Purpose To investigate whether the area and shape of the foveal avascular zone (FAZ) as assessed by optical coherence tomography angiography (OCTA) are altered in glaucomatous eyes with central visual field defects (CVFDs). Methods A total of 78 patients with open-angle glaucoma with central or peripheral visual field defects (PVFDs) confined to a single hemifield were studied retrospectively. Foveal avascular zone area and circularity were measured using OCTA images from the superficial retinal layer. Central retinal visual field (VF) sensitivity using Swedish Interactive Threshold Algorithm 24-2 VF and macular ganglion cell-inner plexiform layer (mGCIPL) thickness were measured. The FAZ area between VF-affected hemimacular segments and VF-unaffected hemimacular segments in eyes with CVFDs and matched hemimacular segments of eyes with PVFDs were compared. Factors associated with the presence and severity of CVFD at initial presentation were determined. Results Eyes with CVFDs showed a significantly larger FAZ area, lower FAZ circularity, and lower mGCIPL thickness than the PVFD group. The mean hemi-FAZ area of VF-affected hemimaculas in eyes with CVFDs was significantly larger than that of the PVFD group (0.256 ± 0.07 mm2 vs. 0.184 ± 0.07 mm2) and the VF-unaffected hemimaculas of the CVFD group (0.179 ± 0.06 mm2; P < 0.05). Age, mean deviation, mGCIPL thickness, FAZ area, and circularity were associated with CVFDs (P < 0.05). Conclusions Microcirculatory alterations in the perifovea are spatially correlated with central VF loss. Loss of FAZ circularity was significantly associated with presence of CVFD, whereas FAZ area was significantly associated with severity of CVFD.

Alterations of the Foveal Avascular Zone Measured by Optical Coherence Tomography Angiography in Glaucoma Patients With Central Visual Field Defects.

Purpose To assess the relationship between the size of the foveal avascular zone (FAZ; area and perimeter) and vessel density (VD) at various retinal regions using optical coherence tomography angiography (OCTA) in patients with open-angle glaucoma (OAG). Methods In this retrospective cross-sectional study, OAG eyes were grouped according to the presence/absence of central visual field (CVF) defects. A control group of normal eyes was also included. OCTA images were obtained from the optic nerve (4.5 × 4.5 mm2) and macular (3 × 3 mm2) area, in which VDs were measured in the circumpapilla, parafovea, and fovea regions. Partial correlation analyses between FAZ parameters representing size and VDs at different retinal regions were performed. The correlation between FAZ parameters and macular ganglion cell-inner plexiform layer thickness (mGCIPLT) and CVF mean sensitivity (MS) was also assessed. For spatial correspondence, correlations between FAZ parameters and corresponding VD, mGCIPLT, and CVF-MS measurements were assessed at each hemiretina. Results A total of 126 OAG eyes and 40 controls were reviewed. Overall, FAZ parameters showed statistically significant correlations with VDs measured at the fovea, parafovea, and circumpapilla (FAZ area: r = -0.603, -0.385, -0.256; P < 0.001, < 0.001, and 0.003, respectively). These correlations were observed regardless of the presence of CVF defects (all P < 0.05). FAZ size showed significant spatial correlations with VD, mGCIPLT, and CVF-MS measurements at each hemiretina. Conclusions OCTA-derived FAZ area and perimeter showed statistically significant correlations with VDs measured at various retinal locations with spatial correspondence in OAG.

