Lecture 3 Flashcards
what 5 things do you examine for for the optic nerve?
disc size, margins, contour of rim tissue, C/D ratio and rim tissue and NFL
what is a distinct margin?
easy to see the edges of the disc 360 - not uncommon for nasal to be indistinct and still be normal
what is an indistinct margin?
unable to see the edges of the disc for the majority of the ONH diameter
what is a normal and abnormal variation of an indistinct nerve?
normal = heaped up appearances or small congenital anomalous nerves abnormal = papilledema
what is a malinserted disc?
congenital - disc is tilted along the vertical axis (appears to tilt upward nasally and down temporal, often has a scleral crescent)
what is a tilted disc?
congenital - the vertical axis is tilted, often downward nasally (often associated with tilted disc syndrome)
what 3 things can cause papilledema?
increased ICP due to brain lesion, idiopathic intracranial hypertension, and hypertensive crisis (bilateral)
what are 3 pseudopapilledemas (AKA congenital disc anomalies)?
optic nerve head drusen, congenitally full disc, and malinserted disc
when looking at a the ONH - how do you know if there is papilledema vs. pseudopapilledema?
if swollen (papilledema) - the view of the vessels will be obscured (like looking through a cloud)
what 5 signs point to papilledema?
indistinct margins, - SVP, + obscuration of vessels and hyperemic rim color
what information does the contour or “type” of ON rim provide?
contour provides information of the neuroretinal rim tissue, also helps to look for notching for glaucoma and vessel deflection
what are the 4 types of ONH contour?
flat, cylinder, slope/bowel, and hooked
what is the C/D and physiological cupping typically for a type 1 nerve (flat)?
C/D = 0-0.2 cupping = less than or equal to 1 diopter in depth
what is the C/D and physiological cupping typically for a type 2 nerve (cylindrical)?
sharp temporal rim
C/D = 0.15-0.65
cupping = 1=5 diopters in depth
what is the C/D and physiological cupping typically for a type 3 nerve (slope/bowel)?
C/D = 0.15-0.65+ cupping = 1-3 diopters in depth
what is the C/D and physiological cupping typically for a type 4 nerve (hooked)?
C/D = 0.2-0.7+ cupping = 1-5 diopters in depth
what is the ISN’T rule?
the inferior border should be the thickest > Superior > Nasal > Temporal (thinnest)
how is the ISN’T rule helpful in glaucoma?
the vertical C/D increases faster than horizontal - doesn’t follow the ISN’T rule
when judging the C/D, where do you measure the disc diameter from?
the first point of deflection of the disc vessels from the neural rim bending towards the optic cup - not color change
what are the average C/D for Caucasians, African Americans and Asian/Latinos?
Caucasians = 0.4
African Americans = 0.6
Asian/Latinos = 0.5
what is a normal amount of asymmetry between the two eyes C/D?
30% = 0.1 difference and 4% have a 0.2 difference
what does a normal healthy, young NFL look like?
with red-free filter it should have a shimmering reflection
what 4 things to you look for during retinal vessel evaluation?
A/V ratio, ALR, delfections or crossing defects, and area around the vessels (white, red, dark stuff)
what is a normal A/V ratio and where do you look to compare?
normal = 2/3 or 3/4
estimation should be made after the first bifurcation and before the third
