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Visual Impairment and Blindness in the Senior Population Content written by: June Smith-Jeffries – FCLSA, NCLE, COT Content originally published in the Winter 2014 edition of The Eighth Line

Table of Contents • Introduction• Age-related Macular Degeneration

o Types of ARMD Dry ARMD Wet ARMD

o 3 Stages of ARMDo ARMD Risk Factorso ARMD Preventiono ARMD Detectiono ARMD Treatment

• Glaucomao Causes of Glaucomao Glaucoma Risk Factorso Types of Glaucoma

Primary Open-Angle Secondary Glaucoma Angle Closure Glaucoma Low-Tension or Normal Pressure Glaucoma Ocular Hypertension Congenital or Infantile Glaucoma

• Measuring Intraocular Pressure• Testing for VF Defects• Conclusion• Post Test

Introduction

A study commissioned for the National Coalition for Vision Health in 2007 states that 278,000 Canadians are visually

impaired and an additional 108,000 are legally blind. (Visual impairment is defined as difficulty seeing ordinary newsprint

or clearly seeing the face of someone from a distance of four meters or 12 feet.) The chances of developing an

irreversible, serious loss of vision are one in nine by age 65 and this figure increases as one ages. Current projections

indicate that over the next twenty-five years with our aging population, these numbers will increase dramatically,

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perhaps even doubling. Dr. David K. Foot, a professor at the University of Toronto, predicts an epidemic of blindness and

impaired vision as the members of the baby boom generation reach their 70’s. That time is close at hand.

Opticians are often the first of the three O’s to see a patient who is having visual difficulties. As health care professionals

we have a responsibility to recognize the signs of eye diseases, and particularly those that most affect our senior

patients. The most common age-related eye diseases are macular degeneration, glaucoma, diabetic retinopathy and

cataract.

Age-related Macular Degeneration Age-related macular degeneration (ARMD) is the leading cause of irreversible vision loss in the western world. Recent

surveys estimate that nearly 80,000 Canadians are currently affected with AMD and as Canadians age that number is

growing at a rate of 10,000 per year.

Two forms of this condition exist. Exudative ARMD is also known as neovascular or wet ARMD. This type is by far the

most severe. Non-exudative ARMD, the most common form, is known as dry macular degeneration and it progresses

more slowly than exudative ARMD. It is possible to have the disease in one eye only, or to have one eye with a later

stage of ARMD than the other.

Types of ARMD

Dry ARMD This condition is an early stage of the disease and may result from the aging and

thinning of macular tissues, deposits of pigment in the macula or a combination of

the two.

Dry macular degeneration is diagnosed when yellowish spots referred to a drusen

begin to accumulate in and around the macula. It is believed these spots are

deposits or debris from deteriorating tissue. Their presence alone does not

indicate disease, but it may mean that the eye is at risk for developing the more

debilitating wet form of ARMD.

Symptoms of gradual central vision loss may occur with dry macular degeneration, but rarely is the loss of vision as

severe as with wet ARMD. Over a period of years, this form of the disease can progress to late-stage geographic atrophy,

a gradual deterioration of retinal cells, which also can cause severe vision loss.

Currently, no FDA-approved treatments are available for dry macular degeneration, although a few now are in clinical

trials.

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Wet ARMD Approximately ten percent of cases of dry ARMD progress to the more

advanced and damaging form of the disease. In wet macular degeneration,

new blood vessels grow beneath the retina and leak blood and fluid. This

leakage causes permanent damage to light-sensitive retinal cells, which die off

and create blind spots in central vision.

Choroidal neovascularization (CNV) is the underlying process causing wet

ARMD. Abnormal blood vessel growth in the retina is the body's misguided

way of attempting to create a new network of blood vessels to supply more

nutrients and oxygen to the eye's retina. Instead, the process creates scarring,

leading to sometimes severe central vision loss.

