Information on some of the most common eye disease/disorders
Cataracts
What is a cataract? The lens is a unique living ocular tissue that is usually clear or transparent
and is referred to as 'the crystalline lens' by doctors. The normal lens focuses light on the lightsensitive
nervous tissue located in the back of the eye which is known as the retina. A cataract is
an opacity (or cloudy change) of the lens that scatters light and looks gray or white. The word
cataract literally means "to break down." The word applies to waterfalls and rapids as well as to
the lens. Cataractous changes of the lens may appear as small insignificant dots, microscopic
blisters, a cracked-glass appearance, a diffuse haze, a "pearl-like" sheen, white streaks or a
completely white lens. The cataract usually starts as small dots or microscopic blisters and
progresses to involve larger areas of the lens. The rate of progression is difficult to predict and
may be very slow or quite rapid. At times the cataract appears to worsen overnight. Cataracts may
develop in one or in both eyes. If a large portion of the lens becomes white, it prevents formed
images from reaching the retina and blurred vision results. When a light is shined into the eye of a
patient with a complete cataract, the patient only sees a white light and no images can be seen.
Visit: http://www.eyevet.info/cataract.html for more information on cataracts.
Glaucoma
Glaucoma is the elevation of pressure inside the eye, known as intraocular pressure (IOP) beyond
a specific point at which vision is compromised or is no longer possible. Glaucoma is a frequent
cause of blindness in humans and animals.
To understand glaucoma, it is necessary to understand how the normal flow of intraocular fluid
maintains normal intraocular pressure. The fluid inside the eye is called the aqueous humor which
is produced in the ciliary body which is located behind the iris. This fluid flows through the pupil
and drains from the eye through a sieve-like network located at the junction of the cornea and the
iris called the iridocorneal cleft or drainage angle. The aqueous humor is produced and drains
from the eye at approximately the same rate, resulting in a stable pressure inside the eye of 15 to
20 mmHg (millimetres of mercury). Glaucoma occurs as a consequence of inadequate outflow of
aqueous humor and a subsequent buildup of pressure inside the eye. The resulting high pressure
damages the optic nerve and results in blindness. For more information on glaucoma visit:
http://www.eyevet.info/glaucoma.html
Diabetes
Diabetic dogs can live healthy lives. Unfortunately, a common complication of diabetes in dogs is
cataracts (cloudy lenses). In fact, 75% of dogs develop cataracts and blindness in both eyes
within one year of being diagnosed with diabetes. The cataracts develop very quickly—sometimes
overnight! If untreated, the cataracts cause intraocular inflammation called Lens-Induced Uveitis
(LIU) that harms the eyes by causing glaucoma (increased intraocular pressure). If the LIU is
uncontrolled and glaucoma develops, cataract surgery might not be possible. Glaucoma causes a
chronic headache (similar to a migraine). Once it is apparent that cataracts are forming, it is
important to have your pet examined by a veterinary ophthalmologist as soon as possible. For
more information on glaucoma visit:
http://www.animaleyecare.net/diseases/CataractsBlindenssDiabeticDogs.htm
PRA. (also known as PRD)
Progressive retinal degeneration (PRD) is also known as progressive retinal atrophy (PRA) and
refers to retinal diseases that cause blindness. Some breeds have blindness by abnormal
development of the retina and this is called dysplasia. Other breeds have a slowly progressive
degeneration or death of the retinal tissue and this is degeneration. These two types of diseases
affect many breeds. In general these diseases are thought to be inherited but inherited differently
in each breed. In all animals with PRD the outcome, age of the patient and what the veterinary
ophthalmologist sees are the basis for the classification of exactly what type of condition the
patient has. Different breeds of dogs have variations in the age the problem starts and speed with
which the blindness develops. The condition of PRD has been seen in almost every registered
breed and in mixed breed dogs as well. This same condition occurs in humans and is known as
retinitis pigmentosa. For more information on P.R.A. visit: http://www.eyevet.info/pra.html
SARDS (Sudden Acquired Retinal Degeneration Syndrome)
Veterinary ophthalmologists are aware of a vision loss syndrome * with changes in appetite and
water consumption in dogs. This condition, known as sudden acquired retinal degeneration
syndrome (SARDS), may strike any pure or mixed breed of dog. These pets are generally
between the ages of 7 and 14 years of age, with females predominating over males. Research
indicates these pets have total destruction of the visual cell layer (the rods and cones) of the
retina with subsequent blindness. Visit: http://eyevet.info/sards.html for more information on
SARDS.
