Letter

Unvalidated Cerebrospinal Fluid Pressure Equations
Should not Be Used for Research

David Fleischman1, MD; Hanspeter E. Killer2, MD

1Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2Kantonsspital Aarau, Department of Ophthalmology, Aarau, Switzerland

ORCID:
David Fleischman: https://orcid.org/0000-0002-1043-2021

J Ophthalmic Vis Res 2022; 17 (4): 601–602

Dear Editor,

We have found an unsettling trend of articles
being published with the use of an unvalidated
formula for estimating cerebrospinal fluid pressure.
The study, “Translaminar Pressure Difference
and Ocular Perfusion Pressure in Glaucomatous
Eyes with Different Optic Disc Sizes’[1] by Cruz
and colleagues has a very intriguing hypothesis.
However, the authors did not do their due diligence
in confirming the origin of the estimation equation
central to their investigation. They erroneously
attributed the formula to Xie et al’s study published
in Critical Care, 2013.[2] Biophysical parameters
including, importantly, the anatomic marker of
width of the orbital cerebrospinal fluid space, were
used to devise their estimation equation. The
equation utilized in Cruz’s study, although found in
other similarly flawed investigations, has not been
validated.

Correspondence to:

David Fleischman, MD, MS, FACS. Bioinformatics
Building #7040, Department of Ophthalmology,
University of North Carolina at Chapel Hill, Chapel Hill,
North Carolina 27599-7040, USA.
E-mail: david8fleischman@gmail.com
Received: 11-08-2021 Accepted: 01-02-2022

Access this article online

Website: https://knepublishing.com/index.php/JOVR

DOI: 10.18502/jovr.v17i4.12343

The use of estimation equations in general
have been found to poorly represent CSF
pressure.[3] Therefore, a parameter that
is already exquisitely difficult to measure,
perioptic subarachnoid space cerebrospinal
fluid pressure, will be further confounded by
using these faulty data. To substantiate the
concept of the translaminar pressure gradient as
a mechanism involved in the pathophysiology
of glaucoma, we need robust data. Flawed
approximation of CSF pressure is in no way
helpful in advancing the science in glaucoma
research.

We obviously encourage further study
into the relationship between cerebrospinal
fluid and ophthalmic disease, but we
must all be diligent to prevent further use
of unvalidated methods infiltrating this
field.

Financial Support and Sponsorship

None.

This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.

How to cite this article: Fleischman D, Killer HE. Unvalidated
Cerebrospinal Fluid Pressure Equations Should not Be Used for
Research. J Ophthalmic Vis Res 2022;17:601–602.

© 2022 Fleischman & Killer. THIS IS AN OPEN ACCESS ARTICLE DISTRIBUTED UNDER THE CREATIVE COMMONS ATTRIBUTION LICENSE | PUBLISHED BY KNOWLEDGE E 601

http://crossmark.crossref.org/dialog/?doi=10.18502/jovr.v17i4.12343&domain=pdf&date_stamp=2019-07-17
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Letter; Fleischman & Killer

Conflicts of Interest

There are no conflicts of interest.

REFERENCES

1. Cruz NF, Santos KS, Matuoka ML, Kasahara N.
Translaminar pressure difference and ocular perfusion
pressure in glaucomatous eyes with different optic disc
sizes. J Ophthalmic Vis Res 2021;16:171–177.

2. Xie X, Zhang X, Fu J, Wang H, Jonas JB, Peng X,
et al. Noninvasive intracranial pressure estimation by
orbital subarachnoid space measurement: The Beijing
Intracranial and Intraocular Pressure (iCOP) study. Crit
Care 2013;17:R162.

3. Fleischman D, Bicket AK, Stinnett SS, Berdahl JP,
Jonas JB, Wang NL, et al. Analysis of cerebrospinal
fluid pressure estimation using formulae derived from
clinical data. Invest Ophthalmol Vis Sci 2016;57:5625–
5630.

602 JOURNAL OF OPHTHALMIC AND VISION RESEARCH Volume 17, Issue 4, October-December 2022