Glaucoma updated flashcards

A branch of medical science that deals with the incidence, distribution and control of disease in a population?

Epidemiology

The number of instances of a given disease or other condition in a given population at a designated time

Prevalence

The number of new cases of illness commencing or persons falling ill during a given period in a specified population

Incidence

On average, what is the prevalence of POAG in Caucasians or European Descent individuals?

2%

On average what is the prevalence of POAG in African americans?

8%

What is considered a slow progressive condition that involves ocular tissue damage at least partially related to intraocular pressure?

Glaucoma

What is the type of glaucoma in which we do not know what caused it?

Primary Glaucoma

What is the type of glaucoma in which it is caused because of meds or trauma?

Secondary Glaucoma

What effect does age have on prevalence of glaucoma?

It has a major effect, prevalence increases with an increase of age

What is the prevalence of ocular hypertension in Caucasians?

3.5%

What effect does age have on incidence of glaucoma?

Incidence raises with age

Are there gender variations seen in angle closure/ narrow angle glaucoma among males and females?

Females are more exposed to angle closure glaucoma than males because they have a smaller eyeball length.

Are there gender variations seen in primary glaucoma among males and females?

It is unclear however other studies show no difference

Which asian ethnicity has high incidence of normal tension glaucoma rates?

Japanese Population

What are the 3 demographic risk factors for glaucoma?

1. age

2. gender

3. race

What are 4 ocular risk factors for glaucoma?

1. IOP

2. Optic Nerve Head

3. Myopia

4. Hypermetropia

5. Central Corneal Thickness

What are 2 Systemic risk factors for glaucoma?

1. diabetes

2. systemic hypertension

What is a genetic risk factor for glaucoma?

Family History

What are 3 other risk factors for glaucoma?

1. cigarette smoking

2. alcohol intake

3. socio economic factors (diff ethnicity treated unequal)

Is diabetes a risk factor for glaucoma according to the consensus guidelines?

Diabetes is a risk factor for glaucoma

What is the correlation with prevalence of glaucoma and IOP

Prevalence of glaucoma increases with increase in IOP

What is the correlation between visual field loss and IOP?

Visual Field loss slows down with decrease in IOP

Hypermetropia is a risk factor associated with which type of glaucoma?

Angle closure risk

Which study shows a protective effect from diabetes to glaucoma?

Baltimore eye study

Diabetes is a major risk factor for secondary angle closure due to ______________

neovascularization

What is the correlation between diastolic perfusion pressure and the prevalence of primary open angle glaucoma?

The higher the diastolic perfusion pressure the lower the prevalence of primary open angle glaucoma

What is a bad combo for glaucoma in terms of IOP and BP?

An increase in IOP and a lower blood pressure is a bad combination

How is systemic blood pressure related to glaucoma?

As blood pressure decreases, IOP increases which is a bad combo for glaucoma

How do you calculate mean ocular perfusion pressure?

MOPP = 2/3 [DBP + 1/3(SMP-DMP)] - IOP

How do you calculate diastolic perfusion pressure?

Diastolic- IOP = diastolic perfusion pressure

What are the odds ratio for glaucoma if the patient has a sibling with glaucoma?

3.69

What are the odds ratio for glaucoma if the patient has parents with glaucoma?

2.67

The rate of blindness is greater in _____________ origin 6-8 times more than caucasians.

African

What are the benefits of aqueous humor for the eye?

1. shape and optical properties to globe

2. nourishment to cornea and lens

3. refraction 1.33332

If you find a high concentration of blood in the aqueous humor, what does this possibly mean?

It would mean that there could be a chance for pathology or more specifically secondary glaucoma.

The production of what hormone happens in the morning and leads to the production of aqueous humor and an IOP spike in the mornings?

cortisol

What is the purpose of longitudinal fibers in the ciliary body muscle?

They attach the ciliary body to the limbus

What is the purpose of circular fibers in ciliary body?

