Need to understand optic nerve terminology

I'm looking at the optic nerve photos and diagrams at

http://www.revoptom.com/osc/3146/Analysis.jpg

http://www.nurseseyesite.nhs.uk/glaucoma/whatisglaucoma?/what_is_the_appearance_of_the_optic_nerve_head_in_glaucoma?.html

"What Your Doctor May Not Tell You About Glaucoma"", p 26-27

Book says "When looking at your optic nerve head, the doctor sees a red saucer with a pale whitish central zone.  This pale central zone is called the cup, and the reddish saucer is referred to as the disc.  The doctor judges what the cup-to-disc ratio is - how big the teacup is relative to the sauer.   In the normal optic nerve head, the cup-to-disc ratio is about one third.  When the cup to disc ratio is greater than that,  this is called cupping.""

I also have two sets of photos of my optic nerve, which I put at http://community.webshots.com/album/564095323hUKiDH
Besides that the eyes look basically healthy I really don't know what I'm looking at.  They look pretty similar, but due to poor quailty scan of the slides from 2006 it isn't all that clear if there is any change.    But the numbers don't seem to think so.  

Right eye
Ave. nerve width @ disk .34 mm
Disk Diameter 2.06 mm
Cup Diameter 1.19 mm
Rim length .88 mm
Disk area3.578 mm
Cup area 1.129 mm
Rim area 2.449 mm
Cup/Disk rea ratio .316
Cup/Disk Horiz ratio .537
Cup/Disk Vert Ratio .572

Left eye
Ave. nerve width @ disk .3 mm
Disk Diamater 2.08 mm
Cup diameter 1.31 mm
Rim Length (Horiz)  .77 mm
Disk area 3.022 mm
Cup Diameter 0.897 mm
Rim Length 2.125 mm
Cup/Disk Area Ratio .297
Cup/Disk Horiz Ratio .563
Cup/Disk Vert ratio .553

The diagrams appear to compare an outer rim with an inner cup.  

I didn't get copies last year because I was told there was absolutely no change - and that is why he took no photos last year.

In 2006 the doctor's estimation of the C/D ratio was 0.6 in both eyes.    


I thought the pale thing sticking out at the center with alot of blood vessels attached to it is the optic nerve head?    

Then the reddish deep saucer shaped area is the disc?  The other daigrams in cros section make it look as if the whitish outer layer that surrounds the reddish saucer is the disk.    I mean ....?

All of hte photos that show progressive glaucomatous damage to the optic nerve appear to show both the white outer layer and the white central thing that sticks out that the blood vessels attach to EXPANDING at the cost of the reddish saucer between the outer layer and the nerve head, which somehow ends up leaving a large white hole and a bunch of strangely displaced blood vessels attached to absolutely nothing.    This doesn't even make logical sense - if the thing in the middle that sticks out that the blood vessels attach to is the nerve head, how does it grow continuously until it abruptly is not there.  

Does anyone know where to find diagrams of the optic nerve, that clearly show AND label ALL of the structures?

Thanks!

Yours,
Dora Smith
Austin, TX
***@****

[villandra]

Found some answers.

Disk is the entire what you see of the optic nerve head.   Cup is the bundle of nerve fibers that stick out in the center.   (Don't ask - because it makes no sense whatever.)
Neuroretinal rim is the dark pink ring between the edge of the cup and the light ring around the outside of the nerve.   I think that the scleral ring is the light ring around the outside of the nerve.   Nasal rim, temporarl rim, superior rim, and inferior rim, are up, down, left and right locations on the neuretinal rim.    

As glaucoma progresses, the rim shrinks at the expense of the scleral ring and especially the cup - which makes no sense whatever if the cup sticks out and is composed of nerve fibers.   If it's really a cup, why does it stick out on photos?

The disk to cup ratio is the ratio of the cup - the big white thing in the center - to the entire nerve head.   It is calculated by area, horizontal and vertical.   So which is the plain ol' ""Cup to disk ratio""?

http://www.opt.pacificu.edu/ce/catalog/web011/course.htm

http://www.timemachine1.com/writeups/ht07.html

http://www.cehjournal.org/0953-6833/19/jceh_19_59_044.html

Glossary:  The optic nerve head in glaucoma:   Community Eye Health Journal (pdf)

http://www.timemachine1.com/writeups/ht07_images/20_01.jpg

Peripapillary atrophy  is some kind of change in the retina around the optic nerve head.  

Notching of the optic rim is jagged intrusions of the cup or the scleral ring into the optic ring.    

Both are often associated with glaucoma.  

There's also pitting, which is a small hole or something on the edge of the optic nerve, and elsewhere, that is associated with glaucoma and/or may be the beginning of a retinal tear.   Very unclear.    

[John C Hagan III, MD, FACS, FAAO]

Assessing cup to disk ration C/D is very subjective and even from expert to expert and from masked studies comparing the same expert rating C/D on the same patient there is variablity. that's why other tests are used.

JCH MD