Blind and Visually Impaired

Quoc Le

Gaby Mariz

Vanessa Romo

Lisa Yocum

Physical Structures of the Eye Physical Structures of the Eye and Visual Acuityand Visual Acuity

Physical structure of the EyePhysical structure of the Eye

How does the Eye Work?How does the Eye Work?

Common Measures of Visual AcuityCommon Measures of Visual Acuity

What do the Results Mean?What do the Results Mean?

Visually Impaired and Blind DefinedVisually Impaired and Blind Defined

Basic Features of the Eye

Structure of the EyeStructure of the Eye

Physical Structures of the Eye Physical Structures of the Eye Important for VisionImportant for Vision

CorneaCornea--The outermost layer of the eye, it The outermost layer of the eye, it refracts light into the lens, which further refracts light into the lens, which further focuses it onto the retina.focuses it onto the retina.IrisIris--The colored part of the eye, which helps to The colored part of the eye, which helps to regulate light intake by regulating pupil size.regulate light intake by regulating pupil size.PupilPupil--The opening at the center of the iris The opening at the center of the iris which expands and contracts to regulate light which expands and contracts to regulate light intake.intake.Macula-Small centrally located area on retina Macula-Small centrally located area on retina that gives “central vision.” that gives “central vision.” (NEI. 2011)(NEI. 2011)

Optic Nerve-Carries electrical stimuli from the Optic Nerve-Carries electrical stimuli from the retina to the brain.retina to the brain.

(NEI. 2011)

LensLensLens- A transparent Lens- A transparent

structure that structure that bends in order to bends in order to focus light onto focus light onto the retina. It the retina. It consists of many consists of many layers “like an layers “like an onion.” onion.” (National Eye (National Eye Institute,2011).Institute,2011).

The lens thickens The lens thickens as you like at as you like at something close something close and thins as you and thins as you look in the look in the distancedistance

Green-Green-Shows the Shows the layers of the layers of the lens.lens.

Blue-Blue-Nuclei of other Nuclei of other cells in the eye.cells in the eye.

National Eye Institute (2011).

Physical Structures of EyePhysical Structures of EyeRetinaRetina-A -A layer at the back of the eye where light hits layer at the back of the eye where light hits photoreceptor cells. There are two types of these nerve photoreceptor cells. There are two types of these nerve cells. Rods and cones, which receive light and convert this cells. Rods and cones, which receive light and convert this into electrical signals delivered to the brain.into electrical signals delivered to the brain.

Rods allow for night visionRods allow for night vision..

Cones allow for color vision and vision in a brightly lit Cones allow for color vision and vision in a brightly lit environment. There are three types:environment. There are three types:

1.1. S cones S cones which are sensitive to shorter wavelengths in which are sensitive to shorter wavelengths in the VLS (the VLS (blueblue), ),

2.2. M cones M cones which are sensitive to medium wavelengths which are sensitive to medium wavelengths ((greengreen). ).

3.3. L cones L cones which are sensitive to longer wavelengths (which are sensitive to longer wavelengths (redred).).

National Eye Institute (2011).

Retina:Night Vision

Shows the interactions of nerve cell networks operating during night vision (rod use.)

Blue-Nerve endings of rod bipolar cells which receive info from the rods.

Green- Helps facilitate communication through neurotransmitters.

Cone Cells-Color and Bright Light Cone Cells-Color and Bright Light VisionVision

Cells in Cells in blueblue are S cones, are S cones, sensitive to sensitive to short short wavelength wavelength blue light.blue light.Other cones Other cones are M cones are M cones sensitive to sensitive to medium medium wavelength wavelength greengreen light. light.

National Eye Institute92011).

How does the Eye Work?How does the Eye Work?

