With the introduction of tonography1 considerable attention has been focused on outflow resistance and its measurement. The performance of tonography and the interpretation of recordings is not difficult, and has found wide application. However, relatively simple techniques for clinical measurement of aqueous flow are not available.
Goldman's fluorescein technique requires considerable specialized equipment not readily available to most glaucoma laboratories.2 The technique of conjunctival transfer of fluorescein through the cornea is not adequately quantitative, particularly at low levels of aqueous flow.3,4 Tonographic calculations of flow are inaccurate for several reasons, one of which is the assumption of values for episcleral venous pressure. Unless simultaneous measurements of this latter variable are obtained, it is impossible to use tonographic analysis for calculations of flow when the intraocular pressure approaches the assumed value of the episcleral venous pressure. Furthermore, it is not certain that the ocular pressure gradient is related
GALIN MA, BARAS I, MANDELL GL. Measurements of Aqueous Flow Utilizing the Perilimbal Suction Cup. Arch Ophthalmol. 1961;66(1):65–69. doi:10.1001/archopht.1961.00960010067014
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