Human vision evolved as a means of gathering information from the environment. Efficient use of this sense requires not only a clear image of an object on the retina, but also suitable transmission of the neural representation of the object to the visual cortex and the addition of memory associations to attach meaning to the image. Conditions that cause visual impairments degrade the optical image. They also alter the transmission of the neural representation and decrease the ability to attach meaning to the image, thus affecting the perception of the object. The assessment of visual impairment should include an assessment of the perceptual capacity of the individual, as well as assessments of visual acuity, visual field, and contrast sensitivity. This paper explores how a better understanding of human visual perception can improve the assessment of visual impairment and provide greater specificity in the provision of rehabilitation services. The possble application of one visual perceptual test, the Frostig Figure- Ground, is described.