Diagnostic value of the water-drinking test in early detection of simple glaucoma

A series of 64 patients (119 eyes) subjected 10 years previously to water provocative tests on a suspicion of simple glaucoma were followed up. At that time the intraocular tension exceeded 20 mmHg, but there were no optic disc changes and no visual field defects. The follow-up examination comprised ophthalmoscopy, visual acuity, gonioscopy, intraocular tension, and perimetry. Setting a rise of 8 mmHg as the lower limit, the water provocative test ten years previously had been positive in 31 eyes. Nine of these developed glaucomatous visual field defects despite treatment (29 per cent). The test had been negative in 88 eyes. Of these, 21 (24 per cent) developed glaucomatous visual field defects. The water-drinking test was negative in 70 per cent of the eyes which subsequently developed visual field defects and negative in 75 per cent of those in which no defects developed. Thus the test was neither of diagnostic nor of prognostic value. All the eyes with a positive test which later developed visual field defects had been treated, whereas 57 per cent of the eyes with a negative test which subsequently developed visual field defects had received no treatment. This indicated that a negative water-drinking test gave a false security. It is shown that an alteration of the lower limit of a tension rise does not render the water provocative test any more useful.