Inadequate diagnostic value of the water-drinking test.

There is a large literature on the subject of the water-drinking test. Many authors have evaluated it and considered it to be a reliable method ofdiagnosing chronic simple glaucoma (Agarwal and Sharma, I953; Bloomfield and Kellerman, I947; Norskov, i967; Scheie, Spencer, and Helmick, 1956; Swanljung and Blodi, 1956). Leydhecker (I95oa, b, 1954) found the test unreliable with Schiotz tonometry. Becker and Gay (1959) and Drance (I963) found it to be reliable with applanation rather than indentation tonometry. Lawrence and Wolff (I962) found no significant difference in their results when both methods were used, but preferred applanation tonometry for other reasons. The inaccuracy of Schi6tz tonometry in the water-drinking test has been ascribed to changes in scleral rigidity resulting from uptake of water by the ocular tissues (Becker and Gay, 1959; Drance, i960, I963; Galin, Aizawa, and McLean, i96i), but no alteration in scleral rigidity was found by Saiduzzafar (I962) and Stepanik (I958). Most authors have agreed that a rise in intraocular pressure (IOP) of 6 mm. Hg is suggestive of the presence of chronic simple glaucoma, but opinions have varied as to what is to be considered as a truly pathological rise (Table I).