Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android



  • Toxic chemicals and systemic drugs can affect all parts of the eye, including cornea, iris, ciliary body, lens, retina, and optic nerve.

  • Ophthalmologic procedures for evaluating the health of the eye include routine clinical screening evaluations using a slit-lamp biomicroscope and ophthalmoscope, and an examination of the pupillary light reflex.

  • Most electrophysiologic or neurophysiologic procedures for testing visual function after toxicant exposure involve stimulating the eyes with visual stimuli and electrically recording potentials generated by visually responsive neurons.


Environmental and occupational exposure to chemicals, toxicants, gases, and vapors as well as systemic and ocular therapeutic drugs may result in structural and functional alterations to the eye and central visual system. The retina and central visual system may be especially vulnerable to toxic insult. Subtle alterations in visual processing of information (e.g., visual perception, visual motor) can have profound immediate, long-term, and delayed effects on the mental, social, and physical health and performance of an individual.

This chapter will provide essential information on ocular pharmacodynamics, pharmacokinetics, and drug metabolism; review the procedures for testing visual function; and evaluate and review the structural and functional alterations in the mammalian eye and central visual system produced by environmental and workplace chemicals, toxicants, gases and vapors, and off-target effects of major therapeutic drugs. The adverse effects of these chemicals on the different compartments of the eye (i.e., cornea, lens, retina, and retinal pigment epithelium [RPE]), central visual pathway (i.e., optic nerve and optic tract), and central processing areas (i.e., lateral geniculate nucleus [LGN] and visual cortex) are listed in Table 17–1. The distribution of phase I and phase II drug metabolizing enzymes, and xenobiotic uptake and efflux transporters in ocular tissues are presented in Tables 17–2 and 17–3, respectively. Table 17–4 provides examples of common signs, symptoms, and potential pathophysiological mechanisms of visual dysfunction associated with acute or chronic exposure to toxicants and selected drugs.

TABLE 17–1Ocular, Retinal, and Central Visual System Sites of Action of Selected Xenobiotics Following Systemic Exposure

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.