The management of exfoliative glaucoma

Proteomic characteristics of the aqueous humor in Uyghur patients with pseudoexfoliation syndrome and pseudoexfoliative glaucoma

Pseudoexfoliation syndrome (PEX) is characterized by the deposition of fibrous pseudoexfoliation material (PEXM) in the eye, and secondary glaucoma associated with this syndrome has a faster and more severe clinical course. The incidence of PEX and pseudoexfoliative glaucoma (PEXG) exhibits ethnic clustering; however, few proteomic studies related to PEX and PEXG have been conducted in Asian populations. Therefore, we aimed to conduct proteomic analysis on the aqueous humor (AH) obtained from Uyghur patients with cataracts, those with PEX and cataracts, and those with PEXG and cataracts to better understand the molecular mechanisms of the disease and identify its potential biomarkers. To this end, AH was collected from patients with cataracts (n = 10, control group), PEX with cataracts (n = 10, PEX group), and PEXG with cataracts (n = 10, PEXG group) during phacoemulsification. Label-free quantitative proteomic techniques combined with bioinformatics were used to identify and analyze differentially expressed proteins (DEPs) in the AH of PEX and PEXG groups. Then, independent AH samples (n = 12, each group) were collected to validate DEPs by enzyme-linked immunosorbent assay (ELISA). The PEX group exhibited 25 DEPs, while the PEXG group showed 44 DEPs, both compared to the control group. Subsequently, we found three newly identified proteins in both PEX and PEXG groups, wherein FRAS1-related extracellular matrix protein 2 (FREM2) and osteoclast-associated receptor (OSCAR) exhibited downregulation, whereas coagulation Factor IX (F9) displayed upregulation. Bioinformatics analysis suggested that extracellular matrix interactions, abnormal blood-derived proteins, and lysosomes were mainly involved in the process of PEX and PEXG, and the PPI network further revealed F9 may serve as a potential biomarker for both PEX and PEXG. In conclusion, this study provides new information for understanding the proteomics of AH in PEX and PEXG.

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.

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

PURPOSE

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

MATERIAL AND METHOD

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

RESULTS

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

CONCLUSION

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

The Importance of Signal Strength Index in Optical Coherence Tomography Angiography: A Study of Eyes with Pseudoexfoliation Syndrome

PURPOSE

To evaluate the effect of the signal strength index (SSI) on a comparison of the vascular and structural OCT measurements between eyes with pseudoexfoliation syndrome (PXF) and healthy controls of Asian-Indian origin.

METHODS

In this cross-sectional study, 33 eyes of 33 PXF patients and 40 healthy eyes of 40 controls underwent OCT and OCT angiography (OCTA). Eyes with intraocular pressure (IOP) >21mmHg, glaucomatous disc changes, or any other ocular pathology were excluded. Peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness were determined from the optic disc scans. Parafoveal VD and ganglion cell complex (GCC) thickness were measured from the macular scans. These parameters were compared between the groups using mixed effect models after adjusting for clinical confounders such as IOP, as well as SSI of the scans.

RESULTS

The 2 groups were demographically similar. Average RNFL (94µm vs 100µm, p = 0.01) and GCC (91µm vs 95µm, p = 0.03) were thinner in the PXF group compared to controls. The average peripapillary VD appeared lower in the PXF groups compared to controls (58.2% vs 58.8%, p = 0.04), but after adjusting for IOP and SSI, no difference was noted (p = 0.39). After accounting for confounders, parafoveal VD in the PXF group was significantly lower compared to controls (44.3% vs 46.8%, p = 0.008).

CONCLUSION

Peripapillary RNFL thickness, parafoveal GCC thickness and parafoveal VD were decreased in eyes with PXF when compared to controls. VD measurements are associated with the SSI and, therefore, clinicians and researchers evaluating OCTA scans quantitatively must consider the SSI value during analysis and interpretation.

Exfoliation Syndrome and Exfoliation Glaucoma in the Navajo Nation

(1) Background: Exfoliation syndrome (XFS) is a common cause of secondary open angle glaucoma. In 1971, Faulkner et al. estimated the prevalence of XFS among 50 Navajo Nation residents as 38%. Given that XFS can cause irreversible blindness secondary to glaucoma (XFG), this study aims to identify the current prevalence of XFS among Navajo Nation residents within the Four Corners region of the U.S. (2) Methods: A retrospective chart review was conducted from 2016 to 2021 for patients aged 18 and older. All patients with XFS or XFG diagnosed by slit lamp exam were identified through chart review. (3) Results: Of the 1152 patient charts available for review, eight patients (11 eyes) were diagnosed with XFS with three patients (4 eyes) demonstrating concomitant XFG. Within this XFS population, 50% of the patients identified as male, with a mean age of 73 years. The overall prevalence of XFS was 0.7% and the overall prevalence of XFG was found to be 0.26%. The rate of XFG among patients with XFS was 37.5%. (4) Conclusion: Compared to Faulkner's study of Navajo Nation residents in 1971, our findings show a considerably lower prevalence of XFS at 0.7%. We present the largest study to date of XFS among this population.

