In its early stages, choroiditis can be seen as a grey or yellowish raised area, which can be discrete or multiple and anywhere in the fundus. A cellular reaction could appear in the overlying vitreous, seen as localised misting with the ophthalmoscope, and eventually the whole vitreous can become clouded, obscuring any view of the fundus and the original site of inflammation. The patient usually presents at this stage so that the origin of the problem only becomes apparent after the inflammation has subsided. Retinitis manifests as an indistinct white cloudy area. When a patch of choroiditis heals, the margins become pigmented and a white patch of bare sclera remains (Figure 18.4). This is the result of atrophy of the pigment epithelium and choroid. Sometimes larger choroidal vessels survive as a clearly seen network overlying the white sclera surrounded by a pigment halo. During the active stage, inspection of the vitreous with the slit-lamp reveals the presence of cells and often the anterior chamber also contains cells. Posterior uveitis comes into the differential diagnosis of a white eye with failing vision. When the vitreous becomes cloudy, the condition must be distinguished from vitreous haemorrhage. The latter nearly always occurs acutely over a period of hours, whereas the cloudiness following uveitis takes a few days to develop. Examination of the vitreous with the slit-lamp can reveal whether the vitreous is filled with inflammatory cells or red cells. Retinal vasculitis can occur. A predominantly arteriolar inflammation can indicate a viral cause, whereas venous involvement is more common with other aetiologies. Optic nerve inflammation or oedema can also occur.
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