Electron microscopic immunohistochemistry of ocular and extraocular pseudoexfoliative material

Plasma adropin level in patients with pseudoexfoliation

The aim of this study was to evaluate plasma adropin levels in patients with pseudoexfoliation (PEX). This retrospective case-control study included 35 patients with PEX and 35 individuals without PEX who served as controls. Plasma adropin levels with triglycerides, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and haemoglobin A1c (HGBA1C) concentrations were measured in both groups. The mean serum adropin levels were 3.24 ± 0.95 ng/mL (range, 1.90-7.88 ng/mL) in patients with PEX syndrome and 5.78 ± 2.85 ng/mL (range, 2.08-5.41 ng/mL) in PEX glaucoma patients. There was no statistically significant difference in mean adropin levels between PEX syndrome and PEX glaucoma patients. However, similar adropin levels were found in the PEX glaucoma patients and the control group (P > 0.05). The mean serum adropin levels were 3.34 ± 0.89 ng/mL (range, 1.90-5.39 ng/mL) in the PEX group and 5.78 ± 2.85 ng/mL (range, 3.08-11.06 ng/mL) in the control group. The mean serum adropin level of the PEX group was significantly lower than that of the control group (P < 0.001). There were no significant differences between the two groups in terms of serum glucose, total cholesterol, LDL, HDL, HGBA1C, triglycerides levels, or body mass index (all P > 0.05). Adropin level is lower in patients with PEX.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Pseudoexfoliation syndrome and pseudoexfoliative glaucoma

BACKGROUND

Pseudoexfoliative glaucoma (PXG) is a common secondary glaucoma that occurs when pigment and abnormal basement membrane material from anterior segment anatomical structures deposit in the trabecular meshwork. This anomaly arises from the predisposing condition, pseudoexfoliation syndrome (PXE). Complications are common, making this one of the most difficult glaucomas to manage.

PURPOSE

The literature is reviewed in order to facilitate understanding of this condition.

Exfoliation syndrome

Exfoliation syndrome (XFS) is an age-related disease in which abnormal fibrillar extracellular material is produced and accumulates in many ocular tissues. Its ocular manifestations involve all of the structures of the anterior segment, as well as conjunctiva and orbital structures. Glaucoma occurs more commonly in eyes with XFS than in those without it; in fact, XFS has recently been recognized as the most common identifiable cause of glaucoma. Patients with XFS are also predisposed to develop angle-closure glaucoma, and glaucoma in XFS has a more serious clinical course and worse prognosis than primary open-angle glaucoma. There is increasing evidence for an etiological association of XFS with cataract formation, and possibly with retinal vein occlusion. XFS is now suspected to be a systemic disorder and has been associated preliminarily with transient ischemic attacks, stroke, systemic hypertension, and myocardial infarction. Further ramifications await discovery. Deposits of white material on the anterior lens surface are the most consistent and important diagnostic feature of XFS. The classic pattern consists of three distinct zones that become visible when the pupil is fully dilated. Whereas the classic picture of manifest XFS has been often described, the early stages of beginning exfoliation have not been well defined. Next to the lens, exfoliation material is most prominent at the pupillary border. Pigment loss from the iris sphincter region and its deposition on anterior chamber structures is a hallmark of XFS. Despite extensive research, the exact chemical composition of exfoliation material (XFM) remains unknown. An overproduction and abnormal metabolism of glycosaminoglycans have been suggested as one of the key changes in XFS. The protein components of XFM include both noncollagenous basement membrane components and epitopes of the elastic fiber system such as fibrillium. Regardless of etiology, typical exfoliation fibers have been demonstrated electron microscopically in close association with the pre-equatorial lens epithelium, the nonpigmented ciliary epithelium, the iris pigment epithelium, the corneal endothelium, the trabecular endothelium, and with almost all cell types of the iris stroma, such as fibrocytes, melanocytes, vascular endothelial cells, pericytes, and smooth muscle cells. The presence of XFS should alert the physician to the increased risks of intraocular surgery, most commonly zonular dehiscence, capsular rupture, and vitreous loss during cataract extraction. Heightened awareness of this condition and its associated clinical signs are important in the detection and management of glaucoma, and preoperative determination of those patients at increased risk for surgical complications.

