The morning the bandages came off in Ingwavuma

In a district hospital in the Lebombo hills of northern KwaZulu-Natal, Dr Hennie Hamilton lifts the covering from an elderly woman's eye and asks whether she can see. Duduzile Phakathi answers Yebo. Her face finds his, and she says thank you.

Hamilton is the medical manager at Mosvold Hospital in Ingwavuma, and he operates on patients drawn from five rural hospitals: Mosvold, Manguzi, Bethesda, Mseleni and Hlabisa. All of them began as mission hospitals — Mosvold as a Swedish Alliance Mission station in 1938 — and all of them sit a very long way from anywhere else. The tertiary eye units are in Durban, roughly 400 km to the south. For a patient here, a referral there means a full day of travel in each direction for an operation that takes minutes.

A cataract is a clouding of the lens: light reaches the eye and stops there. The repair, in settings like this one, is usually a small-incision procedure through a self-sealing scleral tunnel that needs no stitches at all, with an artificial lens set in place of the clouded one. Because the eye is patched afterwards, the reveal always comes the following day. Hamilton has performed it many times. It is routine. It is also, each time, the first thing a person sees.

Primrose Gina, a porter at Mseleni Hospital, shouted when her sight came back. Gwendolin Mthethwa, a teacher from Ndumo, was on the same list. One family, trying to account for what had happened to them, told Hamilton that he had been brought by God himself.

The arithmetic behind these mornings is less forgiving than the mornings themselves. Cataract accounts for close to half of all blindness in sub-Saharan Africa, and uMkhanyakude is among South Africa's poorest districts by household income. The national target has been 2,000 operations per million people each year; the public sector has generally managed about half of that. Rural doctors' organisations have documented the fragility plainly: when one surgeon leaves a district hospital, the cataract list can simply end.

Which is what makes the scene in Ingwavuma worth recording. Not the technique, which is old and well understood, but the fact that someone stayed to perform it, in a place close enough to Maputo to feel far from Durban, on a woman who wanted to see her daughter's face.

This one was brought by God himself.