Negative scotoma is a term used in ophthalmology to describe an area of visual loss in the visual field that is not apparent to the patient. The spelling of scotoma is pronounced /skəʊˈtəʊmə/ (skoh-toh-muh), with the first syllable rhyming with "go" and the second syllable pronounced as "toe." Negative scotoma occurs when there is a loss of sensitivity to light, often due to damage to the optic nerve. Early detection and treatment of negative scotoma can prevent permanent vision loss.
A negative scotoma denotes a specific visual disturbance characterized by the absence or diminished perception of a particular visual stimulus within a person's field of vision. It refers to the perceptual experience of a void or an area of reduced sensitivity or visibility in one's visual field, wherein an object, shape, or specific details are not registered or appear less distinct than its surroundings. This phenomenon is often associated with a deficiency in the functioning of the visual system, particularly the optic nerves or the cerebral cortex.
A negative scotoma differs from positive scotoma in that it represents an area where visual perception is compromised, leading to reduced awareness or complete omission of specific visual information. This condition might manifest differently depending on its underlying causes, such as eye diseases, retinal abnormalities, cortical lesions, or neurological impairments. Negative scotomas can be temporary or permanent and may occur unilaterally or bilaterally, affecting one or both eyes.
The consequences of a negative scotoma can vary, ranging from mild inconveniences and difficulties in fine visual tasks to severe impairments that impede daily activities and quality of life. In some instances, negative scotomas might be compensated for by employing visual aids or making adjustments in lighting and environment. Early detection and prompt medical intervention are crucial to identify the root cause, manage symptoms, and prevent further deterioration of visual functioning.
One which is not ordinarily perceived, but is detected only on examination of the entire visual field.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "scotoma" originated from the Greek word "skotoma" (σκότος), which means "darkness" or "blindness". In medical terminology, a scotoma refers to an area of partial or complete loss of vision within the visual field.
The term "negative scotoma" is used to describe a specific type of scotoma characterized by the absence of a certain visual stimulus or perception. It is called "negative" because it refers to the lack or negation of a visual sensation.
The etymology of the word "negative" comes from the Latin word "negativus", which means "denied" or "opposite". It is used to describe something that is not present or lacking.
So, when combined, "negative scotoma" refers to a visual blind spot where a particular stimulus is not perceived or is absent.