ⓘ Scotoma

                                     

ⓘ Scotoma

A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision.

Every normal mammalian eye has a scotoma in the visual field, usually called his blind spot. This location with no photoreceptor cells, where axons of retinal ganglion cells that comprise the optic nerve exit the retina. This place is called the optic disk. There is no direct awareness of the visual scotoma. They are simply regions of reduced information in the visual field. Instead recognize an incomplete image, scotoma patients report that things "disappear" on them.

The presence of the blind spot, scotoma can be demonstrated subjectively by covering one eye, carefully holding fixation with the open eye, and placing an object like the thumb in the lateral and horizontal visual field, about 15 degrees from fixation to see the blind spot article. The size of the monocular scotoma is 5×7 degree angle.

A scotoma can be a symptom of damage to any part of the visual system, such as retinal damage from exposure to high-powered lasers, macular degeneration and brain damage.

The term scotoma is also used metaphorically in several areas. A common theme in all figurative senses-is the gap not in visual functions, but in conscious perception, cognition, or worldview. The term comes from the Greek σκότος/ skotos, darkness.

                                     
  • Scintillating scotoma is a common visual aura that was first described by 19th - century physician Hubert Airy 1838 1903 It may precede a migraine headache
  • Seidel s sign also called Seidel s scotoma is a sickle - shaped scotoma that is a superior or inferior extension of the blind spot. It occurs in some
  • Multiple types of scotomas form inside Bjerrum s area, typically in patients with open - angle glaucoma. Of particular note is the arcuate scotoma also known
  • negative and positive scotoma blind spot if vision of the scotoma region is a void, it is a negative scotoma and if the scotoma is an area of darkness lightness
  • glaucomatous scotoma that was to become known as a Bjerrum scotoma which is a visual field defect that goes by several other names, such as sickle scotoma
  • manifested as a central scotoma and a defect involving the contralateral superotemporal field. This is also known as a junctional scotoma An alternative explanation
  • Vibrating visual field Scintillating scotoma Shimmering, pulsating patches, often curved Tunnel vision Scotoma Blind or dark spots in the field of vision
  • person s visual field that is suppressed is called the suppression scotoma with a scotoma meaning, more generally, an area of partial alteration in the visual
  • scotoma called junction scotoma since it indicates the site of the lesion at the junction of the optic nerve and chiasma The Traquair scotoma
  • also commonly termed scintillating scotoma Retinal migraine is associated with transient monocular visual loss scotoma in one eye lasting less than one
  • acute unilateral decreased vision, photopsias and central or paracentral scotoma An antecedent viral prodrome occurs in approximately one - third of cases