Pattern electroretinogram: effects of miosis, accommodation, and defocus.

The effect of miosis, lens accommodation, and defocusing on the various components of the pattern electroretinogram elicited by checkerboard reversal was investigated by employing aperture stops of different size, varying the mean luminance of the target, and inserting spherical lenses of various optical diopters in front of the eye. After topical administration of pilocarpine (1%) the following changes in the pattern electroretinogram were observed: (i) a decrease of the pupillary diameter leading to a lowered target luminance, which produced attenuation of PERG amplitudes and prolonged latencies, and (ii) defocusing by accommodation of the crystalline lens, which produced attenuation of PERG amplitudes no effect on latencies.