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Nyctalopia (/ ˌ n ɪ k t ə ˈ l oʊ p i ə /; from Ancient Greek νύκτ-(núkt-) 'night' ἀλαός (alaós) 'blind, invisible' and ὄψ (óps) 'eye'), [1] also called night-blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases.
Congenital blindness is a hereditary disease and can be treated by gene therapy. Visual loss in children or infants can occur either at the prenatal stage (during the time of conception or intrauterine period) or postnatal stage (immediately after birth). [3] There are multiple possible causes of congenital blindness.
Childhood blindness is an important contribution to the national prevalence of the disability of blindness. [3] Blindness in children can be defined as a visual acuity of <3/60 in the eye with better vision of a child under 16 years of age. [4]
For children aged 1–2 years old, visual acuity can be tested by Worth's ivory ball test, Boeck's candy test, the "Screening Test for Young Children and Retards", and Cardiff's acuity test. [4] For children aged 2–3 years old, visual acuity can be tested by miniature toy test, coin test, and LEA symbols tests. [ 4 ]
Night blindness can be caused by a number of factors the most common of which being vitamin A deficiency. If detected early enough nyctalopia can be reversed and visual function can be regained; however; prolonged vitamin A deficiency can lead to permanent visual loss if left untreated.
Night blindness is a symptom in many patients and diagnosis often occurs through the use of various tests including a electroretinogram to reveal any impairment in the retina "as a whole". [ 37 ] [ 38 ] [ 39 ] Tests performed can also include a visual field examination, Fundoscopic examination, and slit-lamp microscopy in addition to ...
Oguchi disease present with nonprogressive night blindness since young childhood or birth with normal day vision, but they frequently claim improvement of light sensitivities when they remain for some time in a darkened environment. [citation needed]
ONH is the single leading cause of permanent legal blindness in children in the western world. [12] The incidence of ONH is increasing, although it is difficult to estimate the true prevalence. Between 1980 and 1999, the occurrences of ONH in Sweden increased four-fold to 7.2 per 100,000, while all other causes of childhood blindness had declined.