Light first enters the eye through the cornea which helps Light first enters the eye through the cornea which helps refract light into the lens.refract light into the lens.The amount of light arriving at the lens is controlled by the iris The amount of light arriving at the lens is controlled by the iris expanding or contracting the pupil, which functions much like expanding or contracting the pupil, which functions much like a camera aperture.a camera aperture.As light passes through the lens it is focused on the back of As light passes through the lens it is focused on the back of the eye at the retina.the eye at the retina.Millions of photoreceptor cells in the retina convert this light Millions of photoreceptor cells in the retina convert this light energy into electrical signals.energy into electrical signals.These signals travel through the optic nerve and reach the These signals travel through the optic nerve and reach the brain, where the brain interprets them.brain, where the brain interprets them.

Common Measures of Visual Common Measures of Visual AcuityAcuity

Snellan ChartSnellan Chart

•Developed in the mid 19th Century by the Dutch ophthalmologist Snellan, this chart measures vision by determining the smallest line a patient can read from 20 feet.

Common Measures of Visual Common Measures of Visual AcuityAcuity

ETDRS ChartETDRS Chart•Developed in 1970’s

•Backlit by a lightbox to ensure equal illumination.

•Has the same number of letters on all lines.

•Lines diminish in size based on a mathematical formula.

•Measures the smallest line read from 20 feet.

Isn’t 20/20 a show on CBS?Isn’t 20/20 a show on CBS?

How are vision results reported and what do How are vision results reported and what do they mean?they mean?

The first number refers to the patient’s vision at 20 feet.The first number refers to the patient’s vision at 20 feet.The second number refers to how many feet away a The second number refers to how many feet away a person with average vision can read the letters.person with average vision can read the letters.20/20 is average vision. 20/20 is average vision. 20/15 is above average vision. What a visually average 20/15 is above average vision. What a visually average person can see at 15 feet, the patient can see from 20 person can see at 15 feet, the patient can see from 20 feet.feet.20/50 is below average vision. What a person with 20/50 is below average vision. What a person with average vision can see from 50 feet, the patient must be average vision can see from 50 feet, the patient must be at 20 feet to see.at 20 feet to see.

Visual ImpairmentsVisual Impairments

““Low visionLow vision is defined as a visual is defined as a visual impairment not corrected by standard impairment not corrected by standard eyeglasses, contact lenses, medication, or eyeglasses, contact lenses, medication, or surgery that interferes with the ability to surgery that interferes with the ability to perform everyday activities.” Defined by perform everyday activities.” Defined by the WHO as only correctable to 20/60 or the WHO as only correctable to 20/60 or less less “(Central Association for the Blind and Visually Impaired, 2012). “(Central Association for the Blind and Visually Impaired, 2012).

Partially Sighted- Partially Sighted- Refers to a loss of Refers to a loss of vision that results in a student needing vision that results in a student needing Special Education Services.Special Education Services.

BlindBlind

Total Blindness- Total Blindness- Is marked by a complete Is marked by a complete lack of light or form.lack of light or form.

Legal Blindness-Legal Blindness- Defined in North Defined in North America as 20/200 visual acuity or less or America as 20/200 visual acuity or less or as having a field of vision of 20 degrees or as having a field of vision of 20 degrees or less which are not correctable.less which are not correctable.

What are the major causes of What are the major causes of blindness and visual blindness and visual

impairment?impairment?

Globally Globally

The major causes of visual impairment The major causes of visual impairment are:are:– Uncorrected refractive errors (myopia, Uncorrected refractive errors (myopia,

hyperopia or astigmatism): 43%hyperopia or astigmatism): 43%– Cataract: 33%Cataract: 33%– Glaucoma: 2%Glaucoma: 2%

80% of all visual impairment can be 80% of all visual impairment can be prevented or cured. prevented or cured.

United StatesUnited States

The major causes of visual impairment in The major causes of visual impairment in the U.S are:the U.S are:– Macular degeneration Macular degeneration – CataractCataract– GlaucomaGlaucoma– Diabetic retinopathyDiabetic retinopathy

Macular DegenerationMacular Degeneration

Macular degeneration affects the macula.Macular degeneration affects the macula.

