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Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Both eyes should appear as roughly spherical structures. The transverse section through the normal eye as demonstrated in Figs 11.55b,c shows the eyelid, cornea, anterior chamber and the posterior chamber. This is behind the lens, and is occupied by the vitreous body or humour, sometimes known simply as the vitreous. The cornea is seen as a thin hypoechoic layer parallel to the eyelid. The anterior chamber is filled with anechoic fluid and is bordered by the cornea, iris and the anterior reflection of the lens capsule. The normal lens is anechoic, and the normal vitreous body is relatively echolucent in a young healthy eye. The evaluation of the retrobulbar area includes the optic nerve, extraocular muscles and bony orbit. Each optic nerve may be demonstrated as a hypoechoic structure approximately 2–3 mm thick, directed medially from the posterior aspect of the globe.
Flashing Lights and Floaters
Published in Amy-lee Shirodkar, Gwyn Samuel Williams, Bushra Thajudeen, Practical Emergency Ophthalmology Handbook, 2019
A vitreous detachment occurs when the ageing vitreous body, which is 4 mL in volume and occupies almost the entirety of the posterior segment, collapses forward and pulls its posterior aspect free from the retina. This can either be a smooth collapse with no retinal tears or haemorrhages, or the blood vessels and retina can be damaged in the separation, resulting in pigment and blood released into the vitreous cavity, and even parts of the retina itself in the form of an operculated tear. Blood and inflammatory debris from diabetes, infection or inflammation of the posterior segment may also cause floaters (see Chapter 14). Diabetic retinopathy is a common cause of posterior segment haemorrhage.
Anterior retinectomy
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Michael D Bennett, Paul Sternberg Jr
The pathogenesis of this proliferative tissue is believed to be derived from retinal pigment epithelial (RPE) cells that are liberated at the time of the original retinal detachment or its repair.7,8 The RPE cells presumably undergo fibroblastic transformation, with the ability to synthesize collagen and transform into macrophages. The fibroblasts arise from myofibroblasts; they contract and form mature fibrocytes, fixing the tissue. These cells can cause retraction of the retina and vitreous body, leading to recurrent retinal detachment. The proliferative membranes, similar to those seen in proliferative vascular and diabetic retinopathy, can cause extensive contraction. Despite aggressive membrane dissection, the effective retinal foreshortening still may prevent reapproximation of the retina to the underlying RPE.
Hyalocyte origin, structure, and imaging
Published in Expert Review of Ophthalmology, 2022
Peter Wieghofer, Michael Engelbert, Toco YP Chui, Richard B Rosen, Taiji Sakamoto, J Sebag
In humans, the use of antibodies, lectins or other proteins is the only way to study hyalocytes and other myeloid cells at the microscopic level in tissue sections. Hyalocytes have the advantage of being the major cell population inside the vitreous body and can be easily identified by nuclear counterstaining (Figure 4). The use of immunofluorescent labeling allows the study of protein expression profiles with a much higher sensitivity than by the use of immunohistochemical staining in combination with light microscopy [30]. By applying pan-macrophage markers such as IBA1, hyalocytes can be specifically identified, for example to validate findings made with RNA-seq, as it has been done to confirm the expression of HLA-DR involved in antigen presentation [30]. The transparency of the vitreous body allows light to easily pass through and reach the photoreceptors of the retina. To visualize biological phases that are transparent under visible light, the phase contrast or differential interference contrast (DIC) between the specimen and the surrounding embedding medium or remaining constitutents of the vitreous body allow the detection of hyalocytes without any prior labeling (Figure 4).
Hyalocytes in proliferative vitreo-retinal diseases
Published in Expert Review of Ophthalmology, 2022
Charlotte H. Jones, Wei Gui, Ricarda G. Schumann, Stefaniya K. Boneva, Clemens A. K. Lange, Koen A. van Overdam, Toco Y. P. Chui, Richard B. Rosen, Michael Engelbert, J. Sebag
In youth, vitreous is a solid clear gel composed of water (98%) and structural macromolecules (collagen and hyaluronan), as well as critical extracellular matrix constituents [3–5]. Aging, myopia, and diabetes are associated with fibrous liquefaction and degeneration of the vitreous body, destabilizing the entire structure. When there is concurrent weakening of vitreo-retinal adhesion, dehiscence at the vitreo-retinal interface and collapse of the vitreous body result in an innocuous posterior vitreous detachment (PVD) [6,7]. However, if there is excess fibrous liquefaction/degeneration internally and/or insufficient weakening of vitreo-retinal adhesion, an anomalous PVD can occur [8–10]. There are various consequences of anomalous PVD, which differ based upon the topographic location of vitreo-retinal separation and whether or not the outer vitreous, called the posterior vitreous cortex, remains intact (Figure 1).
Familial exudative vitreoretinopathy with TGFBR2 mutation without signs of Loeys-Dietz syndrome
Published in Ophthalmic Genetics, 2021
Toshiaki Asano, Kazuma Oku, Hiroyuki Kondo
A 15-year-old boy was aware of reduced vision in his left eye. He had been diagnosed with a retinal detachment in the left eye by a local doctor and was referred to our hospital for surgery. He had no medical history or family history of vision impairment and had no strabismus or hypertelorism. In addition, he had no history of ocular trauma. His best-corrected visual acuity (BCVA) at the first visit was 20/13 with a refractive error of −3.5 diopters (D) OD and 20/222 with +1.0 D OS. The cornea and crystalline lens were clear, and the anterior chamber was of normal depth in both eyes. The vitreous body was transparent bilaterally, but a small number of pigment cells was observed in the vitreous body of the left eye. Fundus examination revealed a straightening and excessive branching of the retinal vessels of the right eye (Figure 1). A total retinal detachment with extensive subretinal proliferative tissue was found with the retinal vessel tortuous in the left eye (Figure 2). Fluorescein angiography showed a straightening and excessive branching of the retinal vessels as well as fluorescein leakage at the border of non-perfused areas in both eyes (Figures 1 and 2). Arteriovenous anastomoses with vascular loops were found in the peripheral temporal area of the left eye (Figure 2). Optical coherence tomography showed that the macula appeared normal in the right eye (Figure 1). No systemic abnormalities of the vascular and skeletal system, and facial appearance were detected. He had no history of prematurity or oxygen supplementation.