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Cornea Mar 2024The aims of this study were to compare the scleral thickness (ST), lamina cribrosa thickness (LCT), and lamina cribrosa curvature index between patients with keratoconus...
PURPOSE
The aims of this study were to compare the scleral thickness (ST), lamina cribrosa thickness (LCT), and lamina cribrosa curvature index between patients with keratoconus and healthy controls and to evaluate the relationship between these values and corneal parameters.
METHODS
This cross-sectional study included 41 eyes of 41 patients with keratoconus and 30 eyes of 30 age-matched, sex-matched, and axial length-matched controls. Nasal and temporal STs were measured vertically, 4 mm posterior to the scleral spur, using anterior segment optical coherence tomography. The LCT was measured on the radial scans of the optic nerve head. The lamina cribrosa curvature index (lamina cribrosa curvature depth/curvature width × 100) was calculated to determine the degree of posterior bowing of the lamina cribrosa.
RESULTS
The nasal ST and temporal ST were significantly lower in the keratoconus group than in the control group ( P = 0.016 and P = 0.023, respectively). The LCT was significantly lower in the keratoconus group compared with the control group ( P < 0.001). There was no significant difference between the groups for the lamina cribrosa curvature index ( P = 0.375). Correlation analysis revealed a significant correlation between the nasal and temporal STs and the central corneal thickness (r = 0.376, P < 0.001 and r = 0.387, P < 0.001, respectively). There was also a significant correlation between the temporal ST and the minimum corneal thickness in the keratoconus group (r = 0.332, P = 0.015). The LCT was significantly correlated with the central corneal thickness (r = 0.445, P < 0.001).
CONCLUSIONS
Structural features of the cornea, sclera, and lamina cribrosa with similar collagen content may be similarly affected in patients with keratoconus. Further histologic studies are needed to confirm our results.
Topics: Humans; Keratoconus; Intraocular Pressure; Cross-Sectional Studies; Optic Disk; Cornea; Tomography, Optical Coherence
PubMed: 37607306
DOI: 10.1097/ICO.0000000000003366 -
Redox Biology Dec 2023Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is... (Review)
Review
Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.
Topics: Antioxidants; Reactive Oxygen Species; Eye; Oxidative Stress; Lens, Crystalline
PubMed: 38006824
DOI: 10.1016/j.redox.2023.102967 -
Molecular Aspects of Medicine Dec 2023Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision... (Review)
Review
Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision loss. Research in recent years has significantly enhanced our understanding of RGC degenerative mechanisms in glaucoma. It is evident that high intraocular pressure (IOP) is not the only contributing factor to glaucoma pathogenesis. The equilibrium of pro-survival and pro-death signalling pathways in the retina strongly influences the function and survival of RGCs and optic nerve axons in glaucoma. Molecular evidence from human retinal tissue analysis and a range of experimental models of glaucoma have significantly contributed to unravelling these mechanisms. Accumulating evidence reveals a wide range of molecular signalling pathways that can operate -either alone or via intricate networks - to induce neurodegeneration. The roles of several molecules, including neurotrophins, interplay of intracellular kinases and phosphates, caveolae and adapter proteins, serine proteases and their inhibitors, nuclear receptors, amyloid beta and tau, and how their dysfunction affects retinal neurons are discussed in this review. We further underscore how anatomical alterations in various animal models exhibiting RGC degeneration and susceptibility to glaucoma-related neuronal damage have helped to characterise molecular mechanisms in glaucoma. In addition, we also present different regulated cell death pathways that play a critical role in RGC degeneration in glaucoma.
Topics: Animals; Humans; Amyloid beta-Peptides; Glaucoma; Retina; Retinal Ganglion Cells; Cell Death; Disease Models, Animal
PubMed: 37856930
DOI: 10.1016/j.mam.2023.101216 -
Progress in Retinal and Eye Research Mar 2024Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much... (Review)
Review
Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much attention. Evidence has shown that high myopia is related to the development of glaucomatous or glaucoma-like optic neuropathy, and that both have many common features. These similarities often pose a diagnostic challenge that will affect the future management of glaucoma suspects in high myopia. In this review, we summarize similarities and differences in optic neuropathy arising from non-pathologic high myopia and glaucoma by considering their respective structural and functional characteristics on fundus photography, optical coherence tomography scanning, and visual field tests. These features may also help to distinguish the underlying mechanisms of the optic neuropathies and to determine management strategies for patients with high myopia and glaucoma.
