The retina has no meaningful collateral supply, so retinal ischaemia behaves like brain ischaemia — a clock in minutes, not days. Sudden vision loss is one of the few complaints where the correct nursing action changes completely depending on which of five diagnoses it is. Sort by pain, pattern and the rest of the story, then look at what chronic loss actually does to a patient's world.
1 · Pain
2 · How the vision went
3 · The rest of the story
Peripheral versus central is the fastest sortGlaucoma takes the periphery and leaves the centre — the patient reads fine but bumps into furniture. Macular degeneration takes the centre and leaves the periphery — the patient walks the hallway safely but cannot see your face or read the discharge sheet. Switch the eye and watch what happens to the grid and to the room.
Look through this eye
How to teach the Amsler grid
Tape it at reading distance.
Wear your reading glasses.
Cover one eye and test each eye separately.
Fix your gaze on the central dot and keep it there.
Report on the same day any new wavy, blurred, missing or dark area.
Do it daily.
That one home test is what converts wet macular degeneration from a catastrophe into a treatable problem, because anti-VEGF injections preserve and often improve vision when started early.