor-driven RA signaling pathway. siRNA-mediated downregulation of RA signaling induces upregulation of LOXL1 and PEX-associated matrix genes in PEX-relevant cell types. These data indicate that dysregulation of STRA6 and impaired retinoid metabolism are involved in the pathophysiology of PEX syndrome and that the variant rs7173049-G, which represents the first common variant at the broad LOXL1 locus without allele effect reversal, mediates a protective effect through upregulation of STRA6 in ocular tissues.

Choroidal vascularity index in pseudoexfoliative glaucoma

PURPOSE

To evaluate choroidal vascular involvement in pseudoexfoliative glaucoma (PEXG) by applying the choroidal vascularity index (CVI) to optic coherence tomography (OCT) images.

METHODS

Seventy-eight eyes from 40 subjects were included the study. Group 1 included healthy eyes (n = 20), group 2 eyes with PEX (n = 16), and group 3 eyes with PEXG (n = 42). OCT imaging of macular and peripapillary regions and retinal nerve fiber layer (RNFL) analyses were performed. CVI was calculated using ImageJ software.

RESULTS

The mean age was 64.89 ± 5.8, 71.2 ± 7.8, and 68.24 ± 7.4 years in groups 1, 2, and 3, respectively (p = 0.046). There were no significant differences between the groups in terms of sex (p = 0.777). In macula, mean CVI rates were 66.97 ± 1.9%, 64.23 ± 1.2%, and 64.63 ± 1.6%, and in the peripapillary areas, mean CVI rates were 67.04 ± 1.5%, 65.20 ± 1.5%, and 64.14 ± 2.1% in groups 1, 2, and 3, respectively (group 1 vs. group 2 and 3, p = 0.000; group 2 vs. group 3, p > 0.05). The decrease in average RNFL thickness was statistically significant in group 3 compared to groups 1 and 2.

CONCLUSION

CVI could be used to assess choroidal vascular changes in ocular diseases. CVI was found to be reduced in PEX and PEXG, indicating an ocular vascular involvement in pseudoexfoliative process.

Aqueous humor metabolite profile of pseudoexfoliation glaucoma is distinctive

Pseudoexfoliation (PEX) is a known cause of secondary open angle glaucoma. PEX glaucoma is associated with structural and metabolic changes in the eye. Despite similarities, PEX and primary open angle glaucoma (POAG) may have differences in the composition of metabolites. We analyzed the metabolites of the aqueous humor (AH) of PEX subjects sequentially first using nuclear magnetic resonance (1H NMR: HSQC and TOCSY), and subsequently with liquid chromatography tandem mass spectrometry (LC-MS/MS) implementing isotopic ratio outlier analysis (IROA) quantification. The findings were compared with previous results for POAG and control subjects analyzed using identical sequential steps. We found significant differences in metabolites between the three conditions. Principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) indicated clear grouping based on the metabolomes of the three conditions. We used machine learning algorithms and a percentage set of the data to train, and utilized a different or larger dataset to test whether a trained model can correctly classify the test dataset as PEX, POAG or control. Three different algorithms: linear support vector machines (SVM), deep learning, and a neural network were used for prediction. They all accurately classified the test datasets based on the AH metabolome of the sample. We next compared the AH metabolome with known AH and TM proteomes and genomes in order to understand metabolic pathways that may contribute to alterations in the AH metabolome in PEX. We found potential protein/gene pathways associated with observed significant metabolite changes in PEX.

The Role of Trace Elements in Pseudoexfoliation Syndrome: A Cross-sectional Study

Purpose

Pseudoexfoliation syndrome (PXF) is an age-related condition, characterized by deposition of whitish flake-shaped materials in the anterior segment of the eye. Although it occurs all over the world, a considerable racial variation exists. According to the high frequency of PXF in Iran and the importance of prevention and early treatment, we evaluated the plasma level of iron, zinc, copper, and magnesium in patients with PXF.

Methods

In this study, 83 individuals were enrolled; 40 patients with cataract and PXF as the case group and 43 age- and sex-matched individuals with cataract but without PXF as the control group. The serum levels of the mentioned microelements were compared in two groups.

