A test that measures the electrical activity of the retina when exposed to flashes of light of varying intensity. Abnormalities in the electroretinogram typically occur in conditions that affect the photoreceptor cells (e.g. retinitis pigmentosa).
A technique of recording electrical impulses from the contraction of a muscle. It is used to confirm the correct position of the needle when botulinum toxin is used to correct strabismus.
A general term for color vision abnormalities. Heritable dyschromatopsias include red (protan), green (deutan), and blue (tritan) color vision deficits. These deficits may be partial (-omaly) or complete (-opia). Red and green color vision defects are X-linked while loss of the blue receptor (tritanopia) is inherited in an autosomal recessive fashion.