Corneal Ulcer
A corneal ulcer is a break in the outer layer or epithelium of the cornea. Uncomplicated ulcers,
although initially painful, should heal in 3 to 4 days with appropriate treatment. Those ulcers that
persist longer than this period of time often prove to be complicated ulcers. For more information
on Corneal Ulcer visit: http://www.eyevet.info/corneal_ulcer.html
Corneal Dystrophy
In most breeds, corneal dystrophy appears as gray-white, crystalline or metallic opacities in the
center of the cornea or close to the periphery. These opacities may affect any layer of the cornea,
the epithelium (outer layer), the stroma (the thick, middle layer), or the endothelium (the inner
layer). The opacities are usually oval or round and are sometimes doughnut-shaped. For more
information on Corneal Dystrophy visit: http://www.eyevet.info/corneal_dystrophy.html
Retinal Dysplasia
Retinal dysplasia is a type of retinal malformation. The word "dysplasia" simply means "a defective
development of an organ or structure". Retinal dysplasia occurs when the 2 primitive layers of the
retina do not form together properly. Mild dysplasia manifests as folds in the inner retinal layer.
These are called "retinal folds". In "geographic" retinal dysplasia there are larger areas of
defective retinal development. In the severe form of dysplasia, the 2 retinal layers do not come
together at all and retinal detachment occurs. Retinal dysplasia is not progressive. It is a
congenital defect and animals are born with as severe a condition as they will ever get. For more
information on Retinal Dysplasia visit: http://www.eyevet.info/ret_dysplasia.html
Dry Eye (KCS)
Keratoconjunctivitis sicca (KCS) or "dry eye" describes the changes in the eye which result from
lack of tear production. To understand "dry eye" it is helpful to know how tears help keep the
cornea healthy. The cornea is the optically clear portion of the eye that allows entry of light into the
eye. Like all living tissue, the cornea requires a supply of oxygen and energy to remain healthy.
Oxygen and nutrients are supplied to most tissues by the blood that moves through the area in
blood vessels. The healthy cornea has no blood vessels, if it did it wouldn't be clear, so the
oxygen and nutrients are supplied through the three-layered 'tear film.' For more information on
Dry Eye visit: http://www.eyevet.info/kcs.html
Cherry Eye
A prolapsed gland of the third eyelid (or "cherry eye") is thought to be * with a laxity of a small
ligament which holds the gland in a normal position behind the third eyelid. The gland is a tear
producing gland, and produces about 30% of the tears, while the main orbital lacrimal gland
produces the rest. Dogs that have had the gland of the third eyelid surgically excised have a
greater risk of development of a dry eye (KCS ) than dogs with intact third eyelid glands. It is
thought that should the main orbital lacrimal gland be damaged later in life that there is no "backup"
for tear production. Dry eye is a serious eye condition that is difficult to treat, and requires
lifelong treatment which may be costly. If the chance of the development of a dry eye can be
lessened by tacking the gland back into a normal position so that it stays functional, then this is
the most desirable way of handling "cherry eye". For more information on Cherry Eye visit:
http://www.eyevet.info/cherry.html
Lens Luxation
The lens can either become loosened (subluxated) or completely detached (luxated). When the
lens completely tears free of its zonular attachments and falls forward into the anterior chamber,
we call this an anterior luxation. It is also possible for the lens to luxate posteriorly into the vitreous
body. Since lens luxation may cause glaucoma, and since glaucoma may cause lens luxation it is
important to determine which disease came first. When lens luxation occurs secondarily to
glaucoma, it usually occurs late in the disease once the elevated pressure within the eye has
caused the sclera to stretch, and the zonular ligaments to tear. This does not occur until long after
vision has been lost. In such a case, attention must be given to resolving the pain * with
glaucoma. For more information on Lens Luxation visit: http://www.eyevet.info/luxlens.html
Lethal White - A Genetic Defect that is Preventable...
A lethal white is a term used to refer to the more politically correct double merle (MM) gene, or
homozygous genetic defect. In people terms: A merle bred to a merle will always produce a lethal
white. At least one, maybe more. A Lethal White pup w/MM gene will be blind or deaf or both. The
double merle genetic defect can be found in the Australian Shepherd, Great Dane, the Dachsund,
the Sheltie, the Collie - any dog with the merle or dapple coat. There is a group in Arizona whose
sole purpose is to educate, inspire, and rescue these Australian Shepherd lethals from certain
death. They can be found at: at http://www.aussielads.com/ or http://www.AmazingAussies.com
Horner's Syndrome
Horner's syndrome is not uncommon and occurs in dogs, cats, horses and many other species.
The symptoms generally include a sunken in eye (enophthalmia) with a small pupil (miosis), a
droopy upper eyelid (ptosis) and a prominant third eyelid. Horner's syndrome must be
differentiated from Uveitis which also produces a constricted pupil and a droopy looking eye. For
more information on Horner's Syndrome visit: http://www.eyevet.info/horner.html
Uveitis
Uveitis is a viral infection which can often occur in horses and humans, but rarely in dogs.
