Pseudoexfoliation syndrome: analysis of systemic comorbidities of 325 PEX-positive patients compared with 911 PEX-negative patients

In Search of Mouse Models for Exfoliation Syndrome

PURPOSE

Exfoliation syndrome (XFS) is a systemic connective tissue disorder with elusive pathophysiology. We hypothesize that a mouse model with elastic fiber defects caused by lack of lysyl oxidase like 1 (LOXL1 encoded by Loxl1), combined with microfibril deficiency due to Fbn1 mutation (encoding fibrillin-1, Fbn1C1041G/+) will display ocular and systemic phenotypes of XFS.

METHODS

Loxl1-/- was crossed with Fbn1C1041G/+ to create double mutant (dbm) mice. Intraocular pressure (IOP), visual acuity (VA), electroretinogram (ERG), and biometry were characterized in 4 genotypes (wt, Fbn1C1041G/+, Loxl1-/-, dbm) at 16 weeks of age. Optic nerve (ON) area was measured by ImageJ, and axon counting was achieved by AxonJ. Deep whole-body phenotyping was performed in wt and dbm mice. Two-tailed Student t test was used for statistical analysis.

RESULTS

There was no difference in IOP between the 4 genotypes. VA was significantly reduced only in dbm mice. The majority of biometric parameters showed significant differences in all 3 mutant genotypes compared with wt, and dbm had exacerbated anomalies compared with single mutants. Dbm mice showed reduced retinal function and significantly enlarged ON area compared with wt. Dbm mice exhibited severe systemic phenotypes related to abnormal elastic fibers, such as pelvic organ prolapse and cardiovascular and pulmonary abnormalities.

CONCLUSIONS

Ocular and systemic findings in dbm mice support functional overlap between fibrillin-1 and LOXL1, 2 prominent components of exfoliation material. Although no elevated IOP or reduction of axon numbers was detected in dbm mice at 16 weeks of age, their reduced retinal function and enlarged ON area indicate early retinal ganglion cell dysfunction. Dbm mice also provide insight on the link between XFS and systemic diseases in humans. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Exploring Cognitive Impairments Associated with Primary Open-Angle Glaucoma and Exfoliation Glaucoma

This study explored the link between different types of glaucoma and cognitive function in a cohort of 620 Japanese patients. Participants were categorized into primary open-angle glaucoma (PG), exfoliation glaucoma (EG), and non-glaucomatous control groups. The findings revealed a significant decline in cognitive function as indicated by the Mini-Cog test in the EG group (mean ± SD: 4.0 ± 1, 95% CI: 3.9 to 4.2) compared to the PG group (4.4 ± 0.1, 4.3 to 4.5, p < 0.0001). Levels of fingertip measured advanced glycation end-products (AGEs) were significantly higher in the EG group (mean ± SD: 0.45 ± 0.006, 95% CI: 0.44 to 0.46) compared to the PG group (0.43 ± 0.004, 0.42 to 0.44, p = 0.0014). Although the multivariate analysis initially showed no direct association between glaucoma types and Mini-Cog scores, the EG group exhibited higher age and intraocular pressure (IOP) compared to the PG group. Further analysis revealed that high levels of AGEs were associated with cognitive decline and decreased mean visual fields in the EG group. Age was identified as a cofounding factor in these associations. An inverse correlation was observed between the accumulation of AGEs and skin carotenoid levels. Early detection of cognitive decline in glaucoma patients could enable timely intervention to preserve visual fields. Fingertip measurements of skin carotenoids and AGEs offer promising potential as non-invasive, straightforward diagnostic tools that could be widely adopted for monitoring ophthalmic and cognitive health in glaucoma patients.

