Pseudoexfoliation syndrome
Encyclopedia
Pseudoexfoliation syndrome, (other names: Exfoliation glaucoma, Pseudoexfoliation glaucoma, Pseudoexfoliation of the lens, Exfoliation syndrome) sometimes abbreviated as PEX, is an aging–related systemic disease
manifesting itself primarily in the eyes which is characterized by the accumulation of microscopic granular amyloid-like protein fibers. Its cause is unknown, although there is speculation that there may be a genetic
basis. It is more prevalent in women than men, and in persons past the age of seventy. Its prevalence in different human populations varies; for example, it is prevalent in Scandinavia
. The buildup of protein clumps can block normal drainage of the eye fluid called the aqueous humor and can cause, in turn, a buildup of pressure leading to glaucoma
and loss of vision. As worldwide populations become older because of shifts in demography, PEX may become a matter of greater concern.
Pseudoexfoliation syndrome (PEX) was first described by an ophthalmologist from Finland
named John Lindberg in 1917. He built his own slit lamp
to study the condition and reported "grey flakes on the lens capsule", as well as glaucoma
in 50% of the eyes, and an "increasing prevalence of the condition with age." Several decades later, an ocular pathologist named Georgiana Dvorak-Theobald suggested the term pseudoexfoliation to distinguish it from a similar ailment which sometimes affected glassblowers called true exfoliation syndrome. The latter ailment is caused by heat or "infrared-related changes in the anterior lens capsule" and is characterized by "lamellar delamination of the lens capsule." Sometimes the two terms "pseudoexfoliation" and "true exfoliation" are used interchangeably but the more precise usage is to treat each case separately.
s or glaucoma
.
PEX is characterized by tiny microscopic white or grey granular flakes which are clumps of proteins within the eye which look somewhat like dandruff
when seen through a microscope and which are released by cells. The abnormal flakes, sometimes compared to amyloid
-like material, are visible during an examination of the lens of an eye by an ophthalmologist, which is the usual diagnosis. The white fluffy material is seen in many tissues both ocular and extraocular: in the anterior chamber structures, trabecular meshwork, central disc, zonular fibres, anterior hyaloid membrane, pupillary and anterior iris
, trabecula, and occasionally the cornea
. The flakes are widespread. One report suggested that the granular flakes were from abnormalities of the basement membrane in epithelial cells, and that they were distributed widely throughout the body and not just within structures of the eye. There is some research suggesting that the material may be produced in the iris pigment epithelium, ciliary epithelium, or the peripheral anterior lens epithelium. A similar report suggests that the proteins come from the lens, iris, and other parts of the eye.
PEX can become problematic when the flakes become enmeshed in a "spongy area" known as the trabecular meshwork
and block its normal functioning, and may interact with degenerative changes in the Schlemm's canal
and the juxtacanalicular area. The blockage leads to greater-than-normal elevated intraocular pressure
which, in turn, can damage the optic nerve
. The eye produces a clear fluid called the aqueous humor which subsequently drains such that there is a constant level of safe pressure within the eye, but glaucoma can result if this normal outflow of fluid is blocked. Glaucoma
is an umbrella term indicating ailments which damage the neural cable from the eye to the brain called the optic nerve
, and which can lead to a loss of vision. In most cases of glaucoma, typically called primary open-angle glaucoma, the outflow does not happen normally but doctors can not see what is causing the blockage; with PEX, however, the flakes are believed to be a cause of the blockage. PEX flakes by themselves do not directly cause glaucoma, but can cause glaucoma indirectly by blocking the outflow of aqueous humor, which leads to higher intraocular pressure, and this can cause glaucoma. PEX has been known to cause a weakening of structures within the eye which help hold the eye's lens in place, called lens zonules.
examination and it is done with an "85% sensitivity rate and a 100% specificity rate." Since the symptom of increased pressure within the eye is generally painless until the condition becomes rather advanced, it is possible for people afflicted with glaucoma to be in danger yet not be aware of it. As a result, it is recommended that persons have regular eye examination
s to have their levels of intraocular pressure
measured, so that treatments can be prescribed before there is any serious damage to the optic nerve
and subsequent loss of vision
.
of pseudoexfoliation glaucoma is generally unknown.
