Measurement of venous outflow pressure in the central retinal vein to evaluate intraorbital pressure in Graves' ophthalmopathy: a preliminary report

Abstract

The increased IOP in GO is not caused by primary glaucoma but by elevated intraorbital pressure. The difference between IOP and VOP must be <5 mmHg to guarantee normal perfusion. We interpret these findings to suggest that loss of visual acuity and visual field defects may not only be caused by optic nerve compression at the apex but also by deterioration of optic nerve head perfusion.

Enhanced Pressure in the Central Retinal Vein Decreases the Perfusion Pressure in the Prelaminar Region of the Optic Nerve Head

“…There are different possible reasons why the CRVP may be increased, including an increased intracranial pressure (ICP) 37,38 ; a circumscribed increase of the pressure in the liquor around the optic nerve [39][40][41] ; a low ICP 42,43 being responsible for a high pressure gradient across the optic disc, 44 which may reduce the lateral cut of the CRV and thereby increase the CRV outflow resistance; a high pressure in the jugular veins; and a high pressure in the orbit. 45 In case signs and symptoms of other diseases may be excluded, the most probable reason for an increased CRVP in POAG patients may be an increased outflow resistance.…”

Retrobulbar haemodynamics and morphometric optic disc analysis in primary open-angle glaucoma

“…32 This phenomenon may be explained by several pathologies. An increased venous pulsation pressure may be due to an increased cerebrospinal fluid 33 or orbital pressure, 34 or increases in arterial blood pressure-that is, altered upstream resistance or an increase in downstream resistance of retinal veins. 32 35 However, Hayreh 29 …”

Ophthalmological evaluation in thyroid‐associated ophthalmopathy

“…The optic nerve may be directly affected from pressure, especially in the apex, from enlarged extraocular muscles (Trobe 1981; Hudson et al 1991; Bahn & Heufelder 1993) or from fat tissue oedema (Trobe 1981; Nafzigger 1933; Day & Carrol 1962; DeSanto 1980). The pressure may also reduce arterial optic nerve blood flow (Wiersinga 1997) or increase the flow resistance in the central vein (Hartmann & Meyer‐Schwickerath 2000). However, recent studies have also demonstrated the possibility of increased orbital blood flow in TAO (Alp et al 2000).…”

“…The equipment is also highly specialized and its use is often limited to larger institutions. Oculodynamometry, in which IOP is compared with venous outflow pressure, has recently been suggested as a tool to identify or predict optic nerve compression (Hartmann & Meyer‐Schwickerath 2000).…”