Central Vision Loss

Wet macular degeneration falls into two categories:

• Occult – This type occurs with new blood vessel growth beneath the retina. The vessels are not as pronounced

and leakage is less evident in this form. This type usually produces less critical vision loss.

• Classic - Blood vessel growth and scarring have very clear, delineated outlines that can be observed beneath the

retina. This is referred to as classic choroidal neovascularization (CNV) and usually produces more damage,

resulting in serious loss of vision.

3 Stages of ARMD There are three stages of ARMD defined, in part, by the size and number of drusen under the retina.

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• Early ARMD - Early ARMD is diagnosed by the presence of medium-sized drusen, which are about the width of

an average human hair. People with early ARMD typically do not have any vision loss.

• Intermediate ARMD. People with intermediate ARMD typically have large drusen, pigment changes in the

retina, or both. These changes can only be detected during an eye exam. Intermediate ARMD may cause some

vision loss, but most people do not experience any symptoms.

• Late ARMD. In addition to drusen, people with late ARMD have vision loss from damage to the macula. There

are two types of late ARMD:

o Geographic atrophy in dry ARMD is caused by gradual breakdown of the light-sensitive cells in the

macula that convey visual information to the brain, as well as interruption of the supporting tissue

beneath the macula.

o In neovascular wet ARMD, abnormal blood

vessels grow underneath the retina. These

vessels can leak fluid and blood, which may

lead to swelling and damage of the macula.

The damage may be rapid and severe,

unlike the more gradual changes in

geographic atrophy. It is possible to have

both geographic atrophy and neovascular

ARMD in the same eye and either condition

can appear first.

Not everyone with early ARMD will develop late ARMD. Approximately five percent of patients, who have early ARMD in

one eye and no signs of ARMD in the other eye, will develop advanced ARMD within ten years.

Approximately fourteen percent of patients who have early ARMD in both eyes will develop late ARMD in at least one

eye after approximately ten years.

ARMD Risk Factors Age is a major risk factor for ARMD. The disease is most likely to occur after age 60, but it can occur earlier. Other risk

factors for ARMD include:

• Smoking - Research shows that smoking doubles the risk of ARMD.

• Family history - People with a family history of ARMD are at higher risk.

• Race – The disease is more common among Caucasians than among most other ethnicities

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ARMD Prevention According to the National Eye Health Education Publication issued in the US, high-dose supplements of vitamins C and E,

beta-carotene, and zinc can be effective in treating ARMD. These supplements have been shown to slow the rate of

progressive vision loss over a 5-year period, but only when the condition is not extremely advanced. It also has been

suggested that these supplements may lower the risk of developing ARMD. Two other nutritional supplements, lutein

and zeaxanthin, have been shown to improve visual function in ARMD patients. Opticians cannot suggest over-the-

counter supplements, but it is prudent to be aware of these and refer patients who develop signs of ARMD. This

particular publication states that if these supplements were in widespread use for a period of five years among people

who are at risk for the disease, vision loss could be prevented for many. A number of manufacturers offer these

nutritional supplements. The label may refer to "AREDS" or "AREDS2."

Modification of lifestyle may reduce the risk of developing ARMD. These changes include refraining from smoking,

preventing high blood pressure, reducing body mass index, increasing intake of the carotenoids found in dark green

leafy vegetables, and wearing sunglasses that block ultraviolet and high-energy radiation.

An article recently published in the Journal of the American Geriatrics Society reported that moderate consumption of

wine is associated with decreased odds of developing ARMD. In a controlled study of people ranging in age from 60 to

75, it was found that 4% of the wine drinkers had ARMD compared with 9% of people in the study who drank no alcohol

at all.

ARMD Detection Early detection of either type of ARMD is critical. The Amsler Grid is used to test for small central visual field defects

and/or distortions of the visual field, in ARMD or glaucoma. These tests are available in tear off sheets and as magnets or

can be downloaded from the CNIB website or from other online sources. Testing can easily be done in your practice and

Amsler grids can be given to patients to use at home.

