Ophthalmology Packet #2: Glaucoma

Major tenants of the conversation with glaucoma (2)

1. Intraocular pressure rises

2. Pressure causes damage to the optic axons

Glaucoma is an ______ ____________ produced by an increased ___________ __________.

-Optic neuropathy

-Intraocular pressure

What does glaucoma damage?

Optic nerve

Function of the optic nerve

Transmit visual information from the eye to the brain

Like a tire, if the eye has too high of a pressure, can cause the eye to what?

Blow/burst

TRUE OR FALSE: Glaucoma is a group of diseases.

True

Two major types of glaucoma

1. Open angle glaucoma (OAG)

2. Closed angle glaucoma (CAG)

Open angle glaucoma is what kind of condition?

Chronic

Since open angle glaucoma is chronic, is the disease slowly progressive or acutely progressive?

Slowly

Which glaucoma is more common/prevalent?

Open angle

Open angle glaucoma is an optic neuropathy characterized by:

Progressive peripheral visual field loss followed by central field loss in a typical pattern

How many cases of open angle glaucoma worldwide?

65.5 million

How many cases in the U.S.?

3.4 million

Most common populations of OAG

European or African

Closed angle glaucoma is also called...

"Narrow Angle Glaucoma" or "Acute Glaucoma"

Since CAG is acute, does the disease occur slowly or fast?

Fast

TRUE OR FALSE: Pts with CAG are overly symptomatic.

True

How many cases of glaucoma are CAG?

5%

What glaucoma is an ophthalmologic emergency?

Closed angle glaucoma

CAG is common in what populations

Asian descent

If you make & absorb 100, pressure should stay the same. What would this look like with OAG and CAG?

OAG: Make 100, absorb 98

CAG: Make 100, absorb 0

Cavities of the eye (2)

1. Posterior cavity

2. Anterior cavity

What is the posterior cavity also called?

Vitreous chamber

What chambers does the anterior cavity separate into? (2)

1. Anterior chamber

2. Posterior chamber

Posterior chamber

Between the iris and the ciliary body and lens

Anterior chamber

Extends from the cornea to the iris

What does the ciliary body secrete?

Aqueous humor fluid

Where is the aqueous humor secreted in?

Posterior chamber

Aqueous humor flows through the _______ to the ______ ___________.

-Pupil

-Anterior chamber

Where is aqueous humor absorbed?

Trabecular network/meshwork

At the base of the anterior chamber the fluid passes through a collecting duct known as...?

The Canal of Schlemm

After the fluid flows through the Canal of Schlemm, it is returned to the...?

Veins of the sclera

Intraocular pressure

Pressure created by the fluid within the anterior chamber of the eye where it pushes against the inner surface of the cornea

Finish the sentence: If aqueous humor cannot enter the canal of Schlemm,...

Fluid pressure rises, distorting soft tissue within the eye

What determines the IOP?

The balance between fluid production and drainage

IOP

Intraocular pressure

Describe fluid flow through the eye of a Pt with OAG.

Aqueous outflow by these pathways is diminished

Describe fluid flow through the eye of a Pt with CAG.

Iris abnormally positioned, blocks aqueous flow through anterior chamber angle

OAG comparison

"A Silent Thief in the Night that Steals Your Vision"

Why is OAG deemed a silent thief?

Because it develops slowly and goes unnoticed for years, robbing the Pt of vision slowly

Individuals with open angle glaucoma rarely...

Experience symptoms

Some patients are unaware of...

Field loss even when it has progressed to central "tunnel vision"

Thus, open-angle glaucoma is generally detected...

Incidentally on comprehensive ophthalmic examination

Open-angle glaucoma is...

An optic neuropathy characterized by progressive peripheral visual field loss followed by central field loss in a typical pattern

What damages the optic nerve with OAG?

Pressure build up

Open angle glaucoma is one of the leading causes of...

blindness among adults in the United States and is particularly dangerous because it can progress gradually and go unnoticed for years

Open-angle glaucoma is an....

Characterized by... (1), (2), (3)

Asymptomatic, progressive optic neuropathy

(1) Enlarging optic disc

(2) Cupping

(3) Visual field loss

Most common type of glaucoma comprising what percentage of glaucoma cases in the U.S.?

90%

OAG affects what percentage of Pts over age 40

2%

Patients experience decreased quality of life and difficulties with what? (2)

1. Driving- loss of peripheral vision

2. Falls

Risk Factors of OAG (6)

1. African American over the age of 40

2. Caucasians older than 65

3. Family history approximately 2.5 fold increase with family history

4. DM

5. HTN

6. Myopic

AA have how much higher of an incidence than Caucasians?

3x

The age-adjusted rate of blindness from glaucoma is how many more times higher than Caucasians with blindness occurring how many years earlier in AAs

-6.6 times higher

-10 years earlier

Why is HTN a risk factor for OAG?

