Imaging of vascular abnormalities in ocular surface disease

Fluorescent Pdots Facilitate High-Resolution Mapping of the Intact Meningeal Vascular Network and Eye-Brain Connections

Meningeal vascular network is significant in neurology and neurosurgery. However, high-resolution imaging of intact meningeal vascular network is lacking. In this work, we develop a practical experimental method to ensure that the intact meninges are morphologically unfolded and fixed in an agarose gel. With the help of high-brightness polymer dots (Pdots) as probe, macroscopic and detailed imaging of the vascular network on the intact dorsal meninges can be performed. Meningeal vessels are symmetrically distributed along the superior sagittal sinus, and the distribution of meningeal vessels had a certain degree of hierarchy. The meninges are thicker blood vessels and capillary networks from the outside to the inside. Moreover, the diameter of the capillaries is 3.96 ± 0.89 μm. Interestingly, meningeal primo vessels in the central nervous system of mice is imaged with the diameter of 4.18 ± 1.18 μm, which has not been reported previously. It is worth mentioning that we found that orthotopic xenografts of brain tumors caused the appearance of corneal neovascularization and morphological changes in optic nerve microvessels. In conclusion, our work provides an effective Pdots-based imaging method for follow-up research on meningeal vascular-related diseases, and illustrates that the eye can serve as a window for the prevention and diagnosis of brain diseases.

Recent advances in corneal neovascularization imaging

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.

Molecular and epigenetic mechanisms governing ocular surface squamous neoplasia: opportunities for diagnostics

INTRODUCTION

Ocular surface squamous neoplasia (OSSN) is the most common ocular malignancy; the pathophysiology is influenced by molecular, genetic, and epigenetic mechanisms. The incidence of OSSN is associated with the anatomy and physiology of the ocular surface, limbal stem cell configuration, limbal vulnerability, cancer stem cells, dysplasia, neoplasia, angiogenesis, invasion, and metastasis. The key etiological factors involved are human papillomavirus (HPV), human immunodeficiency virus (HIV), immunosuppression, p53 tumor suppressor gene, hypovitaminosis A, and failure of Deoxyribonucleic acid (DNA) repair mechanisms.

AREAS COVERED

This special report is a focussed attempt to understand the molecular mechanism, genetic and epigenetic mechanism, and diagnostic modalities for OSSN.

EXPERT OPINION

While these mechanisms contribute to genome instability, promoter-specific hypermethylation might facilitate and promote tumor formation by silencing tumor suppressor genes. OSSN understanding has improved with increased literature available on various genetic, molecular, and epigenetic mechanisms, although the exact genetic and epigenetic mechanisms still need to be elucidated. It is important to note that the molecular mechanisms of OSSN can vary among individuals, and further research is required to elucidate the underlying processes fully. Understanding these mechanisms is crucial for the development of targeted therapies and improved management of OSSN.

Promotor methylation in ocular surface squamous neoplasia development: epigenetics implications in molecular diagnosis

INTRODUCTION

Cancer is heavily influenced by epigenetic mechanisms that include DNA methylation, histone modifications, and non-coding RNA. A considerable proportion of human malignancies are believed to be associated with global DNA hypomethylation, with localized hypermethylation at promoters of certain genes.

AREA COVERED

The present review aims to emphasize on recent investigations on the epigenetic landscape of ocular surface squamous neoplasia, that could be targeted/explored using novel approaches such as personalized medicine.

EXPERT OPINION

While the former is thought to contribute to genomic instability, promoter-specific hypermethylation might facilitate tumorigenesis by silencing tumor suppressor genes. Ocular surface squamous neoplasia, the most prevalent type of ocular surface malignancy, is suggested to be affected by epigenetic mechanisms, as well. Although the exact role of epigenetics in ocular surface squamous neoplasia has mostly been unexplored, recent findings have greatly contributed to our understanding regarding this pathology of the eye.

Diabetic Retinopathy: Soluble and Imaging Ocular Biomarkers

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, represents the leading cause of acquired blindness in the working-age population. Due to the potential absence of symptoms in the early stages of the disease, the identification of clinical biomarkers can have a crucial role in the early diagnosis of DR as well as for the detection of prognostic factors. In particular, imaging techniques are fundamental tools for screening, diagnosis, classification, monitoring, treatment planning and prognostic assessment in DR. In this context, the identification of ocular and systemic biomarkers is crucial to facilitate the risk stratification of diabetic patients; moreover, reliable biomarkers could provide prognostic information on disease progression as well as assist in predicting a patient's response to therapy. In this context, this review aimed to provide an updated and comprehensive overview of the soluble and anatomical biomarkers associated with DR.