The simplest way for a patient to use the device is to attach it to a wall or, if magnetized, to a refrigerator. Instruct

patient to test each eye separately and to wear correction if correction is usually worn. Ask patients to report to you if

they notice a blank spot in central vision or if any of the lines look distorted or wavy when they view the grid. In such a

case, an immediate referral to either an optometrist or an ophthalmologist should be made.

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ARMD Treatment

Until fairly recently, the treatment options for people with neovascular ARMD have been limited; however, the following

are now being used.

• Injections. One option to slow the progression of neovascular AMD is to inject drugs into the eye. With

neovascular AMD, abnormally high levels of vascular endothelial growth factor (VEGF) are secreted in your eyes.

VEGF is a protein that promotes the growth of new abnormal blood vessels. Anti-VEGF injection therapy blocks

this growth. Avastin, Macugen and Lucentis are the brand names of some of these drugs. Unfortunately,

patients may need multiple injections on a very regular basis.

• Photodynamic therapy (PDT). This technique involves “cold” laser treatment of select areas of the retina. A drug

called verteporfin is injected into a vein in the patient’s arm. Verteporfin (Visudyne) therapy is efficacious and

safe in selected patients with ARMD who are at high risk of central vision loss. The drug travels through the

blood vessels in the body, and is absorbed by new, growing blood vessels. A laser is used to activate the drug in

the new abnormal blood vessels, while sparing normal vessels. Once activated, the drug closes off the new

blood vessels, slows their growth and delays the rate of vision loss. This procedure is less common than anti-

VEGF injections, and is often used in combination for specific types of neovascular AMD.

• Laser photocoagulation surgery. Ophthalmologists treat certain cases of neovascular AMD with laser surgery,

though this is less common than other treatments. This intense hot laser treatment is more likely to be used

when blood vessel growth is limited to a compact area of the eye, away from the center of the macula that can

be easily targeted with the laser, although it is sometimes used to cauterize leaking blood vessels beneath the

macula. The heat from the laser beam actually burns a tiny scar, which if done in the macula area, causes a small

blind spot. The surgery may help prevent more severe vision loss from occurring in later years.

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Glaucoma

Glaucoma is a group of eye diseases which cause damage to the optic nerve. Vision can be significantly impaired when

there is damage to the optic nerve and intraocular pressure (IOP) plays a major role in damaging the delicate nerve

fibers. When a significant number of optic nerve fibers are damaged, scotomas (blind spots) develop in the field of

vision.

The optic nerve carries impulses for sight from the retina in the eye to the brain. It is composed of millions of retinal

nerve fibers that bundle together and exit to the brain through the optic disc located at the back of the eye. The center

portion of the optic disc is referred to as the "cup" which is normally quite small in comparison to the entire optic disc.

In people with glaucomatous damage, because of increased IOP and/or loss of blood flow to the optic nerve, these nerve

fibers begin to die. This causes the cup to become larger in comparison to the optic disc in its entirety. Optic nerve

cupping progresses as the cup becomes larger in comparison to the optic disc.

The optic disc is observed through the use of a direct ophthalmoscope. Many Ophthalmologists take an initial

photograph when cupping is found so that cup-to-disc ratio can be compared if the disease progresses. The cup-disc

ratio can be approximated without photographs by comparison of the diameter of the cup to that of the disc.

Optic Disc Observation

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Over 60 million people worldwide have glaucoma. More than 400,000 Canadians are affected by the disease. Glaucoma

develops slowly and is referred to by the Glaucoma Research Foundation as the sneak thief of sight, because there are

virtually no symptoms until late in the disease process. Up to half patients who have glaucoma are unaware that they

have the disease. It is estimated that up to 40 percent of vision can be lost without any notice of the loss to the patient.