PEX is generally believed to be a systemic disorder, possibly of the basement membrane of the eye. Researchers have noticed deposits of PEX material in various parts of the body, including in the skin, heart, lungs, liver, kidneys, and elsewhere. Nevertheless, what is puzzling is that PEX tends to happen in only one eye first, which scientists call unilaterality, and in some cases, gradually afflicts the other eye, which is termed bilaterality. According to this reasoning, if PEX were a systemic disorder, then both eyes should be affected at the same time, but they are not. There are contrasting reports about the extent and speed with which PEX moves from one eye to both eyes. According to one report, PEX develops in the second eye in 40% of cases. A contrasting report was that PEX can be found in both eyes in almost all situations if an electron microscope
is used to examine the second eye, or if a biopsy
of the conjunctiva was done, but that the extent of PEX is the second eye was much less than the first one. A contrasting report was that two thirds of PEX patients had flakes in only one eye. In one long term study, patients with PEX in only one eye were studied, and it was found that over time, 13% progressed to having both eyes afflicted by PEX. Scientists believe that elevated levels of plasma homocysteine are a risk factor for cardiovascular disease
, and two studies have found higher levels of plasma homocysteine
in PEX patients, or elevated homocysteine concentrations in tear fluids produced by the eye.
There is speculation that PEX may be caused by oxidative damage and the presence of free radicals, although the exact nature of how this might happen is still under study. Studies of PEX patients have found a decrease in the concentrations of ascorbic acid
, increase in concentrations of malondialdehyde
, and an increase in concentrations of 8-iso-prostaglandinF2a.
There is speculation that genetics
may play a role in PEX. A predisposition to develop PEX later in life may be an inherited characteristic, according to one account. One report suggested the genetic component was "strong". One study performed in Iceland
and Sweden
has associated PEX with polymorphisms
in gene LOXL1
. A report suggested that a specific gene named LOXL1
which was a member of the family of enzyme
s which play a role in the linking of collagen
and elastin
inside cells. LOXL1 was responsible for "all the heritability" of PEX, according to one source. Two distinct mutations in which a single nucleotide was changed, or called a single nucleotide polymorphism or SNP, was discovered in Scandinavian populations and confirmed in other populations, and may be involved with the onset of PEX.
Researchers are investigating whether factors such as exposure to ultraviolet light, living in northern latitudes, or altitude influence the onset of PEX. One report suggested that climate
was not a factor related to PEX. Another report suggested a possible link to sunlight
as well as a possible autoimmune response, or possibly a virus
.
While PEX itself is untreatable as of 2011, it is possible for doctors to minimize the damage to vision and to the optic nerves by the same medical techniques used to prevent glaucoma.
Patients should continue to have regular eye examinations so that physicians can monitor pressure levels and check whether medicines are working.
Systemic disease
Life-threatening disease redirects here.A systemic disease is one that affects a number of organs and tissues, or affects the body as a whole. Although most medical conditions will eventually involve multiple organs in advanced stage Life-threatening disease redirects here.A systemic disease is one...
manifesting itself primarily in the eyes which is characterized by the accumulation of microscopic granular amyloid-like protein fibers. Its cause is unknown, although there is speculation that there may be a genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
basis. It is more prevalent in women than men, and in persons past the age of seventy. Its prevalence in different human populations varies; for example, it is prevalent in Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
. The buildup of protein clumps can block normal drainage of the eye fluid called the aqueous humor and can cause, in turn, a buildup of pressure leading to glaucoma
Glaucoma
Glaucoma 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...
and loss of vision. As worldwide populations become older because of shifts in demography, PEX may become a matter of greater concern.
History
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
named John Lindberg in 1917. He built his own slit lamp
Slit lamp
The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope...
to study the condition and reported "grey flakes on the lens capsule", as well as glaucoma
Glaucoma
Glaucoma 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...
in 50% of the eyes, and an "increasing prevalence of the condition with age." Several decades later, an ocular pathologist named Georgiana Dvorak-Theobald suggested the term pseudoexfoliation to distinguish it from a similar ailment which sometimes affected glassblowers called true exfoliation syndrome. The latter ailment is caused by heat or "infrared-related changes in the anterior lens capsule" and is characterized by "lamellar delamination of the lens capsule." Sometimes the two terms "pseudoexfoliation" and "true exfoliation" are used interchangeably but the more precise usage is to treat each case separately.
