Fluids Hypertension Syndromes: Migraines, Headaches, Normal ...

Fluids Hypertension Syndromes – Dr. Leonardo Izecksohn – page 170
XII aa) Central Retinal Venous Pulsations and Ophthalmo-dynamometry:
Physiologically, the intraocular pressure is a little higher than the Cerebrospinal fluid pressure. This
allows the drainage of the blood from the Central Retinal Vein from inside the eye, passing by the
middle of the Optic Nerve, which is physiologically and continuously stretched by the Cerebrospinal
fluid pressure. The Central Retinal venous blood must have its pressure a little higher, to surpass that
Cerebrospinal fluid pressure and continually drains: “Under normal conditions, pressure within the
central retinal vein is equal to or greater than Intra-Cranial Pressure, because the central retinal vein
passes through the optic nerve before it drains into the cavernous sinus…The results indicated a highly
significant linear correlation between central retinal vein pressure and intracranial pressure.” (Firsching
R, and others).
Physiologically, the Cerebrospinal fluid pressure rises and downs around 1 mmHg together with the
arterial pulse, and the intraocular pressure does the same but around 3 mmHg. So, the blood inside the
Central Retinal Vein present cycles of drainage with emptying (at cardiac systole), and retention with
engorgement (at cardiac diastole), following the cardiac and arterial pulse, visible with direct ophthalmoscopy,
and denominated as Spontaneous Central Retinal Venous Pulsations. (Jacks A S, and Miller
N R).
“The (central retinal) venous diameter decreased in early systole, increasing thereafter to a maximum
level in early diastole and then declined towards end diastole.”(Chen H C, and others).
When the Cerebrospinal fluid pressure is constantly higher than the intraocular pressure, there is a
chronic stasis of the blood inside the Central Retinal Vein, this vein engorges and there is no more
spontaneous venous pulsations.
“Spontaneous venous pulsations were present in 87.6% of 146 unselected subjects and absent in
100% of 33 patients with raised intracranial pressure without papilledema and 10 patients with papilledema.
Lumbar puncture in nine patients with raised intracranial pressure established the upper level at
which spontaneous pulsations disappear as 190 mm H2O, and no pressure above 180 mm H2O was
found in 29 patients with venous pulsations present prior to lumbar puncture. Some normal subjects
with absent pulsations showed definite pulsations on subsequent examinations.” (Levin B E).
When the patient has glaucomatous damage in his Optic Nerve’s disk, he can present two possibilities:
A – There are spontaneous central venous pulsations: This means that on that moment the intraocular
and the Central Retinal Vein pressures are higher than the Cerebrospinal fluid pressure.
B – There is no spontaneous central retinal venous pulsation: This means that in this moment the
Cerebrospinal fluid pressure is higher than the intraocular and central retinal vein pressures. To cause
the central retinal venous pulsations in this patient, it is necessary to apply extra force over the eye, increasing
his intraocular and central retinal vein pressures, in order to surpass the Cerebrospinal fluid
pressure. This extra force is denominated Ophthalmodynamometric Force.
“Venous dynamometry in vivo means that we use the onset of the venous collapse phenomenon to register
the pressure in the central retinal vein at the point where it leaves the eye.” (Meyer-Schwickerath
R, and others).
In the eye without venous or glaucomatous damage, the central retinal venous dynamometry is a noninvasive
exam that measure the Cerebrospinal fluid pressure.
“Significantly fewer glaucoma patients (54%) were observed to have spontaneous venous pulsation
than suspects (75%) or normals (98%). A worse visual field mean deviation was shown to be the most
significant predictor of a higher ophthalmodynamometric force... A strong relationship between ophthalmodynamometric
force and (visual field damage) mean deviation was found in the glaucoma patients.”
(Morgan W H, and others).
In a glaucomatous eye, this force is predictive of a worst evolution of its glaucoma.
“Forty three patients (with glaucoma or suspected glaucoma) had no spontaneous venous pulsation at
the initial visit, with a mean Ophthalmodynamometric force of 13.4 g…In all, (after 6 years) 28% of
eyes without spontaneous venous pulsation had increased excavation compared with 14% of eyes with
spontaneous venous pulsation…Ophthalmodynamometric force was found to be highly predictive of
increased excavation.” (Balaratnasingam C, and others).
“Eighty-three patients with glaucoma had no spontaneous venous pulsation. There was a strong asso-