POAG Flashcards
Principal site of insult in POAG
Laminar region of ONH
What diurnal variation is common in POAG?
> 5 mmHg
T/F: IOP asymmetry is more common in secondary GLC compared to primary GLC
TRUE
How much asymmetry is common in GLC?
≥ 3 mmHg
Primary cause of elevated IOP in GLC
Reduced outflow facility
Fundamental cause for the increased resistance to outflow in POAG is not known, but is believed to be a consequence of alterations in…
Juxtacanicular region of TM
OHT is associated with higher incidence of ___ (inc/dec) CCT
Increased (>555 mmHg)
NTG is associated with higher incidence of ___ (inc/dec) CCT
Decreased (<555µm)
POAG is diagnosed if angles are open/normal; however Gonio should still be performed on these pts. Why? And especially if they are…
May develop angle closure due to lens changes, esp in HYPEROPES
What is the single most important clinical feature to establish Dx of POAG?
ONH appearance
Floor Effect
RNFL thinning stops (“Reaches its floor”) at 60µm despite progression
OCT features of POAG:
1. RNFL defects
2. Thinning of GCs
3. Decrease in NRR
4. ???
Loss of macular and peripapillary capillaries
visible on OCT angiography but not widely used in practice
Most common meridian for RNFL defects
Inf Temp
What is the difference between local and diffuse RNFL defect in RNFL?
30º
Trans-laminar cribosa pressure gradient becomes higher when the lamina is ___, as in the case of high ___
Thinner; myopia
Low blood pressure is associated with ___ (hi/lo) CSFP
Low
How can a benign tumor in the chiasmal region produce GLC-like optic discs:
Obstructs ON/CSF canal —> Inc TLPD —> thin NRR + large PPA
SVP pulsation occurs in tandem with the ___ pulse
CSF
(Collapses during CSFP diastole, expands during systole)
SVP is ___ (less/more) common in GLC
LESS
Absence of SVP may be ___ (protective/RF) of GLC
RF
Strain in Lamin Cribosa triggers what CT remodeling? Via Via what receptors?
- LC stiffens
- Post mvmt of LC
Via integrin receptors
Other than VF loss, what other visual dysfunction?
Decreased CS, color, and motion perception in early stages
VA affected later stages
How many test locations in a 30-2?
76
How many test locations in a 24-2?
54
Clinical use of 10-2?
Advanced GLC, macular involvement
What results would you expect in a VEP of a GLC pt?
VEP latency
What results would you expect in a ERG of a GLC pt?
Abnormal pattern/flicker w/ VF progression
What results would you expect in a PhNR ERG of a GLC pt?
< 50% b-wave amplitude —> suggest GC abnormality
T/F: VF is a requirement for the Dx of GLC
FALSE; not all pts are able to provide reliable fields (electrophysiology may be used in its place)
According to OHTS, 3 RFs that significantly increase risk of conversion from OHT to GLC
- Higher baseline IOP (<25 mmHg)
- Thinner CCT (< 555 µm)
- Larger VCDR (>0.5)
According to OHTS study, 20% reduction in IOP reduces risk of GLC by ___ in whites, ___ in blacks, and overall: ___.
36% in white
58% in black
50% overall
OHTS: High risk suspects have any of the following… + a ___% risk of conversion
- IOP > 30 mmHg
- CCT < 555 [+IOP > 25 or VCD > 0.5]
- RNFL defect on OCT
- VF defect, consistent w/ GLC
> 20% conversion
TX for Low-Risk
No Tx
Pt edu
F/u: 6-12 mo
RTC x 1 yr CEE + OCT/VF
TX for Medium-Risk
No Tx (if OCT/VF reliable)
Maybe Tx trial (if unreliable)
F/u: every 6 months
TX for High-Risk
Tx rec’d — 15% reduction
Consider: life expectancy, expense, or risk of tx
F/u: every 6 months
NTG suspect might exhibit:
- Cupping
- RNFL loss
- VF defects
But normal IOP
What IOP is normal for NTG?
High end of normal (18-20 mmHg)
T/F: Decreased VA in a NTG suspect is indicative of progression to GLC
FALSE; suspicious for non-GLC disease bc dec VA not expected until late stage GLC
Case HX that may indicate NTG in suspect
- Hypotension
- Prior IOP elevation
- Vasospasms (Migraines, Raynaud’s)
- FOHX of GLC
Central scotomas suggest
ON compression
Why is a peripheral retina exam important in GLC eval?
Scars/lesions may produce VF defects
Pathognomonic sign for GLC
Does not exist
T/F: GLC Dx is urgent and requires immediate TX
FALSE; “time is on your side”
T/F: POAG is diagnosed independent of IOP
FALSE; IOP must be > 21 mmHg
Otherwise, consider NTG
___% of adults in US have vCDR < 0.6
98%
98% of adult pop in US has vCDR asymmetry < ___
Each ___ increase in vCDRE asymmetry increases odds of GLC by ___x
0.2
0.1; 2.5x
T/F: (-) ISNT can be found in non-GLC pt
TRUE; 5-10% of gen pop
T/F: Cirrus = RNFL + GC + IPL
FALSE
GCC = RNFL + GC + IPL
Cirrus = GC + IPL
Rim area < ___ is always suspicious
< 1.0 mm^2
Fovea lies about ___º below ONH
10º
5 steps to manage GLC
- Establish baseline
- Set IOP target
- Lowe pressure
- Long term f/u
- Modify as needed
T/F: IOP lowered below threshold shows no add’l benefit, once threshold already met
TRUE