Associated with aging that gradually Associated with aging that gradually destroys sharp, central vision.destroys sharp, central vision.– Central vision is needed for seeing objects Central vision is needed for seeing objects

clearly and for common daily activities like clearly and for common daily activities like reading and driving.reading and driving.

Two forms of macular degenerationTwo forms of macular degeneration

Wet:  occurs when abnormal blood vessels behind the Wet:  occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its fluid. The blood and fluid raise the macula from its normal place at the back of the eye. Damage to the normal place at the back of the eye. Damage to the macula occurs rapidly. macula occurs rapidly.

Dry (more common): occurs when the light-sensitive Dry (more common): occurs when the light-sensitive cells in the macula slowly break down, gradually blurring cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the center of your worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye. vision is gradually lost in the affected eye.

CataractCataract

A clouding of the lens in the eye that A clouding of the lens in the eye that affects vision. Most cataracts are related affects vision. Most cataracts are related to aging.to aging.– The lens is a clear part of the eye that helps The lens is a clear part of the eye that helps

to focus light, or an image, on the retina. to focus light, or an image, on the retina. – The lens must be clear for the retina to The lens must be clear for the retina to

receive a sharp image. receive a sharp image. – If the lens is cloudy from a cataract, the image If the lens is cloudy from a cataract, the image

you see will be blurred. you see will be blurred.

Types of cataractsTypes of cataracts

Secondary cataract.Secondary cataract. Cataracts can form after surgery for  Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid as diabetes. Cataracts are sometimes linked to steroid use.use.Traumatic cataract.Traumatic cataract. Cataracts can develop after an eye  Cataracts can develop after an eye injury, sometimes years later.injury, sometimes years later.Congenital cataract.Congenital cataract. Some babies are born with  Some babies are born with cataracts or develop them in childhood, often in both eyes. cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect These cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.vision. If they do, the lenses may need to be removed.Radiation cataract.Radiation cataract. Cataracts can develop after exposure  Cataracts can develop after exposure to some types of radiation.to some types of radiation.

GlaucomaGlaucoma

Glaucoma is a group of diseases that damage Glaucoma is a group of diseases that damage the eye’s optic nerve the eye’s optic nerve – The optic nerve is a bundle of more than 1 million The optic nerve is a bundle of more than 1 million

nerve fibers. It connects the retina to the brain. nerve fibers. It connects the retina to the brain. – A healthy optic nerve is necessary for good vision. A healthy optic nerve is necessary for good vision.

Congenital glaucoma in infants is a rare Congenital glaucoma in infants is a rare condition that may be inherited. It is the result of condition that may be inherited. It is the result of incorrect or incomplete development of the eye incorrect or incomplete development of the eye drainage canals before birth.drainage canals before birth.– Can be treated with medication and surgery.Can be treated with medication and surgery.

Diabetic retinopathyDiabetic retinopathy

Most common diabetic eye disease Most common diabetic eye disease

Caused by changes in the blood vessels Caused by changes in the blood vessels of the retina. of the retina. – In some people with diabetic retinopathy, In some people with diabetic retinopathy,

blood vessels may swell and leak fluid. blood vessels may swell and leak fluid. – In other people, abnormal new blood vessels In other people, abnormal new blood vessels

grow on the surface of the retina. grow on the surface of the retina.

