Ocular Disease Ii - Glaucoma Mt Ii

Front 1

What are the average CCT of white ocular hypertensives according to the OHTS study? African Americans?

Back 1

Whites=579 microns
Blacks = 555
All = 573

Front 2

OHTS: which two factors correlated to development of glaucoma?

Back 2

1. CCT: strongest correlation - for every 40 micron decrease in CCT --> 70% increase of glaucoma damage
2. IOP: for every 1 mmHg increase --> 10% greater risk of glaucoma

Front 3

When should you perform pachymetry? (at what step in the workup)

Back 3

Should be done before any measurement is needed that involves touching the cornea. Tono, Gonio, Dilation
-Take 3 hours after arising
-Take > 3 months after cataract surgery and
> 6 months after refractive surgery

Front 4

How do you perform a Ultrasonic pachymetry reading?

Back 4

1. Anesthetize cornea
2. Be sure cornea is moist: Blinking periodically, Use AT
3. Probe should be parallel to visual axis
4. CENTRAL cornea
5. Multiple readings (>5), delete outlyers

Front 5

List some factors that effect the IOP reading

Back 5

1. Valsalva maneuver: Holding breath increases IOP; Body inversion substantially increases IOP
2. Aerobic exercise: Can result in 20% decrease in IOP
-Is not sustained once patient stops
-Additive to meds
-may enhance perfusion to ONH

Factors that influence IOP during actually measurement
1. Accommodation: Decreases IOP
2. Apprehension: Increases IOP; significant in NCT
3. Tight tie/collar: Increases IOP
4. Holding lids/pressure on globe can substantially increase
5. Corneal Edema: falsely low
6. Corneal Scarring: False High

Front 6

Besides the procedure used, pressures and time of day, what other piece of info is needed?

Back 6

If patient on glaucoma med, need to know the TIME the medication was taken

Front 7

When is post-dilated Tonometry indicated?

Back 7

1. Glaucoma patients on miotics
2. Glaucoma patients
3. Narrow, potentially occludable angles
4. Pseudoexfoliation (post-dilated IOP spike)
5. Pigment dispersion

Front 8

When can you bill for serial tonometry?

Back 8

If more than one IOP reading is taken in a day

Front 9

List some factors that are characteristic of a higher risk of glaucoma

Back 9

1. Consistent high IOP >30 or IOP spikes over 30
2. Upward trend of IOPs over time
3. IOP asymmetry > 5
4. Large (diurnal) IOP variation or at least spikes (>5 suspicious, >10 abnormal)
5. large post-dilated IOP spike > 8 mmHg

Front 10

According to evidence, does significant structural damage occur prior to earliest recognizable, classical VF defects in many cases?

Back 10

Yes; Quigley showed that 50% of axons are gone at the 1st sign of VF defect on Goldmann
-Reports of Drance hemes, RNFL defects before VF defects

Front 11

What is the value of perimetry in glaucoma?

Back 11

1. Detection: In ~15% of patients you will notice VF defects before ONH changes
2. Important in glaucoma management: once a defect is detected, VFs are accepted to be more sensitive to glaucoma changes
Why? Because once significant axon damage, it is very hard to detect any further change except thru VF changes (no more redundancy)

Front 12

Is Goldmann or current automated perimeters better for detecting early changes and for monitoring progression?

Back 12

Current automated perimeters are better at detecting, quantifying and monitoring progression

Front 13

Name three "must haves" for perimetry to be effective for picking up progression in glaucoma patients

Back 13

1. Must be able to identify:
-Fluctuations of sensitivity: depth changes = most common change in VF defect over time
-Size changes
-New defects
2. must have consistently repeatable testing conditions and process --> results will fluctuate under normal conditions and even more as VF loss onsets
3. Must be able to minimize the variability of the VF due to the test instrumentation, process and examiner in order to identify that fluctuation caused only by disease

Front 14

T or F? Degree of VF loss at diagnosis is a major risk factor for blindness

Back 14

True

Front 15

List 3 phases of field loss in glaucoma

Back 15

1. Elevated IOP, VF normal or non-specific defect
-Early/subtle ONH changes
2. Unstable, shallow field defects, transient nature
-Static threshold testing necessary
3. Unequivocal early VF defect
-irreversible damage and field loss

Front 16

List 3 field defects that MAY be glaucomatous in nature - no definitively glaucomatous

Back 16

1. Baring of BS
2. *Generalized Depression: many other causes; small pupil, fatigue, wrong lens, media opacity, age, glaucoma
3. Vertical BS enlargement: may be due to peripapillary atrophy

Front 17

List 3 CLASSIC (localized) VF defects in "early" glaucoma

Back 17

1. Paracentral scotoma: Commonly recognized as the earliest single VF defect and earliest to occur in combo with other defects (Nasal step ~ 50%). Use static threshold perimetry
2. Nasal Step: sensitivity drop across the nasal horizontal midline due to arcuate damage sup or inf --> only in or more so in one vs the other.
-Centrally far more common
-~75% occurs as earliest defect combined with paracentral scotoma
3. Temporal sector/Wedge: nasal radial fibers, points toward temporal side of BS, may cross midline

Front 18

What is the criteria for nasal step on Goldmann?