It is the anterior and inner portions of ciliary body

What is the purpose of radial fibers of ciliary body?

Connect longitudinal and circular fibers

What are 3 different Ciliary body vessel complexes?

1. episcleral circle

2. intramuscular circle

3. major arterial circle (paralimbal branches of LPCA)

The Ciliary processes are supplied by what two major branches of the major arterial circle?

1. Anterior ciliary process arteriole

2. Posterior ciliary process arteriole

Name the functional unit of the ciliary body that is responsible for production of aqueous humor

ciliary process: functional unit responsible for production of aqueous humor secretion

What are the two layers of the ciliary epithelium?

1. pigmented epithelium

2. nonpigmented epithelium

Ciliary process capillaries occupy the center of each process. Why is this important?

To supply the processes with the right nutrients to produce the aqueous humor

Is there more ascorbic acid in aqueous humor or the blood?

aqueous humor

How can. you test the rate of aqueous humor production?

Put fluorescein in the eye and see how long it takes to leave

Which process is most responsible for aqueous humor formation?

Secretion: larger size substances or greater charge (80-90% of aqueous humor formation)

What time of the day is aqueous humor production hightest?

8 AM - Noon

What time of the day is aqueous humor production lowest

Midnight to 6AM

What is IOP = (F/C) + P formula mean?

(Aqueous flow rate production/ aqueous outflow) + episcleral venous pressure = intraocular pressure

Why do night time spikes in pressure happen to the eye?

the postural change that involves lying down causes the pressure to increase

T or F: THe process of aqueous formation is a passive process

F: it is an active process that works against the concentration gradient

What are two structures in the eye that take part in the resistance of outflow through the conventional pathway?

1. juxtacanalicular tissue

2. pores of inner wall of Schlemm's canal -funneling from JXT to power of inner wall of schlemms

Name two enzymes responsible for aqueous humor production

1. Na+K+ATPase

2. Carbonic anhydrase

What immediate compound is formed when CO2 combines with water by the aid of carbonic anhydrase?

carbonic acid

In the process of formation of aqueous humor, Carbonic acid splits into what?

1. Bicarbonate ions

2. hydrogen ions

NA, K-ATPase is predominantly bound to the plasma membrane of which part of the ciliary body?

non-pigmented epithelium

What is the role of carbonic anhydrase inhibitors in the posterior chamber?

They cause the reduction of bicarbonate ions

Why is the pressure never 0 in the eye?

Pressure cant be 0 because EVP and AC pressure will equalize but there will always be pressure somwhere in the eye.

Explain the pathway of aqueous humor drainage through trabecular meshwork.

1. TM --> inner wall of schlemm's canal into its lumen --> collector channels --> aq veins, and episcleral venous circulation

2. Conventional Route: 70-95%

What regulates conventional flow of aqueous humor?

Cell stiffness in trabecular meshwork, inner wall of schlemm's canal as well as extracellular matrix

If there is increased stiffness in the TM, this leads to decreased/increased outflow facility.

decreased

What leads to increased cell stiffness in the TM?

Having a chronically high eye pressure

A combination of what two structures lead to the resistance to outflow through conventional pathway ?

1. juxtacanalicular tissue (JCT)

2. Pores of inner wall of Schlemm's Canal (fluid passes through JCT and funnels into pores of inner wall)

Explain the pathway of drainage of aqueous humor through the uveoscleral pathway.

1. Iris root --> uveal meshwork and anterior face of ciliary muscle --> CT between muscle bundles through suprachoroidal space --> out through sclera

2. Unconventional route: 5-30%

Uveoscleral pathway activated by prostaglandin analogs take approximately how many weeks to show effect?

4-6 weeks; its a slow process

What percentage range of aqueous humor outflow is trabecular outflow?

70-95%

What percentage range of aqueous humor outflow is uveoslceral outflow?

5-30%

Does uveoscleral outflow change with age?

Stays the same no matter what age

What is pseudofacility?