Results

In the case group, 25 (62.5%) male and 15 (37.5%) female subjects participated. In the control group, the corresponding figures were 22 (51.2%) and 21 (48.8%), respectively. The mean age of the case group was 66.07 ± 9.46 and that for the control group was 66.88 ± 8.04 years. Regarding the case group, the serum levels of iron, zinc, copper, and magnesium were 60.58 ± 21.04, 84.7 ± 14.37, 120.23 ± 14.43, and 2.11 ± 0.23, respectively. These serum levels in the control group were 89.07 ± 26.06, 97.51 ± 17.42, 123.33 ± 19.01, and 2.14 ± 0.16. The serum levels of iron and zinc were significantly lower in the case group than the control group (P< 0.0001); however, such a difference was not observed in terms of copper and magnesium serum levels.

Conclusion

Our study demonstrated that the serum iron and zinc levels were lower in PXF patients. Nutritional deficiency may be a cause of zonular weakness in these patients. Heme is a cofactor for the enzyme which contributes to the biosynthesis of fibrillin, the major protein in zonular fibers. Therefore, iron can play a substantial role in the biosynthesis of the fibrils and also in the zonular stability.

Proteomics of pseudoexfoliation materials in the anterior eye segment

Pseudoexfoliation syndrome (PEX) is characterized by the production of white extracellular fluffy clumps of microfibrillar material that aggregates in various organs throughout the body but is known to cause disease in the eye. The accumulation of PEX material (PEXM) in the anterior segment ocular structures is believed to cause an increase in intraocular pressure (IOP) resulting in pseudoexfoliation glaucoma (PEXG). The onset of PEXG is often bilateral but asymmetric-one eye often presents with glaucoma prior to the other eye. Proteomics has been used to identify key proteins involved in PEXM formation with the end goal of developing effective treatments for PEX and PEXG which may act through inhibiting the formation of the PEX aggregates. To date, a variety of proteins with various molecular functions have been identified from extracted anterior segment structures and fluids, such as aqueous humor (AH) and blood serum of patients affected by PEX. From past studies, some proteins identified in AH, lens capsule epithelium, iris tissue, and blood serum samples include vitamin D binding protein (GC), apolipoprotein A4 (APOA4), lysyl oxidase like-1 (LOXL1), complement C3, beta-crystalline B1, and B2, and antithrombin-III (SERPINC1). Each of these proteins have been observed in eyes with PEX at varying levels within the different eye structures. In this review, we further examine the anterior segment ocular proteomics of PEXM from past studies to better understand the mechanism of PEX and PEXG development. Both genetic and environmental risk factors have been implicated to be involved in the development of PEX and PEXG. This field is at an early stage of investigation identifying how these factors modify proteins both at the expression and functional level to cause changes leading to the pathophysiology of PEX glaucoma.

Lower Success in Trabeculectomies in Exfoliation Compared With Primary Open-angle Glaucoma Patients in Sweden

PRCIS

In a Sweden-based study, a lower success rate in exfoliation than in open-angle glaucoma patients was found in a 5-year follow-up after trabeculectomy.

PURPOSE

The present study aimed to compare the success of trabeculectomies in exfoliation versus open-angle glaucoma patients.

PATIENTS AND METHODS

Data were gathered through a retrospective chart review. Included patients underwent primary trabeculectomy from January 1 2009 till December 31, 2014 (6 y). All included patients were operated on at the Eye Department, Skaraborg Hospital, Sweden, and followed for at least 5 years after surgery. Included patients had primary open-angle glaucoma (POAG) or exfoliation glaucoma (EXFG). The study followed the recommendations of the World Glaucoma Association (WGA). Successful result: criterion A: eye pressure ≤18 mm Hg and pressure reduction ≥30% without medications (complete success: A1), with or without medications (qualified success: A2). Criterion B: eye pressure ≤15 mm Hg and pressure reduction ≥40% without medications (complete success: B1), with or without medications (qualified success: B2).

RESULTS

A total of 147 patients were included in this study, 92 in the EXFG and 55 in the POAG group. At the baseline, only 3 variables (intraocular pressure, number of medications, and the number of laser treatments) showed a significant difference between EXFG and POAG patients. Complete and qualified success for both criterion A (A1 and A2) and B (B1 and B2) were significantly lower in the EXFG compared with the POAG group (Mantel-Cox test, P<0.0001, P=0.01, P<0.001, P=0.008).

CONCLUSIONS

Trabeculectomies in EXFG seem to have a lower success rate than in POAG patients. EXFG patients should be checked often after trabeculectomy to detect the failure of the surgery.