Back 18

Width: > 5 - 10 degrees (if consistently repeatable then any size)
Depth: > 5 - 10 db
Compare threshold to those of mirror image
-Points across the nasal horizontal midline

Front 19

What is the main goal of glaucoma therapy?

Back 19

To maintain maximal visual function- index currently is VF

Front 20

Is improvement from glaucoma therapy common? What about stabilization?

Back 20

No. <2><10%

Front 21

According to Midelberg/Drance by what percentage does damage increase

Back 21

79% of all VF defects become denser
- 52% increase in size
- 50% develop new VF defects
- 87% progressed, 2% improved, 10% stabilized

Front 22

What are the optimal testing conditions of VF

Back 22

1. Pupil at least 3 mm on every test - dilate
2. Appropriate correction to distance
3. Align pts eye and maintain thruout test - adjust if necessary
4. Do not leave the room during test

Front 23

List 2 types of VF testing

Back 23

1. Screening: good for routine exams (FDT N30)
2. Threshold testing: standard of care in management and detection. Use on glaucoma suspects (ex. Large C/D), those at high risk (high IOPs)
-Types of Threshold
a. White on White: standard
b. SWAP: good if you detect that white on white isn't picking up the defect
c. FDT

Front 24

T or F? VF are more important in glaucoma management than is IOP

Back 24

True. VF testing, ONH and RNFL eval are more important that IOP

Front 25

Which two structures do you need to assess for structural damage?

Back 25

ONH and RNFL

Front 26

ONH eval: Best technique?

Back 26

For stereoscopic view --> high mag, fine slit beam = Fundus lens

Front 27

ONH eval: T or F? You want to evaluate color when judging cup

Back 27

False. Cup is defined by contour.
*Cupping of neural rim w/o pallor w/in the cup is highly specific to early glaucomatous ONH damage - difficult to see
-Keys to judging contour changes
a. use smaller vessels -deflect at edge
b. narrow slit beam - deflection
c. stereopsis optimal at high mag - but may not be too helpful

Front 28

ONH eval: What is the significance of a ONH evaluation

Back 28

Important to R/O non-glaucomatous causes of RNFL dropout, VF loss --> both not very specific for glaucoma. R/O ONH atrophies (pallor)
-Pallor outside of cup = Optic neuropathy
*Harder to slow progression if damage is significant

Front 29

ONH eval: List 2 patterns of ONH damage

Back 29

1. Diffuse/generalized: enlarged round cup. Most common; 50% pts present diffuse - hard to detect. Associated with general RNFL loss, color decrease (BY), general VF loss
2. Focal/Localized: Most commonly inferior rim; superior is second. Associated with focal VF defects (nasal step), RNFL defects (slits), Drance hemes

Front 30

ONH eval: List 4 components of a systematic ONH strategy

Back 30

1. ONH size: Cup size related to ONH size (Increased ONH = Increased C/D)
2. Rim tissue: most important aspect of ONH in glaucoma
3. Cup/Disc: Indirect indicator of rim width
4. Parapapillary atrophy: Zone beta - Closer to ONH; Zone Alpha - more peripheral to beta

Front 31

T or F? Cup size is not strongly related to ONH size

Back 31

False. Larger ONH --> Larger C/D ration
-AA tend to have the largest ratio > Asians/Hispanics > Caucasians
- Larger ONH for higher myopes and small for higher hyperopes
*Always check ONH size before evaluating C/D
- 60D lens best for estimating size because least amount of mag (closer to pt RE)

Front 32

T or F? Rim tissue is the most important feature of the ONH to evaluate in glaucoma

Back 32

True

Front 33

Localized thinning usually appears inferior (notched) rather than superior. But rim tissue is NORMALLY slightly thicker where?

Back 33

ISNT rule: Inferior > sup > nasal > temp; Inf/Sup 1.5-2x thicker than Temporal
- Cup is normally oval horizontally while the ONH is a vertical oval
-Also compare Superior OD vs. Superior OS (also other areas too)

Front 34

Which part of the rim tissue should display this PINKEST color?

Back 34

Nasal is the pinkest. Then Sup/Inf
-Temporal is variable in color (stretching in high myopes)
**Pallor of rim tissue (outside of cup) strongly suggests nonglaucomatous optic neuropathy; pallor fills into the cup in glaucoma and PRECEDES the cup in nonglaucomatous atrophy

Front 35

What is considered the most critical characteristic when evaluating the rim tissue?

Back 35

Contour.
-Saucerization/shelving = cupping w/o pallor in the shelf resulting in two level saucer-shaped cup - must judge contour to detect

Front 36

C/D is judged by contour - not color. T or F?

Back 36

True
-C/D ratio is an indirect indicator of rim width
-2% of normals have C/D > .7

Front 37

What two components of parapapillary atrophy (PPA) are considered in glaucoma?

