Antara Chakraborty, M.Optom
Lecturer, Acharya Institute of Allied Health Sciences( Affiliated to Rajiv Gandhi University of Health Sciences) Bengaluru, India
The Water Drinking Test (WDT) is an important tool for diagnosing intraocular pressure (IOP) changes in glaucoma patients.(1) By creating scenarios that could cause IOP spikes, the WDT assists healthcare providers in assessing the effectiveness of IOP control in patients and determining if further interventions are needed.
The Basics of the Water Drinking Test:
During the water drinking test (WDT), individuals ingest 1 litre of water over a period of 5-10 minutes. Subsequent measurements of intraocular pressure (IOP) are conducted periodically to monitor fluctuations in pressure levels. Through this examination, clinicians can detect maximum IOP values that may go unnoticed in standard IOP assessments.(2)
Detecting IOP Peaks:
Research has shown that the highest intraocular pressure (IOP) levels often occur shortly after drinking water. A study with 100 healthy participants revealed that the average IOP before drinking water was 12.4 mmHg, increasing to 15.3 mmHg one hour later. Particularly, individuals aged 40-50 years experienced a notable increase in IOP (4-4.5 mmHg) compared to younger individuals.(2) This indicates that age may impact the degree of IOP changes in response to water consumption.
The WDT has shown beneficial for identifying IOP peaks in glaucoma patients. Research done at Enugu State University of Science and Technology Teaching Hospital looked at 130 individuals with primary open-angle glaucoma (POAG). The findings showed that 90.2% of patients achieved peak IOP during the first hour. Modified phasing, a longer test, revealed that 74.1% of eyes peaked during the first four hours.(3) These results demonstrate the WDT’s usefulness in detecting important IOP variations in glaucoma therapy.
Postoperative IOP Fluctuations:
Beyond preliminary diagnosis, the WDT is useful. IOP variations continued even after IOP-lowering drugs were stopped after surgery, according to research assessing the effects of phacoemulsification and endo-cyclophotocoagulation (phaco-ECP). The aforementioned suggests that phaco-ECP may elevate outflow resistance, resulting in increased variability of IOP after surgery.(4) The WDT can be used to monitor these variations and direct the care of patients after surgery.
Case Study Insights
A case study of a 66-year-old individual who had high IOP after ingesting a water bolus before radiation therapy showed noteworthy findings. The WDT revealed a peak IOP of 20 mmHg in the right eye and 23 mmHg in the left eye, indicating a dysfunction in the outflow system.(5) This instance demonstrates how the WDT may identify IOP spikes in people with otherwise normal IOP, which may indicate underlying glaucoma concerns.
Conclusion
The Water Drinking Test is an essential adjunct test in the diagnosis of intraocular pressure fluctuations that are not picked up on routine observation.(1) It simulates the spikes of intraocular pressure and allows the determination of peak pressure levels, thus evaluating a glaucoma patient’s intraocular pressure control with much more accuracy. More importantly, its utility goes far beyond that of a simple diagnosis. It is particularly useful for monitoring variations in postoperative IOP, both during and after the course of surgical interventions like phacoemulsification and endo-cyclophotocoagulation or phaco-ECP.(4) The test can reveal underlying issues in the outflow system in individuals who may seem to have normal IOP under typical conditions and, therefore, can identify early signs of glaucoma.(5) In summary, the WDT upgrades the management of glaucoma by enlightening IOP regulation, guiding treatment plans, and upgrading patient care outcomes.
References:
- Eze, G. C., & Anajekwu, C. C. (2022). Clinical Profile and Intraocular Pressure Control of Medically Treated Glaucoma Patients Seen in a Tertiary Hospital in Enugu, Nigeria. International Journal of Medical Science and Clinical Research Studies, 2(12), 1435-1442.
- Marquez-Trochez, J., Vanegas-Ramírez, C. M., Castaño-Alzate, C. F., Muñoz-Gómez, M., & Donado-Gómez, J. H. (2023). Intraocular pressure values during the water drinking test in a Colombian population. Revista de La Sociedad Colombiana de Oftalmología, 56(2). https://doi.org/10.24875/rsco.23000003
- Mohammad Razali, A., Tang, S. F., Syed Zakaria, S. Z., Che-Hamzah, J., Aung, T., Othman, O., & Md Din, N. (2023). The Effect of Combined Phacoemulsification and Endo-Cyclophotocoagulation on Intraocular Pressure Fluctuation Assessed by the Water Drinking Test in Patients with Primary Open Angle Glaucoma. Ophthalmic Research, 66(1), 854–861. https://doi.org/10.1159/000530072
- Ophthalmology A COMPARATIVE STUDY RELATING WATER DRINKING TEST AND INTRA OCULAR PRESSURE IN DIFFERENT AGE GROUPS KEY WORDS: Glaucoma. (n.d.). https://doi.org/10.36106/paripex
- Qin, V. L., Nguyen, B. J., Tripp, P., Lehman, A., Addis, V. M., & Cui, Q. N. (2023). Elevated IOP following a bladder filling protocol: A case report. American Journal of Ophthalmology Case Reports, 29. https://doi.org/10.1016/j.ajoc.2022.101786
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