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Glaucoma is a group of eye diseases that result in damage to the optic nerve and cause vision loss. The most common type is open-angle glaucoma, in which the drainage angle for fluid within the eye remains open, with less common types including closed-angle glaucoma and normal-tension glaucoma. Open-angle glaucoma develops slowly over time and there is no pain. Peripheral vision may begin to decrease, followed by central vision, resulting in blindness if not treated. Closed-angle glaucoma can present gradually or suddenly. The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea. Vision loss from glaucoma, once it has occurred, is permanent. Eyes affected by glaucoma are referred to as being glaucomatous.
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.
Papilledema or papilloedema is optic disc swelling that is caused by increased intracranial pressure due to any cause. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare.
Amaurosis fugax is a painless temporary loss of vision in one or both eyes.
The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point.
The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye.
The Amsler grid, used since 1945, is a grid of horizontal and vertical lines used to monitor a person's central visual field. The grid was developed by Marc Amsler, a Swiss ophthalmologist. It is a diagnostic tool that aids in the detection of visual disturbances caused by changes in the retina, particularly the macula, as well as the optic nerve and the visual pathway to the brain. Amsler grid usually help detecting defects in central 20 degrees of the visual field.
Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision caused by damage to the optic nerve as a result of insufficient blood supply (ischemia). This form of ischemic optic neuropathy is generally categorized as two types: arteritic AION, in which the loss of vision is the result of an inflammatory disease of arteries in the head called temporal arteritis, and non-arteritic AION, which is due to non-inflammatory disease of small blood vessels.
Posterior ischemic optic neuropathy (PION) is a medical condition characterized by damage to the retrobulbar portion of the optic nerve due to inadequate blood flow (ischemia) to the optic nerve. Despite the term posterior, this form of damage to the eye's optic nerve due to poor blood flow also includes cases where the cause of inadequate blood flow to the nerve is anterior, as the condition describes a particular mechanism of visual loss as much as the location of damage in the optic nerve. In contrast, anterior ischemic optic neuropathy (AION) is distinguished from PION by the fact that AION occurs spontaneously and on one side in affected individuals with predisposing anatomic or cardiovascular risk factors.
Ocular hypertension is the presence of elevated fluid pressure inside the eye, usually with no optic nerve damage or visual field loss.
Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain. [1].
Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details.
Sohan Singh Hayreh was an ophthalmologist, clinical scientist, and professor emeritus of ophthalmology at the University of Iowa. As one of the pioneers in the field of fluorescein angiography, he was generally acknowledged to be a leading authority in vascular diseases of the eye and the optic nerve. For over 60 years, Hayreh was actively involved in basic, experimental, and clinical research in ophthalmology, publishing over 400 original peer-reviewed articles in various international ophthalmic journals, six classical monographs and books in his field of research, and more than 50 chapters in ophthalmic books. He made many seminal observations dealing with the ocular circulation in health and disease, the optic disc and the optic nerve, retinal and choroidal vascular disorders, glaucomatous optic neuropathy, fundus changes in malignant arterial hypertension, ocular neovascularization, rheumatologic disorders of the eye, and nocturnal arterial hypotension. He was an elected fellow of the National Academy of Medical Sciences.
Canine glaucoma refers to a group of diseases in dogs that affect the optic nerve and involve a loss of retinal ganglion cells in a characteristic pattern. An intraocular pressure greater than 22 mmHg (2.9 kPa) is a significant risk factor for the development of glaucoma. Untreated glaucoma in dogs leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.
Josef Flammer is a Swiss ophthalmologist and long-time director of the Eye Clinic at Basel University Hospital. Flammer is a glaucoma specialist who developed a new pathogenetic concept of glaucomatous damage according to which unstable blood supply leads to oxidative stress, which in turn plays a major role in apoptosis of cells in the optic nerve and retina in glaucoma patients.
Normal tension glaucoma (NTG) is an eye disease, a neuropathy of the optic nerve, that shows all the characteristics of primary open angle glaucoma except one: the elevated intraocular pressure (IOP) - the classic hallmark of glaucoma - is missing. Normal tension glaucoma is in many cases closely associated with general issues of blood circulation and of organ perfusion like arterial hypotension, metabolic syndrome, and Flammer syndrome.
Humphrey field analyser (HFA) is a tool for measuring the human visual field that is commonly used by optometrists, orthoptists and ophthalmologists, particularly for detecting monocular visual field.
Alon Harris, MS, PhD, FARVO is an internationally-active clinical scientist, professor of ophthalmology, educator, inventor and researcher in the field of ocular blood flow and its relationship to diseases of the eye. Harris served as the principal or co-principal investigator on more than 60 research grants, published more than 368 peer-reviewed articles, and wrote 22 books and 69 book chapters. As of 2021, he holds two patents. Harris sits on the Board of Directors of The Glaucoma Foundation and is the Vice Chair of International Research and Academic Affairs and Director of the Ophthalmic Vascular Diagnostic and Research Program at Icahn School of Medicine at Mount Sinai.
Megalopapilla is a non-progressive human eye condition in which the optic nerve head has an enlarged diameter, exceeding 2.1 mm with no other morphological abnormalities.
The Heidelberg Retinal Tomography is a diagnostic procedure used in ophthalmology. The Heidelberg Retina Tomograph (HRT) is an ophthalmological confocal point scanning laser ophthalmoscope for examining the cornea and certain areas of the retina using different diagnostic modules. However, the most widely used area of application for HRT is the inspection of the optic nerve head (papilla) for early detection and follow-up of glaucoma. The procedure has established itself as an integral part of routine glaucoma diagnostics alongside the visual field examination (perimetry), the chamber angle examination (gonioscopy) and the measurement of intraocular pressure (tonometry). The HRT is the most widely used application of confocal scanning laser ophthalmoscopy.
References
- 1 2 "Professor Helen Danesh-Meyer – The University of Auckland". Unidirectory.auckland.ac.nz.
- ↑ Danesh-Meyer, Helen (2004). Evaluation of diagnostic procedures, visual outcome and optic nerve morphology in giant cell arteritis (MD thesis). ResearchSpace@Auckland, University of Auckland. hdl:2292/5551.
- ↑ Danesh-Meyer, Helen (2013). Evaluation of Optic Nerve Morphology in Non-glaucomatous Optic Neuropathies with Quantitative Optic Nerve Imaging Modalities (Doctoral thesis). ResearchSpace@Auckland, University of Auckland. hdl:2292/22745.
- ↑ "The eyes have it : The Listener". Noted.co.nz.
- ↑ Amy Wiggins (2 November 2017). "Tiny tube saving sight of glaucoma patients in New Zealand". Nzherald.co.nz.
- ↑ "Patrick Gower reveals shock glaucoma diagnosis". Stuff.co.nz.
- ↑ "New Year Honours: New Zealanders recognised across fields from science to sport". Radio New Zealand . 31 December 2022. Retrieved 31 December 2022.