Systemic Vascular Parameters in Ocular Pseudoexfoliation

Background Pseudoexfoliation syndrome (PEX) is characterized by a dandruff-like substance in the anterior chamber, composed of various glycoproteins that have an unclear origin. Its deposition is observed on the pupillary margin, lens zonules, and trabecular meshwork. Proteomic studies have identified numerous proteins in the affected individuals, suggesting associations with systemic conditions like heart disease, stroke, and Alzheimer's disease. However, the systemic associations of PEX remain inconclusive, particularly in regions like southern India. Materials and methods A cross-sectional study was conducted on 114 participants. Pseudoexfoliation was graded as mild, moderate, and severe as per standard photographic grading. Systemic examinations included blood pressure measurements, electrocardiography (ECG), and blood investigations for serum lipid profile, fasting and postprandial blood sugar levels, and serum C-reactive protein levels. Small incision cataract surgery was performed for all the patients. Intraoperative complications and postoperative status were recorded. Results Thirty-eight patients (33.3%) had mild PEX, 44 (38.6%) had moderate PEX, and 32 (28.1%) had severe PEX. Hypertension was present in 54 participants (47.4%), diabetes in 21 (18.4%), coronary artery disease in nine (7.9%), and cerebrovascular accidents in three (2.6%). The mean systolic blood pressure was 140.39 mmHg and the mean diastolic blood pressure was 90.37 mmHg. Systolic blood pressure exceeded 140 mmHg in 29 participants (90.6%) with severe PEX, while diastolic blood pressure surpassed 90 mmHg in 26 participants with severe PEX, both with a p-value of 0.001. Mean fasting and postprandial blood sugar levels were 103.80 ± 31.81 mg/dl and 131.72 ± 48.24 mg/dl, respectively. Serum lipid profiles showed mean low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), cholesterol, and triglyceride levels of 103.00 ± 34.49 mg/dl, 29.04 ± 15.51 mg/dl, 172.73 ± 43.34 mg/dl, and 129.33 ± 64.65 mg/dl respectively. Electrocardiographic results indicated that 54 participants (47.37%) had abnormal ECG including rate abnormality in 13.2%, conduction defects in 12.3%, ischemic changes in 10.5%, and structural defects in 11.4%. Eighty-seven percent of patients had non-dilating pupils and iris atrophy, 13.2% had zonular dialysis and intraoperatively, 78% had capsulorhexis extension, 49.12% had difficult nucleus prolapse, and 28.95% had posterior capsular rent. Conclusion This study highlights the significantly elevated parameters of systemic vascular diseases in PEX patients, like elevated blood pressure and more frequent cardiac anomalies, emphasizing the need for comprehensive systemic evaluation and careful preoperative assessment for ocular comorbidities.

Pseudoexfoliation Syndrome-Clinical Characteristics of Most Common Cause of Secondary Glaucoma

Pseudoexfoliation syndrome (XFS) is a condition in which excess material builds up not only in the structures of the anterior chamber but also throughout the body. The frequency of the syndrome varies significantly (0.3-18%) depending on the region and the method of examination. Environmental risk factors for XFS include a large number of sunny days, proximity to the equator, dietary factors such as higher consumption of coffee and tea, long-term alcohol consumption, exposure to UV, and outdoor work. The pathognomonic sign of XFS is the presence of white material on the lens capsule and other anterior chamber components. In addition, a characteristic Sampaolesi line can be observed during gonioscopy. Systemic alterations indicative of XFS have been observed in the extracellular matrix of the eyelid skin, the heart, lungs, liver, kidneys, gallbladder, meninges, and endothelium of the blood vessels. XFS is the most common cause of secondary open-angle glaucoma, which is called pseudoexfoliative glaucoma and is more severe than primary open-angle glaucoma. It is plausible that a combination of environmental factors and genetic alterations promotes the onset of pseudoexfoliation syndrome, which requires additional research.

Dynamic volume-rendered optical coherence tomography pupillometry

PURPOSE

To assess intrapupillary space (IPS) changes in healthy subjects with regard to decreased iris motility in patients with pseudoexfoliation glaucoma (PEXG) or non-arteritic anterior ischaemic optic neuropathy (NAION) in a feasibility study in a clinical environment.

METHODS

Scotopic and photopic IPS measurements using three-dimensionally rendered swept-source optical coherence tomography (SS-OCT) data were obtained and compared for all subjects. Intrapupillary space (IPS) parameters were evaluated such as absolute volumetric differences, relative light response for volumetric ratios and pupillary ejection fraction (PEF) for functional contraction measurements.

RESULTS

From a total of 122 IPS from 66 subjects, 106 IPS were eligible for comparison providing values for 72 normal, 30 PEXG and 4 NAION eyes. In healthy, PEXG and NAION subjects, scotopic overall mean IPS was 8.90, 3.45 and 4.16 mm³ , and photopic overall mean IPS was 0.87, 0.74 and 1.13 mm³ , respectively. Three-dimensional contractility showed a mean absolute difference of 8.03 mm³ for normals (defined as 100% contractility), 2.72 mm³ for PEXG (33.88% of normal) and 3.03 mm³ for NAION (38.50% of normal) with a relative light response ratio between scotopic and photopic volumes of 10.26 (100%), 4.69 (45.70%) and 3.67 (35.78%), respectively. Pupillary ejection fraction (PEF) showed a contractile pupillary emptying of 88.11% for normals, 76.92% for PEXG and 70.91% for NAION patients.

CONCLUSION

This 3D pupillometry OCT assessment allows for quantitative measurements of pupil function, contractility and response to light. More specifically, PEF is presented as a potential (neuro)-pupillary outcome measure that could be useful in the monitoring of ophthalmic disorders that affect pupillary function.

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.