Peripapillary and fovea avascular zone optical coherence tomography angiography parameters in exfoliation glaucoma versus primary open-angle glaucoma versus healthy eyes

Purpose

To examine the differences in the peripapillary vascular parameters and foveal-avascular-zone (FAZ) vascularity parameters between primary open-angle-glaucoma (POAG) patients versus exfoliation-glaucoma (XFG) patients versus healthy subjects.

Methods

This is cross-sectional study and a comparative clinical study. POAG and XFG patients and healthy subjects underwent a comprehensive ophthalmic examination, including visual field optical coherence tomography (OCT) and OCT angiography (OCTA) of the optic disc and FAZ. Differences in peripapillary vessel density (VD), perfusion density (PD), and FAZ area and circularity were examined between all groups, as well as correlations between clinical parameters and vascularity parameters for each glaucoma group.

Results

A total of 109 subjects (one eye for each patient) were analyzed, including 45 with POAG, 30 with XFG, and 34 controls. The average peripapillary VDs were the lowest among the XFG patients and the highest among the controls (P < 0.05, ANOVA). The average peripapillary PD of the central ring was the lowest in the XFG group and the highest in the control group (P = 0.02, ANOVA). A significant negative correlation was found between the average peripapillary VDs and PDs of the inner ring and full ring and disease severity of the POAG patients. There was a significant positive correlation between the average peripapillary PDs of the central rings and full ring and the central macular thickness of the XFG patients (P < 0.01 and P < 0.04, respectively, Pearson correlation).

Conclusion

The peripapillary vascular parameters of the POAG and XFG patients were lower compared to those of normal participants. A correlation between clinical characteristics of POAG and XFG patients and PD was found. This may hint to a vascular mechanism in glaucoma either primary or secondary to intra-ocular pressure/OAG damage.

Clinical Characteristics and Stage at Presentation of Glaucoma Patients in Sub-Saharan Africa

PURPOSE

To explore regional variations in the presentation of newly diagnosed glaucoma in Sub Saharan Africa (SSA).

METHODOLOGY

This was a multi-centre, cross-sectional study in which newly diagnosed, consecutive, glaucoma patients aged ≥18 years were recruited from 27 eye clinics in 10 countries throughout SSA. Demographic and ophthalmic examination data were collected. Glaucoma severity was based on optic nerve head and visual field assessment. Statistical analyses were performed using STATA version 14.0.

RESULTS

Among 1214 enrolled patients with newly diagnosed glaucoma from Western, Eastern and Southern Africa, the overall mean (standard deviation) age was 59.9 (17.1) years. More than half of all patients (716/1178; 60.8%) presented with severe glaucoma in the worse eye, and one third (36.9%) had severe glaucoma in both eyes. Primary open-angle glaucoma was the commonest form of glaucoma in all regions (77.4%). A family history of blindness (260/1204, 21.6%) was common. Patients from Western Africa had lower mean presenting IOP (26.4 [11.1] mmHg, P <0.001), but had worse glaucoma in the better eye based on mean cup-disc ratio (0.8; P <0.001) and mean visual field mean deviation [10.4 (8.4)] dB, P =0.016) compared to other regions. Exfoliation glaucoma was more common in Eastern Africa (30/170=17.7%, P <0.001) compared to other regions.

CONCLUSION

The initial presentation of glaucoma varies meaningfully across SSA. A comprehensive strategy with regional customization based on local differences is needed to reduce glaucoma blindness in SSA.

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.

The role of microRNAs in glaucoma

In this review, we aim to provide a comprehensive summary of the various microRNAs (miRNAs) shown to be involved in glaucoma and intraocular pressure regulation. miRNAs are short, single-stranded, and noncoding RNAs that regulate gene expression in a number of physiological conditions and human diseases, including glaucoma. Numerous miRNAs display differential expression in glaucoma-affected tissues, such as aqueous humor, tears, trabecular meshwork, and retina analyzed from patients and animal models, suggesting their potential involvement in glaucoma pathogenesis. Several studies summarized here have also investigated the challenge of delivering intact miRNAs to target tissues in order to develop miRNA-based glaucoma therapies. We extend these reports by conducting an additional layer of analysis that integrates the interaction between glaucoma-related miRNAs and glaucoma-associated genes. We conclude with a comprehensive discussion of the therapeutic potential of miRNAs, the cellular pathways that link these miRNAs together, and the most promising miRNAs for future glaucoma research.

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.

Ganglion cell complex and macular thickness layers in primary open-angle glaucoma, pseudoexfoliation glaucoma and healthy eyes: A comparative study

PURPOSE

To investigate the differences in the ganglion cell complex (GCC) and macular thickness measurements between primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and healthy eyes with optical coherence tomography (OCT)optovue.