Comparison of visual field progression in new-diagnosed primary open-angle and exfoliation glaucoma patients in Sweden

Background

The present study aimed to compare visual field progression in new-diagnosed exfoliation versus open-angle glaucoma patients.

Methods

Retrospective study. The study included patients with new-diagnosed primary open-angle and exfoliation glaucoma. All patients were followed for 3 years with reliable visual fields. At least five reliable fields were needed for inclusion. Exfoliation and open-angle glaucoma were defined based on the European Glaucoma Society guidelines. Visual field evaluation was performed using the software threshold 24–2 of the Humphrey Field Analysis. Outcomes: Visual field progression. For visual field progression, three different strategies were used: mean deviation (MD), visual field index (VFI), and the guided progression analysis (GPA).

Results

The study included 128 subjects, of the 54 in the open-angle and 74 in the exfoliation glaucoma group. The MD difference values were higher in the exfoliation (− 3.17 dB) than in the primary open-angle (− 1.25 dB) glaucoma group in the three-year follow-up period. The difference between groups was significant (t-test, p = < 0.001). The difference in VFI was calculated for the 3 years follow-up period. The difference was higher in the exfoliation (− 7.65%) than in the primary open (− 1.90%) glaucoma group (t-test, p = < 0.001). The GPA showed progression in 58% of cases in exfoliation, and 13% in primary open glaucoma group (Chi-square, p = < 0.001).

Conclusion

The present study found a more frequent and faster visual field progression in exfoliation than in primary open-angle glaucoma patients. New-diagnosed exfoliation glaucoma patients must be controlled and treated more strictly than primary open-angle glaucoma patients to avoid visual field deterioration.

Nano-scientific Application of Atomic Force Microscopy in Pathology: from Molecules to Tissues

The advantages of atomic force microscopy (AFM) in biological research are its high imaging resolution, sensitivity, and ability to operate in physiological conditions. Over the past decades, rigorous studies have been performed to determine the potential applications of AFM techniques in disease diagnosis and prognosis. Many pathological conditions are accompanied by alterations in the morphology, adhesion properties, mechanical compliances, and molecular composition of cells and tissues. The accurate determination of such alterations can be utilized as a diagnostic and prognostic marker. Alteration in cell morphology represents changes in cell structure and membrane proteins induced by pathologic progression of diseases. Mechanical compliances are also modulated by the active rearrangements of cytoskeleton or extracellular matrix triggered by disease pathogenesis. In addition, adhesion is a critical step in the progression of many diseases including infectious and neurodegenerative diseases. Recent advances in AFM techniques have demonstrated their ability to obtain molecular composition as well as topographic information. The quantitative characterization of molecular alteration in biological specimens in terms of disease progression provides a new avenue to understand the underlying mechanisms of disease onset and progression. In this review, we have highlighted the application of diverse AFM techniques in pathological investigations.

Link of ocular pseudoexfoliation syndrome and vascular system changes: results from 10-year follow-up study

PURPOSE

To examine the 10-year incidence of the pseudoexfoliation syndrome (PEX) in adults in a population-based follow-up study, to determine its link with vascular diseases, and to identify possible risk factors of the PEX.

METHODS

The baseline examination was performed in 2006 on a random sample of 1033 participants from Kaunas city (Lithuania) population. In 2016, a follow-up study of 686 participants who returned for the examination was conducted. The respondents filled out a questionnaire, an ophthalmological examination was performed, and the presence of vascular diseases was determined by the anamnesis and electrocardiogram evaluation data. Binary univariate and multivariate logistic regression analyses were conducted with the PEX and vascular diseases as predictors, controlling for age. Odds ratios (OR) and 95% confidence intervals of OR were calculated for the risk of new PEX cases.

RESULTS

During 10 years, the prevalence of the PEX in the study population increased from 10.3 to 34.2%. The rates of ischemic heart disease (IHD) and IHD combined with stroke were significantly higher in the PEX subjects than in the non-PEX subjects. The risk of the PEX among persons with IHD was, on the average, by 1.5-fold higher, and among those with IHD and stroke, on the average, by 1.6-fold higher as compared to persons without the aforementioned pathologies (accordingly, p = 0.014 and p = 0.010).

