Retinal detachment (RD) refers to a separation of the inner
neurosensory retina and the outer retinal pigment epithelium
(RPE). The space between them becomes filled with subretinal
fluid which may come from a number of sources (not all of which
are known). If the macula has not yet detached at the time of
presentation, it is said to be a 'macula-on' detachment (the
macula is still 'on' the underlying RPE). If it has detached
from the RPE, it is known as 'macula-off' (it has come 'off' or
away from the underlying RPE). The importance of RD lies in the
fact that it is the most common ophthalmic emergency in the UK
and needs urgent treatment in order to preserve sight. Early
recognition and prompt referral is essential because the rate of
successful re-attachment is higher and the visual results are
better if an RD is repaired before the macula is involved (ie
before it has converted from a 'macula-on' RD to a 'macula-off'
RD). RD broadly falls into two categories: rhegmatogenous and
non-rhegmatogenous. - Rhegm