Hemeralopia: Difference between revisions
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| ⚫ | '''Hemeralopia''' |
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| ⚫ | '''Hemeralopia''' or '''day blindness''' is the inability to see clearly in bright light and is the exact opposite of [[nyctalopia]] (night blindness), the inability to see clearly in low light.<ref name=Ohba>{{cite journal |vauthors=Ohba N, Ohba A |title=Nyctalopia and hemeralopia: the current usage trend in the literature |journal=Br J Ophthalmol |volume=90 |issue=12 |pages=1548–9 |date=December 2006 |pmid=17114591 |pmc=1857511 |doi=10.1136/bjo.2006.097519 }}</ref> It is also called '''heliophobia'''.<ref>{{cite journal |author=Gördüren, S. |year=1950 |title=Day-Blindness |journal=British Journal of Ophthalmology |volume=34 |issue=9 |pages=563–567 |doi=10.1136/bjo.34.9.563 |pmc=1323631 |pmid=14777856}}</ref> It can be described as insufficient [[adaptation (eye)|adaptation]] to bright light. |
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| ⚫ | In hemeralopia, daytime [[Visual perception|vision]] gets worse, characterised by |
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| ⚫ | In hemeralopia, daytime [[Visual perception|vision]] gets worse, characterised by photoaversion (dislike/avoidance of light) rather than [[photophobia]] (eye discomfort/pain in light), which is typical of inflammations of the eye. Nighttime vision largely remains unchanged due to the use of [[Rod cell|rods]] as opposed to [[Cone cell|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. |
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The word ''hemeralopia'' comes from the [[Greek language|Greek]] ''ημέρα'' hemera, "day", and ''αλαός'' alaos, "blindness". [[Hemera]] was the [[Greek mythology|Greek goddess]] of [[day]], and [[Nyx]] was the goddess of night. ''Hemeralopia'' has been used to describe night blindness rather than day blindness by many non-English-speaking doctors, causing confusion.<ref name=Ohba/> |
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==Causes== |
==Causes== |
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Hemeralopia is known to occur in several ocular conditions. [[Cone dystrophy]] and [[achromatopsia]], affecting the cones in the retina, and the anti-epileptic drug [[ |
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; and [[albinism]], where the iris is defectively pigmented, may also cause this. Central [[cataracts]], due to the lens clouding, disperses the light before it can reach the [[retina]] and is a common cause of hemeralopia and photoaversion in the elderly. [[Cancer-associated retinopathy]] (CAR), seen when certain cancers incite the production of deleterious antibodies against retinal components, may cause hemeralopia. |
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Another known cause is a rare genetic condition called [[Cohen |
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 (genetics)|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. |
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Yet another cause of hemeralopia is uni- or bilateral post[[chiasma opticum|chiasmatic]] brain injury.<ref name=zihl/> This may also cause concomitant |
Yet another cause of hemeralopia is uni- or bilateral post[[chiasma opticum|chiasmatic]] brain injury.<ref name=zihl/> This may also cause concomitant nyctalopia.<ref name=zihl/> |
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==Management== |
==Management== |
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People with hemeralopia may benefit from [[sunglasses]]. Wherever possible, environmental illumination should be adjusted to comfortable level.<ref name=zihl>Page 96 in: {{cite book |author=Zihl, Josef |title=Rehabilitation of visual disorders after brain injury |publisher=Psychology Press |location=East Sussex |year=2000 |
People with hemeralopia may benefit from [[sunglasses]]. Wherever possible, environmental illumination should be adjusted to comfortable level.<ref name=zihl>Page 96 in: {{cite book |author=Zihl, Josef |title=Rehabilitation of visual disorders after brain injury |publisher=Psychology Press |location=East Sussex |year=2000 |isbn=0-86377-898-4 }}</ref> Light-filtering lenses appear to help in people reporting [[photophobia]].<ref name=zihl/> |
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Otherwise, treatment relies on identifying and treating any underlying disorder. |
Otherwise, treatment relies on identifying and treating any underlying disorder. |
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Some people with hemeralopia have benefitted from having their eyes tested in a brightly lit room using a Snellen chart. Lens prescriptions obtained using this method can provide significant improvement in vision. |
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==See also== |
==See also== |
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*[[Adaptation (eye)]] |
* [[Adaptation (eye)]] |
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==References== |
==References== |
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{{reflist}} |
{{reflist}} |
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{{Medical resources |
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| ⚫ | |||
| ICD10 = {{ICD10|H53.1}} |
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| ICD9 = {{ICD9|368.6}} |
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4. Thirkill CE. Cancer-Induced Retinal Degenerations. |
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| OMIM = 310500 |
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2005, Ocul Immunol Inflamm 13:119-131 |
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| MeshID = D014780 |
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}} |
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| ⚫ | |||
{{DEFAULTSORT:Hemeralopia}} |
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[[Category:Visual disturbances and blindness]] |
[[Category:Visual disturbances and blindness]] |
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Revision as of 05:25, 25 August 2024
| Hemeralopia | |
|---|---|
| Specialty | Ophthalmology  |
Hemeralopia or day blindness is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly in low light.[1] It is also called heliophobia.[2] 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 the 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.
The word hemeralopia comes from the Greek ημέρα hemera, "day", and αλαός alaos, "blindness". Hemera was the Greek goddess of day, and Nyx was the goddess of night. Hemeralopia has been used to describe night blindness rather than day blindness by many non-English-speaking doctors, causing confusion.[1]
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; and albinism, where the iris is defectively pigmented, may also cause this. Central cataracts, due to the lens clouding, disperses the light before it can reach the retina and is a common cause of hemeralopia and photoaversion in the elderly. Cancer-associated retinopathy (CAR), seen when certain cancers incite the production of deleterious antibodies against retinal components, 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.[3] This may also cause concomitant nyctalopia.[3]
Management
People with hemeralopia may benefit from sunglasses. Wherever possible, environmental illumination should be adjusted to comfortable level.[3] Light-filtering lenses appear to help in people reporting photophobia.[3]
Otherwise, treatment relies on identifying and treating any underlying disorder.
See also
References
- ^ a b 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.
- ^ Gördüren, S. (1950). "Day-Blindness". British Journal of Ophthalmology. 34 (9): 563–567. doi:10.1136/bjo.34.9.563. PMC 1323631. PMID 14777856.
- ^ 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.