Hemeralopia

Hemeralopia
Classification and external resources
ICD-10 H53.1
ICD-9 368.6

Hemeralopia (from Greek ημέρα, hemera "day"; and αλαός, alaos "blindness") is the inability to see clearly in bright light and is the exact opposite of Nyctalopia (night blindness). Hemera was the Greek goddess of day and Nyx was the goddess of night. However, it has been used in an opposite sense by many non-English-speaking doctors.[1] It can be described as insufficient adaptation to bright light.

In hemeralopia, daytime vision gets worse, characterised by photoaversion (dislike/avoidance of light) rather than photophobia (eye discomfort/pain in light) which is typical of inflammations of eye. Nighttime vision largely remains unchanged due to the use of rods as opposed to cones (during the day), which are affected by hemeralopia and in turn degrade the daytime optical response. Hence many patients feel they see better at dusk than in daytime.

Contents

Causes

Hemeralopia is known to occur in several ocular conditions. Cone dystrophy and achromatopsia, affecting the cones in the retina, and the anti-epileptic drug Trimethadione are typical causes. Adie's pupil which fails to constrict in response to light; Aniridia, which is absence of the iris; Albinism where the iris is defectively pigmented may also cause this. Cataracts, due to the lens clouding, disperses the light before it can reach the retina, is a common cause of hemeralopia and photoaversion in elderly. C.A.R (Cancer Associated Retinopathy) seen when certain cancers release deleterious antibodies against retinal structures, may cause hemeralopia.

Another known cause is a rare genetic condition called Cohen Syndrome (aka Pepper Syndrome). Cohen syndrome is mostly characterized by obesity, mental retardation, and craniofacial dysmorphism due to genetic mutation at locus 8q22-23. Rarely it may have ocular complications such as hemeralopia, pigmentary chorioretinitis, optic atrophy or retinal/iris coloboma, having a serious effect on the person's vision.

Yet another cause of hemeralopia is uni- or bilateral postchiasmatic brain injury.[2] This may also cause concomitant night blindness.[2]

Management

People with hemeralopia may benefit from sunglasses. Wherever possible, environmental illumination should be adjusted to comfortable level.[2] Light-filtering lenses appears to help in people reporting photophobia.[2]

Otherwise, treatment relies on identifying and treating any underlying disorder.

See also

References

  1. ^ Ohba N, Ohba A (December 2006). "Nyctalopia and hemeralopia: the current usage trend in the literature". Br J Ophthalmol 90 (12): 1548–9. doi:10.1136/bjo.2006.097519. PMC 1857511. PMID 17114591. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1857511. 
  2. ^ a b c d Page 96 in: Zihl, Josef (2000). Rehabilitation of visual disorders after brain injury. East Sussex: Psychology Press. ISBN 0-86377-898-4. 



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  • hemeralopía — f. oftalm. Disminución considerable de la agudeza visual durante el crepúsculo causada por una falta de vitamina A y ciertas afecciones de la retina. También se denomina ceguera nocturna. (Ver nictalopía.) Medical Dictionary. 20 …   Diccionario médico

  • Hemeralopia — Hem e*ra*lo pi*a, n. [NL., fr. Gr. ?, the opposite of ?; ? day + ? of ?. See {Nyctalopia}.] (Med.) A disease of the eyes, in consequence of which a person can see clearly or without pain only by daylight or a strong artificial light; day sight.… …   The Collaborative International Dictionary of English

  • hemeralopia — hemeralopia. См. куриная слепота. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • hemeralopia — s. f. [Medicina] Doença caracterizada pela visão normal durante o dia, mas nula ou quase nula a uma luz fraca …   Dicionário da Língua Portuguesa

  • hemeralopía — (De hemerálope). f. Med. Pérdida de visión cuando la iluminación es escasa …   Diccionario de la lengua española

  • hemeralopia — [hem΄ər ə lō′pē ə] n. [ModL < Gr hēmeralōps, day blindness (< hēmera, day + alaos, blind + ōps, EYE) + IA] a defect in the eye in which the vision is reduced in the daylight or in bright light: cf. NYCTALOPIA hemeralopic [hem΄ər əläp′ik]… …   English World dictionary

  • hemeralopia —    Also known as hemeralopsia and day blindness. The term hemeralopia comes from the Greek words hèmera (day), alaos (blind), and ops (eye). It was introduced into the biomedical literature during the 18th century to denote an ocular condition… …   Dictionary of Hallucinations

  • hemeralopía — {{#}}{{LM H19951}}{{〓}} {{[}}hemeralopía{{]}} ‹he·me·ra·lo·pí·a› {{《}}▍ s.f.{{》}} Defecto de la visión consistente en la pérdida total o parcial de la vista cuando disminuye la luz ambiente: • La hemeralopía es síntoma de falta de vitamina… …   Diccionario de uso del español actual con sinónimos y antónimos

  • hemeralopía — Eng. Hemeralopia Término equívoco que etimológicamente significa dificultad de visión en pleno día, aunque en la actualidad se emplea en sentido contrario como disminución de la agudeza visual en el crepúsculo o con luz poco intensa. Ceguera… …   Diccionario de oftalmología

  • hemeralopía — ► sustantivo femenino MEDICINA Disminución de la agudeza visual con luz poco intensa o crepuscular. SINÓNIMO [ceguera nocturna] * * * hemeralopía. (De hemerálope). f. Med. Pérdida de visión cuando la iluminación es escasa …   Enciclopedia Universal

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