Diabetic retinopathy has four Diabetic retinopathy has four stages stages

Mild Nonproliferative Retinopathy.Mild Nonproliferative Retinopathy. At this earliest stage,  At this earliest stage, microaneurysms occur. They are small areas of balloon-like microaneurysms occur. They are small areas of balloon-like swelling in the retina's tiny blood vessels.swelling in the retina's tiny blood vessels.Moderate Nonproliferative Retinopathy.Moderate Nonproliferative Retinopathy. As the disease  As the disease progresses, some blood vessels that nourish the retina are progresses, some blood vessels that nourish the retina are blocked.blocked.Severe Nonproliferative Retinopathy.Severe Nonproliferative Retinopathy. Many more blood  Many more blood vessels are blocked, depriving several areas of the retina with vessels are blocked, depriving several areas of the retina with their blood supply. These areas of the retina send signals to the their blood supply. These areas of the retina send signals to the body to grow new blood vessels for nourishment.body to grow new blood vessels for nourishment.Proliferative Retinopathy.Proliferative Retinopathy. At this advanced stage, the signals  At this advanced stage, the signals sent by the retina for nourishment trigger the growth of new sent by the retina for nourishment trigger the growth of new blood vessels. This condition is called proliferative retinopathy. blood vessels. This condition is called proliferative retinopathy. These new blood vessels are abnormal and fragile. They grow These new blood vessels are abnormal and fragile. They grow along the retina and along the surface of the clear, vitreous gel along the retina and along the surface of the clear, vitreous gel that fills the inside of the eye. By themselves, these blood that fills the inside of the eye. By themselves, these blood vessels do not cause symptoms or vision loss. However, they vessels do not cause symptoms or vision loss. However, they have thin, fragile walls. If they leak blood, severe vision loss and have thin, fragile walls. If they leak blood, severe vision loss and even blindness can result. even blindness can result.

Retinal DisordersRetinal Disorders

Retinal DisordersRetinal DisordersRetinoblastomaRetinoblastoma

Cancer that develops Cancer that develops in the cells of the in the cells of the retinaretina

Mutation of Mutation of chromosome 13, the chromosome 13, the RBI GeneRBI Gene

Portions of the code Portions of the code are missing or alteredare missing or altered

Can develop in the Can develop in the early stages of fetal early stages of fetal developmentdevelopment

SymptomsSymptoms-Enlarged or dilated pupil-Enlarged or dilated pupil

-Deterioration of vision-Deterioration of vision

-Red and irritated eye-Red and irritated eye

-Inflammation of tissue -Inflammation of tissue around eyearound eye

-Crossed eyes-Crossed eyes

-Faltering grown or -Faltering grown or delayed development delayed development

Retinal DisordersRetinal DisordersRetinitis PigmentosaRetinitis Pigmentosa

Deformation in the Deformation in the receptors of the retina receptors of the retina

Retina has difficulty Retina has difficulty perceiving lightperceiving light

Progressive dysfunction Progressive dysfunction for the photoreceptors for the photoreceptors (rods and cones) (rods and cones)

Leads to cell loss and Leads to cell loss and eventual deteriorate of eventual deteriorate of several retina layers several retina layers

SymptomsSymptoms

--Defective dark adaptation Defective dark adaptation (night blindness)(night blindness)

-Loss of central vision-Loss of central vision

-Reduction of the peripheral -Reduction of the peripheral visual field (tunnel vision)visual field (tunnel vision)

Retinal DisordersRetinal DisordersRetinal DetachmentsRetinal Detachments

• Occur when the retina Occur when the retina peels away from the peels away from the underlying layer of the underlying layer of the support tissue support tissue

• Without rapid treatment Without rapid treatment the entire retina may the entire retina may detach and lead to detach and lead to vision loss and vision loss and blindnessblindness

• Usually occurs in one Usually occurs in one eye but has a 15% eye but has a 15% chance of developing in chance of developing in the other eyethe other eye

Retinal DisordersRetinal DisordersRetinal DetachmentsRetinal Detachments

• 1. Tear, break, or hole in 1. Tear, break, or hole in the retina allowing fluid the retina allowing fluid from the middle of the from the middle of the eye to collect under the eye to collect under the retinaretina

• 2. Inflammation, injury or 2. Inflammation, injury or vascular abnormalities vascular abnormalities that results in fluid that results in fluid accumulating underneath accumulating underneath the retina. Fluid buildup the retina. Fluid buildup causes the layers of the causes the layers of the retina to separateretina to separate

• 3.Traction pulls the retina 3.Traction pulls the retina away from the layers away from the layers beneath itbeneath it