METHODS

In this non-randomized comparative cross-sectional study, 43 healthy eyes, 68 POAG eyes, and 57 PXG eyes were included. Patients were matched for age and disease severity. OCT angiography images were obtained for automated measurement of the GCC and macular thickness layers (inner and outer).

RESULTS

All GCC parameters were significantly difference between healthy and glaucomatous eyes (mild, and moderate to severe disease).There were no significant differences in GCC parameters between POAG and PXG patients except focal loss volume (FLV) after adjustment. Moderate to severe PXG eyes exhibited significantly lower GCC, larger global loss volume (GLV) values, and FLV values when compared with mild PXG eyes (p<= 0.05). We found significant thinning patterns in inner retinal thickness (fovea, parafovea, and perifovea), and total retinal thickness (parafovea, and perifovea) in moderate to severe PXG eyes when comparing with POAG eyes. Patients with moderate to severe PXG also showed significantly thinning patterns in inner retinal layers (fovea, parafovea and perifovea) and total retinal thickness (nasal parafovea) in compared to mild PXG.

CONCLUSION

It appears that GCC thickness is not significantly different between POAG and PXG except FLV. Despite similar retinal thickness in mild disease, a significant reduction in total and inner retinal thickness was demonstrated in moderate to severe PXG compared to moderate to severe POAG, in fovea, parafovea and perifovea region.

The haplotype of the CDKN2B-AS1 gene is associated with primary open-angle glaucoma and pseudoexfoliation glaucoma in the Caucasian population of Central Russia

PURPOSE

To replicate the finding of the association of five CDKN2B-AS1 gene polymorphisms (rs7865618, rs1063192, rs944800, rs2157719, and rs4977756) with primary open-angle glaucoma (POAG) and to analyze them for possible association with pseudoexfoliation glaucoma (PXFG) in a Caucasian population of Central Russia.

METHODS

A total of 932 participants of Russian ethnicity (self-reported), including 328 patients with PXFG, 208 patients with POAG (high-tension glaucoma), and 396 controls, were enrolled in the study. The SNPs were analyzed for possible associations using logistic regression.

RESULTS

Several haplotypes based on the studied SNPs were associated with POAG (three haplotypes) and PXFG (six haplotypes). Haplotype AAAGG of loci rs1063192-rs7865618-rs2157719-rs944800-rs4977756 conferred the highest risk for both POAG (OR = 3.99, р_perm = 0.001) and PXFG (OR = 2.84, р_perm = 0.001).

CONCLUSIONS

The CDKN2B-AS1 gene was associated with an increased risk of both POAG and PXFG in Caucasians of Central Russia. The gene may be related to the development of various types of glaucoma.

Metabolomics Reveals Differences in Aqueous Humor Composition in Patients With and Without Pseudoexfoliation Syndrome

Pseudoexfoliation syndrome (XFS) is stress- or inflammation-induced elastosis accompanied by excessive production of microfibrils and their deposition in the anterior segment of the eye. Approximately 60–70 million people are affected by XFS worldwide. It is a component of a systemic disorder, considered a major risk factor for accelerated cataract formation, cataract surgery complications and development of glaucoma, which untreated or inadequately treated may lead to blindness. Moreover, XFS has been associated with cardiovascular and cerebrovascular morbidity, dementia, sensorineural hearing loss and pelvic organ prolapse. The pathogenesis of XFS has not been fully elucidated yet. Aqueous humor (AH) is a transparent fluid filling the anterior and posterior chambers of the eye. Determination of AH metabolites that are characteristic for XFS may provide valuable information about the molecular background of this ocular disorder. The aim of this study was to compare the composition of AH in XFS and non-XFS patients undergoing cataract surgery. The AH samples from 34 patients (15 with XFS and 19 without) were analyzed using liquid chromatography coupled to a Quadrupole Time-of-Flight mass spectrometer (LC-QTOF-MS). The obtained metabolic fingerprints were analyzed using multivariate statistics. Eleven statistically significant metabolites were identified. Compared with the non-XFS group, the AH of patients with XFS contained significantly lower levels of amino acids and their derivatives, for example, arginine (−31%, VIP = 2.38) and homo-arginine (−19%, VIP = 1.38). Also, a decrease in the levels of two acylcarnitines, hydroxybutyrylcarnitine (−29%, VIP = 1.24) and decatrienoylcarnitine (−46%, VIP = 1.89), was observed. However, the level of indoleacetaldehyde in XFS patients was significantly higher (+96%, VIP = 2.64). Other significant metabolites were two well-recognized antioxidants, ascorbic acid (−33%, VIP = 2.11) and hydroxyanthranilic acid (−33%, VIP = 2.25), as well as S-adenosylmethionine, a compound with anti-inflammatory properties (−29%, VIP = 1.93). Metabolic pathway analysis demonstrated that the identified metabolites belonged to eight metabolic pathways, with cysteine and methionine metabolism as well as arginine and proline metabolism being the most frequently represented. XFS can be associated with enhanced oxidative stress and inflammation, as well as with the disturbances of cellular respiration and mitochondrial energy production. Implementation of non-targeted metabolomics provided a better insight into the still not fully understood pathogenesis of XFS.