CONCLUSION

The prevalence of the PEX increased significantly with age. The risk of the PEX was significantly higher among persons with IHD and even higher among persons with IHD and stroke. In the future, a greater understanding of the cardiovascular, metabolic, and environmental components associated with the PEX may lead to more specific lifestyle-related preventive strategies to decrease the disease burden.

Epidemiology of Exfoliation Syndrome

BACKGROUND

From a historical standpoint the epidemiology of exfoliation syndrome (XFS) is one of the most controversial subjects in ophthalmic literature. Current literature abounds with studies on the prevalence of XFS in various ethnic populations and clearly XFS is a common condition, but its true prevalence is difficult to ascertain. Overall, XFS is considered to be the most common identifiable cause of glaucoma worldwide.

PURPOSE

This review critically examines the published literature documenting the epidemiological features of XFS and attempts to provide a unified concept concerning existing controversy.

METHODS

A critical review of selected literature pertaining to the epidemiology of XFS.

RESULTS

It is well established that XFS and the ensuing exfoliative glaucoma have a worldwide prevalence and a progressively increasing age-related incidence. The prevalence of the condition is significantly underestimated. Many past studies have proposed clear geographic variations within and between ethnic groups. In contrast, there has also been some epidemiological evidence suggesting that the prevalence of XFS is similar within various ethnic groups. Published literature fails to address the potential role and impact of suspected exfoliation cases in the reported prevalence figures of the condition. Incidence figures for the condition are limited and vary extensively. Cumulative data have indicated that several, as yet partly understood genetic, ethnic, and environmental factors contribute to the varied prevalence of this condition.

CONCLUSIONS

Further understanding on XFS epidemiology is needed. Only a future large prospective study conducted by the same investigators, using similar methodologies for different ethnic populations will prove beyond doubt the hypothesis that significant geographic variations exist. Since patients with exfoliative glaucoma are at significant risk of losing vision it is vital to elucidate the causes and the risk of developing XFS. To reach this goal, it is important to better delineate the early changes of XFS and to focus research efforts on modifiable factors for XFS development.

Effect of Tropicamide on Laser Flare Meter Measurements in Patients with Pseudoexfoliation

PURPOSE

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.

METHODS

Thirty-three eyes of 33 patients with pseudoexfoliation were enrolled. Patients with the history of other ocular diseases, intraocular surgeries, and the presence of severe posterior synechia were excluded. Besides routine ophthalmological examination, ACAF levels were measured by laser flare meter device (Kowa FM 600) before and after instillation of 1% tropicamide.

RESULTS

The mean age of 33 patients was 67.3±7.1 (53-85) years. Patients had a mean best corrected visual acuity of 0.25±0.41 (1.80-0.00) logMAR, cup-to-disc ratio of 0.45±0.22 (0.2-1), and IOP of 15.33±2.82 (9-20) mmHg. Although the mean ACAF value increased from 14.68±8.40 (3.4-40.4) photon/ms predilation to 15.41±10.74 (3.8-46.8) photon/ms post-dilation, the difference was not statistically significant (p=0.835).

CONCLUSIONS

ACAF values in patients with pseudoexfoliation did not significantly differ after instillation of 1% tropicamide.

Comparison of total/active ghrelin levels in primary open angle glaucoma, pseudoexfoliation glaucoma and pseudoexfoliation syndrome

AIM

To investigate the levels of ghrelin (Gh), acylated ghrelin (AGh) and AGh/Gh ratio in the humor aqueous (HA) of cases with pseudoexfoliation syndrome (PXS), pseudoexfoliation glaucoma (PXG), primary open angle glaucoma (POAG) and to compare these with control subjects.

METHODS

A prospective examination was made of the total Gh, and AGh levels in HA of 67 patients undergoing cataract surgery. Patients were divided into 4 groups. HA samples were aspirated at the beginning of the surgery, stored at -70°C. Gh and AGh quantification was performed with ELISA kits and the AGh/total-Gh ratios were calculated. ANOVA, Kruskal-Wallis, Chi-square and post-hoc tests were used for statistical analysis.

RESULTS

Total Gh levels in HA were 189.2±45.6 pg/mL in the control group, 199.2±32.9 pg/mL in PXS, 180.6±20.9 pg/mL in PXG and 176.8±21.4 pg/mL in POAG groups (P>0.05). AGh levels in HA were 23.09±5.01 pg/mL in the control group, 24.13±5.22 pg/mL in PXS, 22.29±1.55 pg/mL in PXG and 19.69±2.93 pg/mL in POAG groups (P>0.05). The ratio of AGh/Gh was 10.3%±2.34% in the control group, 13.03%±2.58% in PXS, 12.3%±1.54% in PXG and 11.79%±1.41% in POAG groups (P=0.044). The difference between the PXS and control groups was significant (P=0.03).

