Lecture 7: The Optic Nerve in Glaucoma Flashcards
List the 9 generalized signs of optic nerve damage
- Generalized enlargement c/d ratio
- Increased dept of cupping
- saucerization
- Vertical elongation of c/d ratio
- Cup-to-disc asymmetry
- Loss of neuro-retinal rim
- Peripapillary atrophy
- Laminar dot sign
- Pallor?
List 2 localized signs of optic nerve damage
- Notching
- Acquired pit of the ON
List 7 abnormalities of retinal vasculature
- Hemes of the NFL
- Focal narrowing
- Vascular attenuation
- Baring of circumlinear vessels
- Overpass cupping
- Nasalization of retina vessels
- Optic disc shunt vessel
Larger discs have (larger/smaller) physiological cups
larger
The more ellipitical discs have (more/less) elliptical cups
more
optic disc is generally large in eyes with ____ and significantly smaller in eyes with marked ___.
high myopia; hyperopia (>+5)
Optic disc size may vary with race. list from smallest to largest.
- Caucasians = smallest
- Mexicans
- Asian
- African americans = largest
What is the normal optic disc size? What is the average size?
- Normal size: 1.33-2.66mm in diameter
- Average: 1.5
Approximately ___ neurons enter ONH
1.2 million
Why do we need to evaluate the RIM of the optic disc closely?
this is where nerve tissue is
___ and ___ have higher predictive power than the neuro-retinal rim as a whole. Why?
- Inferotemporal and superotemporal
- Preferential loss of rim in these regions in medium to advanced stages of GON (Lamina distortion theory)
______ of the cup is the most common type of change in progressive glaucoma. This disc change was found to preced VF loss by several years.
Generalized/concentric enlargement
Concentric enlargement most often seen in ___, ___ and __ pt who convert to glaucoma
NTG, early POAG and OHTN
T/F Depth is a specific finding for glaucoma. What is it affected by?
- False, it is NOT SPECIFIC
- Affected by
- disc area
- ethnicity, refractive error
In advanced stages of glaucoma, the ON may demonstrate “bean potting”. What is bean potting?
- This relates to stress/strain & biomechanical principles applied to peripapillary sclera
- Beanpotting: retinal blood vessels disappear as they follow the lateral excavation of the optic cup and reappear at the bottom of the cup
In normal eyes (Horizontal/Vertical) is larger than (Horizontal/Vertical)
horizontal is larger than vertical
Vertical elongation develops secondarily to the loss of … ?
neuro-retinal rim at superior and inferior poles
- occurs less frequently than generalized enlargment of the cut BUT
- more clinically significant; more easily diagnostic for glc
- Can precede development of VF loss by several years
Vertical Elongation: c/d ratio more than __ greater vertically than horizontally (this would naturally violate ISNT)
What is focal notching?
Area of localized damage
- focal ischemia
- correlate with VF defects (structure & function relationship)
- May be preceded by drance heme
- common in NTG
- Typically at inferotemporal and superotemporal nerve
- May lead to vertical elongation
Focal loss of ganglion cell axons usually at the ___ & ___ poles of ONH
superior temporal & inferior temporal
Notching happens most often at the ___ pole & is consistent with which theory?
inferior; lamina distortion theory
Notching usually produces scotomas in ____ area
Bjerrum area
What is zone alpha? Is this a normal or abnormal finding?
- irregular pigmentation of RPE
- Normal finding
What is zone beta?
- Atrophy of both RPE and choriocapillaris
- crescet like region where you can view choroidal vessels
- Progressive
- Can respond to areas of rim loss
- BUT NOT pathognomonic for glc
List the area of progressive loss of rim in order
- Inferotemporal –>
- Superotemporal –>
- Temporal –>
- Inferonasal –>
- Supernasal –>
Asymmetry of c/d between the eyes: A difference of ___ or more is usually considered significant.
A C/D difference of >__ exists in only __% of normal eyes
- 2
- 2;1%
If a person has an asymmetry of their ___ and overall ___ size, they wil lhave a physiological asymmetry (normal)
scleral canals and overall ONH size
What is laminar dot sign?
It is visiable in only __% of myopic eyes
- exposure of laminar structure due to loss of neural tissue
- laminar dots become more obvious in eyes with significant glaucomatous nerve damage
- remember they are not completely specific to glc
- 34%
- Represent holes in the lamina cribosa
if lamina dots have a ___ or ___ shape, it may an indication of glaucoma
distorted or striate shape
overall lamina dotes may indicate (mild/moderate/severe) glacuomatous damage and striate slit shapes may indicate more ____ glaucoma.
moderate; advanced
T/F pallor in glaucoma is caued by loss of capillaries
FALSE, it is NOT
- caused by increased visibility of supporting structures (e.g. sclera, CT, etc) due to enlargement of the cup
Pallor is more typical of ____ optic neuropathy
non-glaucomatous
Hemorrhage of NFL occur most frequently ___ and ___
- can be seen in any location
- more prevalent in ___ glaucoma
temporally and inferotemporally
NTG
____ is highly specific for glaucoma
flame shaped heme - vasospastic activity of retinal vasculature could lead to disc heme
Heme of NFL VF changes can occur when?
weeks to months later
- sig risk that VF changes WILL happpen following a drance heme - ominous
focal narrowing of vessels occur where?
where cupping is most significant
Why does focal narrowing occur?
less demand for blood supply because fewer ganglion cells to supply
Arterioles should be widest where?
inferotemporal and superotemporal
___ is associated with overall loss of sensitivity VF testing
vascular attenuation
Baring of circumlinear vessels occur in __% normal eyes and __% of eyes with glc
14%, 73%
___ is considered a “soft sign”
nasalizatio of vessels
____ vessels have a Z appearance due to sharpening of the border of the notch
bayonetic sign - rarely found in glaucomatous eyes
- found in area of rim affected by focal notching
The optic disc is best examined by ___
stereoophthalmoscopy