Integral role for lysyl oxidase-like-1 in conventional outflow tissue function and behavior

Lysyl oxidase-like-1 (LOXL1), a vital crosslinking enzyme in elastin fiber maintenance, is essential for the stability and strength of elastic vessels and tissues. Variants in the LOXL1 locus associate with a dramatic increase in risk of exfoliation syndrome (XFS), a systemic fibrillopathy, which often presents with ocular hypertension and exfoliation glaucoma (XFG). We examined the role of LOXL1 in conventional outflow function, the prime regulator of intraocular pressure (IOP). Using Loxl1^-/- , Loxl1^+/- , and Loxl1^+/+ mice, we observed an inverse relationship between LOXL1 expression and IOP, which worsened with age. Elevated IOP in Loxl1^-/- mice was associated with a larger globe, decreased ocular compliance, increased outflow facility, extracellular matrix (ECM) abnormalities, and dilated intrascleral veins, yet, no dilation of arteries or capillaries. Interestingly, in living Loxl1^-/- mouse eyes, Schlemm's canal (SC) was less susceptible to collapse when challenged with acute elevations in IOP, suggesting elevated episcleral venous pressure (EVP). Thus, LOXL1 expression is required for normal IOP control, while ablation results in altered ECM repair/homeostasis and conventional outflow physiology. Dilation of SC and distal veins, but not arteries, is consistent with key structural and functional roles for elastin in low-pressure vessels subjected to cyclical mechanical stress.

Personalising surgical treatments for glaucoma patients

Surgical treatments for glaucoma have relied for decades on traditional filtering surgery such as trabeculectomy and, in more challenging cases, tubes. Antifibrotics were introduced to improve surgical success in patients at increased risk of failure but have been shown to be linked to a greater incidence of complications, some being potentially vision-threatening. As our understanding of glaucoma and its early diagnosis have improved, a more individualised management has been suggested. Recently the term "precision medicine" has emerged as a new concept of an individualised approach to disease management incorporating a wide range of individual data in the choice of therapeutic modalities. For glaucoma surgery, this involves evaluation of the right timing, individual risk factors, targeting the correct anatomical and functional outflow pathways and appropriate prevention of scarring. As a consequence, there is an obvious need for better knowledge of anatomical and functional pathways and for more individualised surgical approaches with new, less invasive and safer techniques allowing for earlier intervention. With the recent advent of minimally invasive glaucoma surgery (MIGS) a large number of novel devices have been introduced targeting potential new sites of the outflow pathway for lowering intraocular pressure (IOP). Their popularity is growing in view of the relative surgical simplicity and apparent lack of serious side effects. However, these new surgical techniques are still in an era of early experiences, short follow-up and lack of evidence of their superiority in safety and cost-effectiveness over the traditional methods. Each year several new devices are introduced while others are withdrawn from the market. Glaucoma continues to be the primary cause of irreversible blindness worldwide and access to safe and efficacious treatment is a serious problem, particularly in the emerging world where the burden of glaucoma-related blindness is important and concerning. Early diagnosis, individualised treatment and, very importantly, safe surgical management should be the hallmarks of glaucoma treatment. However, there is still need for a better understanding of the disease, its onset and progression, the functional and structural elements of the outflow pathways in relation to the new devices as well as their long-term IOP-lowering efficacy and safety. This review discusses current knowledge and the future need for personalised glaucoma surgery.

Systematic Analysis of Transcriptomic Profile of the Effects of Low Dose Atropine Treatment on Scleral Fibroblasts using Next-Generation Sequencing and Bioinformatics

This study has two novel findings: it is not only the first to deduct potential genes involved in scleral growth repression upon atropine instillation from a prevention point of view, but also the first to demonstrate that only slight changes in scleral gene expression were found after atropine treatment as side effects and safety reasons of the eye drops are of concern. The sclera determines the final ocular shape and size, constituting of scleral fibroblasts as the principal cell type and the major regulator of extracellular matrix. The aim of our study was to identify differentially expressed genes and microRNA regulations in atropine-treated scleral fibroblasts that are potentially involved in preventing the onset of excessive ocular growth using next-generation sequencing and bioinformatics approaches. Differentially expressed genes were functionally enriched in anti-remodeling effects, comprising of structural changes of extracellular matrix and metabolic pathways involving cell differentiation. Significant canonical pathways were correlated to inhibition of melatonin degradation, which was compatible with our clinical practice as atropine eye drops are instilled at night. Validation of the dysregulated genes with previous eye growth-related arrays and through microRNA-mRNA interaction predictions revealed the association of hsa-miR-2682-5p-KCNJ5 and hsa-miR-2682-5p-PRLR with scleral anti-remodeling and circadian rhythmicity. Our findings present new insights into understanding the anti-myopic effects of atropine, which may assist in prevention of myopia development.