Symptoms Symptoms -Flashes of light at the edge -Flashes of light at the edge

of the field of visionof the field of vision

-Increase in the number of -Increase in the number of floaters (strands of floaters (strands of vitreous gel)vitreous gel)

-See a shadow across part -See a shadow across part of the visual field that of the visual field that does not go awaydoes not go away

-New or sudden vision loss-New or sudden vision loss

Retinal DisordersRetinal DisordersRetinopathy of Prematurity Retinopathy of Prematurity

Affects babies who are born Affects babies who are born premature/low birth weightpremature/low birth weight

Scaring or retinal detachmentScaring or retinal detachment

Five StagesFive Stages

I: Mildly abnormal blood I: Mildly abnormal blood vessel growthvessel growth

II: Moderately abnormal II: Moderately abnormal blood vessel growthblood vessel growth

III: Blood vessel growth is III: Blood vessel growth is severely abnormal.severely abnormal.

IV: Severely abnormal IV: Severely abnormal growth and partially detached growth and partially detached retinaretina

V: There is a total retinal V: There is a total retinal detachmentdetachment

SymptomsSymptoms

--Abnormal eye movementsAbnormal eye movements

-Crossed eyes-Crossed eyes

-Severe nearsightedness-Severe nearsightedness

-White-looking pupils -White-looking pupils

Optic Nerve DisordersOptic Nerve Disorders

Optic Nerve DisordersOptic Nerve DisordersOptic Nerve AtrophyOptic Nerve Atrophy

Tissue death of the nerve Tissue death of the nerve that carries information that carries information from the eye to the brainfrom the eye to the brain

Caused by:Caused by:

-Poor blood flow-Poor blood flow

-Damage due to shock, -Damage due to shock, toxic substances, toxic substances, radiation, or traumaradiation, or trauma

-Various eye, brain, and -Various eye, brain, and central nervous system central nervous system diseasesdiseases

SymptomsSymptoms

--Dimming of visionDimming of vision

-Loss of the ability to see -Loss of the ability to see fine detailfine detail

-Color seems faded-Color seems faded

-The pupils reaction to light -The pupils reaction to light may diminish and may may diminish and may eventually be losteventually be lost

Optic Nerve DisordersOptic Nerve DisordersHemianopia Hemianopia

Common after stroke Common after stroke and/or brain injuryand/or brain injury

SymptomsSymptomsdecreased vision or decreased vision or blindness in one quarter blindness in one quarter or half of the visual field or half of the visual field of one or both eyesof one or both eyes

-Blind on the same side in -Blind on the same side in both eyes.  This allows both eyes.  This allows only objects to the right or only objects to the right or to the left sides to be to the left sides to be seen. seen.

Optic Nerve GliomasOptic Nerve GliomasNeurofibromatosis Neurofibromatosis

Genetic disorders that Genetic disorders that cause tumors to grow in cause tumors to grow in the nervous system  the nervous system  

tumors grow on nerves tumors grow on nerves and produce other and produce other abnormalities such as abnormalities such as skin changes, bone skin changes, bone deformities, and/or deformities, and/or damage to the eyesdamage to the eyes

SymptomsSymptoms

--Cataracts at an early age Cataracts at an early age or changes in the retina or changes in the retina that may affect vision that may affect vision

-Two or more growths on -Two or more growths on the iris or the optic nervethe iris or the optic nerve

Disorders of the brain that affect Disorders of the brain that affect visionvision

Disorders of the brain that affect visionDisorders of the brain that affect visionCortical BlindnessCortical Blindness

Abnormal visual Abnormal visual responses due to brain responses due to brain dysfunction that cannot dysfunction that cannot be attributed to the eyes be attributed to the eyes themselvesthemselves

Due to:Due to:

- infections like Meningitis - infections like Meningitis and Encephalitisand Encephalitis

