Dark spot on retina scan1/18/2024 ![]() ![]() The reduction in light scattered by the retinal nerve fiber layer (RFNL) near the optic nerve head is reported to be an early indicator of axonal degeneration and a sensitive way to detect glaucomatous damage. However, this information is not utilized in current clinical OCT systems. Furthermore, measuring changes in the angular (directional) scattering of retina layers might further enhance our ability to sense microscopic changes in cellular and subcellular morphology that might precede and/or follow disease progression. The amount of light backscattered/reflected from the retinal layers can provide critical information regarding tissue properties and underlying changes. 1, 2 OCT extracts depth-resolved information about the intensity of backscattered light from retinal layers using low coherence interferometry. Over the past several years, optical coherence tomography (OCT) has evolved into a powerful tool for the in vivo investigation of cross-sectional retinal anatomy and pathology. The differences in directional scattering between strains shows that directionality decreases with an increase in melanin concentrations in RPE, suggesting increasing contribution of Mie scattering by melanosomes. The reflections from the RPE are largely insensitive in highly pigmented mice. The intensity of light backscattered from these layers was found highly sensitive to the angle of illumination, whereas the inner/outer segment (IS/OS) junctions showed a reduced sensitivity. The directional reflectivity of other retinal melanin-free layers, including the internal and external limiting membranes, and Bruch’s membrane (albinos) were also measured and compared between the strains. The backscattering signal strength was measured with a directional OCT system in which the pupil entry position of the narrow OCT beam can be varied across the dilated pupil of the eyes of the mice. The directional scattering of the RPE was studied in three mice strains with three distinct melanin concentrations: albino (BALB/c), agouti (129S1/SvlmJ), and strongly pigmented (C57BL/6J). The directional (angular) reflectivity of the retinal layers was investigated with focus on the scattering from retinal pigment epithelium (RPE). Dark spots on the iris and loss of peripheral vision are symptoms an eye doctor may spot that the patient has not.Optical coherence tomography (OCT) is a powerful tool in ophthalmology that provides in vivo morphology of the retinal layers and their light scattering properties. But it may not involve any symptoms a person is likely to notice. It may cause symptoms a patient might notice, like sensation of flashing lights or poor vision in one eye. Melanoma of the eye, although rare, is still the most common kind of cancer affecting the eyes. The pituitary gland is a tiny gland in the brain that controls many other hormone glands. Loss of visual fields, which some patients may not even be aware of without the help of their eye doctor, can be a symptom of a tumor in the pituitary gland. A ruptured aneurysm in the brain causes hemorrhaging in the brain and could be fatal. An aneurysm is a bulging and weakening of an artery. Pupil-involving third cranial nerve palsy, which impairs eye movement, may signal a brain aneurysm. These can be early symptoms of stroke, transient ischemic attack (mini-stroke) brain tumor, or myasthenia gravis, which is an autoimmune neuromuscular disease. Neuro-ophthalmic conditions can be serious and have symptoms like a drooping eyelid, dilated pupil, or an in-turned eye. Your doctor might also order a type of MRI that requires an injection to make the optic nerve visible. But an MRI is a useful diagnostic procedure your eye doctor may want because it gives him a good view of your soft tissues in the eye orbit and brain. Your eyes, the tissues around them and your brain don’t show up well, and sometimes not at all, on standard x-rays. IIf an eye doctor spots something that concerns him, he may suggest or order an MRI for a closure look, just to determine if you’ll need assistance finding some eyewear. In some cases of life-threatening diseases and conditions, the first symptoms may be noticeable only through your eyes. When your eye doctor examines your eyes, he’s looking for more than just how well you read the eye chart and what, if any, sort of correction you’ll need to see better. In some cases, an eye doctor has saved a life. Many people might be surprised to learn that an eye doctor can do more than save your vision. ![]()
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