Uveitis means "inflammation of the uvea", or the middle layer of the eye. The uvea consists of
three structures: the iris, the ciliary body, and the choroid. The iris is the colored structure
surrounding the pupil, visible in the front of the eye. The ciliary body is a structure containing
muscle and is located behind the iris which focuses the lens. The choroid is a layer containing
blood vessels that line the back of the eye and is located between the inner visually sensitive
layer, called the retina, and the outer white eye wall, called the sclera. Inflammation occurring in
any of these three structures is termed "uveitis". For more information on Uveitus visit:
http://www.veterinarypartner.com/Content.plx?P=A&A=1714&S=1&SourceID=42
Information on some of the most common eye disease/disorders
Cataracts
What is a cataract? The lens is a unique living ocular tissue that is usually clear or transparent
and is referred to as 'the crystalline lens' by doctors. The normal lens focuses light on the lightsensitive
nervous tissue located in the back of the eye which is known as the retina. A cataract is
an opacity (or cloudy change) of the lens that scatters light and looks gray or white. The word
cataract literally means "to break down." The word applies to waterfalls and rapids as well as to
the lens. Cataractous changes of the lens may appear as small insignificant dots, microscopic
blisters, a cracked-glass appearance, a diffuse haze, a "pearl-like" sheen, white streaks or a
completely white lens. The cataract usually starts as small dots or microscopic blisters and
progresses to involve larger areas of the lens. The rate of progression is difficult to predict and
may be very slow or quite rapid. At times the cataract appears to worsen overnight. Cataracts may
develop in one or in both eyes. If a large portion of the lens becomes white, it prevents formed
images from reaching the retina and blurred vision results. When a light is shined into the eye of a
patient with a complete cataract, the patient only sees a white light and no images can be seen.
Visit: http://www.eyevet.info/cataract.html for more information on cataracts.
Glaucoma
Glaucoma is the elevation of pressure inside the eye, known as intraocular pressure (IOP) beyond
a specific point at which vision is compromised or is no longer possible. Glaucoma is a frequent
cause of blindness in humans and animals.
To understand glaucoma, it is necessary to understand how the normal flow of intraocular fluid
maintains normal intraocular pressure. The fluid inside the eye is called the aqueous humor which
is produced in the ciliary body which is located behind the iris. This fluid flows through the pupil
and drains from the eye through a sieve-like network located at the junction of the cornea and the
iris called the iridocorneal cleft or drainage angle. The aqueous humor is produced and drains
from the eye at approximately the same rate, resulting in a stable pressure inside the eye of 15 to
20 mmHg (millimetres of mercury). Glaucoma occurs as a consequence of inadequate outflow of
aqueous humor and a subsequent buildup of pressure inside the eye. The resulting high pressure
damages the optic nerve and results in blindness. For more information on glaucoma visit:
http://www.eyevet.info/glaucoma.html
Diabetes
Diabetic dogs can live healthy lives. Unfortunately, a common complication of diabetes in dogs is
cataracts (cloudy lenses). In fact, 75% of dogs develop cataracts and blindness in both eyes
within one year of being diagnosed with diabetes. The cataracts develop very quickly—sometimes
overnight! If untreated, the cataracts cause intraocular inflammation called Lens-Induced Uveitis
(LIU) that harms the eyes by causing glaucoma (increased intraocular pressure). If the LIU is
uncontrolled and glaucoma develops, cataract surgery might not be possible. Glaucoma causes a
chronic headache (similar to a migraine). Once it is apparent that cataracts are forming, it is
important to have your pet examined by a veterinary ophthalmologist as soon as possible. For
more information on glaucoma visit:
http://www.animaleyecare.net/diseases/CataractsBlindenssDiabeticDogs.htm
PRA. (also known as PRD)
Progressive retinal degeneration (PRD) is also known as progressive retinal atrophy (PRA) and
refers to retinal diseases that cause blindness. Some breeds have blindness by abnormal
development of the retina and this is called dysplasia. Other breeds have a slowly progressive
degeneration or death of the retinal tissue and this is degeneration. These two types of diseases
affect many breeds. In general these diseases are thought to be inherited but inherited differently
in each breed. In all animals with PRD the outcome, age of the patient and what the veterinary
ophthalmologist sees are the basis for the classification of exactly what type of condition the
patient has. Different breeds of dogs have variations in the age the problem starts and speed with
which the blindness develops. The condition of PRD has been seen in almost every registered
breed and in mixed breed dogs as well. This same condition occurs in humans and is known as
retinitis pigmentosa. For more information on P.R.A. visit: http://www.eyevet.info/pra.html
SARDS (Sudden Acquired Retinal Degeneration Syndrome)
Veterinary ophthalmologists are aware of a vision loss syndrome * with changes in appetite and
water consumption in dogs. This condition, known as sudden acquired retinal degeneration
syndrome (SARDS), may strike any pure or mixed breed of dog. These pets are generally
between the ages of 7 and 14 years of age, with females predominating over males. Research
indicates these pets have total destruction of the visual cell layer (the rods and cones) of the
retina with subsequent blindness. Visit: http://eyevet.info/sards.html for more information on
SARDS.
