Visual Tests and Demonstrations


Snellen eye chart 3" x 5" card (plain)

3" x 5" card with word typed in center astigmatism chart meter stick metric ruler pen flashlight

Ichikawa's or Ishihara's color plates for color-blindness test

Normal vision (emmetropia) results when light rays from objects in the external environment are refracted by the cornea and lens of the eye and focused onto the photoreceptors of the retina. Irregular curvatures in the surface of the cornea or lens, inability to change the shape of the lens, or defects in the shape of the eyeball can result in defective vision.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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