Association between HTN and increased IOP

Myopic

Nearsighted Pts

Pathophysiology of OAG

The blockage of aqueous flow is subtler, involving a microscopic blockage of aqueous outflow near the canal of Schlemm

Symptoms of OAG (6)

1. Patients rarely experience any symptoms

2. The dx is detected during comprehensive ophthalmic examination

3. A "modest" amount of pressure builds up over time

4. The eye is not red or painful

5. The pupil and cornea appear to be WNL

6. Often affects both eyes simultaneously

According to the American Academy of Ophthalmology (AAO) what is the recommendation for adult patients without risk factors for eye disease for a comprehensive exam to be performed?

-Every 5-10 years in Pts

According to the American Academy of Ophthalmology (AAO) what is the recommendation for patients with risk factors for glaucoma (eg, persons of African descent and Hispanics, or family history of vision loss from glaucoma) for a comprehensive eye exam to be performed?

-Every 1-2 years in Pts

-Every 1-3 years in Pts 40-54

The only way to detect the disease before it becomes a serious problem is...

With regular eye examinations that include a painless pressure test

How often should regular eye examinations be given to a Pt?

Every year

Diagnosis is made by: (3)

1. Evidence of increased intraocular pressure > 22 mmHg

2. Retinal changes

3. Loss in visual fields- peripheral vision gradually shrinks

What is normal IOP?

8-21 mmHg

Tonometry

Measures the force necessary to make an indentation on the eye

How can tonometry be done?

Tono-pen or non-contact device air puff machine

What retinal changes indicate OAG? (3)

1. Pale optic disc

2. Cup enlarges (>50% of vertical disc diameter of the disc)

3. Cupping

What is cupping?

A "scooped out" appearance of the central cup and nasal displacement of the blood vessels

What would the Snellen chart exam show on Pt with OAG?

Usually WNL; Often Pt has very good visual acuity but poor peripheral vision

How can you stimulate poor peripheral vision?

Rolling up a piece of paper and looking through it; You can see straight ahead well but not in the periphery

Automated perimetry

An important diagnostic tool that is much more reliable at detecting visual field loss in glaucoma compared with confrontational field testing

Perimetry test (Visual field test)

Measures all areas of eyesight, including peripheral vision

How is a perimetry test done? (4 steps)

1. Pt will sit and look inside a bowl-shaped instrument called a perimeter

2. Pt will stare at centre of the bowl

3. Lights flash

4. Pt presses a button each time they see a flash

The darker the area....

The worse the vision

Best way to monitor glaucoma progression

Perimetry test

Black on perimetry test

Indicates optic nerve or areas that do not allow Pt to see

How does the example of the perimetry test in the notes order?

From early disease with focal deficits to diffuse, end-stage glaucoma

Treatment for OAG

No cure

Why is there no Tx for OAG?

Nerves will never regenerate, vision will never improve

Primary Goal of Tx for OAG

Lowering IOP which has shown to reduce the risk of progression of visual field loss and optic disc changes

Two Focuses of Primary Tx

1. Pharmacological Therapy

2. Laser Therapy

Pharmacological therapy often requires...

Usage of multiple medications

Medications are ________ for once or twice a day dosing.

Expensive

Medications are ____ _____ ____ ___ _____ (3-4x/day) less costly

High dosing per day regiments

What is the concern with high dosing per day regimens?

Compliance

What can the medications do? (2)

1. Increase aqueous outflow

2. Decreasing aqueous production

Meds that increase aqueous outflow (3)

1. Prostaglandins

2. Alpha adrenergic agonists

3. Cholinergic agonists

Prostaglandin meds (3)

1. Latanoprost

2. Bimatoprost

3. Travoprost

Alpha adrenergic agonist med

Brimonidine

Cholinergic agonist meds (3)

1. Acetylcholine

2. Carbachol

3. Pilocarpine

Brand name for Acetylcholine

Miochol-E

Brand Name for Carbochal

Miostat

Meds that Decrease Aqueous Production (2)

1. Alpha adrenergic agonists

2. Beta blockers

Beta blocker meds (3)

1. Levobunolol

2. Carteolol

3. Metipranolol

Laser Therapy Tx

Trabeculoplasty

Trabeculoplasty

Increases aqueous outflow by improving drainage through the trabecular meshwork

How is trabeculoplasty done?

A procedure using a laser to burn 80 to 100 tiny holes into the trabecular meshwork

What do these holes do?

Cause the burnt tissue to contract, pulling the meshwork more open on the adjacent tissue, allowing for better drainage

First line treatment options for OAG (2)

1. Laser therapy

2. Pharmacological therapy

Medication adherence is a.....?

Concern

How much of glaucoma does closed angle glaucoma account for?

5%