Corneal Ulcer
A corneal ulcer is a break in the outer layer or epithelium of the cornea. Uncomplicated ulcers,
although initially painful, should heal in 3 to 4 days with appropriate treatment. Those ulcers that
persist longer than this period of time often prove to be complicated ulcers. For more information
on Corneal Ulcer visit: http://www.eyevet.info/corneal_ulcer.html
Corneal Dystrophy
In most breeds, corneal dystrophy appears as gray-white, crystalline or metallic opacities in the
center of the cornea or close to the periphery. These opacities may affect any layer of the cornea,
the epithelium (outer layer), the stroma (the thick, middle layer), or the endothelium (the inner
layer). The opacities are usually oval or round and are sometimes doughnut-shaped. For more
information on Corneal Dystrophy visit: http://www.eyevet.info/corneal_dystrophy.html
Retinal Dysplasia
Retinal dysplasia is a type of retinal malformation. The word "dysplasia" simply means "a defective
development of an organ or structure". Retinal dysplasia occurs when the 2 primitive layers of the
retina do not form together properly. Mild dysplasia manifests as folds in the inner retinal layer.
These are called "retinal folds". In "geographic" retinal dysplasia there are larger areas of
defective retinal development. In the severe form of dysplasia, the 2 retinal layers do not come
together at all and retinal detachment occurs. Retinal dysplasia is not progressive. It is a
congenital defect and animals are born with as severe a condition as they will ever get. For more
information on Retinal Dysplasia visit: http://www.eyevet.info/ret_dysplasia.html
Dry Eye (KCS)
Keratoconjunctivitis sicca (KCS) or "dry eye" describes the changes in the eye which result from
lack of tear production. To understand "dry eye" it is helpful to know how tears help keep the
cornea healthy. The cornea is the optically clear portion of the eye that allows entry of light into the
eye. Like all living tissue, the cornea requires a supply of oxygen and energy to remain healthy.
Oxygen and nutrients are supplied to most tissues by the blood that moves through the area in
blood vessels. The healthy cornea has no blood vessels, if it did it wouldn't be clear, so the
oxygen and nutrients are supplied through the three-layered 'tear film.' For more information on
Dry Eye visit: http://www.eyevet.info/kcs.html
Cherry Eye
A prolapsed gland of the third eyelid (or "cherry eye") is thought to be * with a laxity of a small
ligament which holds the gland in a normal position behind the third eyelid. The gland is a tear
producing gland, and produces about 30% of the tears, while the main orbital lacrimal gland
produces the rest. Dogs that have had the gland of the third eyelid surgically excised have a
greater risk of development of a dry eye (KCS ) than dogs with intact third eyelid glands. It is
thought that should the main orbital lacrimal gland be damaged later in life that there is no "backup"
for tear production. Dry eye is a serious eye condition that is difficult to treat, and requires
lifelong treatment which may be costly. If the chance of the development of a dry eye can be
lessened by tacking the gland back into a normal position so that it stays functional, then this is
the most desirable way of handling "cherry eye". For more information on Cherry Eye visit:
http://www.eyevet.info/cherry.html
Lens Luxation
The lens can either become loosened (subluxated) or completely detached (luxated). When the
lens completely tears free of its zonular attachments and falls forward into the anterior chamber,
we call this an anterior luxation. It is also possible for the lens to luxate posteriorly into the vitreous
body. Since lens luxation may cause glaucoma, and since glaucoma may cause lens luxation it is
important to determine which disease came first. When lens luxation occurs secondarily to
glaucoma, it usually occurs late in the disease once the elevated pressure within the eye has
caused the sclera to stretch, and the zonular ligaments to tear. This does not occur until long after
vision has been lost. In such a case, attention must be given to resolving the pain * with
glaucoma. For more information on Lens Luxation visit: http://www.eyevet.info/luxlens.html
Lethal White - A Genetic Defect that is Preventable...
