Term
| Does using 24 mmHg as a break point for glaucoma give reliable dx of glaucoma? |
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Definition
| No, too many false positives AND too many false negatives |
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Term
| Does VF alone provide reliable results for dx of glaucoma? |
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Definition
| No, WAY too many false positives, but few false negatives |
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Term
| What is the FIRST change usually seen in glaucoma? |
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Definition
| ONH changes/optic atrophy |
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Term
| Does the NFL need to be reduced by 50% before VF loss is evident? |
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Definition
| Probably not. Study that stated that is old and the methods used were not very rigorous |
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Term
| Are VF changes a sign of early stage glaucoma? |
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Definition
| No, there is enough redundancy that other s/sx will present earlier |
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Term
| What are the advantages of an FDT VF (4 things)? |
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Definition
Fast
Easy for pt
No operator skill necessary
Test can be performed on pt's who are not fully corrected |
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Term
| When is an FDT abnormal(5 things)? |
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Definition
Defect in any of 5 central locations
two or more mild defects in outer twelve locations
One or more moderate or severe defects in outer twelve sections
>90s/eye to perform test |
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Term
| What is the 'learning effect' with regards to VF testing? |
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Definition
| The Humphrey test is pushing the limits of what level most pt's can respond to, so there is a learning curve for repeated tests |
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Term
| If a defect is found on VF, what should be looked for on the ONH? |
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Definition
| If the area of VF loss corresponds to loss of NFL In the cup |
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Term
| Is a single VF ever used as a baseline for glaucoma progression? |
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Definition
| No, at least 3 VF's will need to be done to reliably detect glaucoma |
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Term
| What level of fixation losses indicate an unreliable test? |
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Definition
Blind spot check failed >20%
False (+) <33%
False (-) <33% |
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Term
| On a fixation loss 'timeline' for a VF, what does an upward deviation indicate? Downward deviation? |
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Definition
Up = Eye moved out of primary gaze
Down = blink or could not determine eye position |
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Term
| How does tear film affect the reliability of VF testing? |
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Definition
| The VF machine tracks eye position by reflecting two IR lights off of cornea. Poor tear film will give a poor light reflex |
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Term
| If the first few blind spot checks in a VF test are failed by the pt, what should the practitioner do? |
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Definition
| Give new instructions and VF machine should be able to still get a reliable test provided they are good at blind spot checks from there on out |
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Term
| How does the OHTS testing criteria for blind spot testing differ from the standard? |
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Definition
>20% is considered an unreliable test
However, >33% was considered unreliable for OHTS study |
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Term
| How does personality type affect VF reliability? |
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Definition
Type A' personalities will typically have few false positives
Laid back personalities will have more false positives |
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Term
| What is short term fluctuation with regards to VF testing? |
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Definition
| There are 10 points that a VF machine checks at the beginning and then again at the end. How repeatable the threshold is determines what the short term fluctuation is |
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Term
| Should short term fluctuation on VF testing be used alone to determine test reliability? |
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Definition
| No, look at the other factors as well. In fact, short term fluctuations can be an indicator for early glaucoma |
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Term
| How is short term fluctuation abbreviated on the VF printout? |
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Definition
|
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Term
| Are SF results age related? |
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Definition
| yes, it changes as we get older |
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Term
| What is the raw data display for VF? |
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Definition
| What the true thresholds found in VF testing were. No norming for age performed on the results yet. |
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Term
| What is the spacing for test points on the Humphrey 30-2? |
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Definition
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Term
| What is the glaucoma hemifield? |
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Definition
| Compares points above midline to points below midline looking for symmetry. Asymmetry can lead to being tagged as either 'borderline' or 'abnormal' |
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Term
| Is glaucoma the only dz that can trigger a positive glaucoma hemifield assessment on VF? |
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Definition
| No, arcuate scotoma due to AION can as well. A positive simply indicates more evaluation must be done, not a definitive dx |
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Term
| Is the gray field useful for diagnosis or analysis? |
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Definition
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Term
| What is the Total Deviation in VF testing? |
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Definition
| Subtract the raw data from aged norms and you get total deviation |
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Term
| What is the probability plot of total deviation in VF testing? |
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Definition
| Determines likelihood that an anomalous point is anomalous due to pathology vs random error |
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Term
| How do edge points compare statistically to points within central VF? |
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Definition
| The further out in VF you go, the more unreliable and variable the results end up, so they are weighted less heavily when diagnosing for glaucoma |
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Term
| What is Pattern Deviation? |
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Definition
| The VF computes the 'median sensitivity' for the pts hill of vision and weights the test results around that to try and remove uniform/overall loss or increase in sensitivity compared to normal (i.e. if a pt was normal, but wearing tinted lenses) |
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Term
| What is a common pathological condition that can cause a total deviation, but not a pattern deviation? |
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Definition
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Term
| How does senile miosis affect VF testing? |
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Definition
| Pay more attention to the pattern deviation due to low levels of light reaching retina causing a uniform total deviation |
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Term
|
Definition
| Overall depression or elevation of sensitivity expressed as a mean value across all points |
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Term
| What is pattern standard deviation? |
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Definition
| Calculates overall smoothness of hill of vision. |
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Term
| What are common types of defects found by VF in early glaucoma (4 things)? |
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Definition
partial arcuate
paracentral
nasal step
temporal wedge |
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|
Term
| What are commontypes of defects found by VF in later stage glaucoma? |
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Definition
|
|
Term
| What is a partial arcuate scotoma? |
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Definition
Extends from blind spot to nasal meridian
MUST have 1 or more abnormal spots in temporal field |
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Term
| What is a paracentral scotoma? |
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Definition
Defect NOT contiguous with blind spot or nasal meridian
Does NOT involve points outside 15* that are adjacent to nasal meridian |
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Term
| What is the most common type of paracentral scotoma? |
|
Definition
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|
Term
|
Definition
field loss adjacent to nasal horizontal meridian
one or more abnormal spot at or outside of 15* from center on the horizontal meridian
Cannot include more than 1 significant point in nerve fiber bundle on temporal side |
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Term
| What are the guidelines for determining if a VF loss pattern is a true nasal step? |
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Definition
| Must be incongruous and not neurologic in origin (i.e. CVA, TIA) |
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Term
| What is a temporal wedge? |
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Definition
| Small defect temporal to blind spot in VF due to damage to nasal fibers |
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Term
| What is an arcuate scotoma? |
|
Definition
extends from blind spot to at least 1 point outside 15* adjacent to nasal meridian
Expect obvious ONH damage |
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|
Term
| What type of VF defect will have obvous ONH damage? |
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Definition
|
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Term
| What is an altitudinal scotoma? |
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Definition
VF defect in one hemifield that respects horizontal midline
Late stage glaucoma loss |
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Term
| What is a generalized depression in VF testing? |
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Definition
diffuse defect from severe nerve fiber loss
Very late stage glaucoma loss |
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Term
| What are the six criteria for determining if VF points are significant for diagnosing glaucoma? |
|
Definition
A single non-edge point worse than P<0.5%
2 or more adjacent non-edge points with at least one worse than P<1% and the other worse than P<5%
3 or more adjacent non-edge points at P<5%
2 adjacent points differ from points across the horizontal midline by at least 10dB (nasal step); edge points OK
CPSD is flagged
GHT outside normal limits |
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