Swollen Disc
The optic disc can swell for many reasons. If it is a result of raised intra-cranial pressure, it is termed papilloedema. Papilloedema causes an enlarged blind spot but does not affect vision unless the underlying optic nerve becomes atrophic. The commonest cause of optic nerve swelling is as a result of occlusion of the central retinal vein, which always affects vision.
Retinal Detachment
Retinal detachment occurs when fluid, usually from the vitreous cavity, accumulates between the retinal pigmented epithelium and the overlying neurosensory retina. The site of entry is usually a tear or hole in the retina as the overlying vitreous detaches itself from the retina (posterior vitreous detachment). Posterior vitreous detachment is a normal feature of ageing but occurs at a younger age in people who have had trauma to the eye or who have an underlying predisposition such as pathological myopia. As the vitreous detaches any tugging of retina results in flashing lights being seen by the patient. If the retina detaches this causes a large shadow to occur. Initially this shadow is in the visual periphery but may progress rapidly over days to affect the centre of vision.