By the time a person is aware of the loss of vision, the disease is usually quite advanced. If the entire nerve is destroyed,

total blindness results. Of the estimated number of Canadians affected by glaucoma, a staggering number (70 to 75

percent) of those who are legally blind from the disease are over the age of 65.

Causes of Glaucoma

The structures involved in the pathology of glaucoma are anatomically located within the uvea. The ciliary body

produces aqueous humor which is composed predominately of water with electrolytes, lactate glucose, ascorbic acid

and oxygen. Aqueous provides nutrients for the crystalline lens and the corneal endothelium.

Aqueous humor is produced in the posterior chamber by the epithelium of the ciliary processes of the ciliary body. It

flows from the posterior chamber, the area behind the iris and in front of the vitreous, into the pupil. It then flows

through the pupil, into the anterior chamber and on to the trabecular meshwork in the anterior chamber angle. The

trabecular meshwork is a filter-like structure which surrounds the entire circumference of the anterior chamber.

Aqueous flows through these openings into the canal of Schlemm. It then travels through the circular canal, which in

turn connects with the venous system and is carried away from the eye.

If the rate of aqueous outflow is obstructed because of

abnormalities within any portion of the drainage system, IOP in

the eye will be raised. Rigidity of the eye is determined by the

amount of aqueous humor within the eye at any given time.

This can be compared to the amount of air in a balloon or an

exercise ball; if there isn’t enough air, there is a lack of rigidity. If

there is too much, there will be excessive expansion. When

aqueous is being produced at a faster rate than the outflow, the

eye becomes too rigid (scleral rigidity) and the IOP is raised,

causing damage to the retina.

Flow of Aqueous

Intraocular pressure (IOP) is considered normal when it measures between 13 and 20 mmHg. Measurements are taken

by means of various types of tonometers. Response to intraocular pressure differs in individual eyes. Some can tolerate

pressures in the high 20s. This is referred to as ocular hypertension. On the other hand, some eyes will have damage to

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the optic nerve with much lower pressures, referred to as low-tension glaucoma. Both of these conditions are discussed

later in this article.

Glaucoma Risk Factors • Increasing age

• High degree of myopia

• Hypertension

• Family history of glaucoma and/or diabetes

Types of Glaucoma

Primary Open-Angle

The most prevalent form of glaucoma is primary open-angle glaucoma (POA). This type of glaucoma is responsible for

approximately 10 percent of cases of blindness in Canada. Primary open-angle glaucoma affects men and women

equally. It is is a chronic, slowly progressive disease. Patients with this type of glaucoma are almost always asymptomatic

until late in the course of the disease, after suffering significant visual field loss. Primary open-angle glaucoma is usually

bilateral but may be asymmetric.

Secondary Glaucoma

Secondary glaucoma occurs as a result of some other disease within the eye. The condition is often more difficult to

treat because the eye has two diseases—the original cause and the glaucoma secondary to that condition.

The following may lead to secondary glaucoma: trauma, dislocation or swelling of the crystalline lens, iritis, uveitis as

well as anterior synechiae (scar tissue) between the iris and the trabecular meshwork and posterior synechiae.

Anterior synechiae is most commonly caused by angle-closure glaucoma and the most common cause of posterior

synechiae is chronic and/or severe iritis.

Angle Closure Glaucoma (ACG)

Age-related factors that contribute to primary angle-closure glaucoma include increasing thickness of the crystalline

lens, increasing anterior lens surface curvature and slight anterior displacement of the lens. Narrow or shallow anterior

angles occur more frequently in hyperopic eyes than in emmetropic or myopic eyes, because hyperopic eyes are

generally smaller in globe volume.

Acute angle-closure glaucoma constitutes a very low percentage of all glaucoma cases; however an acute attack is a true

ophthalmic emergency and appropriate therapy must be begun immediately to prevent vision loss. Treatments for ACG

depends upon the severity of the condition. Drug therapy and laser surgery are the most common.