CONCLUSION

In spite of statistically insignificant results, the HA total Gh levels were lower than those of the control subjects but not parallel with the AGh levels in glaucoma patients. The relative increase in the AGh/Gh ratio in glaucoma cases supports the view that proportional increases of AGh might play a role in the pathogenesis of glaucoma.

Comparison of macular choroidal thickness in patients with pseudoexfoliation syndrome to normal control subjects with enhanced depth SD-OCT imaging

Purpose

To test the hypothesis that macular choroidal thickness is lower in patients with pseudoexfoliation syndrome (PXS) as compared to healthy control subjects.

Methods

In this cross-sectional, observational study, 38 non-glaucomatous PXS subjects and 37 healthy volunteers were enrolled in a tertiary care Glaucoma Clinic. The macular region was scanned with the enhanced depth imaging (EDI) protocol of a spectral domain optical coherence tomography (SD-OCT) device (Spectralis OCT, Heidelberg Engineering, Heidelberg, Germany). Macular choroidal thickness and volumes were compared in nine sectors of the Early Treatment Diabetic Retinopathy Study (ETDRS) layout profile across the central 3.45 mm zone after manual segmentation of the choroidal thickness. Linear mixed modeling was used to adjust for confounding variables.

Results

Six PXS eyes and 8 control eyes were excluded due to poor image quality leaving 32 PXS and 29 control eyes for final analyses. The average age and axial length of the PXS and control groups were 67.94 ± 7.30 vs 64.86 ± 7.04 and 22.91 ± 0.77 vs 23.24 ± 0.66 mm, respectively, (P = 0.10 and 0.20). There was no significant difference in retinal nerve fiber layer (RNFL) thickness between the two groups (P = 0.24). The choroidal thickness was significantly lower in the central subfield subfoveal area (P = 0.02) and in the inner superior (P = 0.03) and inner nasal quadrants (P = 0.03) in the PXS group compared to the control group, as was the choroidal volume (P = 0.02). No significant difference was found in macular choroidal thickness after adjusting for age, gender, and axial length. While there was a significant negative association between age and central subfield choroidal thickness in the control group (r = -0.48, P = 0.01), this association was not significant in the PXS group (r = -0.08, P = 0.68).

Conclusions

Our findings demonstrate that the choroid does not seem to be significantly altered in PXS eyes. Choroidal thickness changes need to be explored in PXS eyes with glaucoma.

Genetics of glaucoma

Genetic and genomic studies, including genome-wide association studies (GWAS) have accelerated the discovery of genes contributing to glaucoma, the leading cause of irreversible blindness world-wide. Glaucoma can occur at all ages, with Mendelian inheritance typical for the rare early onset disease (before age 40) and complex inheritance evident in common adult-onset forms of disease. Recent studies have suggested possible therapeutic targets for some patients with early-onset glaucoma based on the molecular and cellular events caused by MYOC, OPTN and TBK1 mutations. Diagnostic genetic tests using early-onset glaucoma genes are also proving useful for pre-symptomatic disease detection and genetic counseling. Recent GWAS completed for three types of common adult-onset glaucoma have identified novel loci for POAG (primary-open-angle glaucoma) (ABCA1, AFAP1, GMDS, PMM2, TGFBR3, FNDC3B, ARHGEF12, GAS7, FOXC1, ATXN2, TXNRD2); PACG (primary angle-closure glaucoma (EPDR1, CHAT, GLIS3, FERMT2, DPM2-FAM102); and exfoliation syndrome (XFS) glaucoma (CACNA1A). In total sixteen genomic regions have been associated with POAG (including the normal tension glaucoma (NTG) subgroup), 8 with PACG and 2 with XFS. These studies are defining important biological pathways and processes that contribute to disease pathogenesis.

A Pilot Study to Evaluate the Oral Microbiome and Dental Health in Primary Open-Angle Glaucoma

PURPOSE

To evaluate possible associations between primary open-angle glaucoma (POAG), dental health, and the oral microbiome.

