| Knowledge-base domain | Evidence-based summary | Key quantitative values | Suggested ontology annotations | Evidence |
|---|---|---:|---|---|
| Identity and definition | Exfoliation syndrome (XFS; pseudoexfoliation syndrome, PXS/PEX) is a late-onset, systemic extracellular-matrix disorder characterized by progressive production and deposition of abnormal fibrillar exfoliation material, with clinically dominant manifestations in the ocular anterior segment. Exfoliation glaucoma (XFG/PXG) is the secondary open-angle glaucoma that may complicate XFS; it is not synonymous with uncomplicated XFS. | Estimated prevalence varies geographically from **<0.4% to >20%**; approximately **80 million** people may be affected worldwide. | **MONDO:0008327** exfoliation syndrome; MeSH concept: pseudoexfoliation syndrome; HPO: **HP:0003584** late onset | (pqac-00000000, pqac-00000003, pqac-00000007, pqac-00000012) |
| Genetics | XFS is a complex, polygenic susceptibility disorder—not a proven Mendelian LOXL1 disease. Common coding and regulatory variants in **LOXL1** are the strongest replicated associations, but risk-allele reversal and high risk-allele frequencies across ancestries preclude classification as individually pathogenic variants. Additional GWAS loci include **CACNA1A, POMP, TMEM136, AGPAT1, RBMS3,** and **SEMA6A**. A rare LOXL1 coding variant was reported as protective. | 2017 GWAS: **9,035 cases and 17,008 controls** across 25 strata; initial LOXL1 SNP ORs reported in the range **2.46–20.10**. A 2021 meta-analysis included **5,022 cases and 8,962 controls**. | HGNC genes: **LOXL1, CACNA1A, POMP, TMEM136, AGPAT1, RBMS3, SEMA6A**; GO: extracellular-matrix organization, elastic-fiber assembly | (pqac-00000000, pqac-00000008, pqac-00000009, pqac-00000012) |
| Environment and gene–environment interaction | Age is the dominant non-genetic risk factor. Latitude, cold climate, greater summer outdoor exposure, reflected light over snow or water, UV-related skin-cancer history, heavy coffee intake, and low folate have observational associations. UV can induce LOXL1 and matrix responses experimentally, supporting—but not proving—a LOXL1–UV interaction. Sunglasses are a plausible protective exposure, but no intervention trial demonstrates prevention. | Each degree farther from the equator: OR **1.11** (95% CI 1.05–1.17); each additional summer outdoor hour/week: OR **1.04** (1.00–1.07); US work over snow/water: OR **3.86** (1.36–10.9); each 1% increase in sunglasses use: OR **0.98** (0.97–0.99), not replicated in Israel. | Exposure concepts: ultraviolet radiation, cold temperature, outdoor occupational exposure; CHEBI candidates for research annotation: folate, homocysteine, caffeine | (pqac-00000023, pqac-00000024, pqac-00000025, pqac-00000029) |
| Core ocular phenotypes | Characteristic manifestations are white-gray fibrillar deposits on the anterior lens capsule and pupillary margin, iris depigmentation and peripupillary transillumination, poor pharmacologic mydriasis, trabecular hyperpigmentation, elevated or fluctuating intraocular pressure, zonular weakness, phacodonesis, lens subluxation/dislocation, cataract, and reduced corneal endothelial-cell density. Disease may appear unilateral but is often biologically asymmetric and ultimately bilateral. | Approximately **44%** has been estimated to progress to XFG, although estimates vary by cohort. | HPO suggestions: glaucoma, increased intraocular pressure, visual-field defect, cataract, lens subluxation, poor pupillary dilation, iris transillumination defect; UBERON: anterior lens capsule, iris, ciliary body, trabecular meshwork, zonular fibers, corneal endothelium | (pqac-00000000, pqac-00000006, pqac-00000007, pqac-00000019) |
| Mechanism | Genetic susceptibility and aging, potentially amplified by UV, oxidative stress, and low-grade inflammation, alter **TGF-β–LOXL1** signaling and elastic-fiber/ECM homeostasis. Increased or dysregulated matrix synthesis, LOXL1 misfolding, impaired proteasome–autophagy–lysosome clearance, mitochondrial dysfunction, and reduced antioxidant defense promote extracellular fibril accumulation. Deposits and liberated iris pigment obstruct trabecular outflow, raising intraocular pressure; sustained pressure and vascular/oxidative stress then cause retinal-ganglion-cell and optic-nerve injury. Several upstream links remain inferred rather than proven. | Early XFS aqueous-humor **IL-6 and IL-8 were about threefold higher** than controls. Lens-capsule RNA-seq identified **2,882 differentially expressed genes** in **25 XFS vs 39 controls**. | GO: extracellular-matrix organization, elastic-fiber assembly, response to oxidative stress, autophagy, lysosomal transport, mitochondrial respiratory-chain activity, TGF-β signaling; CL: lens epithelial cell, non-pigmented ciliary epithelial cell, iris pigment epithelial cell, trabecular-meshwork cell, fibroblast, retinal ganglion cell | (pqac-00000002, pqac-00000003, pqac-00000005, pqac-00000011) |
