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—We appreciate the comments by Dr Sadun et al regarding our article. The data derived from their recreation of our model were interesting and not unexpected. However, we do not agree with their conclusions.In the article, we pointed out that this was a simple model designed to illustrate a concept rather than to exactly simulate a biologic system. There are many simplifications in the model. The fluid volume available for flow is overestimated because brain and nerve tissue are not represented. In addition, variable resistances to flow caused by normal trabeculations of tissue in the fluid spaces are not accounted for. We stated that these and other simplifications make actual calculations of flow and pressure by Bernoulli's equation unrealistic in this model. Therefore, we are not surprised that Sadun et al found that a drop in pressure from 210 to 55 mm of water required a flow
Seiff SR, Shah L. Model for Optic Nerve Sheath Decompression: Bernoulli's Principle Applied-Reply. Arch Ophthalmol. 1991;109(5):612–613. doi:10.1001/archopht.1991.01080050018006
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