A lethal white is a term used to refer to the more politically correct double merle (MM) gene, or
homozygous genetic defect. In people terms: A merle bred to a merle will always produce a lethal
white. At least one, maybe more. A Lethal White pup w/MM gene will be blind or deaf or both. The
double merle genetic defect can be found in the Australian Shepherd, Great Dane, the Dachsund,
the Sheltie, the Collie - any dog with the merle or dapple coat. There is a group in Arizona whose
sole purpose is to educate, inspire, and rescue these Australian Shepherd lethals from certain
death. They can be found at: at http://www.aussielads.com/ or http://www.AmazingAussies.com
Horner's Syndrome
Horner's syndrome is not uncommon and occurs in dogs, cats, horses and many other species.
The symptoms generally include a sunken in eye (enophthalmia) with a small pupil (miosis), a
droopy upper eyelid (ptosis) and a prominant third eyelid. Horner's syndrome must be
differentiated from Uveitis which also produces a constricted pupil and a droopy looking eye. For
more information on Horner's Syndrome visit: http://www.eyevet.info/horner.html
Uveitis
Uveitis is a viral infection which can often occur in horses and humans, but rarely in dogs.
Uveitis means "inflammation of the uvea", or the middle layer of the eye. The uvea consists of
three structures: the iris, the ciliary body, and the choroid. The iris is the colored structure
surrounding the pupil, visible in the front of the eye. The ciliary body is a structure containing
muscle and is located behind the iris which focuses the lens. The choroid is a layer containing
blood vessels that line the back of the eye and is located between the inner visually sensitive
layer, called the retina, and the outer white eye wall, called the sclera. Inflammation occurring in
any of these three structures is termed "uveitis". For more information on Uveitus visit:
http://www.veterinarypartner.com/Content.plx?P=A&A=1714&S=1&SourceID=42
Diabetes
Diabetic dogs can live
healthy lives. Unfortunately, a common complication of diabetes in dogs is
cataracts (cloudy lenses).
In fact, 75% of dogs develop cataracts and blindness in both eyes
within one year of
being diagnosed with diabetes. The cataracts develop very quickly—sometimes
overnight! If
untreated, the cataracts cause intraocular inflammation called Lens-Induced Uveitis
(LIU) that harms the
eyes by causing glaucoma (increased intraocular pressure). If the LIU is
uncontrolled and
glaucoma develops, cataract surgery might not be possible. Glaucoma causes a
chronic headache
(similar to a migraine). Once it is apparent that cataracts are forming, it is
important to have your
pet examined by a veterinary ophthalmologist as soon as possible. For
more information on
glaucoma visit:
http://www.animaleyecare.net/diseases/CataractsBlindenssDiabeticDogs.htm
Corneal Ulcer
A corneal ulcer is a
break in the outer layer or epithelium of the cornea. Uncomplicated ulcers,
although initially
painful, should heal in 3 to 4 days with appropriate treatment. Those ulcers
that
persist longer than
this period of time often prove to be complicated ulcers. For more information
on Corneal Ulcer
visit: http://www.eyevet.info/corneal_ulcer.html
Corneal Dystrophy
In most breeds,
corneal dystrophy appears as gray-white, crystalline or metallic opacities in
the
center of the cornea
or close to the periphery. These opacities may affect any layer of the cornea,
the epithelium (outer
layer), the stroma (the thick, middle layer), or the endothelium (the inner
layer). The opacities
are usually oval or round and are sometimes doughnut-shaped. For more
information on Corneal
Dystrophy visit: http://www.eyevet.info/corneal_dystrophy.html
Retinal Dysplasia
Retinal dysplasia is a
type of retinal malformation. The word "dysplasia" simply means
"a defective
development of an
organ or structure". Retinal dysplasia occurs when the 2 primitive layers
of the
retina do not form
together properly. Mild dysplasia manifests as folds in the inner retinal
layer.
These are called
"retinal folds". In "geographic" retinal dysplasia there
are larger areas of
defective retinal
development. In the severe form of dysplasia, the 2 retinal layers do not come
together at all and
retinal detachment occurs. Retinal dysplasia is not progressive. It is a
congenital defect and
animals are born with as severe a condition as they will ever get. For more
information on Retinal
Dysplasia visit: http://www.eyevet.info/ret_dysplasia.html
Dry Eye (KCS)
Keratoconjunctivitis
sicca (KCS) or "dry eye" describes the changes in the eye which
result from
lack of tear
production. To understand "dry eye" it is helpful to know how tears
help keep the
cornea healthy. The
cornea is the optically clear portion of the eye that allows entry of light
into the
eye. Like all living
tissue, the cornea requires a supply of oxygen and energy to remain healthy.
