Episcleral Venous Pressure and Glaucoma

Are your eyes on the floor?...

Understanding episcleral venous pressure (EVP) is important for all of us in the management of glaucoma and is a significant determinant of intraocular pressure (IOP). Unfortunately, accurate measurement of EVP is challenging and perhaps not clinically practical currently, but we need to be aware of its contribution in terms of aqueous humor dynamics and therefore selecting treatment strategies. Various techniques, both invasive and non-invasive, are being utilized to measure EVP including technology such as computerized venomanometry.

The correlation and dynamics between EVP and IOP is key, with EVP creating an opposing "floor" pressure which can limit the efficacy of our most common IOP-lowering topical treatments. This can be especially true with our normal tension glaucoma (NTG) patients, for which even a slight drop in IOP may equate to a significant percentage of neuro-protection.

We therefore also need to be aware of the "how and why" of newer targeted treatments such as Rho kinase inhibitors. The mechanism of action of this therapeutic approach matters as the target is involved in trabecular cytoskeletal and episcleral venous "remodeling" - potentially dropping floor pressure thereby permitting more streamlined aqueous outflow and lowering of IOP.

By understanding and then integrating episcleral venous pressure into our thought process when selecting management strategies, we can improve personalized treatment approaches. This in turn will ultimately enhance individual outcomes for many of our glaucoma patients in a sometimes complicated multifactorial condition.

Go to the article in Survey of Ophthalmology HERE.

- JRM