Topics: Humans; Optic Disk; Intraocular Pressure; Glaucoma; Optic Nerve Diseases; Myopia; Tomography, Optical Coherence
PubMed: 38262557
DOI: 10.1016/j.preteyeres.2024.101246 -
Clinical & Experimental Optometry Mar 2024The use of optical coherence tomography angiography (OCTA) holds significant promise for optometrists in the diagnosis and management of glaucoma. It offers reliable... (Review)
Review
The use of optical coherence tomography angiography (OCTA) holds significant promise for optometrists in the diagnosis and management of glaucoma. It offers reliable differentiation of glaucomatous eyes from healthy ones and extends monitoring capabilities for advanced cases. OCTA represents a valuable addition to traditional assessment methods, particularly in complex cases. Glaucoma, a major cause of irreversible blindness, is traditionally diagnosed using structural and functional metrics. With growing interest, OCTA is being explored to diagnose, monitor, and manage glaucoma. This review focuses on the application of OCTA in glaucoma patients. A database search was carried out using Embase Elsevier ( = 664), PubMed ( = 574), and Cochrane Central Register of Controlled Trials ( = 19) on 15 August 2023. After deduplication and screening, 272 original papers were included in the narrative review. Inclusion criteria comprised English-language original studies on OCTA use in human glaucoma patients, with or without healthy controls. Exclusion criteria encompassed animal studies, in-vivo/in-vitro research, reviews, and congress abstracts. OCTA has good repeatability and reproducibility. OCTA metrics have good discriminatory power to differentiate glaucomatous eyes from healthy eyes and show strong associations with structural changes and visual field defects. OCTA can extend the monitoring of advanced glaucoma, addressing the 'floor effect' of traditional structural measurements. OCTA metrics can be affected by the choice of OCTA machine, post-image processing algorithms, systemic diseases, and ocular factors. Image artefacts can affect the accuracy of OCTA measurements, and proper scan quality evaluation is crucial to ensure reliable results. Additionally, artificial intelligence techniques offer promise for enhancing the diagnostic accuracy of OCTA by combining data from various retinal layers and regions. OCTA complements traditional methods in assessing glaucoma, especially in challenging cases, providing valuable insights for detection and management. Further research and clinical validation are needed to integrate OCTA into routine practice.
Topics: Humans; Optic Disk; Fluorescein Angiography; Tomography, Optical Coherence; Artificial Intelligence; Reproducibility of Results; Retinal Vessels; Retinal Ganglion Cells; Glaucoma
PubMed: 38266148
DOI: 10.1080/08164622.2024.2306963 -
European Journal of Ophthalmology May 2024Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment... (Review)
Review
Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. Although the outer retina appears to be mainly affected in this disorder, several evidences exhibit that also the inner retina may be impaired. In this review we will provide a description of the prominent histologic and imaging findings suggesting an inner retinal loss in these eyes. In details, structural optical coherence tomography (OCT) technology proved either the inner and outer retina is impacted by AMD and that these two impairments are associated. Therefore, the purpose of this review is to provide a description of the role of neurodegeneration in AMD in order to better understand the relationship between neuronal loss and the outer retinal damage in this disease.
Topics: Humans; Macular Degeneration; Tomography, Optical Coherence; Retinal Pigment Epithelium; Retina
PubMed: 37394731
DOI: 10.1177/11206721231186166 -
Translational Vision Science &... Jul 2023Glaucomatous optic neuropathy (GON) is the major cause of irreversible visual loss worldwide and can result from a range of disease etiologies. The defining features of...
Glaucomatous optic neuropathy (GON) is the major cause of irreversible visual loss worldwide and can result from a range of disease etiologies. The defining features of GON are retinal ganglion cell (RGC) degeneration and characteristic cupping of the optic nerve head (ONH) due to tissue remodeling, while intraocular pressure remains the only modifiable GON risk factor currently targeted by approved clinical treatment strategies. Efforts to understand the mechanisms that allow species such as the zebrafish to regenerate their retinal cells have greatly increased our understanding of regenerative signaling pathways. However, proper integration within the retina and projection to the brain by the newly regenerated neuronal cells remain major hurdles. Meanwhile, a range of methods for in vitro differentiation have been developed to derive retinal cells from a variety of cell sources, including embryonic and induced pluripotent stem cells. More recently, there has been growing interest in the implantation of glial cells as well as cell-derived products, including neurotrophins, microRNA, and extracellular vesicles, to provide functional support to vulnerable structures such as RGC axons and the ONH. These approaches offer the advantage of not relying upon the replacement of degenerated cells and potentially targeting earlier stages of disease pathogenesis. In order to translate these techniques into clinical practice, appropriate cell sourcing, robust differentiation protocols, and accurate implantation methods are crucial to the success of cell-based therapy in glaucoma. Translational Relevance: Cell-based therapies for glaucoma currently under active development include the induction of endogenous regeneration, implantation of exogenously derived retinal cells, and utilization of cell-derived products to provide functional support.
