This Bailliart Ophthalmodynamometer, manufactured by Giroux of France and retailed through W.J. Koch Optical, represents a distinct and more sophisticated variant of the Bailliart dynamometer design. Where the earlier Bailliart dynamometer used a simple spring-loaded plunger, this Giroux version features a circular dial gauge — clearly visible in the photograph — that allows the examiner to read the applied pressure directly and precisely from a calibrated scale, eliminating the guesswork of earlier designs and improving the clinical reliability of the measurement.
The instrument was used to measure intraocular arterial pressure by applying controlled force to the globe of the eye while observing the central retinal artery through an ophthalmoscope. The dial gauge design made this version particularly favored by clinicians who needed reproducible, documented pressure readings for patient records and research purposes. The Giroux manufacturing firm was one of the leading French producers of precision ophthalmic instruments, and their instruments were widely distributed through optical dealers across Europe and North America — as evidenced by the W.J. Koch retailer label inside the lid of this case.
The original fitted case with its striking red velvet lining is in remarkable condition, and the presence of the original retailer label adds significant provenance and historical interest to this piece. Together the instrument and case represent a complete, well-preserved example of early twentieth century French ophthalmic instrument making at its finest.
