| 摘要 |
A tonometer divides internally incident light at the applanating surface of a prism so that light incident in the applanation area is refracted into the eye and light incident around the applanation area is internally reflected within the prism. Infrared light is preferred for this, and the amount of the reflected light is detected to provide an objective indication of the size of the area that is applanated. This allows intraocular pressure to be determined objectively from the force difference applied to the prism to change the applanation area between reference and measurement sizes, both of which are reliably determined from previous calibration for the amount of the reflected light. Many variations are possible in applying a variable force to the applanating prism and on operating the instrument with the preferred microprocessor, which can also store, display, and manipulate relevant patient data.
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