Symptoms
Patients may have no specific symptoms. In some cases, patients may complain of lessened visual acuity or changes in their perceived visual field, and such changes may be secondary to or different from symptoms normally associated with cataractCataract
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 glaucoma
Glaucoma
Glaucoma 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...
.
PEX is characterized by tiny microscopic white or grey granular flakes which are clumps of proteins within the eye which look somewhat like dandruff
Dandruff
Dandruff is the shedding of dead skin cells from the scalp . Dandruff is sometimes caused by frequent exposure to extreme heat and cold. As it is normal for skin cells to die and flake off, a small amount of flaking is normal and common; about 487,000 cells/cm2 get released normally after...
when seen through a microscope and which are released by cells. The abnormal flakes, sometimes compared to amyloid
Amyloid
Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various neurodegenerative diseases.-Definition:...
-like material, are visible during an examination of the lens of an eye by an ophthalmologist, which is the usual diagnosis. The white fluffy material is seen in many tissues both ocular and extraocular: in the anterior chamber structures, trabecular meshwork, central disc, zonular fibres, anterior hyaloid membrane, pupillary and anterior iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
, trabecula, and occasionally the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
. The flakes are widespread. One report suggested that the granular flakes were from abnormalities of the basement membrane in epithelial cells, and that they were distributed widely throughout the body and not just within structures of the eye. There is some research suggesting that the material may be produced in the iris pigment epithelium, ciliary epithelium, or the peripheral anterior lens epithelium. A similar report suggests that the proteins come from the lens, iris, and other parts of the eye.
PEX can become problematic when the flakes become enmeshed in a "spongy area" known as the trabecular meshwork
Trabecular meshwork
The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber .The tissue is spongy and lined by trabeculocytes; it allows fluid to drain into a set of...
and block its normal functioning, and may interact with degenerative changes in the Schlemm's canal
Schlemm's canal
Schlemm's canal, also known as canal of Schlemm or the scleral venous sinus, is a circular channel in the eye that collects aqueous humor from the anterior chamber and delivers it into the bloodstream via the anterior ciliary veins....
and the juxtacanalicular area. The blockage leads to greater-than-normal elevated intraocular pressure
Intraocular pressure
Intraocular pressure is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk from glaucoma...
which, in turn, can damage the optic nerve
Optic nerve
The 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...
. The eye produces a clear fluid called the aqueous humor which subsequently drains such that there is a constant level of safe pressure within the eye, but glaucoma can result if this normal outflow of fluid is blocked. Glaucoma
Glaucoma
Glaucoma 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...
is an umbrella term indicating ailments which damage the neural cable from the eye to the brain called the optic nerve
Optic nerve
The 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...
, and which can lead to a loss of vision. In most cases of glaucoma, typically called primary open-angle glaucoma, the outflow does not happen normally but doctors can not see what is causing the blockage; with PEX, however, the flakes are believed to be a cause of the blockage. PEX flakes by themselves do not directly cause glaucoma, but can cause glaucoma indirectly by blocking the outflow of aqueous humor, which leads to higher intraocular pressure, and this can cause glaucoma. PEX has been known to cause a weakening of structures within the eye which help hold the eye's lens in place, called lens zonules.
Diagnosis
PEX is usually diagnosed by an eye doctor who examines the eye using a microscope. The method is termed slit lampSlit lamp
The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope...
examination and it is done with an "85% sensitivity rate and a 100% specificity rate." Since the symptom of increased pressure within the eye is generally painless until the condition becomes rather advanced, it is possible for people afflicted with glaucoma to be in danger yet not be aware of it. As a result, it is recommended that persons have regular eye examination
Eye examination
An eye examination is a battery of tests performed by an ophthalmologist, optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes....
s to have their levels of intraocular pressure
Intraocular pressure
Intraocular pressure is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk from glaucoma...
measured, so that treatments can be prescribed before there is any serious damage to the optic nerve
Optic nerve
The 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...
and subsequent loss of vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
.
Causes
The cause or etiologyEtiology
Etiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
of pseudoexfoliation glaucoma is generally unknown.
