Ophthalmic Calipers and Rulers: Braunstein, Osher, Stahl and Scleral Rulers
Instrument guides
Ophthalmic Calipers and Rulers: Braunstein, Osher, Stahl and Scleral Rulers
How fixed Braunstein calipers differ from adjustable calipers, which ones measure incisions, the cornea and the sclera, and the sizes we make.
Eye surgery measures in fractions of a millimetre. Braunstein calipers have two fixed spans, such as 3.0 and 3.5 mm, so one touch marks an incision width without setting anything. Adjustable calipers such as the Jameson and the Stahl corneal caliper measure any distance in their range. The Osher internal caliper measures inside the eye. Press on and scleral rulers, such as the Thornton and Helveston, follow the curve of the cornea and sclera.
Where do eye calipers come from?
Fine calipers became standard as eye surgery moved to small incisions and precise muscle surgery. The Castroviejo pattern, named after the corneal surgeon Ramón Castroviejo, is covered in our plastic surgery markers and calipers guide. Strabismus surgery measures muscle recession and resection along the curved sclera, which is why a curved scleral ruler exists. We did not find reliable histories for the Braunstein, Osher or Stahl patterns, so we describe them by use.
Which calipers and rulers do we make?
| Instrument | Range | Use |
|---|---|---|
| Braunstein 2.0/2.5, 3.0/3.5, 3.5/4.0, 4.0/5.0 | Fixed spans, 7 cm | Marking incision widths |
| Braunstein titanium 2.0/2.5, 3.0/3.5, 3.5/4.0, 4.0/5.0 | Fixed spans, 7 cm | The same, lighter |
| Jameson caliper | Adjustable | Strabismus and general measuring |
| Stahl corneal caliper | Adjustable | Corneal diameter |
| Osher internal caliper | 7.5 cm | Measuring inside the eye |
| Thornton corneal press on ruler | 10 cm | Measuring on the cornea |
| Helveston scleral ruler | 15 cm | Measuring along the sclera |
| Stainless ruler | 15 or 20 cm, mm and inches | General measuring |
Fixed or adjustable?
Fixed calipers are fastest and cannot drift: if your incisions are always 2.2 to 2.4 or 2.75 mm, the nearest Braunstein span marks them every time. Adjustable calipers cover everything else but must be set and checked. Many surgeons keep a set of fixed Braunsteins for incisions and one adjustable caliper for the rest.
How should calipers be cleaned?
Remove all marking ink before sterilizing. Check that the points meet cleanly and, on adjustable calipers, that the scale reads zero when closed. Never leave instruments in saline, because it causes corrosion. Our instrument care guide gives the full routine, and the CDC guidance on cleaning instruments before sterilization explains why cleaning comes before the autoclave.
Frequently asked questions
What is a Braunstein caliper?
A small fixed caliper with two set spans, such as 3.0 and 3.5 mm, used to mark incision widths in eye surgery.
Steel or titanium?
Both measure the same. Titanium is lighter, and steel costs less.
What is a scleral ruler for?
Measuring along the curved sclera, for example muscle recession in strabismus surgery.
Can calipers be autoclaved?
Yes. Remove marking ink first.
Related instrument guides
- Lid speculum types
- Plastic surgery markers and calipers
- LASEK and corneal trephines
- Westcott scissors and blade breakers
Order calipers
See the full caliper range. For a set for a hospital, a clinic or a distributor, send us your list and we will send you a quote.