The keratometer

I’ve been using my keratometer since 1992. It’s now on its third equipment stand, a standard Bausch & Lomb one-position instrument, made by Topcon. I don’t rate two position instruments. The keratometer is reliably there on every instrument table, and requires no movement of either the optometrist or the patient to a different room or area. Key equipment I use alongside it includes the Visionix DNE aberrometer and Topcon’s Myah, as well as other topographers.

Uses in practice

In terms of the specific parts of the eye test that the keratometer can help with, I’d say assessing the cornea, whether regular or irregular; anyone with unusual cylinders; identifying refractive error post-cataract operation, and axial length inference (which the keratometer could do for 100 years before measuring axial length became fashionable). In addition, the rapid non-invasive tear breakup time measurement tells me quickly who needs to go to the tear clinic.

Take one specific scenario in practice: an rigid gas permeable (RGP) wearer needing cataract extraction. A 10-year history of identical keratometer readings gives the receiving ophthalmologist a big hint that they may not need weeks without lenses to stabilise the cornea prior to biometry.

The keratometer is vital in basic RGP fitting and aftercare. Granted, in irregular corneas I’ll use topography – but that’s at the next stage; the actual complex fitting. It’s also very helpful when you have toric softs that won’t stabilise, and gives a clear steer on tear film quality. I’ve used it on patients with Down’s syndrome, where high cylinders are not unusual, but sometimes matching the axis is easier than in the subjective refraction.

The first keratometer was designed in 1880. Development stopped a few years ago as topographers took over. However, they need IT, logins, and to be shared across rooms. I find them too much of a fuss. The retinoscope is even older than the keratometer, but is equally vital and an amazing tool in experienced hands.

I think the keratometer has been forgotten in undergraduate teaching. Few of our placement students appear familiar with it

I think the keratometer has been forgotten in undergraduate teaching. Few of our placement students appear familiar with it, and for those who qualified less than 15 years ago, it seems to be looked at with disdain. I find clinicians have to be reminded to think about using it. There are some people who think they were melted down into spitfires after the war. I think there is still an important role for the keratometer in practice, though.