Oxygen and nutrients
are supplied to most tissues by the blood that moves through the area in
blood vessels. The
healthy cornea has no blood vessels, if it did it wouldn't be clear, so the
oxygen and nutrients
are supplied through the three-layered 'tear film.' For more information on
Dry Eye visit: http://www.eyevet.info/kcs.html
Cherry Eye
A prolapsed gland of
the third eyelid (or "cherry eye") is thought to be * with a laxity
of a small
ligament which holds
the gland in a normal position behind the third eyelid. The gland is a tear
producing gland, and
produces about 30% of the tears, while the main orbital lacrimal gland
produces the rest.
Dogs that have had the gland of the third eyelid surgically excised have a
greater risk of
development of a dry eye (KCS ) than dogs with intact third eyelid glands. It
is
thought that should
the main orbital lacrimal gland be damaged later in life that there is no
"backup"
for tear production.
Dry eye is a serious eye condition that is difficult to treat, and requires
lifelong treatment
which may be costly. If the chance of the development of a dry eye can be
lessened by tacking
the gland back into a normal position so that it stays functional, then this is
the most desirable way
of handling "cherry eye". For more information on Cherry Eye visit:
http://www.eyevet.info/cherry.html
Lens Luxation
The lens can either
become loosened (subluxated) or completely detached (luxated). When the
lens completely tears
free of its zonular attachments and falls forward into the anterior chamber,
we call this an
anterior luxation. It is also possible for the lens to luxate posteriorly into
the vitreous
body. Since lens
luxation may cause glaucoma, and since glaucoma may cause lens luxation it is
important to determine
which disease came first. When lens luxation occurs secondarily to
glaucoma, it usually
occurs late in the disease once the elevated pressure within the eye has
caused the sclera to
stretch, and the zonular ligaments to tear. This does not occur until long
after
vision has been lost.
In such a case, attention must be given to resolving the pain * with
glaucoma. For more
information on Lens Luxation visit: http://www.eyevet.info/luxlens.html
Lethal White - A Genetic Defect
that is Preventable...
A lethal white is a
term used to refer to the more politically correct double merle (MM) gene, or
homozygous genetic
defect. In people terms: A merle bred to a merle will always produce a lethal
white. At least one,
maybe more. A Lethal White pup w/MM gene will be blind or deaf or both. The
double merle genetic
defect can be found in the Australian Shepherd, Great Dane, the Dachsund,
the Sheltie, the
Collie - any dog with the merle or dapple coat. There is a group in Arizona
whose
sole purpose is to
educate, inspire, and rescue these Australian Shepherd lethals from certain
death. They can be
found at: at http://www.aussielads.com/ or http://www.AmazingAussies.com
Horner's Syndrome
Horner's syndrome is
not uncommon and occurs in dogs, cats, horses and many other species.
The symptoms generally
include a sunken in eye (enophthalmia) with a small pupil (miosis), a
droopy upper eyelid
(ptosis) and a prominant third eyelid. Horner's syndrome must be
differentiated from
Uveitis which also produces a constricted pupil and a droopy looking eye. For
more information on
Horner's Syndrome visit: http://www.eyevet.info/horner.html
Uveitis
Uveitis is a viral
infection which can often occur in horses and humans, but rarely in dogs.
Uveitis means
"inflammation of the uvea", or the middle layer of the eye. The uvea
consists of
three structures: the
iris, the ciliary body, and the choroid. The iris is the colored structure
surrounding the pupil,
visible in the front of the eye. The ciliary body is a structure containing
muscle and is located
behind the iris which focuses the lens. The choroid is a layer containing
blood vessels that
line the back of the eye and is located between the inner visually sensitive
layer, called the
retina, and the outer white eye wall, called the sclera. Inflammation occurring
in
any of these three
structures is termed "uveitis". For more information on Uveitus
visit:
http://www.veterinarypartner.com/Content.plx?P=A&A=1714&S=1&SourceID=42
Information on some of the most common eye disease/disorders
Cataracts
What is a cataract? The lens is a unique living ocular tissue that is usually clear or transparent
and is referred to as 'the crystalline lens' by doctors. The normal lens focuses light on the lightsensitive
nervous tissue located in the back of the eye which is known as the retina. A cataract is
an opacity (or cloudy change) of the lens that scatters light and looks gray or white. The word
cataract literally means "to break down." The word applies to waterfalls and rapids as well as to
the lens. Cataractous changes of the lens may appear as small insignificant dots, microscopic
blisters, a cracked-glass appearance, a diffuse haze, a "pearl-like" sheen, white streaks or a
completely white lens. The cataract usually starts as small dots or microscopic blisters and
progresses to involve larger areas of the lens. The rate of progression is difficult to predict and
may be very slow or quite rapid. At times the cataract appears to worsen overnight. Cataracts may
develop in one or in both eyes. If a large portion of the lens becomes white, it prevents formed
images from reaching the retina and blurred vision results. When a light is shined into the eye of a
patient with a complete cataract, the patient only sees a white light and no images can be seen.