PEX is generally believed to be a systemic disorder, possibly of the basement membrane of the eye. Researchers have noticed deposits of PEX material in various parts of the body, including in the skin, heart, lungs, liver, kidneys, and elsewhere. Nevertheless, what is puzzling is that PEX tends to happen in only one eye first, which scientists call unilaterality, and in some cases, gradually afflicts the other eye, which is termed bilaterality. According to this reasoning, if PEX were a systemic disorder, then both eyes should be affected at the same time, but they are not. There are contrasting reports about the extent and speed with which PEX moves from one eye to both eyes. According to one report, PEX develops in the second eye in 40% of cases. A contrasting report was that PEX can be found in both eyes in almost all situations if an electron microscope
Electron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...
is used to examine the second eye, or if a biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
of the conjunctiva was done, but that the extent of PEX is the second eye was much less than the first one. A contrasting report was that two thirds of PEX patients had flakes in only one eye. In one long term study, patients with PEX in only one eye were studied, and it was found that over time, 13% progressed to having both eyes afflicted by PEX. Scientists believe that elevated levels of plasma homocysteine are a risk factor for cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...
, and two studies have found higher levels of plasma homocysteine
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
in PEX patients, or elevated homocysteine concentrations in tear fluids produced by the eye.
There is speculation that PEX may be caused by oxidative damage and the presence of free radicals, although the exact nature of how this might happen is still under study. Studies of PEX patients have found a decrease in the concentrations of ascorbic acid
Ascorbic acid
Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form of vitamin C. The name is derived from a- and scorbutus , the...
, increase in concentrations of malondialdehyde
Malondialdehyde
Malondialdehyde is the organic compound with the formula CH22. The structure of this species is more complex than this formula suggests. This reactive species occurs naturally and is a marker for oxidative stress.- Structure and synthesis :...
, and an increase in concentrations of 8-iso-prostaglandinF2a.
There is speculation that genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
may play a role in PEX. A predisposition to develop PEX later in life may be an inherited characteristic, according to one account. One report suggested the genetic component was "strong". One study performed in Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
has associated PEX with polymorphisms
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
in gene LOXL1
LOXL1
Lysyl oxidase-like 1, also known as LOXL1, is an enzyme which in humans is encoded by the LOXL1 gene.- Function :This gene encodes a member of the lysyl oxidase gene family...
. A report suggested that a specific gene named LOXL1
LOXL1
Lysyl oxidase-like 1, also known as LOXL1, is an enzyme which in humans is encoded by the LOXL1 gene.- Function :This gene encodes a member of the lysyl oxidase gene family...
which was a member of the family of enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s which play a role in the linking of collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
and elastin
Elastin
Elastin is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of...
inside cells. LOXL1 was responsible for "all the heritability" of PEX, according to one source. Two distinct mutations in which a single nucleotide was changed, or called a single nucleotide polymorphism or SNP, was discovered in Scandinavian populations and confirmed in other populations, and may be involved with the onset of PEX.
Researchers are investigating whether factors such as exposure to ultraviolet light, living in northern latitudes, or altitude influence the onset of PEX. One report suggested that climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
was not a factor related to PEX. Another report suggested a possible link to sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
as well as a possible autoimmune response, or possibly a virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
.
Prevalence
Scientists are studying different populations and relationships to try to learn more about the disease. They have found associations with different groups but it is not yet clear what the underlying factors are and how they affect different peoples around the world.- Glaucoma patients. While PEX and glaucoma are believed to be related, there are cases of persons with PEX without glaucoma, and persons with glaucoma without PEX. Generally, a person with PEX is considered as having a risk of developing glaucoma, and vice versa. One study suggested that the PEX was present in 12% of glaucoma patients. Another found that PEX was present in 6% of an "open-angle glaucoma" group. Pseudoexfoliation syndrome is considered to be the most common of identifiable causes of 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...
. If PEX is diagnosed without glaucoma, there is a high risk of a patient subsequently developing glaucoma.
- Country and region. Prevalence of PEX varies by geography. In EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, differing levels of PEX were found; 5% in England, 6% in Norway, 4% in Germany, 1% in Greece, and 6% in France. One contrary report suggested that levels of PEX were higher among Greek peopleGreeceGreece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
. One study of a county in MinnesotaMinnesotaMinnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
found that the prevalence of PEX was 25.9 cases per 100,000 people. It is reportedly high in northern European countries such as NorwayNorwayNorway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, SwedenSwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
and FinlandFinlandFinland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, as well as among the Sami people of northern Europe, and high among Arabic populations, but relatively rare among African Americans and Eskimos. In southern Africa, prevalence was found to be 19% of patients in a glaucoma clinic attending to persons of the Bantu tribes.
