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Porphoria, or latent squint, describes the situation where the eyes move out of the aligned state when they are dissociated.

Latent squint is a very common finding, and is rarely pathological.

Factors unmasking a latent squint include fatigue, alcohol, sedative drugs, unilateral visual impairment and bright sunlight (1).

A latent squint can be demonstrated by an alternative-cover test (by alternatively covering one eye then the other). If a latent squint is present then a movement will be seen in each as it is uncovered. Visual defects, such a cataract or refractive error, should be remedied and the patient reassured (1).


  • (1) GP (28/9/2001), 48.

Last reviewed 01/2018