The von Graefe knife

For the better part of a century, cataract surgery passed through a blade barely two millimetres wide, wielded on an eye with no anaesthesia.

Before von Graefe

Two manoeuvres coexisted. Couching — pushing the opacified lens back into the vitreous to clear it from the visual axis — had been practised since antiquity: it returned a crude perception and left the eye aphakic, often inflamed. Then Daviel, in 1747, proposed extracting the lens outright through an inferior corneal section. Extraction became conceivable, but it remained dangerous: the wound sat in a dependent position, permanently exposed.

The knife

In 1865, in Berlin, Albrecht von Graefe presented his modified linear extraction, built around a knife he had designed himself: a long, narrow, lance-shaped blade mounted on a tapered octagonal handle.

Nothing about the shape is decorative. A narrow blade enters through a minimal opening; its length carries it across the whole anterior chamber without a second pass; its two cutting edges allow the section to be made as it advances. The octagonal handle, for its part, gives the surgeon a tactile reading of how the cutting plane is oriented — on an instrument you cannot watch as you push it home, knowing where the edge lies is something the hand has to tell you.

Where the blade entered

The real innovation, though, is not the blade. It is where it enters.

von Graefe moved the incision from the inferior cornea to the superior limbus. That single change of site places the wound under the upper eyelid, which covers it, shields it from rubbing and holds it apposed. A protected wound is one that becomes infected less often and gapes less often. Fuchs, in his Lehrbuch der Augenheilkunde, puts the gain at roughly half the failures of the earlier methods.

The shift is conceptual as much as topographical: whether an operation succeeds depends not only on the quality of the manoeuvre, but on what becomes of the wound once the surgeon has left.

The manoeuvre

Execution tolerated no hesitation. The surgeon punctured the limbus on one side, counter-punctured on the opposite side, then completed the section in a single upward sweep of the blade across the anterior chamber.

The whole thing took a few seconds. It had to: until Koller introduced cocaine drops in 1884, the patient had no anaesthesia at all. Assistants held the head still. It is hard, today, to appreciate what steadiness of hand those conditions demanded — or how far speed was itself a principle of safety.

Why the knife disappeared

It was the right tool for its reasoning, and it died with it.

A section running half the corneal circumference is a considerable wound. It brought instability, iris prolapse, major astigmatism and infective risk, and it imposed several days of strict immobilisation, the head wedged between sandbands. Keratome and scissors techniques took over in the middle of the twentieth century: they allow the section to be calibrated rather than produced in a single stroke.

Then, in 1967, Kelman inverted the logic entirely. Until then, the incision had been enlarged until the lens could come out. Phacoemulsification proposes the opposite: fragment the lens inside the eye so that the incision can shrink. It is no longer the blade that adapts to the nucleus, but the nucleus that is adapted to the incision.

Two millimetres, a hundred and sixty years on

We operate today through self-sealing incisions of about two millimetres, under topical anaesthesia, as day cases, with no sutures and no immobilisation.

The coincidence is worth noting: that is roughly the width of von Graefe’s blade itself. What has changed is not the fineness of the instrument — that was already there — but what we ask of it. The 1865 blade was there to open; today’s is there to enter. Between the two, the whole of surgical reasoning has moved: from a wound sized for extraction to a wound sized for aspiration.

The instrument changed because the reasoning changed. It is almost always in that order.

Techniques pass. The discipline that grounds the indication endures.

References

1. Daviel J. Sur une nouvelle méthode de guérir la cataracte par l’extraction du cristallin. Mém Acad Roy Chir. 1753;2:337-354.
2. von Graefe A. Ueber modificirte Linearextraction. Albrecht von Graefes Arch Ophthalmol. 1865;11(3):1-106.
3. Koller C. Über die Verwendung des Cocaïn zur Anästhesirung am Auge. Wien Med Wochenschr. 1884;34:1276-1278.
4. Fuchs E. Lehrbuch der Augenheilkunde. 1^re éd. Leipzig / Wien : Franz Deuticke ; 1889.
5. Kelman CD. Phaco-emulsification and aspiration. A new technique of cataract removal. A preliminary report. Am J Ophthalmol. 1967;64(1):23-35.