Visual-evoked potentials elicited by laser speckle patterns. Studies on the characteristics and assessment of visual...

Visual-evoked potentials (VEPs) were recorded using a laser speckle pattern. Stimulation with a speckle pattern was elicited either by pattern appearance-disappearance or by pattern shift. The VEPs obtained by this method were similar in properties to the previous pattern VEPs that were obtained either by pattern appearance-disappearance or by pattern reversal. Patients in whom dense and diffuse ocular media opacity defied measurement by the interferometric visual acuity method were studied to test if the speckle pattern generated by diffusion from lens opacity itself could act as a stimulus for obtaining VEPs. It is concluded that the present method enables one to obtain a reliable VEP and to assess the visual function of the retino-cortical system, even in patients with mature cataracts.