Visit: http://www.eyevet.info/cataract.html for more information on cataracts.
Glaucoma
Glaucoma is the elevation of pressure inside the eye, known as intraocular pressure (IOP) beyond
a specific point at which vision is compromised or is no longer possible. Glaucoma is a frequent
cause of blindness in humans and animals.
To understand glaucoma, it is necessary to understand how the normal flow of intraocular fluid
maintains normal intraocular pressure. The fluid inside the eye is called the aqueous humor which
is produced in the ciliary body which is located behind the iris. This fluid flows through the pupil
and drains from the eye through a sieve-like network located at the junction of the cornea and the
iris called the iridocorneal cleft or drainage angle. The aqueous humor is produced and drains
from the eye at approximately the same rate, resulting in a stable pressure inside the eye of 15 to
20 mmHg (millimetres of mercury). Glaucoma occurs as a consequence of inadequate outflow of
aqueous humor and a subsequent buildup of pressure inside the eye. The resulting high pressure
damages the optic nerve and results in blindness. For more information on glaucoma visit:
http://www.eyevet.info/glaucoma.html
Diabetes
Diabetic dogs can live healthy lives. Unfortunately, a common complication of diabetes in dogs is
cataracts (cloudy lenses). In fact, 75% of dogs develop cataracts and blindness in both eyes
within one year of being diagnosed with diabetes. The cataracts develop very quickly—sometimes
overnight! If untreated, the cataracts cause intraocular inflammation called Lens-Induced Uveitis
(LIU) that harms the eyes by causing glaucoma (increased intraocular pressure). If the LIU is
uncontrolled and glaucoma develops, cataract surgery might not be possible. Glaucoma causes a
chronic headache (similar to a migraine). Once it is apparent that cataracts are forming, it is
important to have your pet examined by a veterinary ophthalmologist as soon as possible. For
more information on glaucoma visit:
http://www.animaleyecare.net/diseases/CataractsBlindenssDiabeticDogs.htm
PRA. (also known as PRD)
Progressive retinal degeneration (PRD) is also known as progressive retinal atrophy (PRA) and
refers to retinal diseases that cause blindness. Some breeds have blindness by abnormal
development of the retina and this is called dysplasia. Other breeds have a slowly progressive
degeneration or death of the retinal tissue and this is degeneration. These two types of diseases
affect many breeds. In general these diseases are thought to be inherited but inherited differently
in each breed. In all animals with PRD the outcome, age of the patient and what the veterinary
ophthalmologist sees are the basis for the classification of exactly what type of condition the
patient has. Different breeds of dogs have variations in the age the problem starts and speed with
which the blindness develops. The condition of PRD has been seen in almost every registered
breed and in mixed breed dogs as well. This same condition occurs in humans and is known as
retinitis pigmentosa. For more information on P.R.A. visit: http://www.eyevet.info/pra.html
SARDS (Sudden Acquired Retinal Degeneration Syndrome)
Veterinary ophthalmologists are aware of a vision loss syndrome * with changes in appetite and
water consumption in dogs. This condition, known as sudden acquired retinal degeneration
syndrome (SARDS), may strike any pure or mixed breed of dog. These pets are generally
between the ages of 7 and 14 years of age, with females predominating over males. Research
indicates these pets have total destruction of the visual cell layer (the rods and cones) of the
retina with subsequent blindness. Visit: http://eyevet.info/sards.html for more information on
SARDS.
Corneal Ulcer
A corneal ulcer is a break in the outer layer or epithelium of the cornea. Uncomplicated ulcers,
although initially painful, should heal in 3 to 4 days with appropriate treatment. Those ulcers that
persist longer than this period of time often prove to be complicated ulcers. For more information
on Corneal Ulcer visit: http://www.eyevet.info/corneal_ulcer.html
Corneal Dystrophy
In most breeds, corneal dystrophy appears as gray-white, crystalline or metallic opacities in the
center of the cornea or close to the periphery. These opacities may affect any layer of the cornea,
the epithelium (outer layer), the stroma (the thick, middle layer), or the endothelium (the inner
layer). The opacities are usually oval or round and are sometimes doughnut-shaped. For more
information on Corneal Dystrophy visit: http://www.eyevet.info/corneal_dystrophy.html
Retinal Dysplasia
Retinal dysplasia is a type of retinal malformation. The word "dysplasia" simply means "a defective
development of an organ or structure". Retinal dysplasia occurs when the 2 primitive layers of the
retina do not form together properly. Mild dysplasia manifests as folds in the inner retinal layer.
