Although a hypothetical role of cerebrospinal fluid (CSF) pressure in glaucoma pathogenesis has existed for many years, not enough data has been available to evaluate the hypothesis until recently. Recent comprehensive chart reviews of CSF pressures in neurological patients receiving lumbar punctures at Mayo Clinic revealed a correlation between primary open-angle glaucoma and low CSF pressure. The correlation appeared in patients with elevated intraocular pressure (IOP) as well as with normal IOP. The chart reviews also found higher CSF pressures in patients who had ocular hypertension but no glaucomatous damage. These interesting observations have been verified in a series of two prospective studies at Beijing Tongren Hospital. The first study examined data of lumbar CSF pressures in glaucoma patients (Ren et al, Ophthalmology 2010;117:259-266). The second, current study by Ren et al. (43) examined lumbar CSF pressure data collected from ocular hypertensive patients. Results from the current study confirm the possibility that higher CSF pressure provides a protective role against glaucoma, as opposed to lower CSF pressure being associated with glaucoma in the first study.

Higher CSF pressure provides a protective role against glaucoma

The overall evidence from both studies supports the concept that a high pressure difference across the lamina cribrosa, termed the translaminar pressure difference (IOP minus CSF pressure), represents a major risk factor for glaucoma more accurately than the traditional thinking of an elevated IOP.

As discussed by the authors, there are limitations for the application of CSF pressure information from lumbar punctures to the understanding of glaucoma pathogenesis. Standard lumbar puncture is performed with patients in a lateral decubitus body position. The pressure reading obtained may be close to the habitual CSF pressure in a recumbent person who is asleep, but should be much higher than the resting CSF pressure at eye level for the same person in a vertical body position during the diurnal/wake period. Another critical limitation is that a single lumbar puncture provides CSF pressure information at one moment of time. Like IOP, CSF pressure may be dynamic in real life. Repeated lumbar punctures over time are simply impossible. For achieving a good statistical power in research, one may compensate data variability by increasing the sample size. However, a broad use of lumbar punctures to collect CSF pressure data prospectively may be difficult to justify since the invasive procedure does carry some risks with little proved medical benefits to glaucoma patients. Despite these limitations, the current study and related reports have energized our interests on this challenging topic in glaucoma research. A leap forward may be to develop a reliable non-invasive method for measuring CSF pressure in different body positions. The task is daunting, but potential reward is also high.