Choroidal Microvascular Dropout in Pseudoexfoliation Glaucoma

Purpose

To compare the prevalence of choroidal microvasculature dropout (CMvD) in pseudoexfoliation glaucoma (PXG) and disease severity–matched primary open-angle glaucoma (POAG) eyes.

Methods

In a cross-sectional study, 39 eyes with PXG (33 patients) and 39 glaucoma severity–matched POAG eyes (34 patients) underwent visual fields, optical coherence tomography and optical coherence tomography angiography examination. Peripapillary vessel density (VD) was evaluated from the radial peripapillary capillary slab, parafoveal VD was measured on the superficial vascular plexus slab of the macula, and CMvD was evaluated on the choroidal slabs of the optic disc scan.

Results

The PXG and POAG groups were similar with respect to average mean deviation on visual fields (−12.1 vs. −12.0 decibel, P = 0.96) and average peripapillary retinal nerve fiber layer thickness on optical coherence tomography (71 vs. 74 μ, P = 0.29). Average peripapillary superficial VD (49.7% vs. 51.3%, P = 0.35) and parafoveal VD (44.8% vs. 45.8%, P = 0.33) were similar between the PXG and POAG groups. CMvD was seen in 18 PXG and 31 POAG eyes (46.2% vs. 79.5%, P = 0.002). On multivariate analysis that accounted for the severity of glaucoma, the odds of CMvD was significantly lower in the PXG group when compared with the POAG group (odds ratio: 0.18–0.21, P < 0.01).

Conclusions

The prevalence of CMvD was significantly lower in the PXG eyes when compared with the POAG eyes.

Effects of Oral Supplementation with Docosahexaenoic Acid (DHA) plus Antioxidants in Pseudoexfoliative Glaucoma: A 6-Month Open-Label Randomized Trial

PURPOSE

To assess the effects of antioxidant oral supplementation based on docosahexaenoic acid (DHA) in pseudoexfoliative (PEX) glaucoma.

PATIENTS AND METHODS

A prospective 6-month open-label randomized controlled trial was conducted in patients with PEX glaucoma and adequate intraocular pressure (IOP) control. Patients in the DHA group received a high-rich DHA (1 g) nutraceutical formulation. Ophthalmological examination, DHA erythrocyte membrane content (% total fatty acids), plasma total antioxidant capacity (TAC), plasma malondialdehyde (MDA), and plasma IL-6 levels were assessed.

RESULTS

Forty-seven patients (DHA group 23, controls 24; mean age 70.3 years) were included. In the DHA group, the mean IOP in the right eye decreased from 14.7 [3.3] mmHg at baseline to 12.1 [1.5] mmHg at 6 months (P=0.01). In the left eye, IOP decreased from 15.1 [3.3] mmHg at baseline to 12.2 [2.4] mmHg at 6 months (P=0.007). DHA erythrocyte content increased in the DHA group, with significant differences versus controls at 3 months and 6 months (8.1% [0.9] vs. 4.4% [0.7]; P < 0.0001). At 6 months and in the DHA group only, TAC levels as compared with baseline increased significantly (919.7 [117.9] vs. 856.9 [180.3] µM copper-reducing equivalents; P=0.01), and both MDA (4.4 [0.8] vs. 5.2 [1.1] nmol/mL; P  =  0.02) and IL-6 (2.8 [1.3] vs. 4.7 [2.3] pg/mL; P=0.006) levels were lower than in controls.

CONCLUSIONS

Targeting pathophysiology mechanisms of PEX glaucoma by reducing oxidative stress and inflammation with a high-rich DHA supplement might be an attractive therapeutic approach. Despite the short duration of treatment, decrease in IOP supports the clinical significance of DHA supplementation.

One-year follow-up of the XEN® implant with mitomycin-C in pseudoexfoliative glaucoma patients

PURPOSE

To evaluate the intraocular pressure-lowering effect, the safety profile, and the success rate of the XEN45 Gel Stent (Allergan, Dublin, Ireland) in patients with pseudoexfoliative glaucoma.

METHODS

Retrospective study conducted on patients with pseudoexfoliative glaucoma, with or without cataract, who underwent XEN45 implantation surgery with subconjunctival mitomycin-C and had a minimum postoperative follow-up period of 12 months. The primary outcome measure was intraocular pressure reduction at 1 year as compared to baseline. Complete success was defined as a postoperative intraocular pressure reduction of ⩾20% from preoperative baseline at 12 months without any glaucoma medications. Qualified success was defined as a postoperative intraocular pressure reduction of ⩾20% at 12 months with medications.