Exfoliation syndrome and exfoliation glaucoma

Exfoliation syndrome abnormal deposition in the anterior segment of the eye of an unknown substance thought to be related to elastic fibres and basement membrane components is associated with accelerated cataract progression. increased frequency of intraoperative and postoperative complications and increased risk for glaucoma and. therefore, is a clinically important finding. A clear association has been shown with age. The syndrome occurs worldwide but its prevalence seems to vary from country to country. The best-known sign of exfoliation syndrome is deposits of greyish-white material on the anterior lens surface. Sometimes exfoliation material can also be seen at the pupillary border, on the anterior iris surface, corneal endothelium, and on the anterior vitreous face. When clinically detected, exfoliation syndrome is somewhat more often unilateral than bilateral. According to recent investigations clinically unilateral exfoliation syndrome is probably never truly unilateral but rather asymmetric, because exfoliation material has been detected ultrastructurally and immunohistochemically around iris blood vessels of the nonexfoliative fellow eyes. Indeed, electron microscopy identifies in various organs of patients with exfoliation syndrome fibrils similar to those seen in intraocular exfoliation deposits. Other clinical signs associated with exfoliation syndrome are pigment dispersion, transillumination defects of the iris and reduced response to mydriatics. In unilateral exfoliation syndrome, intraocular pressure (IOP) of the exfoliative eye is approximately 2 mmHg higher than IOP of the nonexfoliative fellow eye. Whether elevated IOP, vascular changes or exfoliation syndrome itself is the main factor causing optic nerve head damage and conversion of an exfoliative eye to glaucomatous, is not known. Glaucoma in the exfoliation syndrome has been shown to have a more serious clinical course than in primary open-angle glaucoma (POAG). At the time of diagnosis, IOP and its diurnal variation are generally higher and visual field defects tend to be greater in exfoliation glaucoma than in POAG. Because the decrease in lOP variation and lowering of the mean IOP level has been shown to improve visual field prognosis more in exfoliation glaucoma than in POAG, the glaucomatous process is considered to be more pressure-related in exfoliation glaucoma. Furthermore, progression of optic disc damage has been shown to be similar in exfoliation glaucoma and POAG when lOPs are lowered to a comparable level by the treatment. However, vascular disturbances in the posterior segment of the eye might after all be of equal importance in these two types of glaucoma; optic disc haemorrhages and venous occlusions have been reported to be as frequent in exfoliation glaucoma as in POAG. Perhaps in exfoliation glaucoma circullatory disturbances combined with high IOP lead to a particularly relentlessly progressing form of the disease.

Cardiovascular and cerebrovascular mortality associated with ocular pseudoexfoliation

PURPOSE

In recent years, several studies have shown the presence of vascular, cardiac, and other organ pseudoexfoliative material in patients with ocular pseudoexfoliation. The purpose of this study was to determine whether an association exists between ocular pseudoexfoliation and cardiovascular, cerebrovascular, or all-cause mortality.

METHODS

This retrospective study included 472 residents of Olmsted County, Minnesota, who were diagnosed with pseudoexfoliation syndrome or pseudoexfoliative glaucoma at Mayo Clinic from 1976 through 1995. Of these 472 cases, 151 subsequently died from 1976 through 1997. Cause of death for these patients, as determined by the National Center for Health Statistics was compared with the entire Rochester, Minnesota, population using Kaplan-Meier analysis.

RESULTS

Of the 472 patients with ocular pseudoexfoliation, 358 (76%) were female and 114 (24%) were male. The mean age at diagnosis was 74 years, with a SD of 10 years and a range from 39 to 106 years. Cardiovascular disease resulted in 40 deaths, with a 15-year cumulative probability of cardiovascular mortality of 22%, compared with an expected 20% (no significant difference with P = .19). Cerebrovascular disease resulted in 26 deaths with a 15-year cumulative probability of cerebrovascular mortality of 12%, compared with an expected 10% (no significant difference with P = .38). Finally, the 15-year observed all-cause cumulative mortality was 53% versus an expected rate of 59% (significant difference with P = .0002).

CONCLUSIONS

No association was found between ocular pseudoexfoliation and cardiovascular or cerebrovascular mortality. All-cause mortality was significantly less in patients with ocular pseudoexfoliation.