An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

Background: Non-communicable diseases (NCDs) such as hypertension and diabetes are rapidly emerging public health problems worldwide, and they associate with primary open-angle glaucoma (POAG). POAG is the most common cause of irreversible blindness. The most effective ways to prevent glaucoma blindness involve identifying high-risk populations and conducting routine screening for early case detection. This study investigated whether POAG associates with hypertension and diabetes in a Nepalese population. Methods: To explore the history of systemic illness, our hospital-based casecontrol study used non-random consecutive sampling in the general eye clinics in three hospitals across Nepal to enroll patients newly diagnosed with POAG and controls without POAG. The study protocol included history taking, ocular examination, and interviews with 173 POAG cases and 510 controls. Data analysis comprised descriptive and inferential statistics. Descriptive statistics computed the percentage, mean, and standard deviation (SD); inferential statistics used McNemar’s test to measure associations between diseases. Results: POAG affected males more frequently than females. The odds of members of the Gurung ethnic group having POAG were 2.05 times higher than for other ethnic groups. Hypertension and diabetes were strongly associated with POAG. The overall odds of POAG increased 2.72-fold among hypertensive and 3.50-fold among diabetic patients. Conclusion: POAG associates significantly with hypertension and diabetes in Nepal. Thus, periodic glaucoma screening for hypertension and diabetes patients in addition to opportunistic screening at eye clinics may aid in detecting more POAG cases at an early stage and hence in reducing avoidable blindness. Keywords: non-communicable disease (NCD); hypertension; diabetes mellitus; blindness; primary open-angle glaucoma (POAG) (Published: 4 November 2013) Citation: Glob Health Action 2013, 6 : 22636 - http://dx.doi.org/10.3402/gha.v6i0.22636

https://www.tandfonline.com/doi/pdf/10.3402/gha.v6i0.22636

Do non-communicable diseases such as hypertension and diabetes associate with primary open-angle glaucoma? Insights from a case-control study in Nepal

Glaucoma and ocular hypertension are major causes of vision loss worldwide. Recent clinical studies have highlighted the importance of central corneal thickness in diagnosing these disorders. However, current instrumental methods of measuring corneal thickness are not ideal for widespread clinical deployment. Here we compare the existing state of the art in corneal pachymetry with a novel, simple optical technique that will allow for the use of corneal pachymetry as a diagnostic tool in a non-research clinical setting.

A low-cost optical pachymeter for the diagnosis of glaucoma and ocular hypertension

Human eyes with exfoliation syndrome (XFS) exhibit a distinctive pattern of iris transillumination defects that are recapitulated in Lyst mutant mice carrying the beige allele. Here I present the identification and characterization of the B6-Lyst mouse model of XFS, modifiers of Lyst mediated ocular phenotypes, mechanisms of intraocular pressure (IOP) pathology related to circadian rhythms, and mechanisms of iris transillumination defects in the B6-Lyst mice. Clinical and histological analysis shows that the B6-Lyst mice have multiple similarities to human XFS including: iris transillumination defects, production of an exfoliative-like material, and pronounced pigment dispersion. Despite these insults, Lyst mutation does not cause increased IOP or optic nerve damage within the context of a C57BL/6J genetic background. However, defects in the circadian rhythm regulation of IOP were identified. Sequence analysis identifies that the beige mutation is predicted to delete a single isoleucine from the WD40 domain of the LYST protein. I identified CSNK2B as a binding partner of LYST and showed that LYST completely disrupts the interaction. CSNK2B function in regulating E-cadherin and β-catenin binding is subsequently disrupted. These results lead to a working hypothesis that aspects of the XFS phenotype involve LYST and CSNK2B pathways, likely influencing cell-cell adherens junctions. Epistasis experiments were used to test for genetic modifiers of Lyst, which demonstrated that albino Lyst mutant mice exhibited complete rescue of Lyst-dependent iris phenotypes. In a genetic background-driven approach, a DBA/2J strain of congenic mice was created. The DBA/2J background, which harbors multiple mutations influencing melanosomal-proteins, enhanced Lyst dependent iris phenotypes. Thus, both experimental approaches implicated melanosomes, a potential source of oxidative stress,

https://ir.uiowa.edu/cgi/viewcontent.cgi?article=2081&context=etd

Genetic pathways of Lyst and exfoliation syndrome

Glaucoma is a leading cause of blindness within the United States and the leading cause of blindness among African-Americans. Measurement of intraocular pressure only is no longer considered adequate for screening. Recognition of risk factors and examination of the optic nerve are key strategies to identify individuals at risk. Medical and surgical treatment of glaucoma have significantly improved in recent years. Early diagnosis and appropriate therapy will aid in reducing the potential of irreversible blindness.

Higginbotham Ej

Papers

Glaucoma: a preventable cause of blindness