Глауко

It shows how the cup slowly develops and the nerve rim narrows ( I said shallows on the vid (sorry)). The job is to analyse this at an early stage, preferably before there is visual field damage.

You will see that the vessels start to protrude from the nerve fiber layer at an early stage and that the inferior rim narrows first. Watch out for disc haemorrhages, tht turn into little notches. The vessels move slowly to the nazal rim and that ppa is a late stage development (some papers say it appears with field damage).
Things become more complex with different disk sizes and tilted disks.

Don't forget the ISNT rule and also your red-free filter.

However, its best to make sure the disk is seen in stereo narrow the slit and check the nerve fiber layer. You can guesstimate the layer thickness by knowing that the arteriole that cross the disk rim average about 120 microns and a veinule at the disk rim is likely to be 140 microns. They are covered by the nerve fiber layer showing the nerve fiber layer to be at least 140 microns thick.

Protruding vessels is always wrong and shows a thin layer. With practice you can estimate the thickness of most of the nerve fiber layer across the disc: this helps future analysis a great deal. The other way of checking the nerve fiber rim thickness is to beam a light into the middle of the disk and flick its brightness UP: in a normal disk this will seem to expand the disk size as light leaks into the nerve fibers (acting like light pipes) but the disk stays the same size in glaucoma.

Because so much is happening in early glaucoma - its best to draw and label what you see.