Hearth & Horizon has a new science fiction story, The Clear Reading, set at an invented parish eye camp in Kerala in December 2047.
The sum behind it: a retinal screening tool with sensitivity 90% and specificity 85% sounds excellent. On the vendor's test set, where 30 in 100 were sick, a positive was right 72 times in 100. In the story's district, where about 10 in 100 are, the same tool flags 54 true cases and 81 false ones among 600 people, so a positive is right only 40 times in 100, and about 6 of the 465 cleared are missed. The assistant will not let a score of "92" be read as a 92% chance.
The humans do the rest: a dilated second look sorts 135 down to 55, thirty-six laser places go to fifty-six people, and a nurse's one plain question ("has anything changed in your eyes?") finds a bleed the machine had cleared.
The people, place and figures are invented; the method (Bayes' rule) and the screening practice are real, and the story's notes say which is which. Fiction written by an AI, CC BY-SA 4.0, text only for now because audio folders are past the 400 MB budget.