Two Cathay Pacific captains lose eyesight during flights
 

On two separated, non-related flights:

https://www.scmp.com/news/hong-kong/...during-flights

Fume event?

Classical migraine can start at any age. There can be substantial loss of vision in the early stages. This symptom can be the first one knows about it. Shock could easily cause the other symptoms the captain suffered.

This is not the place to ramble, but will go over the issues on the medical section if needed.

There is a type of migraine that causes sudden blindness in one hemisphere. Totally black on one side of a central vertical line.

In my opinion, although very rare to begin with no previous history, the danger is real enough to consider when deciding on the minimum qualifications of the only other pilot on board.

Presumably the minimum qualifications of the only other pilot on board - for every commercial operation - is sufficient to divert the aircraft to the nearest suitable airport, and land it safely with weather at the IFR minimum?

Also another that starts as a pinprick in the centre of your vision and spreads across your field of vision with a jagged multi-coloured edge.
It can last about 30 minutes as it progresses across your field of vision.

Also very low BP BTDT

but I'm quite sure the incident was followed by in depth interviews and medical analysis, so no need for our speculation without knowing more.

Other auto-immunes can do it as well, in fact anything thrombophilic leading to ischemia in the back of the eye. Antiphospholipid syndrome is one example, rare and often asymptomatic until stroke (been there got that T shirt) or sudden vision loss or basically a major clot anywhere....

These events are most likely coincidental and unrelated, but we'll see what comes out of the diagnoses - if they are made public.