Ocular hypotony

Abstract

In hypotony, where the intraocular pressure is lower than the episcleral venous pressure, aqueous humour outflow must be via unconventional channels, such as uveoscleral outflow pathways. The level of intraocular pressure will be determined by the rate of aqueous humour production and the facility of unconventional outflow. The facility of unconventional outflow has been shown to be increased in eyes with experimentally-induced hypotony from cyclodialysis, ciliochoroidal detachment, iridocyclitis, or retinal detachment. Aqueous humour production is reduced in eyes with hypotony during the acute phase following cyclodialysis, and in eyes with iridocyclitis or rhegmatogenous retinal detachment. Chronic cyclodialysis or ciliochoroidal detachment does not lead to reduced aqueous humour production, if unassociated with iridocyclitis. Detachment of the ciliary body in hypotony is often associated with, but does not appear to cause, reduced aqueous humour formation. Apart from treatment of the specific cause of hypotony, reduction of the accompanying inflammatory response is essential for normalisation of aqueous dynamics and intraocular pressure.