Wondering what can cause someone in their last hours of life to have the white of their eyes to turn black?

I went online and read that the exposed cornea dries out which causes it to turn an orange and eventually a black color.

Thats the simplified explanation. But I found a few articles that go into more detailed answers.

The only thing that I could possibly think of if this is the whites of the eyes there may have been a bleed and this was old blood pooling but usually fluids would go to the lowest portion of the body.
Are you sure it was the whites and not the eyes dilated so that the dark portion of the eye the iris and pupil appeared very large in comparison to the whites.

Not only did they turn black . Instead of being white . But all off the white had turned. She had a oxygen mash on for the whole day . And eyes were fine I had left for about a hour or so before getting the call that my mom was not going .make it And when I got back the said we can take off the mask he o2 levels were not coming up . so let take it off so my mom would be more compertable and soon as they did I seen her eyes . I was not expecting to see that . . R n didn't know why.her eyes had turned black . I took that as this must not happen too often if they don't know what makes this happen . My mom was gone with in the next 30 min after they removed mask. I was to upset to ask for more info at that time. . And now during this last month I keep seen my mom in that last day . I keep thinking . What was that . Why did they turn complealey black.. . ?
Thank u . For your input.

Are you sure it was the white of the eye you saw? My mom's pupils were so dilated from the opiates that they were freakishly large, it was very startling.