Progress in understanding pseudoexfoliation syndrome and pseudoexfoliation-associated glaucoma

Corneal Endothelial Cell Loss in Glaucoma and Glaucoma Surgery and the Utility of Management with Descemet Membrane Endothelial Keratoplasty (DMEK)

The corneal endothelium has a crucial role in maintaining a clear and healthy cornea. Corneal endothelial cell loss occurs naturally with age; however, a diagnosis of glaucoma and surgical intervention for glaucoma can exacerbate a decline in cell number and impairment in morphology. In glaucoma, the mechanisms for this are not well understood and this accelerated cell loss can result in corneal decompensation. Given the high prevalence of glaucoma worldwide, this review aims to explore the abnormalities observed in the corneal endothelium in differing glaucoma phenotypes and glaucoma therapies (medical or surgical including with new generation microinvasive glaucoma surgeries). Descemet membrane endothelial keratoplasty (DMEK) is increasingly being used to manage corneal endothelial failure for glaucoma patients and we aim to review the recent literature evaluating the use of this technique in this clinical scenario.

Intraocular pressure changes after phacoemulsification in pseudoexfoliation versus healthy eyes

Background

Pseudoexfoliation (PXF) syndrome is the most common cause of secondary glaucoma worldwide. This systemic disorder causes further damage to the optic nerve and ultimately increases the need for surgical interventions. Therefore, intraocular pressure (IOP) control is very important in these patients. The aim of this study was to compare IOP changes after phacoemulsification in subjects with PXF syndrome compared to those without this syndrome.

Methods

61 patients were enrolled in this prospective clinical study. Subjects were assigned into two groups based on presence or absence of PXF syndrome. IOP and anterior chamber angle parameters including: angle opening distance (AOD) and trabecular-iris surface area (TISA) measured one day preoperatively and 3 months postoperatively. Intraoperative metrics factors including: infusion fluid usage (IFU), cumulative dissipated energy (CDE) and aspiration time (AT) were obtained from the phacoemulsification machine at the end of each surgery. IOP changes, anterior chamber angle parameters and intraoperative metrics factors were compared between groups.

Results

Mean IOP before surgery was significantly higher in the PXF group (14.70 mm Hg) compared to controls (12.87 mm Hg) (P-value < 0.01). Phacoemulsification decreased IOP in both, but to greater extent in the PXF group (p-value < 0.01). AOD and TISA also increased significantly following surgery in both groups. The results showed that postoperative IOP was negatively correlated with preoperative IOP in both groups (p-value < 0.01). Also, IOP after phacoemulsification was negatively correlated with IFU in the PXF group (p-value = 0.03).

Conclusions

Patients with PXF syndrome exhibited a reduction in IOP and increase in anterior chamber angle parameters after phacoemulsification. We observed a greater IOP reduction in PXF subjects when it was compared to controls. Higher preoperative IOP and intraoperative IFU were associated with more IOP reduction in the PXF group.

Multiple Gene Polymorphisms Associated with Exfoliation Syndrome in the Uygur Population

Background

Our previous data suggested that three single-nucleotide polymorphisms (SNPs), rs1048661, rs3825942, and rs2165241, of the lysyl oxidase-like 1 gene (LOXL1) are significantly associated with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG). The following study investigated other SNPs that potentially effect XFS/XFG.

Methods

A total of 216 Uygur patients diagnosed with XFS/XFG, and 297 Uygur volunteers were admitted to the First Affiliated Hospital at Xinjiang Medical University between January 2015 and October 2017. Blood samples were collected by venipuncture. Alleles and genotypes of LOXL1, TBC1D21, ATXN2, APOE, CLU, AFAP1, TXNRD2, CACNA1A, ABCA1, GAS7, and CNTNAP2 were analyzed by direct sequencing.

Results

The allele G of rs41435250 of LOXL1 was a risk allele for XFS/XFG (P < 0.001), whereas the allele G of rs893818 of LOXL1 was a protective allele for XFS/XFG (P < 0.001). After adjusting all data for age and gender, the following results were obtained: the frequency of genotype CC for rs7137828 of ATXN2 was significantly higher in XFS/XFG patients than in controls (P = 0.027), while no significance was found with reference to the frequency of genotype TT. The frequency of genotype GG for rs893818 of LOXL1 (P < 0.001) and the frequency of genotype AA were both significantly higher in XFS/XFG groups compared to the control group (P < 0.001). In addition, the frequency of genotype TT for rs41435250 of LOXL1 was higher in XFS/XFG patients than in controls (P = 0.003), while no significant difference was found with reference to the frequency of genotype GG after adjusting for age and gender. In addition, the haplotypes G-A/T-G/G-G for rs41435250 and rs893818 were significantly associated with XFS/G.

Conclusions

With reference to LOXL1, the rs41435250 resulted as a risk factor and rs893818 as a protective factor for XFS/XFG in the Uygur populations. Meanwhile, the rs16958445 of TBC1D21 and the rs7137828 of ATXN2 have also shown to be associated with pathogenesis of XFS/XFG.

Comparison of cytokine profiles in the aqueous humor of eyes with pseudoexfoliation syndrome and glaucoma

PURPOSE

To compare the cyto- and chemokine profiles in the aqueous humor of PEXS eyes in the absence or presence of secondary glaucoma with or without luxation of the intraocular lens (IOL).

METHODS

Samples of aqueous humor were collected intraoperatively from 20 healthy controls and from 73 eyes with PEX-syndrome, which was manifested in the absence of any other local or systemic desease. The latter group was sub-devided into eyes with an early form of PEX-syndrome in the absence of complications (PEX, n = 33), those with a late form of PEX-syndrome and glaucoma (PEXG, n = 30), and those with a late form of PEX-syndrome with luxation of the IOL that required surgery (PEXL, n = 10). The samples were analyzed in parallel after storage at -80°C. The levels of 40 cytokines were simultaneously quantified using the Bio-Plex® multiplex beads system. The inter-group data were statistically compared using the Kruskal-Wallis test (p ≤ 0.01).

RESULTS

PEX and PEXG were comparable in their cytokine profiles for all 40 cytokines, whereas the cytokine profile in PEXL-eyes revealed higher levels of all but 5 cytokines (CXCL13, CCL27, IL-2, CCL3, CCL20; p ≤ 0.01). This latter finding is indicative of a non-specific inflammatory reaction in the context of IOL-luxation. The concentrations of 6 cytokines lay below the detection limit in all groups.

CONCLUSIONS

The local up-regulation of 85% of the detectable cytokines in the aqueous humor of PEXL-eyes may be linked either with a progression of the disease or a breakdown of the antero-posterior barrier in the context of IOL-luxation.

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.