As IOP increases during breakdown of blood aqueous barrier, aqueous inflow by ultrafiltraion is suppressed --> slows down the rise in IOP

Inflammation of what structure in the eye can cause it to shut down and lower the IOP

ciliary body

inflammation of what structure in the eye can disrupt outflow and may increase IOP?

anterior uveal tract

The optic nerve head is divided into what 4 parts?

1. surface nerve fiber layer

2. prelaminar region

3. lamina cribrosa region

4. retrolaminar

Glaucoma pathogenesis takes place at the level of what structure?

lamina cribrosa

Where do you find thin astrocytes when considering astroglial support of NFL and blood vessels?

accompanies NFL axons

Where do you find thick astrocytes when considering astroglial support of NFL and blood vessels?

Direct prelaminar axons to laminar region

What is the effect of age and IOP on level of hyaluronate?

Level of hyaluronate goes down with age and further decreases with increased IOP

How do you known if the lamina cribrosa pores are healthy?

They appear round with physiological cupping

How do you know to recognize lamina cribrosa pores of glaucomatous patients?

1. they show as compressed pores (pathologic)

2. lamina dot sigsn in glaucoma

3. striae shaped, not round

What is lamina dots sign?

Compressed pores of the lamina cribrosa

In what areas are the pores bigger in the lamina cribrosa?

1. inferior

2. superior

• can think of ISNT rule

Why does the increase in vertical cupping occuring normally signify glaucoma?

The rim tissue in the superior and inferior part of the optic nerve is getting thinner and thinner first which is why the vertical cupping gets bigger before the horizontal for glaucoma.

Why do the axons in the superior and inferior lamina cribrosa pores get damaged easier?

Because the pores are bigger in those areas, they allow more axons to pass through, in turn, this means that there is less connective tissue protecting the axons so they can get damaged easier.

Why is the central vision more protected in terms of glaucoma?

1. 50% of the axons are at the macula

2. intermingling of the macular fibers with other fibers in the surrounding areas

What is the average size of the optic nerve?

1.55 mm^2

At what age does size of optic nerve head reach 95% of adult dimenions?

Before age 1

In which patient are you likely to see reversibility of cupping?

1. Children whose lamina cribrosa are not fully developed

2. ONH damage also allows for reversal cupping of the ONH

Can a child or adult get some of their vision back if the pressure in their eyes go back down?

a child may get their vision back but not an adult

How many axons do you normally lose a year?

There is a progressive loss of 4000 to 12000 axons a year

If Neuroretinal rim decreases, there is a concomitant increase in what?

cupping

Pallor of ONH is likely due to what?

Optic Neuropathies other than glaucoma

What did researchers believe glutamate did to the eye?

They believe that an increase in glutaate lead to an increase in intracellular calcium which lead to the death of RGC

What is the relationship between glaucomal neuroretinal rim and cupping of the optic disc?

Glaucomal neuroretinal rim decreases with concomitant increase in cupping at optic disc

Axonal compression blocks what at lamina cribrosa?

Retrograde axoplasmic flow

Nitric oxide is beneficial at lower concentrations because?

vasodilator properties

How does Nitric Oxide affect the trabecular meshwork?

It allows the TM to open and relax when the TM absorbs the Nitric Oxide

High levels of nitric oxide lead to?

Neurotoxic - it inhibits mitochondrial function and disrupts DNA

In patients with glaucoma, there is a high or low concentration of nitric oxide in the eye.

There is a lesser amount of nitric oxide in the eye which leads to decreased blood circulation. In the anterior chamber it leads to less relaxation of the trabecular meshwork.

In patients that have glaucoma, what amount of endothelin 1 can you find in them and which particular type of glaucoma?

increased levels of endothelin 1 which is a vasoconstrictor in patients that may have normal tension glaucoma

If the trabecular meshwork is less relaxed in the eye due to a decrease of nitric oxide, what happens to IOP?

It increases and there is less outflow of aqueous humor meaning it does not effectively get drained from the eye.