Photophobia
Encyclopedia
Photophobia is a symptom
of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia
, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical photosensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear
of light such as heliophobia
.
or the nervous system
.
Photophobia can be caused by an increased response to light starting at any step in the visual system
, such as:
Common causes of photophobia include migraine headaches, cataract
s, or severe ophthalmologic diseases such as uveitis
or corneal abrasion
. A more extensive list follows:
Patients with photophobia will avert their eyes from direct light (sunlight and room lights), or may seek the shelter of a dark room or wear sunglasses
.
A study by Stringham and Hammond, published in the Jan-Feb issue of Journal of Food Science, discusses the improvement in visual performance and decrease in light senitivity (glare) in subjects taking 10 mg Lutein and 2 mg Zeaxanthin per day.
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia
Phobia
A phobia is a type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational...
, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical photosensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear
Fear
Fear is a distressing negative sensation induced by a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger...
of light such as heliophobia
Heliophobia
Heliophobia has two meanings:* in psychology, heliophobia refers to a morbid fear of sunlight.* in medicine, heliophobia refers to an excessive sensitivity to sunlight.-Causes:...
.
Causes
Patients may develop photophobia as a result of several different medical conditions, related to the eyeHuman eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
or the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
.
Photophobia can be caused by an increased response to light starting at any step in the visual system
Visual system
The visual system is the part of the central nervous system which enables organisms to process visual detail, as well as enabling several non-image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world...
, such as:
- Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasionCorneal abrasionCorneal abrasion is a medical condition involving the loss of the surface epithelial layer of the eye's cornea.-Symptoms and signs:Symptoms of corneal abrasion include pain, photophobia, a foreign-body sensation, excessive squinting, and a reflex production of tears...
and retinal damage, or if a pupil(s) is unable to normally constrict (seen with damage to the oculomotor nerveOculomotor nerveThe oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...
). - Overstimulation of the photoreceptors in the retinaRetinaThe vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
- Excessive electric impulses to the optic nerveOptic nerveThe optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
- Excessive response in the central nervous systemCentral nervous systemThe central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
Common causes of photophobia include migraine headaches, cataract
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
s, or severe ophthalmologic diseases such as uveitis
Uveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
or corneal abrasion
Corneal abrasion
Corneal abrasion is a medical condition involving the loss of the surface epithelial layer of the eye's cornea.-Symptoms and signs:Symptoms of corneal abrasion include pain, photophobia, a foreign-body sensation, excessive squinting, and a reflex production of tears...
. A more extensive list follows:
Eye-related
Causes of photophobia relating directly to the eye itself include:- AchromatopsiaAchromatopsiaAchromatopsia , is a medical syndrome that exhibits symptoms relating to at least five separate individual disorders. Although the term may refer to acquired disorders such as color agnosia and cerebral achromatopsia, it typically refers to an autosomal recessive congenital color vision disorder,...
- AniridiaAniridiaAniridia is the absence of the iris. Aniridia usually involves both eyes. It can be congenital or caused by a penetrant injury. Isolated aniridia is a congenital disorder which is not limited to a defect in iris development, but is a panocular condition with macular and optic nerve hypoplasia,...
- AnticholinergicAnticholinergicAn anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....
drugs may cause photophobia by paralyzing the iris sphincter muscleIris sphincter muscleThe iris sphincter muscle is a muscle in the part of the eye called the iris...
. - AphakiaAphakiaAphakia is the absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, hyperopia, and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.Aphakic people are...
(absence of the lens of the eye) - BuphthalmosBuphthalmosBuphthalmos is a medical term that describes enlargement of the eyeball and is most commonly seen in infants and young children. It is sometimes referred to as buphthalmia . It usually appears in the newborn period or the first 3 months of life...
(abnormally narrow angle between the cornea and iris) - Cataracts
- Cone dystrophyCone dystrophyA cone dystrophy is an inherited ocular disorder characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision....