-Lack of oxygen-Lack of oxygen

-Drugs during pregnancy-Drugs during pregnancy

SymptomsSymptoms

--Abnormal light response Abnormal light response

-Avoidant social gaze-Avoidant social gaze

-Brief fixations and -Brief fixations and intermittent gazeintermittent gaze

-Poor visual perception-Poor visual perception

-Visual field loss-Visual field loss

Lens DisordersLens Disorders

Congenital CataractsCongenital Cataracts

Pressure DisordersPressure Disorders

Congenital GlaucomaCongenital Glaucoma

Pigment DisordersPigment Disorders

Ocular AlbinismOcular Albinism

What is it?What is it?– Ocular albinism in an inherited condition in which the eyes Ocular albinism in an inherited condition in which the eyes

lack melanin pigment which is needed for the growth lack melanin pigment which is needed for the growth processes that occur before birth. Therefore, the fovea does processes that occur before birth. Therefore, the fovea does not fully develop. not fully develop.

CausesCauses– Ocular albinism is caused by mutations in the GPR143 gene. Ocular albinism is caused by mutations in the GPR143 gene.

This gene provides instructions for making protein that plays This gene provides instructions for making protein that plays a role in pigmentation of the eyes and skin. a role in pigmentation of the eyes and skin.

SymptomsSymptoms– Reduced visual acuity from 20/60 to 20/400 and sometimes Reduced visual acuity from 20/60 to 20/400 and sometimes

as good as 20/25 in African-Americans, as good as 20/25 in African-Americans, – Nystagmus (involuntary back-and-forth movement of the Nystagmus (involuntary back-and-forth movement of the

eyes)eyes)– Strabismus (crossed eyes or "lazy" eye)Strabismus (crossed eyes or "lazy" eye)– Sensitivity to bright light and glare. Sensitivity to bright light and glare. 

Nystagmus: Color Vision DisordersNystagmus: Color Vision Disorders

AchromatopsiaAchromatopsia

AniridiaAniridia

What is it?What is it?– It is a condition in which the individual is born It is a condition in which the individual is born

without the iris. The iris is the colored part of the without the iris. The iris is the colored part of the eye that controls the amount of light that goes eye that controls the amount of light that goes into the eye. into the eye.

CauseCause-2/3-2/3rdrd of the time it is hereditary. of the time it is hereditary.SymptomsSymptoms– Decreased visual acuityDecreased visual acuity– Photophobia (sensitivity to light)Photophobia (sensitivity to light)– Dry eyeDry eye

Other Structural DefectsOther Structural Defects

What is it?What is it?– Individuals with hyperopia have difficulty viewing objects Individuals with hyperopia have difficulty viewing objects

up close. Farsightedness occurs if your eyeball is too short up close. Farsightedness occurs if your eyeball is too short or the cornea has too little curvature, so light entering your or the cornea has too little curvature, so light entering your eye is not focused correctly.eye is not focused correctly.

CauseCause– This vision problem occurs when light rays entering the This vision problem occurs when light rays entering the

eye focus behind the retina, rather than directly on it. The eye focus behind the retina, rather than directly on it. The eyeball of a farsighted person is shorter than normal.eyeball of a farsighted person is shorter than normal.

SymptomsSymptoms– Common signs of farsightedness include difficulty in Common signs of farsightedness include difficulty in

concentrating and maintaining a clear focus on near concentrating and maintaining a clear focus on near objects, eye strain, fatigue and/or headaches after close objects, eye strain, fatigue and/or headaches after close work, aching or burning eyes, irritability or nervousness work, aching or burning eyes, irritability or nervousness after sustained concentration.after sustained concentration.

  Hyperopia (farsightedness)Hyperopia (farsightedness)

Myopia (Nearsightedness)Myopia (Nearsightedness)

What is it?What is it?– Nearsightedness is when light entering the eye is Nearsightedness is when light entering the eye is

focused incorrectly, making distant objects appear focused incorrectly, making distant objects appear blurred. Nearsightedness is a type of refractive error blurred. Nearsightedness is a type of refractive error of the eye.of the eye.