| Diagnosis | Diagnosis is clinical by slit-lamp examination before and after dilation, looking for exfoliation material, the classic lens-capsule pattern, pupillary-border deposits, poor dilation, transillumination defects, and zonular instability. Tonometry, gonioscopy, optic-disc examination, OCT retinal-nerve-fiber/ganglion-cell analysis, and automated perimetry stage ocular hypertension or XFG. There is no validated blood, genetic, omics, biopsy, imaging, or molecular test for routine diagnosis. | No standardized molecular diagnostic threshold or clinically validated predictive genetic test is available. | SNOMED/LOINC domains: slit-lamp examination, intraocular pressure, gonioscopy, automated visual-field testing, optic-nerve OCT | (pqac-00000006, pqac-00000007, pqac-00000009, pqac-00000012) |
| Prognosis and burden | XFS itself does not have an established disease-specific mortality effect, but it confers substantial ocular morbidity through XFG, cataract, zonular failure, and surgical complications. XFG generally has higher pressure, greater fluctuation, poorer medical response, and faster visual-field deterioration than primary open-angle glaucoma. | Three-year study: mean-deviation change **−3.17 dB** in XFG vs **−1.25 dB** in POAG; progression by guided progression analysis **58% vs 13%**. Indian tertiary cohort: XFG in **29%** of 6,284 XFS eyes and overall absolute blindness **28.2%** at presentation. | HPO: progressive visual-field loss, optic atrophy/glaucomatous optic neuropathy, visual impairment, blindness | (pqac-00000000, pqac-00000009) |
| Treatment and implementation | No therapy removes exfoliation material or modifies the underlying systemic matrix disease. Uncomplicated XFS requires surveillance. XFG is treated by lowering intraocular pressure with standard topical agents, selective laser trabeculoplasty (SLT), lens extraction when indicated, trabeculectomy, drainage implants, or selected minimally invasive procedures. Cataract surgery requires anticipation of poor dilation and zonular weakness, with iris-expansion devices, capsular hooks, or capsular-tension rings as needed. | 2024 SLT series: IOP **26.7→18.9 mmHg** at 3 months, **29.2%** reduction, **69.4%** success. PreserFlo series: IOP **32.6→16.9 mmHg**, medications **3.4→1.0**, but **31%** reoperation and **17%** hypotony. Croatian registry: PEX cataract surgery cost **1.4-fold higher**. | NCIT suggestions: ophthalmic solution, selective laser trabeculoplasty, phacoemulsification, trabeculectomy, glaucoma drainage implant, minimally invasive glaucoma surgery, capsular-tension ring placement | (pqac-00000013, pqac-00000019, pqac-00000020, pqac-00000021, pqac-00000022) |
| Research and evidence gaps | Major gaps include the initiating lesion, functional interpretation of ancestry-dependent LOXL1 alleles, validated gene–environment interactions, reliable conversion biomarkers, single-cell and spatial atlases, faithful animal models, and disease-modifying therapy. Existing omics studies are generally small and require independent, multi-ancestry replication. Active implementation research includes phacoemulsification versus SLT and cataract surgery plus iStent versus SLT; completed XEN45 real-world evidence enrolled 350 participants, but the registry excerpt did not provide numerical outcomes. | Prediagnostic metabolomics: **205 incident XFG cases and 205 controls**, mean **11.8 years** before diagnosis; cortisone OR **0.49 per SD** (95% CI 0.32–0.74). CANPEX1: planned **n=200**; iStent-versus-laser trial: planned **n=285**; XEN45 observational study: **n=350**. | Study annotations: bulk RNA sequencing, metabolomics, prospective cohort study, randomized controlled trial, model-organism limitation | (pqac-00000003, pqac-00000010, pqac-00000011, pqac-00000014, pqac-00000015, pqac-00000021) |


*Table: Compact evidence-based summary of exfoliation syndrome identity, risk architecture, phenotypes, mechanism, diagnosis, prognosis, management, and research gaps. Quantitative findings and suggested knowledge-base ontology annotations are included.*