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Editors Selection IGR 21-2
Intraocular Pressure: Water-drinking test
Comment by Remo Susanna Jr on:
25634 Understanding the mechanism of the water drinking test: the role of fluid challenge volume in patients with medically controlled primary open angle glaucoma, Kerr NM; Danesh-Meyer HV, Clinical and Experimental Ophthalmology, 2010; 38: 4-9
Kerr and Danesh-Meyer (244) compared in a prospective, observermasked, cross-over, observational study the IOP elevation elicited by the ingestion of 500 ml and 1000 ml of water (water-drinking test/ WDT) in 15 patients. From similar IOP at baseline, the mean maximum increase in IOP was less in the 500-ml WDT (3.3 ± 1.8 mmHg [23.9%]) as compared with the 1000-mL WDT (4.9 ± 2.3 mmHg [32.5%]; p = 0.0095). Study design and statistical analysis were appropriate.
This study is timely presented, as several papers have been recently published pointing out for the clinical use of this test.1-8 The peak IOP obtained during the WDT has been shown to correlate strongly with the IOP peaks that occur during the day 1,2 and also, as a long-term follow-up study showed, during different days.3
The magnitude of the IOP peak obtained during this test also correlates with the severity of glaucomatous damage and the likelihood of progression.4-7
The exact mechanism of the waterdrinking test is still unknown; expansion of the choroidal bed may cause an increased IOP
This paper addresses an interesting clinical question regarding this test: is the IOP elevation caused by the ingestion of 500 ml of water similar to the IOP elevation elicited by the intake of 1000 ml? The results of this study might change the way that the test is done, making it more comfortable to the patients. The result showed that the IOP elevation with 500 ml was less than 1000 ml. As stated by the authors, the 500-ml WDT cannot be used for clinical purpose without further studies to show its clinical relevance.
In an unpublished study, our group found the same results with the intake of 500 ml. However, the IOP rise drinking 800 ml was similar to 1000 ml.
As stated by the authors, the exact mechanism of the WDT is still unknown, but a recent study published by de Moraes et al. suggested that expansion of the choroidal bed is the main reason for the increase of the IOP.8
References
- Correlation between the water drinking test and modified diurnal tension curve in untreated glaucomatous eyes. Vasconcelos-Moraes CG, Susanna R Jr. Clinics (Sao Paulo). 2008; 63:433-6.
- Does peak intraocular pressure measured by water drinking test reflect peak circadian levels? A pilot study. Kumar RS, de Guzman MH, Ong PY, Goldberg I. Clin Experiment Ophthalmol. 2008; 36:312-5
- Agreement between stress intraocular pressure and long-term intraocular pressure measurements in primary open angle glaucoma. De Moraes CG, Furlanetto RL, Reis AS, Vegini F, Cavalcanti NF, Susanna R Jr. Clin Experiment Ophthalmol. 2009; 37:270-4.
- Correlation of asymmetric glaucomatous visual field damage and water-drinking test response. Susanna R Jr, Hatanaka M, Vessani RM, Pinheiro A, Morita C. Invest Ophthalmol Vis Sci. 2006; 47:641.
- The relation between intraocular pressure peak in the water drinking test and visual field progression in glaucoma. Susanna R Jr, Vessani RM, Sakata L, Zacarias LC, Hatanaka M. Br J Ophthalmol. 2005; 89:1298-301.
- Yoshikawa K, Inohue T, Inohue Y. Normal tension glaucoma: The value of predictive tests. Acta Ophthalmol 1993; 71:463-470.
- Stamper R et al: The relationship between progression of glaucoma and supine and water drinking test. Presented at WGC-Boston 2009, p 282.
- De Moraes CG, Reis AS, Cavalcante AF, Sano ME, Susanna R Jr. Graefes Arch Clin Exp Ophthalmol. 2009; 247:385-9.
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