RESULTS

Of the 24 screened patients, 21 eyes of 20 patients met the inclusion/exclusion criteria and were included in the study. A total of 13 (62%) eyes underwent XEN alone surgery and 8 (38%) eyes had combined XEN + cataract surgery. Mean intraocular pressure was significantly reduced from 21.1 (3.8) mmHg at baseline to 15.2 (3.9) mmHg at 1 year, p < 0.001. Mean antiglaucoma medications dropped from 2.95 (0.97) preoperatively to 1.23 (1.22) at month 12 (p < 0.001). Of the 21 eyes included in the study, 18 (85.7%) were considered as success, 6 (28.6%) as complete success, and 12 (57.1%) as qualified success. Five eyes required needling revision. Complications included uveitis, choroidal detachment, hyphema, and cystoid macular edema in 2, 1, 1, and 1 eye, respectively.

CONCLUSION

XEN45 Gel Stent implant significantly reduced the intraocular pressure and the number of antiglaucoma medications in patients with pseudoexfoliative glaucoma.

Predictive Value of the Water Drinking Test and the Risk of Glaucomatous Visual Field Progression

PURPOSE

The purpose of this is to test the hypothesis the intraocular pressure (IOP) peaks during a stress test [the water drinking test (WDT)] can estimate the risk of future visual field progression in treated primary open-angle glaucoma (POAG) patients.

PATIENTS AND METHODS

Design: Prospective, longitudinal study.

SETTING

Clinical practice.

STUDY POPULATION

Treated POAG patients whose IOP was ≤18 mm Hg and who had no IOP-lowering interventions between the date of the WDT and the last eligible visual field.

INTERVENTION

At baseline examination, patients underwent the WDT and were then followed at regular intervals with office-based IOP measurements and visual field testing.

MAIN OUTCOME MEASURE

Cox-proportional hazards survival analysis testing the predictive value of IOP peaks during the WDT versus IOP measurements during office hours on visual field progression.

RESULTS

A total of 144 eyes of 96 patients with baseline visual field damage ranging from mild to severe followed for a mean of 28 months were analyzed. In the multivariable analysis adjusting for potential confounders, higher IOP peaks during the WDT were predictive of future visual field progression (hazard ratio=1.11; 95% confidence interval, 1.02 to 1.21; P=0.013). The average and peak IOP during office hours over the same follow-up period were not significantly associated with progression (P=0.651 and 0.569, respectively).

CONCLUSIONS

IOP peaks detected with the WDT were predictive of future visual field progression in a treated POAG population. This stress test could be a useful tool for risk assessment in daily practice.

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.

LOXL1 Gene Polymorphism With Exfoliation Syndrome/Exfoliation Glaucoma: A Meta-Analysis

AIM

There were several studies that have researched the associations between lysyl oxidase-like 1 (LOXL1) gene polymorphism and the susceptibility to exfoliation syndrome (XFS)/exfoliation glaucoma (XFG), but results have been inconclusive.

MATERIALS AND METHODS

A meta-analysis was performed for deriving more exact estimation of the relationship. Twenty-five studies were selected for studying rs1048661 and rs3825942. Sixteen studies were selected for studying rs2165241.

RESULTS

Single nucleotide polymorphism (SNP) rs1048661 was found to be associated with XFS/XFG, but the risk allele in white populations was found to be G, as opposite to the T allele in Japanese, Chinese, and Korean populations. The SNP rs3825942 was significantly associated with XFS in this black South African population. However, the AA genotype of rs3825942 confers XFS risk in this population, as opposed to the GG genotype described in all other populations. SNP rs2165241 was found to be associated with XFS/XFG, but the risk allele in white populations was found to be T, as opposite to the "C" allele in Japanese and Korean populations.

CONCLUSIONS

Our meta-analysis indicates that rs1048661 ("G" alleles) had weak association with XFG/XFS; rs3825942 ("G" alleles) had strongly association with XFG/XFS; and rs2165241("T" alleles) had significant risk with XFG/XFS in some ethnicity.

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.

Exome array analysis identifies CAV1/CAV2 as a susceptibility locus for intraocular pressure

PURPOSE

Intraocular pressure (IOP) is an important clinical parameter in the evaluation of ocular health. Elevated IOP is a major risk factor for primary open-angle glaucoma (POAG). The goal of this study was to identify rare and less common variants that influence IOP.

METHODS

We performed an exome array analysis in a subset of 1660 individuals from a population-based cohort, the Beaver Dam Eye Study. Associations with IOP were tested on 45,849 single nucleotide variants and 12,390 autosomal genes across the genome.

