The Berens-Tolman Ocular Hypertension Checking Device, dating from around 1950, represents an important chapter in the history of glaucoma detection and the democratization of intraocular pressure screening. Developed by Conrad Berens and colleagues, this portable tonometer was designed specifically for mass screening purposes — allowing clinicians and optometrists to quickly identify patients with intraocular pressures above what was considered normal, flagging them for further glaucoma evaluation before vision loss could occur.
Based on the principles of the Schiotz tonometer — the indentation tonometry device that had been the standard method of measuring intraocular pressure since its introduction in 1905 — the Berens-Tolman device simplified the measurement process to make it practical for screening large numbers of patients efficiently. The Schiotz principle works by measuring how deeply a small weighted plunger indents the cornea under a known force, with higher indentation indicating lower intraocular pressure and vice versa. The Berens-Tolman adaptation focused on identifying pressures above a defined threshold rather than producing a precise numerical reading, making the screening process faster and the results easier for non-specialist practitioners to interpret.
The inclusion of original instructions with this example is particularly valuable, as it documents the exact clinical protocol recommended by the instrument’s developers. This complete example with its gold anodized barrel — prominently labeled “Berens-Tolman Ocul. AR Hypertension” — and accompanying documentation represents a well-preserved piece of mid-twentieth century preventive ophthalmology history.
