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Glaucoma
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Zhi Da Soh, Victor Koh, Ching-Yu Cheng
Glaucoma is an optic neuropathy that is characterized by progressive degeneration of the retinal ganglion cells, resulting in the thinning of retinal nerve fiber layer (RNFL) and optic disc excavation (cupping).1 This leads to the eventual development of a distinctive pattern of visual field defect.1 Intra-ocular pressure (IOP) is no longer regarded as a defining criterion for glaucoma, although it remains the most important and modifiable risk factor.2
Inflammatory Disorders of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Reduced visual acuity, which varies from a slight dulling of color vision to complete monocular blindness, together with pain around or behind the eye that is exacerbated by eye movement or touching the eye, are symptoms of optic neuritis. Flashes of light on eye movement may occur (phosphenes). The signs include a central or paracentral scotoma in most patients, particularly using a red target (most of the optic nerve fibers transmit information from the macula), and a swollen optic disc (papillitis) in the acute phase if there is demyelination of the anterior part of the optic nerve. A unilateral afferent pupillary defect may be observed. Optic disc pallor due to optic atrophy ensues later.
Head and Neck
Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
The optic nerve receives its inputs at the optic disc of the retina. It leaves the retina at its site of origin (optic disc) and follows an intraconal course (approximately 2.5 cm), exiting the orbit at the optic foramen superomedially to the ophthalmic artery to enter the middle cranial fossa. It passes medially to the internal carotid artery before reaching the optic chiasm, located above the sella turcica. The intracranial component of the nerve is 1.25 cm long. There is some decussation of fibres at the chiasm after which the nerve travels on its respective side to synapse in the lateral geniculate body within the thalamus. Fibres pass from here to the occipital cortex.
Immune Checkpoint Inhibitors and Optic Neuropathy: A Systematic Review
Published in Seminars in Ophthalmology, 2023
James Pietris, Sanjana Santhosh, Gianni Ferdinando Cirocco, Antoinette Lam, Stephen Bacchi, Yiran Tan, Aashray K. Gupta, Joshua G. Kovoor, WengOnn Chan
Vogrig et al. documented three cases of optic neuropathy, each with a unique clinical presentation.21 The first was a 26-year-old male on pembrolizumab therapy for melanoma who presented with acute painless blurred vision of the right eye and a right relative afferent pupillary defect (RAPD). This patient also exhibited hyperintensity of the right optic nerve on MRI of the brain.21 A 58-year-old female also on pembrolizumab therapy for melanoma developed a painless reduction in visual acuity in the right eye, subsequently followed 3 weeks later by the same symptoms in the left eye. Examination showed bilateral optic disc pallor.21 Thirdly, a 75-year-old female prescribed ipilimumab–pembrolizumab combination therapy for melanoma experienced a bilateral painless reduction in visual acuity associated with extra-ocular symptoms including tinnitus, vertigo, and ear pain. This patient’s optical coherence tomography (OCT) scan showed oedema of the optic nerve head bilaterally, and MRI of the brain revealed hyperintensity of the right optic nerve. Interestingly, the left optic nerve was unremarkable on MRI despite similar symptoms clinically.21
Prevalence of Refractive Error in Vientiane Province, Lao People’s Democratic Republic
Published in Ophthalmic Epidemiology, 2023
Chirag Patel, Yiran Tan, Stephen Nygaard, Brad Guo, Cesar Carrillo, Jerida Burgess, Kitar Souksamone, Kham Od Nouansavanh, Robert Casson
The participant completed a standardised medical and ophthalmic questionnaire. Unaided and pinhole visual acuity was obtained using a 6 m front-illuminated E Log MAR acuity chart. Automatic objective refraction was measured with a portable keratometer-autorefractor (Retinomax K-plus 2, Right manufacturing Co. Ltd., Tokyo, Japan). Goldmann applanation tonometry was used to measure intraocular pressure (IOP) (Haag-Streit, Koeniz, Switzerland); The anterior segment was examined using a slit lamp. The presence of previous iris ischaemia or pseudoexfoliation was recorded. Gonioscopy (static and dynamic) was performed with a Sussman goniolens. Optic disc and retinal examination were performed by an experienced ophthalmologist with a 78D lens and reference to standard disc images. The vertical cup: disc ratio (CDR) and the presence of focal notching were recorded. Axial length was measured using a scanning ultrasound. Cataract was graded using the WHO simplified grading system.
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
Purkyně (1819) described how, when moving a candle flame several inches from his eye in different directions within the temporal visual field, he could observe in the diffuse light, “a dark pattern of vessels [on an orange background] that originates from the optic nerve [head] and has two principal branches toward the top and bottom; they ramify and bend toward the center of the visual field” (quoted in Wade and Brožek, 2001, 87). These vessels are the central artery and the central vein, which enter and exit the eye, respectively, at the optic nerve head (optic disk, blind spot). He observed a complementary pattern in his other eye and sketched their projections (now known as the Purkinje tree) as shown in Figure 1.1, reproduced from his thesis published in 1819. Note the similarity with fundus photographs shown in Figure 1.2; one can think of the photograph as “seen” from the front and the entoptic image as “seen” from the back (Ratliff 1971). Snodderly et al. (1977) used an eye tracker with retinal image stabilization and demonstrated precise correspondence between threshold elevations for punctate stimuli and angioscotomata around the blind spot. Drawings of the entoptic image are remarkably similar to the corresponding color fundus photographs (Bradley et al. 1998) and provide an image of the foveal capillaries even superior to that in the fluorescein angiogram, a suggestion made earlier by Bird and Weale (1974).