intro and iop

Define Glaucoma

describes a GROUP of conditions that share a CHRONIC PROGRESSIVE OPTIC NEUROPATHY characterized by loss of retinal ganglion cells and their axons

Glaucomatous Optic Neuropathy (GON) is characterized by:

structural changes in the ONH in which the neural rim is thinned and the cup is enlarged

Structural changes in the ONH lead to a corresponding _______

VF defect

(T/F) Glaucoma is always associated with a raise in IOP

FALSE

MAY be associated with a raise in IOP - IOP elevation is not fully included in the definition of glaucoma because no all glaucomatous cases come with the IOP increase

In glaucoma, you lose (function/structure) before (function/structure)

structure before function

(T/F) All humans have the same NFL organization

TRUE

List the 6 common Glaucomatous visual field defects

- Centrocecal

- Paracentral

- Enlarged blind spot

- Nasal step

- Arcuate (Bjerum)

- Temporal wedge

picture on slide 10

What makes a glaucoma case a 2° glaucoma

secondary glaucoma is when you can identify a specific ocular or systemic pathology that is causing the glaucoma

List the 18 risk factors for glaucoma

(you actually need to know these so dont skip it just cause its a big list)

- age

- low corneal hysteresis

- thin central cornea thickness

- elevated IOP

- large c/d ration

- race

- family Hx.

- myopia

- 2° ocular conditions

- Systemic hypertension

- Systemic hypotension

- Diabetes

- Migraines

- Vasospasms

- Obstructive sleep apnea

- Corticosteroids

- Smoking

Activities that cause fluctuations in IOP

List 4 of the secondary ocular conditions that can increase the risk for glaucoma

- pigment dispersion syndrome

- pseudoexfoliation syndrome

- ocular trauma

- angle recession

List 3 activities that can cause fluctuations in IOP and therefore can increase the risk for glaucoma

- yoga

- high wind musical instruments

- weight lifting

The typical AH production rate is approx. ___ micro-liters/minute

2.5 uL

The typical AH drainage rate is approx. ___ micro-liters/minute

2.5 uL

WHat is the simplified equation of determining IOP

IOP = F / C + PV

F = AH flow

C = outflow rate

PV = episcelral pressure

Give the 5 stepps of AH flow

- produced by CB

- flows anteriorly in front of the lens toward pupil

- moves anterior toward cornea

- moves laterally toward angle

- drains from angle via TM to Schlemms canal OR Uveoscleral outflow

What is the average IOP

15.5 mmHg

What is the normal range of IOP

10-21 mmHg

List the 5 dynamics factors that contribute to IOP, which factors has the highest impact on IOP

- AH production

- AH circulation

- AH outflow **HIGHEST IMPACT

- Vitreous volume

- Ocular rigidity (cornea and scleral elasticity)

What is the normal difference of IOP between the 2 eyes

2 mmHg or less is normal

When during the day is IOP typically the highest

early morning (5-7am)

When during the day is IOP typically the lowest

late evening (7-9pm)

Diurnal variations of IOP between __-__mmHg are considerd normal

3-5mmHg

IOP has a normal pulsatile variation of approx. ___mmHg

2 mmHg

this is the shift you see on the mires during Goldmann with the px heart beat

(not really used a lot)

IOP (increases/decease) with increasing age

increases

IOP (increases/decease) with valsalva maneuvers

increases

IOP (increases/decease) with blockage of the TM

increases

IOP (increases/decease) with relaxation of accommodation

increase

IOP (increases/decease) with administration of cycloplegic agents

increase

IOP (increases/decease) with administration of corticosteroids

increase

IOP (increases/decease) with general anesthesia

decrease

IOP (increases/decease) with acute inflammation

decrease

IOP (increases/decease) with sustained accommodation

decrease

IOP (increases/decease) with majority of medications

decrease

(NOT INCLUDING CYCLOPLEGICS AND CORTICOSTEROIDS)

How does corneal conditions affect IOP

it doesn't actually affect true IOP but it will affect the reading that you get

IOP measurements during the night while we're sleeping are (lower/higher) than during the day in which px populations

higher

- this is why IOP is highest when taken in the morning because just woke up and then lowest later in the day after we have been up the whole day

all px show this... young, old, glaucomatous and non-glaucomatos)

IOP is ___-___mmHg higher when lying down

4-5mmHg

IOP monitoring between ___AM and ___PM have a ___% chance of catching peak IOP

8am - 4pm

60% chance

(T/F) The episcleral venous pressure has an indirect relationship with IOP

FALSE

EVP and IOP have a direct relationship - when EVP increases IOP increases

What is the most obvious difference in diurnal IOP fluctuation between untreated glaucomatous eyes and normal subjects

greater mean IOP range in glaucomatous eyes

(T/F) Diurnal variations and peak IOP may vary between different types of glaucoma

TRUE

What are the 2 most important parameters of long term IOP fluctuations in the management of glaucoma

- Tmax (the peak IOP)

- Mean range

Define peak IOP

the highest IOP reading that we have on record for that px

List the 3 categories of IOP fluctuations and the time frames they are describing

- ultra short term (sec-minutes)

- short term (hours-days)

- long term (months-years)

List the 5 potential causes of ultra short term IOP fluctuations, which one is the most important

- systolic cardiac cycle

- changing external ocular pressure

- episcleral venous pressure

- AH flow

- scleral rigidity * MOST IMPORTANT *

List the 3 potential causes of short term IOP fluctuations

- diurnal changes

- nocturnal changes

- circadian, total 24hours changes

List the 3 potential causes of long term IOP fluctuations

- AH flow rate changes

- EVP changes

- TM outflow changes

Diurnal variations of ___mmHg or more are a significant and independent risk of the development and progression of glaucoma

5mmHg

IOP trends can drift over months to years, this is likely due to what 2 factors

- AH flow

- TM outflow

List the 2 clinical means of assessing "true" long term IOP fluctuation

1. repeated diurnal IOP curves over a period of time

2. measuring IOP at the same time of the day over a few years

Explain why we DO NOT tell glaucoma px to sleep sitting up as a form of glaucoma treatment and management

IOP increases significantly when lying down - so it may be thought to be beneficial to recommend a progressive glc. px sleep sitting up

however, not all glc cases have increase IOP and IOP may not be that cause of the glc progression, another parameter equally if not more important is ON perfusion

ON perfusion actually INCREASES when lying down - so in some cases laying down would actually be the best suggestion for the px... but we don't test ON perfusion in office so we don't know which one has the larger impact

AH flow has an impact on (ultra short/short/long) term IOP fluctuations

all 3

(tbl on slide 15)

TM outflow has an impact on (ultra short/short/long) term IOP fluctuations

short term (?maybe)

long term

(tbl on slide 15)

Uveoscleral outflow has an impact on (ultra short/short/long) term IOP fluctuations

none

(tbl on slide 15)

EVP has an impact on (ultra short/short/long) term IOP fluctuations

ultra short term

short term

(tbl on slide 15)

At what time of day is IOP expected to be highest due to the regular diurnal variation

5:30AM