Back 37

Zone Beta: closer to ONH - has large choroidal vessels showing. More significant
Zone Alpha: more peripheral to Beta, irregular pigment

Front 38

List common signs/changes of the ONH that are highly suggestive of glaucoma

Back 38

1. Overall decrease in rim tissue --> Increase in C/D ratio
2. Focal decrease rim width/focal notching/polar notching
3. Saucerization - subtle
4. C/D asymmetry in OD vs OS
5. Vertical Cupping: normal cup is horizontally oval
6. PPA: can be due to age; *increase in Beta predictive of onset
7. Pallor: fills cup; *cupping precedes pallor toward disc margin
8. Laminar dot sign: *In location where they were not previously - more slit shapped
9. Drance hemes: at edge of disc usually at 12 and 6 oclock
10. Focal constrictions of arterioles as they leave the ONH
11. Baring of the circumlinear vessel - cup has progressed beyond vessel
12. Acquired pit of ONH (APON): focal excavation of rim tissue often precedes focal VF loss

Front 39

T or F? Drance hemes are highly specific to glaucoma (LTG > POAG) and they precede focal ONH/RNFL damage and local VF loss by years

Back 39

True.
-Suggests inadequate IOP control
-#1 ddx of Drance Heme = LTG or POAG

Front 40

RNFL evaluation: ___% of axon damage occurs before a RNFL defect appears

Back 40

30-50%.
-RNFL defect can precede ONH damage and usually precedes VF loss.

Front 41

RNFL loss can be used to predict presence of and the TYPE of subsequent VF defect. What are the two types?

Back 41

1. Diffuse RNFL loss: general depression of VF possible but r/o artifacts
2. Focal RNFL loss (slit or wedge) may have localized VF loss (scotoma, NS) in corresponding area of VF

Front 42

RNFL loss appears:
1. ___% axon loss on Goldmann
2. ___% axon loss on white-on-white threshold perimetry
3. ____% axon loss on SWAP

Back 42

1. 40-50%
2. 20-40%
3. 20-30%

Front 43

Which type of RNFL pattern loss is easier to detect and why?

Back 43

Localized/Focal defects are easier because of the difference in appearance from the surrounding fibers (appear darker)
-Most often inferior or superior arcuate
-Diffuse much more common in early glaucoma
-In diffuse look for: increased visibility and contrast of larger vessels close to disc

Front 44

What would you do in this situation... Glaucoma suspect presents with a RNFL defect with no associated VF loss

Back 44

Initiate Glaucoma therapy
*10-15% of normals have slit defects - if you have not seen this pt before then you cannot be certain this is a change. If other signs then follow as a suspect.

Front 45

Pseudo-slit defects (slit defects in normals) are narrow ( < 1 vessel width) defects. But how do you differentiate them from a TRUE defect of the RNFL?

Back 45

Pseudo defects don't continue into the ONH.
-Any cause of ONH damage causes RNFL loss - RNFL loss is NOT very specific to glaucoma. Evaluate ONH or other findings to DDx

Front 46

What is the most reliable way to decide if glaucomatous suspects have early glaucoma damage?

Back 46

Review Fundus photos. Documenting is the easiest and most reliable way to follow change
*Gold standard = 20 degree stereo photos of ONH at high magnification

Front 47

What are some advantages of these new technology devices such as OCT, HRT, and GDx?

Back 47

1. Identify glaucoma now; however wide variation in normal
2. Identify change over time that could not be detected by other instruments

Front 48

Which instrument measures the retardation of polarized light from the RNFL and which one generates a 3-D image from a series of focal cuts thru the long axis of the ONH?

Back 48

1. GDx: Polarized change is directly proportional to RNFL thickness
2. HRT: Calculates quantitative characteristics of the ONH relative to a reference plane

Front 49

Which instrument is similiar to a B scan ultrasound but uses low coherence light which analyzes the backscatter from the retinal layers?
Which one uses a digital fundus cmera with scanning slit lamp to capture images of the x-section of the retina?

Back 49

1. OCT
2. Retinal thickness analyzer

Front 50

When should you use ONH/RNFL imaging?

Back 50

*1. High risk: high IOP, numerous strong risk factors
2. Possible evidence of ONH/RNFL damage
3. Glaucomatous appearing VFs with high IOP but no apparent structural damage
4. Anomalous ONHs which make glaucoma changes difficult (i.e. tilted disc)
5. Early to moderate stage glaucoma

Front 51

According to the OHTS study - what was the strongest risk factor related to progression to POAG in OC hypertensive pts?

Back 51

Thin corneas
*Pachymetry has become the standard of care in diagnosis/management of ocular hypertensives.

Front 52

Are provocative tests for OAG used?

Back 52

Not really
1. Water provocative: too many false positives/negatives
2. Dilation/cycloplegic

Front 53

What are the provocative tests for Narrow AG?

Back 53

1. Prone Dark Room (PDRP): most physiologic test
-positive > 8mmHG rise
2. Dark Room: sitting up instead
3. Dilation: Positive if > 8mmHg

Front 54

List other tests of visual function

Back 54

1. Color: Good evidence of color defect in early glaucoma
2. Contrast sensitivity
3. Dark adaptometry
4. ERG/VER
5. Color Fields
6. SWAP/FDT/High pass resolution perimetry