Assessment of Corneal Angiography Filling Patterns in Corneal Neovascularization

The purpose of the paper is to describe vascular filling patterns in corneal neovascularization (CoNV) and evaluate the effect of corneal lesion location, CoNV surface area and multi-quadrant CoNV involvement on the filling pattern. It is a retrospective study of patients who were investigated for CoNV using fluorescein angiography (FA) or indocyanine green angiography (ICGA) between January 2010 and July 2020. Angiography images were graded and analyzed multiple independent corneal specialists. The corneal surface was divided into four quadrants and patient information was obtained through electronic records. A total of 133 eyes were analyzed. Corneal lesions were located on the peripheral (72%) or central (28%) cornea. Central lesions were associated with multi-quadrant CoNV more frequently than peripheral lesions (p = 0.15). CoNV located within the same quadrant of the corneal lesion was often first to fill (88.4%). In multi-quadrant CoNV, the physiological inferior-superior-nasal-temporal order of filling was usually respected (61.7%). Central lesions resulted in larger CoNV surface area than peripheral lesions (p = 0.09). In multi-quadrant CoNV, the largest area of neovascularization was also the first to fill in (peripheral lesion 74%, central lesion 65%). Fillings patterns in healthy corneas have previously been reported. Despite CoNV development, these patterns are usually respected. Several factors that may influence filling patterns have been identified, including corneal lesion location, CoNV surface area and aetiology of CoNV. Understanding filling patterns of neovascularization allows for the identification of areas at higher risk of developing CoNV, aiding in earlier detection and intervention of CoNV.

High-Resolution Imaging of the Ocular Vasculature of Conjunctivitis in Mice Using Highly Bright Polymer Dots

Ocular diseases are mainly caused by vascular aberrations in the eye, and accurate imaging and analysis of the ocular vascular structure is crucial. In this study, poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT) polymer dots (Pdots), with the advantages of easy synthesis, high brightness, and low toxicity, are used as nanoprobes to perform high-resolution imaging of the vasculature of the eyeball and optic nerve. Moreover, rapid imaging of the choroidal microvessels is carried out by stereoscopic fluorescence microscopy with a resolution of up to 1.6 µm. The comprehensive 3D vascular information of retinal aorta and optic nerve microvessels is obtained by combining tissue clearing and multiphoton microscopy. In addition, the vascular density of Schlemm's canal and iris blood vessels is compared between the conjunctivitis mice and the normal mice. These results suggest that PFBT Pdots have great application potential in the fast and accurate imaging of ocular diseases.

Editorial: Imaging in Ophthalmology

Over the last decade, ophthalmology has significantly benefited from advances in vivo non-invasive ophthalmic imaging techniques that play currently a fundamental role in the clinical assessment, diagnosis, management, and monitoring of a wide variety of conditions involving both the anterior and posterior segment [...]

Retinal and Corneal Changes Associated with Intraocular Silicone Oil Tamponade

Silicone oils (SO) are used as long-term intraocular tamponades and have an irreplaceable role in vitreoretinal surgery. They can, however, be associated with multiple and potentially severe complications, involving different ocular tissues, in particular retina and cornea. Recent advances in ophthalmic imaging have allowed the precise characterization of retinal and corneal microstructural changes, at a subclinical level. This detailed analysis of SO-related retinal and corneal changes has improved our understanding of their pathogenesis and offer the potential for optimized monitoring and management of patients with SO-filled eyes. This review aims to provide clinicians and ophthalmic scientists with an updated and comprehensive overview of the corneal and retinal changes associated with SO tamponade.

Ocular surface angiography: from neovessels to neoplasia

The ocular surface vascular system plays a key role in corneal and conjunctival inflammatory, infectious and neoplastic pathology. Angiographic vessel analysis using intravenous dyes and optical coherence tomography technology allow both the quantitative and functional assessment of conjunctival vasculature and corneal neovessels. Based on a thorough understanding of vascular alterations in ocular surface disease, angiographic assessment facilitates the clinical management of corneal neovascularisation, the grading of ocular surface inflammation and the identification of tumour angiogenesis in dysplastic or malignant lesions. This review summarises key aspects of the clinical application of corneal and conjunctival angiography as presented at the 2021 virtual Bowman Club meeting.

Applications of in vivo confocal microscopy in the management of infectious keratitis in veterinary ophthalmology

In vivo confocal microscopy (IVCM) is a relatively new ocular imaging technique that permits morphological and quantitative assessment of the living cornea on the cellular level. The applications for IVCM in clinical ophthalmology are numerous and diverse. There are several advantages inherent to IVCM over standard diagnostic techniques currently used to confirm a diagnosis of infectious keratitis in veterinary ophthalmology. With IVCM, images can be viewed in real-time providing immediate diagnostic information. Traumatic corneal sampling techniques are avoided, and the procedure can be repeated as frequently as is clinically indicated without risk of corneal tissue damage. Both superficial and deep corneal lesions can be evaluated by IVCM in an atraumatic fashion. Microorganism viability is not required for their detection and specialized diagnostic laboratory assay procedures are not necessary. Many larger infectious agents can be directly identified within corneal lesions by IVCM, including fungi and parasites such as Acanthamoeba spp. In other situations, such as bacterial infectious crystalline keratopathy, the biological systems associated with the microorganism can be detected within the cornea. The current resolution of IVCM is inadequate to directly visualize some corneal infectious agents, such as herpesviruses, but host responses and virus-infected epithelial cells can be identified. This review summarizes the current knowledge and applications of IVCM in the management of infectious keratitis in veterinary ophthalmology, including its use in animals with bacterial, fungal, parasitic, and viral keratitis.