Topics: Animals; Zebrafish; Glaucoma; Optic Disk; Retina; Intraocular Pressure; Optic Nerve Diseases
PubMed: 37494052
DOI: 10.1167/tvst.12.7.23 -
Journal of Biomedical Optics Dec 2023The assessment of biomarkers in the eye is rapidly gaining traction for the screening, diagnosis, and monitoring of ocular and neurological diseases. Targeted ocular...
SIGNIFICANCE
The assessment of biomarkers in the eye is rapidly gaining traction for the screening, diagnosis, and monitoring of ocular and neurological diseases. Targeted ocular spectroscopy is a technology that enables concurrent imaging of the eye fundus and analysis of high-quality spectra from a targeted region within the imaged area. This provides structural, compositional, and functional information of specific regions of the eye fundus from a non-invasive approach to ocular biomarker detection.
AIM
The aim of our study was to demonstrate the multimodal functionality and validation of targeted ocular spectroscopy. This was done , using a reference target and a model eye, and .
APPROACH
Images and spectra from different regions of a reference target and a model eye were acquired and analyzed to validate the system. Targeted ocular fluorescence spectroscopy was also demonstrated with the same model. Subsequently, imaging and diffuse reflectance spectra were acquired to assess blood oxygen saturation in the optic nerve head and the parafovea of healthy subjects.
RESULTS
Tests conducted with the reference target showed accurate spectral analysis within specific areas of the imaging space. In the model eye, distinct spectral signatures were observed for the optic disc, blood vessels, the retina, and the macula, consistent with the variations in tissue composition and functions between these regions. An ocular oximetry algorithm was applied to spectra from the optic nerve head and parafovea of healthy patients, showing significant differences in blood oxygen saturation. Finally, targeted fluorescence spectral analysis was performed .
CONCLUSIONS
Diffuse reflectance and fluorescence spectroscopy in specific regions of the eye fundus open the door to a whole new range of monitoring and diagnostic capabilities, from assessment of oxygenation in glaucoma and diabetic retinopathy to photo-oxidation and photodegradation in age-related macular degeneration.
Topics: Humans; Fundus Oculi; Retina; Optic Disk; Oximetry; Spectrometry, Fluorescence
PubMed: 38111476
DOI: 10.1117/1.JBO.28.12.126004 -
Seminars in Ophthalmology Nov 2023Matrix metalloproteinases (MMPs) are important regulators of the extracellular matrix (ECM) and are involved in many stages of cellular growth and development. An... (Review)
Review
Matrix metalloproteinases (MMPs) are important regulators of the extracellular matrix (ECM) and are involved in many stages of cellular growth and development. An imbalance of MMP expression is also the basis of many diseases, including eye diseases, such as diabetic retinopathy (DR), glaucoma, dry eye, corneal ulcer, keratoconus. This paper describes the role of MMPs in the glaucoma and their role in the glaucomatous trabecular meshwork (TM), aqueous outflow channel, retina, and optic nerve (ON). This review also summarizes several treatments for glaucoma that target MMPs imbalance and suggests that MMPs may represent a viable therapeutic target for glaucoma.
Topics: Humans; Intraocular Pressure; Glaucoma; Trabecular Meshwork; Extracellular Matrix; Matrix Metalloproteinases; Aqueous Humor
PubMed: 37224230
DOI: 10.1080/08820538.2023.2211149 -
Experimental Eye Research Jul 2024Corneal neovascularization (CoNV) is a vision-threatening ocular disease commonly secondary to infectious, inflammatory, and traumatic etiologies. Slit lamp photography,... (Review)
Review
Corneal neovascularization (CoNV) is a vision-threatening ocular disease commonly secondary to infectious, inflammatory, and traumatic etiologies. Slit lamp photography, in vivo confocal microscopy, angiography, and optical coherence tomography angiography (OCTA) are the primary diagnostic tools utilized in clinical practice to evaluate the vasculature of the ocular surface. However, there is currently a dearth of comprehensive literature that reviews the advancements in imaging technology for CoNV administration. Initially designed for retinal vascular imaging, OCTA has now been expanded to the anterior segment and has shown promising potential for imaging the conjunctiva, cornea, and iris. This expansion allows for the quantitative monitoring of the structural and functional changes associated with CoNV. In this review, we emphasize the impact of algorithm optimization in anterior segment-optical coherence tomography angiography (AS-OCTA) on the diagnostic efficacy of CoNV. Through the analysis of existing literature, animal model assessments are further reported to investigate its pathological mechanism and exhibit remarkable therapeutic interventions. In conclusion, AS-OCTA holds broad prospects and extensive potential for clinical diagnostics and research applications in CoNV.
Topics: Corneal Neovascularization; Humans; Tomography, Optical Coherence; Animals; Fluorescein Angiography; Cornea; Microscopy, Confocal
PubMed: 38750782
DOI: 10.1016/j.exer.2024.109930