CauseCause– Occurs equally in males and females.Occurs equally in males and females.– People with a family history of Myopia than they are People with a family history of Myopia than they are

more likely to develop it. more likely to develop it. SymptomsSymptoms– Difficulty seeing objects at a distance.Difficulty seeing objects at a distance.– EyestrainEyestrain

Amblyopia (Lazy Eye)Amblyopia (Lazy Eye)

What is it?What is it?– Amblyopia, or "lazy eye," is the loss of one eye's ability to see Amblyopia, or "lazy eye," is the loss of one eye's ability to see

details. It is the most common cause of vision problems in details. It is the most common cause of vision problems in children.children.

CausesCauses– Amblyopia occurs when the nerve pathway from one eye to the Amblyopia occurs when the nerve pathway from one eye to the

brain does not develop during childhood. This occurs because brain does not develop during childhood. This occurs because the abnormal eye sends a blurred image or the wrong image to the abnormal eye sends a blurred image or the wrong image to the brain.the brain.

– Strabismus is the most common cause of amblyopia. There is Strabismus is the most common cause of amblyopia. There is often a family history of this condition.often a family history of this condition.

– Childhood cataractsChildhood cataracts– Farsightedness, nearsightedness, or astigmatism, especially if it Farsightedness, nearsightedness, or astigmatism, especially if it

is greater in one eye.is greater in one eye.SymptomsSymptoms– Eyes that turn in or outEyes that turn in or out– Eyes that do not appear to work togetherEyes that do not appear to work together– Inability to judge depth correctlyInability to judge depth correctly– Poor vision in one eyePoor vision in one eye

AstigmatismAstigmatism

What is it?What is it?– Astigmatism is a condition in which the uneven curvature Astigmatism is a condition in which the uneven curvature

of the cornea blurs and distorts both distant and near of the cornea blurs and distorts both distant and near objects. The cornea is abnormally curved like the back of a objects. The cornea is abnormally curved like the back of a spoon which causes vision to be out of focus.spoon which causes vision to be out of focus.

CausesCauses– The specific cause is unknown. It is usually present from The specific cause is unknown. It is usually present from

birth, and often occurs together with nearsightedness or birth, and often occurs together with nearsightedness or farsightedness. farsightedness.

  SymptomsSymptoms– Astigmatism makes it difficult to see fine details, either Astigmatism makes it difficult to see fine details, either

close up or from a distance. close up or from a distance.

Educational ImplicationsEducational Implications

Student may need optical aids like:Student may need optical aids like:

- sunglasses or tinted contact lenses to cope with bright light - sunglasses or tinted contact lenses to cope with bright light in the classroomin the classroom

-eye patch -eye patch

-thick glasses -thick glasses

-protective eyewear during sports and other hazardous -protective eyewear during sports and other hazardous activities.activities.– Student may need magnifiers to help with readingStudent may need magnifiers to help with reading– Increased illuminationIncreased illumination

Some are recommended to avoid contact sports and strenuous Some are recommended to avoid contact sports and strenuous activityactivity

Educational ImplicationsEducational Implications– Some students may have difficulties reading and Some students may have difficulties reading and

playing ball sports due to the low visual acuity.playing ball sports due to the low visual acuity.

– Some potential modifications include:Some potential modifications include:Moving the student’s seat to the front row so the Moving the student’s seat to the front row so the student can see the chalkboard, marker board, student can see the chalkboard, marker board, overhead projector, or videooverhead projector, or videoChanging where the student sits so they can avoid Changing where the student sits so they can avoid glare from overhead lights or windows.glare from overhead lights or windows.Provide the student with a hard copy of the material Provide the student with a hard copy of the material that is presented on the white board or via the that is presented on the white board or via the overhead project.overhead project.Allow the student to copy another student’s notes if Allow the student to copy another student’s notes if they can’t see the board.they can’t see the board.Enlarge tests and handouts.Enlarge tests and handouts.

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