The canal communicates directly with the episcleral vein. Around 20% of the outflow occurs through the uveoscleral route.
 Increased blood viscosity in the episcleral veins raise the IOP by increasing resistance to outflow of aqueous into the veins.
However, despite being not clinically evident, it has been shown that retinal and choroidal blood flow is frequently compromised and the episcleral vein
pressure is elevated [3, 4].
This type of secondary glaucoma in the setting of pulmonary hypertension, with dilated episcleral veins, has been documented before [2-4] (Parikh et al., 2011; Radius and Maumenee, 1978; Keltner et al., 1987).
Kothari, "Dilated episcleral veins with secondary open angle glaucoma," Indian Journal of Ophthalmology, vol.
When injected into periocular tissues, both small molecules (ophthalmic steroids) and macromolecules (proteins) have determined to be rapidly eliminated into conjunctival lymphatics and episcleral veins
. However, on a positive note, long term transscleral delivery can be obtained by utilizing drug-containing microspheres; retention of microspheres has been demonstrated at the site for approximately 2 months.
Obesity increases blood viscosity by increasing red cell count, haemoglobin and hematocrit, thus increasing outflow resistance of episcleral veins
.  obesity results in increased insulin resistance and corticosteroid secretion.
Obesity increases blood viscosity and consequently outflow-resistance of episcleral veins
. Furthermore obesity is also a risk factor for hypertension.
The conventional route of aqueous outflow involves movement of aqueous humour through the trabecular meshwork, a connective tissue which acts like a filter, across the inner vascular-like endothelial wall of Schlemm's canal, into collector channels and finally out of the eye in episcleral veins
via the aqueous veins.