A Case-Cohort Study of Exfoliation Risk Factors and Literature Review

The purpose of the study is to evaluate the risk factors associated with exfoliation in a case-cohort setting and literature review. This single-center, prospective, case-cohort study was carried out from January 2010 to April 2020 on patients operated for cataract surgery by a single surgeon in Lebanon. Forty-nine consecutive patients with exfoliation syndrome (XFS) and 62 consecutive control patients were identified and further investigated for selected systemic (diabetes mellitus, systemic hypertension, asthma, or atopy) and ocular variables (baseline vision, severity of nuclear sclerosis, glaucoma, eye rubbing, history of dry eye, or allergic eye disease). The mean baseline Snellen visual acuity was 20/283 in XFS versus 20/145 in control cases (P = 0.012). XFS also demonstrated significantly denser nuclear sclerosis than controls (P = 0.00958). By univariate analysis, allergic conjunctivitis (15 [30.6%] vs. 2 [3.2%]; P < 0.001), dry eye (20 [40.8%] vs. 13 [21.0%]; P = 0.0133), and habitual rubbing of the eyes (33 [67.3%] vs. 19 [30.6%]; P < 0.001) were associated with the presence of XFS. Habitual ocular rubbing was closely associated with allergic conjunctivitis (odds ratio [OR] = 13.0; 95% confidence interval [CI]: 2.8–58.8; P = 0.032). After multivariable analysis, the following variables showed significant results: glaucoma (OR = 34.5; 95% CI: 4.4–250; P = 0.010), duration of surgery (OR = 5.6; 95% CI 2.43–12.9; P < 0.001), and habitual ocular rubbing (OR = 4.42; 95% CI: 1.97–9.90; P = 0.029). This study shows a novel potential correlation between eye rubbing and XFS in a Lebanese cohort. Chronic eye rubbing induces or may exacerbate preexistent zonular damage in subjects with XFS, hence the need to better manage concurrent ocular surface disorder in these patients.

Significant lifespan difference between primary open-angle glaucoma and pseudoexfoliation glaucoma

PURPOSE

Open-angle glaucoma (OAG) is a collective term for various subgroups of glaucoma of which primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PEG) are the most common. There is increasing evidence that both conditions have systemic ramifications. We wanted to examine to what extent lifespan and cause of death are influenced by POAG, pseudoexfoliation syndrome (PES), and PEG.

MATERIALS AND METHODS

Of 1864 people who underwent an eye examination in 1985-86, the presence of PES and/or glaucoma, along with date and cause of death were recorded. Based on information from the National Death Registry, the individuals were classified into the following groups of systemic diseases regarded as causing death: Cardiovascular disease (with two subgroups), cerebrovascular disease and neoplasms.

RESULTS

All 1864 persons were followed to death, up to 30 years after examination. No difference in lifespan was observed when comparing OAG (i.e. POAG and PEG together) with the rest of the population. When adjusting for gender and age at inclusion, patients with POAG showed a reduced lifespan in the cardiovascular death group (2.44 years, p = 0.043). When comparing lifespan in the neoplastic group in the glaucoma patients, POAG and PEG, directly against each other, a mean age difference of 6.87 years (p = 0.017) was found.

CONCLUSIONS

POAG patients showed reduced lifespan due to neoplasia and cardiovascular disease. Persons with PES and PEG did not show these lifespan reductions. Our main conclusion is that POAG and PEG, the two main OAG subgroups, are very different disease entities both from an ocular and a systemic point of view.

The association between ethnicity, environmental and lifestyle factors and chronic disease in the development of pseudoexfoliation syndrome

Objectives

To determine the association between ethnicity, environmental factors, lifestyle factors, chronic diseases and pseudoexfoliation syndrome (PEX).

Methods

A case control study conducted at four major hospitals in Pakistan from January to November 2019, with 241 cases and 294 controls, aged ≥ 40 years, who were administered a questionnaire assessing demographics, lifestyle factors, chronic diseases and ethnicity. Multivariate binary logistic regression was applied to calculate the odds ratio between cases and controls.

Results

PEX was found to be positively associated with ethnicity (p<0.001), time spent outdoors (p<0.001), educational status (p<0.001), asthma (p<0.001), mean age (p<0.001), daily tea intake (p=0.003), weighted maximum temperature (p<0.001) and weighted mean temperature (p=0.004). Poor association was found with weighted latitude (p=0.526) and weighted minimum temperature (p=0.079). Odds ratios for patients with asthma (OR=7.366, regression coefficient=1.993, p<0.001) Pathan ethnicity (OR=1.616, regression coefficient=0.48, p=0.016) and mean weighted temperature (OR=0.907, regression coefficient-0.097, p=0 .000) were significant in diagnosed cases of PEX.

Conclusion

Individuals with Pathan ethnicity and asthmatics should be made aware of the risk of developing PEX and the importance of periodic screening. Limiting exposure to sunlight and cold and reducing the intake of tea may help in reducing in the chances of developing PEX.