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Typical signs and symptoms of Acute ACG include:

• Redness

• Pain (mild to excruciating)

• Blurred vision

• Halos around lights

• Tearing and photophobia

• Nausea and vomiting

• Headache

Low-Tension or Normal Pressure Glaucoma

Normal pressure glaucoma, also referred to as low-tension glaucoma, is characterized by progressive optic nerve

damage and visual field loss with a statistically normal intraocular pressure. This type of glaucoma is thought to be

related to poor blood flow to the optic nerve, which leads to death of the cells which carry impulses from the retina to

the brain. People who have normal pressure glaucoma are prone to pressure-related damage even if the pressure is

measured in the normal range.

Ocular Hypertension

Ocular hypertension is characterized by increased intraocular pressure when there is no demonstrable visual field loss or

optic nerve damage. Patients with this condition are considered glaucoma suspects and should undergo regular

monitoring and testing by an appropriate eye care professional. Ocular hypertension is ten times more common than

primary open-angle glaucoma. Therefore, any patient with consistent pressure readings above the normal range should

be referred for further workup.

Congenital or Infantile Glaucoma

Another name for this type of glaucoma is buphthalmos. The infant eyeball distends as a result of the elevated

intraocular pressure and comes to resemble the eye of an ox.

Measuring Intraocular Pressure

Intraocular pressure is considered normal if measurements are between 13 mmHg (mm of mercury) and 20 mmHg.

Some experts consider measurements between10 mmHg and 21 as normal mmHg. Certainly, pressure over 21 mmHg is

considered abnormal and further testing should be initiated. The tonometer, which is designed to measure IOP, is used

in the most important single test in the detection of glaucoma. There are two major types of these instruments:

applanation tonometers and indentation tonometers. Tonometry measures IOP by recording the resistance of the

cornea to pressure or indentation.

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Applanation or Goldmann Tonometry

This method uses a small probe to flatten a portion of the cornea. These tonometers are attached to a slit lamp and the

cobalt blue light is used when testing for glaucoma. Topical anesthetic eye drops, often combined with fluorescein or

these two types of eye drops used individually must be instilled prior to this test. The pressure is then measured by how

much force is needed to flatten the cornea. This type of tonometry is considered by most to be the most accurate

method.

Goldman Applanation Tonometry

Other Applanation Instruments

The Perkin’s tonometer, the Tonopen and Tonomat are brand names of several types of hand-held instruments which

utilize applanation as a means of measuring IOP. These require the use of anesthetic drops. Most of the hand held

instruments, excluding the Perkin’s tonometer, have rubber tips which are replaced after every use to prevent the

spread of infection from one patient to another

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Non-contact “Air-puff” Method

Centration and proper focusing of the mire are crucial to the accuracy of this test. The instrument is simple to use once

the examiner has become adept at aligning the instrument with the patient’s eye. This instrument does not require

touching the patient’s eye, however the patient should be instructed that a puff of air will be felt, as it can be very

startling. The air puff actually flattens the cornea. This type of tonometer works on the principle of interval timing,

measuring the time it takes from the generation of the puff of pair to the point at which the cornea is flattened. The air-

puff does render slightly higher readings than Goldmann applanation.

Schiotz

Schiotz indentation tonometry uses a plunger to gently push on the cornea. The pressure is

measured by how much weight is needed to flatten the cornea. This test is not as accurate

as applanation tonometry and is not often used except in cases where it is impossible for the

patient to sit at a slit lamp. Topical anesthetic drops without fluorescein is used for this test.

Through the Lid Tonometer

A through the lid tonometer measures IOP in the scleral

area through the upper eyelid, avoiding pressure on the

cornea. It device requires no anesthetic, is portable,

simple to use and can be used on patients who are unable

to cooperate for other methods. This method is probably

the simplest to perform and has been compared, in terms

of ease of use, to a distometer for measurement of vertex

distance.

