Post-traumatic iridocyclitis – eg, direct facial trauma.Fixed and dilated pupils in comatose patients indicate a poor prognosis, especially when present bilaterally.Ĭauses of a unilateral non-reactive pupil Ī unilateral fixed dilated pupil suggests injury or compression of the third cranial nerve and the upper brain stem. Very severe unilateral macular degeneration.Retinal detachment : an RAPD can often be seen if the macula is detached.Severe ischaemic retinal disease – eg, ischaemic central retinal vein occlusion, central retinal artery occlusion, sickle-cell retinopathy.Sarcoidosis can cause inflammation of the optic nerve. Optic nerve infections or inflammations: cryptococcus can cause severe optic nerve infection in the immunocompromised.Optic atrophy : such as Leber’s optic atrophy.Orbital disease: including compressive damage to the optic nerve from thyroid-related orbitopathy, orbital tumours, or vascular malformations.Optic nerve tumour : this is a rare cause.Traumatic optic neuropathy: this includes direct ocular trauma, orbital trauma, and head injuries which damage the optic nerve as it passes through the optic canal.Severe glaucoma : while glaucoma normally is a bilateral disease, if one optic nerve has particularly severe damage, an RAPD can be seen.Optic neuritis : even very mild optic neuritis can lead to a very strong RAPD.Usually there will be a loss of vision or of part the visual field. These include arteritic ( giant cell arteritis ) and non-arteritic causes. Unilateral optic neuropathies are common causes of an RAPD.Comparing the direct and consensual reaction to light in both eyes is helpful in locating a lesion, remembering that the retina and optic nerve are needed for the afferent signal and that the oculomotor nerve provides the efferent component of both the direct and consensual reflexes.Īn RAPD is a defect in the direct pupillary response and usually suggests optic nerve disease or severe retinal disease. Normally, pupils react (ie constrict) equally.
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