METHODS

Case-control study was conducted at SUNY Downstate. Adult subjects (40 to 87 y) were recruited as POAG cases (n=119) and controls without glaucoma (n=78) based on visual field and optic nerve criteria. Overall 74.6% were African Americans (AA). Information on medical history and oral health was collected and ophthalmologic examinations were performed. Mouthwash specimens (28 AA cases and 17 controls) were analyzed for bacterial DNA amounts. Analyses were limited to AAs as the predominant racial group. Outcome measures included number of natural teeth, self-reported periodontal health parameters, and amounts and prevalence of oral bacterial species. Logistic regression was used to evaluate associated factors and potential interactions.

RESULTS

Cases and controls had similar age (mean: 62.2 and 60.9 y, respectively, P>0.48), and frequency of hypertension, diabetes, but cases had a higher proportion of men (P<0.04). On average (±SD), cases had fewer natural teeth than controls [18.0 (±11.1) vs. 20.7 (±9.4)]. Having more natural teeth was inversely associated with POAG, in multivariable analyses, at older ages [eg, odds ratio (95% confidence interval) at age 55: 1.0 (0.95-1.06), P=0.98 vs. at age 85: 0.87 (0.79-0.96), P=0.007]. Amounts of Streptococci were higher in cases than controls (P<0.03) in samples from the subset of subjects analyzed.

CONCLUSIONS

The number of teeth (an oral health indicator) and alterations in the amounts of oral bacteria may be associated with glaucoma pathology. Further investigation of the association between dental health and glaucoma is warranted.

Pseudoexfoliation syndrome-associated genetic variants affect transcription factor binding and alternative splicing of LOXL1

Although lysyl oxidase-like 1 (LOXL1) is known as the principal genetic risk factor for pseudoexfoliation (PEX) syndrome, a major cause of glaucoma and cardiovascular complications, no functional variants have been identified to date. Here, we conduct a genome-wide association scan on 771 German PEX patients and 1,350 controls, followed by independent testing of associated variants in Italian and Japanese data sets. We focus on a 3.5-kb four-component polymorphic locus positioned spanning introns 1 and 2 of LOXL1 with enhancer-like chromatin features. We find that the rs11638944:C>G transversion exerts a cis-acting effect on the expression levels of LOXL1, mediated by differential binding of the transcription factor RXRα (retinoid X receptor alpha) and by modulating alternative splicing of LOXL1, eventually leading to reduced levels of LOXL1 mRNA in cells and tissues of risk allele carriers. These findings uncover a functional mechanism by which common noncoding variants influence LOXL1 expression.

LOXL1 is a genetic risk factor for pseudoexfoliation syndrome of the eye but a causal variant has not been identified. Here, Pasutto et al., find intronic LOXL1 risk variants influence transcription factor binding and alternative splicing of LOXL1 in affected tissues reducing levels of LOXL1 mRNA.

Prevalence of pseudoexfoliation syndrome and its association with ocular and systemic diseases in Eskisehir, Turkey

AIM

To investigate the prevalence of pseudoexfoliation syndrome (PEX) and its associations with ocular and systemic diseases in a population sample aged over 40y.

METHODS

A total of 2356 subjects were randomly chosen for the sample population based on the database of the Turkish Statistical Agency in Eskisehir. Of the invited 2356 subjects, 2017 subjects participated, out of which 2009 were eligible for the study. Systemic diseases, drug use, smoking and body mass index were assessed using questionnaires. Measurements of central corneal thickness (CCT), anterior chamber depth (ACD) and intraocular pressure (IOP) were performed during June to December, 2015. After pupillary dilation, the anterior segment and lenses were evaluated using a slit lamp.

RESULTS

Prevalence of PEX in this sample was 5.0% (n=100). Of patients with PEX, 26% also had glaucoma. Incidence of cataracts, and using drugs for hypertension, cardiac and psychiatric conditions was higher in patients with PEX compared to normal cases (P<0.05). Hearing loss was more common in PEX cases (34.0% vs 5.4%; P<0.001). The mean CCT, ACD and IOP were not significantly different between PEX and non-PEX cases.

CONCLUSION

This study is the first population-based, randomized trial in Turkey. Prevalence of PEX in patients over 40 years old was found to be 5.0%. Besides glaucoma and cataract, hypertension, hearing loss, using drugs for cardiac and psychiatric diseases were associated with PEX.

