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Optical Coherence Tomography (Oct) and Fundus Fluorescein Angiography (FFA) in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Ramandeep Singh, Deeksha Katoch, Mohit Dogra, Basavaraj Tigari, Simar Rajan Singh, Sahil Jain, Bruttendu Moharana, Sabia Handa, Mangat R. Dogra
Retinal ganglion cell layer (RGL) analysis by spectral domain OCT (SD-OCT) has been shown to decrease both in thickness and volume. The most significant decrease in RGL thickness and volume has been reported in the inferonasal quadrants, supporting early papillomacular bundle impairment in its inferotemporal sector.
Low-grade Glioma Presenting in the Optic Pathways and Hypothalamus
Published in David A. Walker, Giorgio Perilongo, Roger E. Taylor, Ian F. Pollack, Brain and Spinal Tumors of Childhood, 2020
Peter M.K. de Blank, Ian Simmons, Astrid Sehested, Michael J. Fisher
OCT measures the thickness of the retinal nerve fiber layer (RNFL) and the ganglion cell layer-inner plexiform layer (GCL-IPL) using the back-scatter of infrared light (Figure 10.5). Retinal ganglion cell loss leads to thinning of these structures.64 RNFL thickness of less than 80 µm was associated with abnormal visual acuity or visual field deficit in 48 children and young adults with OPHG tumors.65 In addition, a 10% decline in RNFL in two or more retinal quadrants has been used to identify children with visual acuity or visual field loss with 70% sensitivity and 100% specificity in a longitudinal study of 46 children with OPHG (31 with NF1-OPHG).66 Decreased GCL-IPL measures may also discriminate normal from abnormal vision with improved accuracy.67
The thin-film optical detector: a novel approach to artificial vision
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Garcia Charles A, Uwaydat Sami H, Soula Thouria Ben, Zomorrodian A.l.i, Wu Na Juan, Ignatiev Alex
Ceramic detectors with diameters of 80–500μm were inserted into blebs formed in the subretinal space using an ab externo approach. The operated eyes were examined by indirect ophthalmoscopy 1, 2, and 6 weeks after surgery. Fundus photography was performed periodically. Six weeks after implantation, a section of the retina containing the detector was removed for histologic examination. Microscopic examination of the retina outside the site of implantation revealed well-preserved structures. The inner retinal layers overlying the implant (inner nuclear, inner plexiform, and ganglion cell layers) were also well preserved in thickness and architecture. However, the outer nuclear layers and outer plexiform layers were disorganized. These changes were similar to those observed in the sham surgical eyes, and are therefore more likely to be attributable to surgical manipulation and trauma. Occasionally, a few macrophages were seen proximal to the scleral entry site. These results indicate that the TOD mounted on a PLGA polymer is well tolerated when inserted in the subretinal space of rabbits for up to 6 weeks. Biocompatibility was also shown in previous experiments where the TOD was added to cultures of human retinal pigment epithelial cells for periods of up to 6 weeks with no adverse effects.
Mimicking chronic glaucoma over 6 months with a single intracameral injection of dexamethasone/fibronectin-loaded PLGA microspheres
Published in Drug Delivery, 2022
Alba Aragón-Navas, María J. Rodrigo, David Garcia-Herranz, Teresa Martinez, Manuel Subias, Silvia Mendez, Jesús Ruberte, Judit Pampalona, Irene Bravo-Osuna, Julian Garcia-Feijoo, Luis E. Pablo, Elena Garcia-Martin, Rocío Herrero-Vanrell
Animals were euthanized under humanity conditions with an intracardiac injection of sodium thiopental (25 mg/ml) under general anesthesia and eyes were immediately enucleated. Paraffin-embedded eyes were sectioned (5 µm) along the eye axis, deparaffinized and rehydrated. After several washes in phosphate-buffered saline (PBS), sections were incubated overnight at 4 °C with mouse anti-Brn3a (Santa Cruz Biotechnology, Heidelberg, Germany) at 1:50 dilution. After washing the sections in PBS, slides were incubated for 2 hours at room temperature with biotinylated horse anti-mouse at 1:50 dilution (Vector Laboratories, Burlingame, CA, USA). Then, incubation with ABC-HRP (Thermo Fisher Scientific, Waltham Massachusetts, USA) at 1:50 dilution at room temperature was performed. Finally, sections were stained with DAB (Sigma-Aldrich) for 3 minutes and counterstained with Harrys Hematoxylin (Sigma-Aldrich) for 20 minutes at room temperature. Ganglion cells were counted in radial sections of the retina, along 2 mm of a linear region of the ganglion cell layer, at four areas, two in both sides of the optic nerve head. Images were analyzed by an operator blinded to treatment groups. Statistical analysis of the number of ganglion cells was conducted in R (v. 3.6.0) using a paired t-test. The results are shown as mean ± SEM. Values of p < 0.05 were considered statistically significant. Procedural immunohistochemistry controls were carried out by omitting the primary antibody in a sequential tissue section.
Heinrich Müller (1820-1864) and the entoptic discovery of the site in the retina where vision is initiated
Published in Journal of the History of the Neurosciences, 2022
John S. Werner, Iwona Gorczynska, Lothar Spillmann
At the time of Müller’s 1855 paper, it was known that light must be absorbed by a pigment in order to convert electromagnetic energy into neural signals. In the cadaver eye, the photopigment cannot be seen without careful preparation due to bleaching (photo-isomerization). It had generally been thought that transduction must occur in the ganglion cell layer because it is the first retinal layer that is reached by the incident light, as shown in Figure 2.3. Müller correctly deduced from his careful entoptic experiments using the Purkyně tree that this was incorrect and that, instead, vision is initiated in cells we now know to be the photoreceptors located in the back of the retina. The elegance of Müller’s (1855) experiments and analyses prompted us to translate his paper. His scientific approach stands out for his use of perceptual observations to understand anatomical and physiological function, an approach used by other nineteenth-century anatomists and histologists such as Max Schultze, Hermann Munk, and others—a perspective that continues to guide vision science. Müller showed how careful observations (entoptic phenomena) and simple mathematics can be used to make inferences about retinal structures.
Dose and time response study to develop retinal degenerative model of zebrafish with lead acetate
Published in Cutaneous and Ocular Toxicology, 2022
Histopathological images of control group depicted regular shaped retina and the seven retinal layers were typically organised. (Figure 1). Pigmented epithelial layer is present towards choroid layer. It consists of single layer of cells containing photosensitive pigmented granules. These pigmented granules consist of melanin pigment. Cell processes called villi are directed towards the photoreceptors. The second nuclear layer consists of three different types of cells i.e. bipolar cells, amacrine cells and horizontal cells. The horizontal cells are present closest to the receptors and amacrine cells are present towards ganglion cell layer. The synaptic junction of two nuclear layers is present in outer plexiform layer. The synaptic contacts of inner nuclear layer and ganglion cell layer have been observed in inner plexiform layer. Visual information passes through these synaptic junctions before leaving the eye.