- Congenital abnormalitiesCongenital disorderA congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
of the eye - Viral conjunctivitis ("pink eye")
- Corneal abrasionCorneal abrasionCorneal abrasion is a medical condition involving the loss of the surface epithelial layer of the eye's cornea.-Symptoms and signs:Symptoms of corneal abrasion include pain, photophobia, a foreign-body sensation, excessive squinting, and a reflex production of tears...
- Corneal dystrophyCorneal dystrophyCorneal dystrophy is a group of disorders, characterised by a noninflammatory, inherited, bilateral opacity of the transparent front part of the eye called the cornea.The distrophies could be subdivided based on specie affected:...
- Corneal ulcerCorneal ulcerA corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
- Disruption of the corneal epitheliumCorneal epitheliumThe corneal epithelium is made up of epithelial tissue and covers the front of the cornea. It acts as a barrier to protect the cornea, resisting the free flow of fluids from the tears, and prevents bacteria from entering the epithelium and corneal stroma.The corneal epithelium consists of several...
, such as that caused by a corneal foreign bodyForeign bodyA foreign body is any object originating outside the body. In machinery, it can mean any unwanted intruding object.Most references to foreign bodies involve propulsion through natural orifices into hollow organs....
or keratitisKeratitisKeratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:... - Ectopia lentisEctopia lentisEctopia lentis is a displacement or malposition of the eye's crystalline lens from its normal location. A partial dislocation of a lens is termed lens subluxation or subluxated lens; a complete dislocation of a lens is termed lens luxation or luxated lens.-Ectopia lentis in dogs and cats:Although...
- EndophthalmitisEndophthalmitisEndophthalmitis is an inflammation of the internal coats of the eye. It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. Infectious etiology is the most common and various bacteria and fungi have been isolated as...
- EyeHuman eyeThe human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
trauma caused by disease, injury, or infection such as chalazionChalazionA chalazion , also known as a meibomian gland lipogranuloma, is a cyst in the eyelid that is caused by inflammation of a blocked meibomian gland, usually on the upper eyelid. Chalazia differ from styes in that they are subacute and usually painless nodules...
, episcleritis, glaucomaGlaucomaGlaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...
, keratoconusKeratoconusKeratoconus , is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve....
, or optic nerve hypoplasiaOptic nerve hypoplasiaOptic nerve hypoplasia is a medical condition arising from the underdevelopment of the optic nerve. This condition is the most common congenital optic nerve anomaly. The optic disc appears abnormally small, because not all the optic nerve axons have developed properly... - HydrophthalmosHydrophthalmosHydrophthalmos is a congenital form of glaucoma....
, or congenital glaucomaGlaucomaGlaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye... - IritisIritisIritis is a form of anterior uveitis and refers to the inflammation of the iris of the eye.-Types:There are two main types of iritis: acute and chronic. They differ in numerous ways....
- Optic neuritisOptic neuritisOptic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
- Pigment dispersion syndromePigment dispersion syndromePigment dispersion syndrome is an affliction of the eye that can lead to a form of glaucoma known as pigmentary glaucoma. It takes place when pigment cells slough off from the back of the iris and float around in the aqueous humor...
- Pupillary dilation (naturally or chemically induced)
- Retinal detachmentRetinal detachmentRetinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...
- ScarScarScars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
ring of the cornea or sclera - UveitisUveitisUveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
Nervous-system-related
Neurological causes for photophobia include:- Autism spectrumAutism spectrumThe term "autism spectrum" is often used to describe disorders that are currently classified as pervasive developmental disorders. Pervasive developmental disorders include autism, Asperger syndrome, Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise...
disorders - Chiari malformation
- DyslexiaDyslexiaDyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...
- EncephalitisEncephalitisEncephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
including Myalgic encephalomyelitis aka Chronic fatigue syndromeChronic fatigue syndromeChronic fatigue syndrome is the most common name used to designate a significantly debilitating medical disorder or group of disorders generally defined by persistent fatigue accompanied by other specific symptoms for a minimum of six months, not due to ongoing exertion, not substantially... - MeningitisMeningitisMeningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
- Subarachnoid haemorrhage
- TumorTumorA tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
of the posterior cranial fossaPosterior cranial fossaThe posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum.This is the most inferior of the fossae. It houses the cerebellum, medulla and pons....