The prevalence of exfoliation syndrome in Turkey

PURPOSE

To investigate the prevalence of the exfoliation syndrome and its relationship with ocular and cardiovascular diseases in the Central Anatolia region of Turkey.

METHODS

This cross-sectional and population-based study was conducted at the Sivas Province among the population aged 40 years and over. The diagnosis of XFS was made when exfoliative material was found on the anterior lens capsule or iris on slit-lamp examination. The subjects were divided into an XFS group and a non-XFS group according to the presence of exfoliative material, and the groups were compared for the presence of glaucoma, cataract, age-related macular degeneration, phacodonesis, hypertension, diabetes mellitus, coronary artery disease, smoking and alcohol-use frequency.

RESULTS

XFS was present in 63 subjects consisting of 42 males (8.0%) and 21 females (3.6%) for an overall rate of 5.7% (95% CI: 0.054-0.060). Once we adjusted the values for age, we found a statistically significant relationship of increased age and male gender with the presence of XFS (p = 0.001, p = 0.027, respectively). The relationship between XFS and glaucoma, cataract and phacodonesis was found to be statistically significant (p = 0.001). No relationship was found between exfoliation syndrome and hypertension, diabetes mellitus and coronary artery disease.

CONCLUSION

The prevalence of exfoliation syndrome was 5.7% in this population-based study. There was a statistically significant relationship between XFS and advancing age and male gender.

Anterior chamber aqueous flare, pseudoexfoliation syndrome, and glaucoma

The purpose of this study is to evaluate anterior chamber aqueous flare (ACAF) in Tunisian patients with pseudoexfoliation (PEX) syndrome with or without associated glaucoma. This is a prospective, cross-sectional, comparative study including 53 patients (88 eyes) with PEX syndrome, 48 patients with PEX glaucoma (86 eyes), and 53 healthy sex-and age-matched control subjects (106 eyes). All patients underwent a complete ophthalmic examination and laser flare photometry. Mean ACAF was significantly higher in the PEX syndrome group in comparison with the control group (17.96 ± 10.05 vs 7.06 ± 2.95 ph/ms; p = 10(-4)), in patients with PEX glaucoma compared to PEX syndrome without associated glaucoma (27.99 ± 15.45 vs 17.96 ± 10.05 ph/ms; p = 10(-4)), in the PEX glaucoma group in comparison with control group (27.99 ± 15.45 vs 7.06 ± 2.95 ph/ms; p = 10(-4)), and in patients with unilateral PEX syndrome in comparison with contralateral-unaffected eyes (25.72 ± 14.88 vs 8.58 ± 3.45 ph/ms; p = 0.000). For patients with PEX syndrome, a high ACAF might be a predictor for the development of glaucoma. Further investigations are needed to clarify the role of laser flare photometry in predicting the risk of glaucoma in patients with PEX syndrome.

Genetic variants and cellular stressors associated with exfoliation syndrome modulate promoter activity of a lncRNA within the LOXL1 locus

Exfoliation syndrome (XFS) is a common, age-related, systemic fibrillinopathy. It greatly increases risk of exfoliation glaucoma (XFG), a major worldwide cause of irreversible blindness. Coding variants in the lysyl oxidase-like 1 (LOXL1) gene are strongly associated with XFS in all studied populations, but a functional role for these variants has not been established. To identify additional candidate functional variants, we sequenced the entire LOXL1 genomic locus (∼40 kb) in 50 indigenous, black South African XFS cases and 50 matched controls. The variants with the strongest evidence of association were located in a well-defined 7-kb region bounded by the 3'-end of exon 1 and the adjacent region of intron 1 of LOXL1. We replicated this finding in US Caucasian (91 cases/1031 controls), German (771 cases/1365 controls) and Japanese (1484 cases/1188 controls) populations. The region of peak association lies upstream of LOXL1-AS1, a long non-coding RNA (lncRNA) encoded on the opposite strand of LOXL1. We show that this region contains a promoter and, importantly, that the strongly associated XFS risk alleles in the South African population are functional variants that significantly modulate the activity of this promoter. LOXL1-AS1 expression is also significantly altered in response to oxidative stress in human lens epithelial cells and in response to cyclic mechanical stress in human Schlemm's canal endothelial cells. Taken together, these findings support a functional role for the LOXL1-AS1 lncRNA in cellular stress response and suggest that dysregulation of its expression by genetic risk variants plays a key role in XFS pathogenesis.