These are called "retinal folds". In "geographic" retinal dysplasia there are larger areas of
defective retinal development. In the severe form of dysplasia, the 2 retinal layers do not come
together at all and retinal detachment occurs. Retinal dysplasia is not progressive. It is a
congenital defect and animals are born with as severe a condition as they will ever get. For more
information on Retinal Dysplasia visit: http://www.eyevet.info/ret_dysplasia.html
Dry Eye (KCS)
Keratoconjunctivitis sicca (KCS) or "dry eye" describes the changes in the eye which result from
lack of tear production. To understand "dry eye" it is helpful to know how tears help keep the
cornea healthy. The cornea is the optically clear portion of the eye that allows entry of light into the
eye. Like all living tissue, the cornea requires a supply of oxygen and energy to remain healthy.
Oxygen and nutrients are supplied to most tissues by the blood that moves through the area in
blood vessels. The healthy cornea has no blood vessels, if it did it wouldn't be clear, so the
oxygen and nutrients are supplied through the three-layered 'tear film.' For more information on
Dry Eye visit: http://www.eyevet.info/kcs.html
Cherry Eye
A prolapsed gland of the third eyelid (or "cherry eye") is thought to be * with a laxity of a small
ligament which holds the gland in a normal position behind the third eyelid. The gland is a tear
producing gland, and produces about 30% of the tears, while the main orbital lacrimal gland
produces the rest. Dogs that have had the gland of the third eyelid surgically excised have a
greater risk of development of a dry eye (KCS ) than dogs with intact third eyelid glands. It is
thought that should the main orbital lacrimal gland be damaged later in life that there is no "backup"
for tear production. Dry eye is a serious eye condition that is difficult to treat, and requires
lifelong treatment which may be costly. If the chance of the development of a dry eye can be
lessened by tacking the gland back into a normal position so that it stays functional, then this is
the most desirable way of handling "cherry eye". For more information on Cherry Eye visit:
http://www.eyevet.info/cherry.html
Lens Luxation
The lens can either become loosened (subluxated) or completely detached (luxated). When the
lens completely tears free of its zonular attachments and falls forward into the anterior chamber,
we call this an anterior luxation. It is also possible for the lens to luxate posteriorly into the vitreous
body. Since lens luxation may cause glaucoma, and since glaucoma may cause lens luxation it is
important to determine which disease came first. When lens luxation occurs secondarily to
glaucoma, it usually occurs late in the disease once the elevated pressure within the eye has
caused the sclera to stretch, and the zonular ligaments to tear. This does not occur until long after
vision has been lost. In such a case, attention must be given to resolving the pain * with
glaucoma. For more information on Lens Luxation visit: http://www.eyevet.info/luxlens.html
Lethal White - A Genetic Defect that is Preventable...
A lethal white is a term used to refer to the more politically correct double merle (MM) gene, or
homozygous genetic defect. In people terms: A merle bred to a merle will always produce a lethal
white. At least one, maybe more. A Lethal White pup w/MM gene will be blind or deaf or both. The
double merle genetic defect can be found in the Australian Shepherd, Great Dane, the Dachsund,
the Sheltie, the Collie - any dog with the merle or dapple coat. There is a group in Arizona whose
sole purpose is to educate, inspire, and rescue these Australian Shepherd lethals from certain
death. They can be found at: at http://www.aussielads.com/ or http://www.AmazingAussies.com
Horner's Syndrome
Horner's syndrome is not uncommon and occurs in dogs, cats, horses and many other species.
The symptoms generally include a sunken in eye (enophthalmia) with a small pupil (miosis), a
droopy upper eyelid (ptosis) and a prominant third eyelid. Horner's syndrome must be
differentiated from Uveitis which also produces a constricted pupil and a droopy looking eye. For
more information on Horner's Syndrome visit: http://www.eyevet.info/horner.html
Uveitis
Uveitis is a viral infection which can often occur in horses and humans, but rarely in dogs.
Uveitis means "inflammation of the uvea", or the middle layer of the eye. The uvea consists of
three structures: the iris, the ciliary body, and the choroid. The iris is the colored structure
surrounding the pupil, visible in the front of the eye. The ciliary body is a structure containing
muscle and is located behind the iris which focuses the lens. The choroid is a layer containing
blood vessels that line the back of the eye and is located between the inner visually sensitive
layer, called the retina, and the outer white eye wall, called the sclera. Inflammation occurring in
any of these three structures is termed "uveitis". For more information on Uveitus visit:
http://www.veterinarypartner.com/Content.plx?P=A&A=1714