RESULTS

Intraocular pressure was suggestively associated with novel variants located in FAR2 at 12p11.22 (rs4931170, P = 1.2 × 10(-5)), in GGA3 at 17q25.1 (rs52809447, P = 6.7 × 10(-5)), and in PKDREJ at 22q13.31 (rs7291444, P = 7.4 × 10(-5)). Gene-based analysis found suggestive associations between IOP and the genes HAP1, MTBP, FREM3, and PHF12. We successfully replicated the associations with GAS7 (P = 7.4 × 10(-3)) for IOP, and also identified a previously reported POAG locus in the CAV1/CAV2 region to be associated with IOP (P = 3.3 × 10(-3)). This association was confirmed in a meta-analysis with three published genome-wide association studies (Pcombined = 4.0 × 10(-11)).

CONCLUSIONS

Our results suggest that novel genetic variants and genes with multiple, less common variants may play a role in the control of IOP. The implication of the caveolin genes, CAV1/CAV2, as a common genetic factor influencing both IOP variations and POAG may provide new insights of the underlying mechanism leading to glaucoma and glaucomatous visual field loss.

Relation between time spent outdoors and exfoliation glaucoma or exfoliation glaucoma suspect

PURPOSE

To evaluate the relation between time spent outdoors at various life periods and risk of exfoliation glaucoma or exfoliation glaucoma suspect.

DESIGN

Retrospective cohort study in the United States.

METHODS

Participants (49 033 women in the Nurses Health Study and 20 066 men in the Health Professionals Follow-up Study) were 60+ years old, were free of glaucoma and cataract, reported eye examinations, and completed questions about time spent outdoors in direct sunlight at midday at 3 life periods: high school to age 24 years, age 25-35 years, and age 36-59 years (asked in 2006 in women and 2008 in men). Participants were followed biennially with mailed questionnaires from 1980 women/1986 men to 2010. Incident cases (223 women and 38 men) were confirmed with medical records. Cohort-specific multivariable-adjusted rate ratios from Cox proportional hazards models were estimated and pooled with meta-analysis.

RESULTS

Although no association was observed with greater time spent outdoors in the ages of 25-35 or ages 36-59 years, the pooled multivariable-adjusted rate ratios for ≥11 hours per week spent outdoors in high school to age 24 years compared with ≤5 hours per week was 2.00 (95% confidence interval = 1.30, 3.08; P for linear trend = .001). In women, this association was stronger in those who resided in the southern geographic tier in young adulthood (P for interaction = .07).

CONCLUSIONS

Greater time spent outdoors in young adulthood was associated with risk of exfoliation glaucoma or exfoliation glaucoma suspect, supporting an etiologic role of early exposures to climatic factors.

FACE analysis as a fast and reliable methodology to monitor the sulfation and total amount of chondroitin sulfate in biological samples of clinical importance

Glycosaminoglycans (GAGs) due to their hydrophilic character and high anionic charge densities play important roles in various (patho)physiological processes. The identification and quantification of GAGs in biological samples and tissues could be useful prognostic and diagnostic tools in pathological conditions. Despite the noteworthy progress in the development of sensitive and accurate methodologies for the determination of GAGs, there is a significant lack in methodologies regarding sample preparation and reliable fast analysis methods enabling the simultaneous analysis of several biological samples. In this report, developed protocols for the isolation of GAGs in biological samples were applied to analyze various sulfated chondroitin sulfate- and hyaluronan-derived disaccharides using fluorophore-assisted carbohydrate electrophoresis (FACE). Applications to biologic samples of clinical importance include blood serum, lens capsule tissue and urine. The sample preparation protocol followed by FACE analysis allows quantification with an optimal linearity over the concentration range 1.0–220.0 µg/mL, affording a limit of quantitation of 50 ng of disaccharides. Validation of FACE results was performed by capillary electrophoresis and high performance liquid chromatography techniques.

Disruption of the blood-aqueous barrier and lens abnormalities in mice lacking lysyl oxidase-like 1 (LOXL1)

PURPOSE

Exfoliation syndrome (ES) is commonly associated with glaucoma, premature cataracts, and other ocular and systemic pathologies. LOXL1 gene variants are significantly associated with ES; however, the role of the protein in ES development remains unclear. The purpose of this study was to characterize the ocular phenotype in Loxl1(-/-) (null) mice.

METHODS

Loxl1 null mice and strain-matched controls (C57BL) were evaluated by clinical and histologic analyses.

RESULTS

Anterior segment histology showed a pronounced vesiculation of the anterior lens in the null mice. The lesions were subcapsular and in direct apposition with the posterior iris surface. Fluorescein angiography showed increased diffusion of fluorescein into the anterior chamber of the null mice compared with age-matched controls (P = 0.003, two-tailed, unequal variance t-test), suggesting compromise of the blood-aqueous barrier. Intraocular pressure measurements were within the normal range (16.5 ± 2.0 mm Hg) in null mice up to 1 year of age. Immunohistochemistry showed decreased elastin in the iris and ciliary body in the null mouse compared with controls.

