Visual impairment

Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses. Some also include those who have a decreased ability to see because they do not have access to glasses or contact lenses. Visual impairment is often defined as a best corrected visual acuity of worse than either 20/40 or 20/60. The term blindness is used for complete or nearly complete vision loss. Visual impairment may cause people difficulties with normal daily activities such as driving, reading, socializing, and walking.

The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%). Refractive errors include near sighted, far sighted, presbyopia, and astigmatism. Cataracts are the most common cause of blindness. Other disorders that may cause visual problems include age related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections. Visual impairment can also be caused by problems in the brain due to stroke, prematurity, or trauma among others. These cases are known as cortical visual impairment. Screening for vision problems in children may improve future vision and educational achievement. Screening adults may also be beneficial. Diagnosis is by an eye exam.

Blindness (novel)

Blindness (Portuguese: Ensaio sobre a cegueira, meaning Essay on Blindness) is a novel by Portuguese author José Saramago. It is one of his most famous novels, along with The Gospel According to Jesus Christ and Baltasar and Blimunda.

Plot summary

Blindness is the story of an unexplained mass epidemic of blindness afflicting nearly everyone in an unnamed city, and the social breakdown that swiftly follows. The novel follows the misfortunes of a handful of characters who are among the first to be stricken and centers on "the doctor's wife," her husband, several of his patients, and assorted others, thrown together by chance. After lengthy and traumatic quarantine in an asylum, the group bands together in a family-like unit to survive by their wits and by the unexplained good fortune that the doctor’s wife has escaped the blindness. The sudden onset and unexplained origin and nature of the blindness cause widespread panic, and the social order rapidly unravels as the government attempts to contain the apparent contagion and keep order via increasingly repressive and inept measures.

Wakefulness

Wakefulness is a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world such as communication, ambulation, eating, and sex. Being awake is the opposite of the state of being asleep in which most external inputs to the brain are excluded from neural processing.

Effects upon the brain

The longer the brain has been awake, the greater the spontaneous firing rates of cerebral cortex neurons with this increase being reversed by sleep. Another effect of wakefulness (which may or may not be related to this) is that it lowers the small stores of glycogen held in the astrocytes that can supply energy to the brain's neurons—one of the functions of sleep, it has been proposed, is to create the opportunity for them to be replenished.

Maintenance by the brain

Wakefulness is produced by a complex interaction between multiple neurotransmitter systems arising in the brainstem and ascending through the midbrain, hypothalamus, thalamus and basal forebrain. The posterior hypothalamus plays a key role in the maintenance of the cortical activation that underlies wakefulness. Several systems originating in this part of the brain control the shift from wakefulness into sleep and sleep into wakefulness. Histamine neurons in the tuberomammillary nucleus and nearby adjacent posterior hypothalamus project to the entire brain and are the most wake-selective system so far identified in the brain. Another key system is that provided by the orexins (also known as hypocretins) projecting neurons. These exist in areas adjacent to histamine neurons and like them project widely to most brain areas and associate with arousal. Orexin deficiency has been identified as responsible for narcolepsy.

Awake (Donkeyboy song)

Awake is an English language hit in Norway for the Norwegian band Donkeyboy, their fourth single taken from their album Caught in a Life after singles "Ambitions" and "Sometimes" (both #1s for 13 and 8 weeks consecutively in the Norwegian Singles Chart) and "Broke My Eyes" (that reached #6).

"Awake" released in 2009 reached #8 in the Norwegian Singles Chart.

Charts

References

Awake (EP)

Awake is the first EP release from American rock band Bleed the Dream on their own label "Noize Pollution" in 2003.

Track listing

Personnel