Testing for Visual Field (VF) DefectsAn optician can easily perform a confrontation visual field test as it requires no special facilities or equipment. The

examiner stands facing the patient at a distance of approximately 60 cm (2 feet). Opposite eyes are occluded using

either a paddle or one’s hand. In other words, the patient's right eye is covered while the examiner closes his or her left

eye and vice versa. Then the patient and the examiner fixate on the exposed eye of the other.

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While one eye is occluded, the examiner brings in from the periphery one, two, or three fingers and asks the patient to

count the number of fingers brought in from each quadrant. All four quadrants (superior, inferior, nasal and temporal)

of the visual field should be tested from two different approaches in each quadrant. The examiner and the patient

should see the fingers at the same time if there is no compromise in the patient’s VF. If a patient fails to see the

examiner’s fingers at the same time referral must be made.

Further examination and tests needed when a patient is suspected of having glaucoma will usually include automated or

manual perimetry testing to determine the exact nature of the visual defect and what course of action should be taken

to prevent further visual field loss. These test map areas of visual field loss as shown below.

This representation reveals the majority of VF loss in the superior and nasal quadrants of the eye.

Conclusion Statistics Canada predicts seniors will make up 21 per cent of the population by 2026 (one in five), compared to 13 per

cent in 2000. In an attempt to decrease the potential for blindness due to age-related conditions, opticians have an

obligation to make their older patients aware of the possibility of these diseases.

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Post Test: Visual Impairment and Blindness in the Senior Population Complete the following quiz based on the above information and submit the quiz via email, fax, or mail to the ACAO to

receive 2EC credits. Note: More than one answer may apply

Name: _______________________________________

License #: _________________________________________

Date: _________________________________

1. What are the most common age-related eye diseases?

a. diabetic retinopathy

b. cataract

c. herpes zoster

d. glaucoma

e. optic nerve degeneration

f. optic atrophy

g. macular degeneration

2. Which of the following is a category of wet ARMD?

a. dry/wet

b. occult

c. basic

d. advanced

3. What percentage dry ARMD cases will likely advance to wet ARMD?

a. 3%

b. 5%

c. 8%

d. 10%

e. 12%

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4. Early ARMD is diagnosed by the presence of which of the following:

a. changes in pigment in the retina

b. geographic atrophy

c. neovascularization

d. drusen

5. What are the risk factors for ARMD?

a. drinking of alcohol

b. smoking

c. increasing age

d. family history of diabetes

e. ethnicity

6. Which of the following are treatments for ARMD?

a. PTD

b. Avastin injections

c. Avastin eye drops

d. Laser photocoagulation

7. What are the risk factors for developing glaucoma?

a. hypertension

b. increasing age

c. family history of diabetes

d. coronary artery disease

e. high degree of hyperopia

8. What is the most common type of glaucoma?

a. angle closure

b. open-angle

c. secondary

d. ocular hypertension

e. low tension

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at a faster rate than the outflow?

a. True

b. False

10. What is the most common cause of anterior synechiae?

a. secondary glaucoma

b. chronic iritis

c. chronic uveitis

d. angle closure glaucoma

11. What IOP is considered abnormally high?

a. 18 mmHg

b. 19 mmHg

c. 20 mmHg

d. 21 mmHg

e. 22 mmHg

12. When performing confrontational visual fields, how many approaches should be made in each of the four

quadrants?

a. one

b. two

c. three

d. four

e. five

13. True or False: When performing confrontational visual fields the examiner and the patient should fixate on

opposite eyes?

a. True

b. False

9. True or False: IOP will be elevated if the rate of aqueous outflow is obstructed or if aqueous is being produced

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14. Which of the following are applanation type tonometers?

a. Through the lid

b. Tonopen

c. Schiotz

d. Tonomat

15. True or False: Schiotz tonometry does not require topical anesthetic drops?

a. True

b. False