- Race. It varies considerably according to race.
- Gender. It affects women more than men. One report was that women were three times more likely than men to develop PEX.
- Age. Older persons are more likely to develop PEX. And persons younger than 50 are highly unlikely to have PEX. A study in NorwayNorwayNorway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
found that the prevalence of PEX of persons aged 50–59 was 0.4% while it was 7.9% for persons aged 80–89 years. If a person is going to develop PEX, the average age in which this will happen is between 69 to 75 years, according to the Norwegian study. A second corroborating report suggested that it happens primarily to people 70 and older. While older people are more likely to develop PEX, it is not seen as a "normal" part of aging.
- Other diseases. Sometimes PEX is associated with the development of medical problems other than merely glaucoma. There are conflicting reports about whether PEX is associated with problems of the heart or brain; one study suggested no correlations while other studies found statistical links with Alzheimer's diseaseAlzheimer's diseaseAlzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
, senile dementia, cerebral atrophyCerebral atrophyCerebral atrophy is a common feature of many of the diseases that affect the brain. Atrophy of any tissue means loss of cells. In brain tissue, atrophy describes a loss of neurons and the connections between them...
, chronic cerebral ischemia, strokeStrokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, transient ischemic attacks, heart diseaseHeart diseaseHeart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
, and hearing loss.
Treatment
- Eyedrops. This is usually the first treatment method. Eyedrops can help reduce intraocular pressure within the eye. The medications within the eyedrops can include beta blockerBeta blockerBeta blockers or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly for the management of cardiac arrhythmias, cardioprotection after myocardial infarction ,...
s (such as levobunolol or timolol) which slow the production of the aqueous humor. And other medications can increase its outflow, such as prostaglandin analogues (e.g. latanoprost). And these medicines can be used in various combinations. In most cases of glaucoma, eyedrops alone will suffice to solve the problem.
- Laser surgery. A further treatment is a type of laser therapy known as trabeculoplastyTrabeculoplastyTrabeculoplasty is a treatment for glaucoma plastic surgery. It is done on a argon laser equipped slit lamp, using a Goldmann gonioscope lens mirror. The laser is directed to the trabecular meshwork...
in which a high-energy laser beam is pointed at the trabecular meshwork to cause it to "remodel and open" and improve the outflows of the aqueous humor. These can be done as an outpatient procedure and take less than twenty minutes. One report suggests this procedure is usually effective.
- Eye surgery. Surgery is the treatment method of last resort if the other methods have not worked. It is usually effective at preventing glaucoma. Eye surgery on PEX patients can be subject to medical complications if the fibers which hold the lens have become weakened because of a buildup from the flakes; if the lens-holding fibers have weakened, then the lens may become loose, and complications from eye surgery may result. In such cases, it is recommended that surgeons act quickly to repair the phacodonesis before the lenses have dropped. A surgeon cuts an opening in the white portion of the eye known as the scleraScleraThe sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...
, and removes a tiny area of the trabecular meshwork which enables the aqueous humor to discharge. This lowers the internal pressure within the eye and lessens the chance of future damage to the optic nerve. Cases with pseudophacodonesis and dislocated IOL have been increasing in number, according to one report. In cataract surgery, complications resulting from PEX include capsular rupture and vitreous loss.
- Drug therapy. There are speculations that if genetics plays a role in PEX, and if the specific genes involved can be identified, that possibly drugs can be developed to counteract these mutations or their effects. But such drugs have not been developed as of 2011.
Patients should continue to have regular eye examinations so that physicians can monitor pressure levels and check whether medicines are working.
Research
Scientists and doctors are actively exploring how PEX happens, its causes, and how it might be prevented or mitigated. Research activity to explore what causes glaucoma has been characterized as "intense". There has been research into the genetic basis of PEX. One researcher speculated about a possible "two-hit hypothesis" in which a single mutation in the LOXL1 gene puts people at risk for PEX, but that a second still-to-be-found mutation has some affect on the proteins, possibly affecting bonds between chemicals, such that the proteins are more likely to clump together and disrupt the outflow of aqueous humor.Alternative names
- Exfoliation glaucoma; XFG
- Pseudoexfoliation glaucoma
- Pseudoexfoliation of the lens
- Exfoliation syndrome; XFS