Other causes
- Ankylosing spondylitisAnkylosing spondylitisAnkylosing spondylitis , previously known as Bekhterev's disease, Bekhterev syndrome, and Marie-Strümpell disease is a chronic inflammatory disease of the axial skeleton with variable involvement of peripheral joints and nonarticular structures...
- Causes Uveitis as an extra-articular feature. - AlbinismAlbinismAlbinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved in the production of melanin...
- AriboflavinosisAriboflavinosisAriboflavinosis is the medical condition caused by deficiency of riboflavin . Ariboflavinosis is most often seen in association with protein-energy malnutrition, and also in cases of alcoholism....
- Benzodiazepines (long term use of or withdrawal from benzodiazepines)
- ChemotherapyChemotherapyChemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
- ChikungunyaChikungunyaChikungunya virus is an insect-borne virus, of the genus Alphavirus, that is transmitted to humans by virus-carrying Aedes mosquitoes. There have been recent breakouts of CHIKV associated with severe illness...
- CystinosisCystinosisCystinosis is a lysosomal storage disease characterized by the abnormal accumulation of the amino acid cystine. It is a genetic disorder that typically follows an autosomal recessive inheritance pattern. Cystinosis is the most common cause of Fanconi syndrome in the pediatric age group...
- Ehlers-Danlos syndromeEhlers-Danlos syndromeEhlers–Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen . The collagen in connective tissue helps tissues to resist deformation...
- HangoverHangoverA hangover describes the sum of unpleasant physiological effects following heavy consumption of alcoholic beverages. The most commonly reported characteristics of a hangover include headache, nausea, sensitivity to light and noise, lethargy, dysphoria, diarrhea and thirst, typically after the...
- InfluenzaInfluenzaInfluenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...
- Infectious MononucleosisInfectious mononucleosisInfectious mononucleosis is an infectious, widespread viral...
- Magnesium deficiencyMagnesium deficiency (medicine)Magnesium deficiency refers to an intake of dietary magnesium below minimal levels, which can result in numerous symptoms and diseases. These can generally be remedied by an increase of magnesium in diet or oral supplements...
- Mercury poisoningMercury poisoningMercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses...
- MigraineMigraineMigraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
- RabiesRabiesRabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...
- Tyrosinemia type IITyrosinemia type IITyrosinemia type II is an autosomal recessive condition with onset between ages 2 and 4 years, when painful circumscribed calluses develop on the pressure points of the palm of the hand and sole of the foot.-Pathophysiology:Type II tyrosinemia is caused by a deficiency of the enzyme tyrosine...
, also known as "Richner-Hanhart syndrome"
Treatment
The best treatment for light sensitivity is to address the underlying cause. Once the triggering factor is treated, photophobia disappears in many but not all cases.Patients with photophobia will avert their eyes from direct light (sunlight and room lights), or may seek the shelter of a dark room or wear sunglasses
Sunglasses
Sunglasses or sun glasses are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes. They can sometimes also function as a visual aid, as variously termed spectacles or glasses exist, featuring lenses that...
.
A study by Stringham and Hammond, published in the Jan-Feb issue of Journal of Food Science, discusses the improvement in visual performance and decrease in light senitivity (glare) in subjects taking 10 mg Lutein and 2 mg Zeaxanthin per day.
See also
- Light sensitivityLight sensitivityLight sensitivity or photosensitivity is an increase in the reactivity of the skin to sunlight. Apart from vision, human beings have many physiological and psychological responses to light. In rare individuals an atypical response may result in serious discomfort, disease, or injury. Some drugs...
- Photic sneeze reflexPhotic sneeze reflexThe photic sneeze reflex is a condition of uncontrollable sneezing in response to numerous stimuli, such as looking at bright lights or periocular injection...
, a medical condition by which people exposed to bright light sneeze - Photosensitivity in humans