You died with cataracts in your eyes.

Too much time above the surface. Too much radiation. They were an inevitable consequence.

They were a price that you were only too willing to pay.

So many of our desires come back to sight, to the ability to see clearly. Cataracts are a physical manifestation. Objects viewed through that cloudy, compromised lens are soft about the edges, discoloured. With cataracts, it is harder to look at the light. With cataracts, it is harder to see in the darkness.

You said darkness was all that we had.

I tried to tell you different. That the illumination below ground was sufficient. Artificial, but sufficient. It’s still no substitute for sunlight. Lack of sunlight has its own consequence. Everything . . . fades. Even the gardens are dull, laid out straight for productive purpose as they are, in long rows underneath lights. I tried to tell you the colours were the same, that the flowers we pollinated by hand in order to get beans and zucchini and pumpkin were as bright as they were when we lived above ground, but you didn’t believe me.

“I remember them looking different from this,” you said, and I couldn’t tell you that, against the memory of happier times, everything looked dull now.

You knew that already. Your eyes, like mine, had become accustomed to darkness.

Seasonal affective disorder, they called it once. The result of hard winters and high latitudes, or scientists wintering over at poles. Of colonists too, gone to other planets, to the moon, and spending their time underground because what was above lacked the atmosphere to support life, or to reflect solar rays.

For those of us that survive on Earth, it was nuclear war. All the populations live underground now, with all that weight of history over our heads and there’s nothing to look up to now but rock. No sunlight, not unless we go above.

It’s stay underground until everything looks dark, regardless of lamps, or it’s go to surface for solace and cataracts.

Either way, it’s so hard to see clearly.

You managed it, in the end. I didn’t think that you would. You spent so long in blankets, until it was harder and harder to drag you out of bed. Harder to get you to eat, to be social. Depression affected your perspective long before the cataracts did. Medication blunted the effects, a little, and there was light therapy. I gave you my rations of it, my time under the brightest lights we had, until the lack began to slow my own bones and I couldn’t give you any more.

“It’s so dark,” you said, and your cheeks were wet and salt. You missed the sun so badly. And then one day I came home and your blankets were empty. I knew you had gone above. You came back and your face was red and open, and though you didn’t smile, not yet, it was as if something inside you had let go. A small and silent loosening, and I knew you would go back.

There was nothing to stop you. To stop anyone. The surface is always there. They tried, once, to keep it blocked away, to keep us out of sunlight but too many, in the end, grieved the loss of it too badly. I remember a time when I was the only one left in the green rooms, the only one monitoring sprouts and asparagus under lamps because everyone else assigned to shift was sickened on the falsity of the light we gave them.

I came back to our quarters and you told me that no-one had gone to the mushroom farms for days, that it was too dark there and the man who had the managing of them opened his wrists in the aisles, between composts.

No-one can be cut off from sunshine for so long and not feel the effects. No population is immune. Regulations were loosened then, the doors to the surface unlocked.

You tried so hard for balance. Everyone did. Too long underground and depression set in, the world around dimmed and softened. Too much time above and the cataracts came, but though your eyes went milky you could see more clearly. I was glad for your return, glad for the cataracts that were the return of your perception.

“If I must go blind,” you said, “let it be with laughter.” You were satisfied with small trips, then, and while you were they were treatment enough.

Some people saw more blackly, and the cataracts came more quickly, their need for surface and sunlight overwhelming the poor resource we had for treatment. “It’s suicide, going up there,” you said, even with the small and scattered trips you took. You knew what you were doing. “But it’s suicide not to go as well.” Radiation wasn’t melancholy, but it was impossible to see a path than didn’t lead to either.

“I know what I want,” you said, and you said it clearly, as you might have done before the darkness took you, before it drained away all that had made you active and the little medication left had proved insufficient.

You wanted to die in sunlight.

“Don’t you remember,” you said. “Don’t you remember what it was like?” Life above, and sunshine every day. Less in winter, and I remember feeling cooped up, feeling dull and unhappy inside at the long nights. Other species hibernate. I’d always thought that a sensible thing. The thought of polar winters made me cringe: six months of darkness. How little that seems now.

“Not that,” you say. Your hands are warm in mine, but then I always feel cold these days, remembering. “The good times. That’s what I was thinking of.”

I know there were good times. I suppose I went to the beach, like everyone else. The parks, the forest. I suppose I lay outside on the lawn, soaking. I must have done, but I can’t remember what it felt like. The dull days are easier to recall.

“That’s how it started for me,” you said.

I think you were glad to go first. It’s easier to lose sight of things yourself than to watch the light drain away from the eyes of someone you love. And then to watch it come back, and not to see it as strongly, because their lens has clouded.

“You were always the strong one,” you say, tucking me down, under the blanket. “I’d hoped this wouldn’t happen to you.”

I want to say it happens to everyone but that wouldn’t be true. Some people have adapted better. Some seem to be immune. For them, the light therapy is enough. They’ve adjusted to this, the best possible world that is left, and see no need for anything else.

The rest of us, the most of us, we wait for our choice of blindness.