CONCLUSIONS

Elimination of LOXL1 in mice impairs the blood-aqueous humor barrier in the ocular anterior segment and causes lens abnormalities consistent with cataract formation, but does not result in deposition of macromolecular material or glaucoma. These results show that mice lacking LOXL1 have some ES features but that complete disease manifestation requires other factors that could be genetic and/or environmental.

Visual field progression outcomes in glaucoma subtypes

PURPOSE

To determine whether glaucoma subtype is an independent risk factor for visual field (VF) progression.

METHODS

We reviewed the charts of glaucoma suspects and glaucoma patients seen in a referral practice between 1999 and 2009. Automated pointwise linear regression analysis determined the rates of VF change. A progression endpoint was determined when two or more adjacent test locations in the same hemifield showed a threshold sensitivity decline at a rate of ≥1.0 dB/year with p < 0.01.

RESULTS

We included 841 eyes (841 patients; mean age, 64.1 ± 12.6 years; mean number of VF tests, 10.8 ± 2.8; mean follow-up, 6.4 ± 1.7 years). The glaucomatous group consisted of angle-closure glaucoma (76 eyes), juvenile primary open-angle glaucoma (37 eyes), normal-tension glaucoma (81 eyes), pigmentary glaucoma (34 eyes), primary open-angle glaucoma (275 eyes) and exfoliative glaucoma (XFG, 84 eyes). Normal-tension glaucoma eyes were more likely to present with beta-zone parapapillary atrophy and disc haemorrhage (p < 0.01). Exfoliative glaucoma eyes had the fastest rates of global VF change (-0.65 dB/year), as well as the highest mean, fluctuation, and peak intraocular pressure during follow-up (16.5, 3.0 and 22.0 mmHg, respectively) and reached a progression endpoint more frequently (40%). After adjusting for all covariates, including the glaucoma phenotype, there was no difference among groups regarding global rates of VF change and the risk of reaching a progression endpoint.

CONCLUSIONS

Despite different clinical features, epidemiology and genetics, glaucoma phenotype is not an independent risk factor for VF progression. Rather, variations in well-known, reported risk factors remain important disease parameters that affect progression.

Demographic and geographic features of exfoliation glaucoma in 2 United States-based prospective cohorts

PURPOSE

To examine prospectively the association between demographic and geographic factors in relation to exfoliation glaucoma (EG) or exfoliation glaucoma suspect (EGS).

DESIGN

Prospective cohort study.

PARTICIPANTS

Seventy-eight thousand nine hundred fifty-five women in the Nurses' Health Study and 41 191 men in the Health Professionals Follow-up Study.

METHODS

Female and male health professionals were followed prospectively from 1980 through 2008 and from 1986 through 2008, respectively. Eligible participants were 40 years of age or older, did not have EG or EGS at baseline, and reported undergoing eye examinations during follow-up. Information regarding demographic features, lifetime geographic residence, and potential confounders was collected. During follow-up, 348 EG or EGS cases were confirmed with medical record review. The relative risk of EG or EGS in each cohort was estimated separately and the results were pooled with meta-analysis.

MAIN OUTCOME MEASURES

Multivariate rate ratios (MVRRs) of EG or EGS and their 95% confidence intervals (CIs).

RESULTS

Exfoliation glaucoma or EGS was strongly age related with subjects 75 years of age or older at 46.22-fold (95% CI, 22.77-93.80) increased risk compared with those between 40 and 55 years of age. Although men were 68% less likely to develop EG or EGS than women (MVRR, 0.32; 95% CI, 0.23-0.46), no predisposition to EG or EGS by ancestry, particularly Scandinavian ancestry, emerged. Compared with a lifetime of living in the northern tier of the continental United States, lifetime residence in the middle geographic tier (MVRR, 0.53; 95% CI, 0.40-0.71) and in the southern geographic tier (MVRR, 0.25; 95% CI, 0.09-0.71) was associated with markedly reduced risks of EG or EGS.

CONCLUSIONS

In this mainly white cohort from the United States, increasing age and female gender were significant risk factors for EG or EGS; however, Scandinavian heritage was not. Living in the middle or southern regions of the United States relative to living in the northern region was associated with a reduced risk of EG or EGS.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Molecular genetics in glaucoma

Glaucoma is a family of diseases whose pathology is defined by the progressive loss of retinal ganglion cells. Clinically, glaucoma presents as a distinctive optic neuropathy with associated visual field loss. Primary open-angle glaucoma (POAG), chronic angle-closure glaucoma (ACG), and exfoliation glaucoma (XFG) are the most prevalent forms of glaucoma globally and are the most common causes of glaucoma-related blindness worldwide. A host of genetic and environmental factors contribute to glaucoma phenotypes. This review examines the current status of genetic investigations of POAG, ACG, XFG, including the less common forms of glaucoma primary congenital glaucoma (PCG), the developmental glaucomas, and pigment dispersion glaucoma.