Drugs acting on the eye
The eye is a complex sensory organ responsible for sight. Injury or disease to the ocular system can result in vision loss. A variety of ophthalmic preparations (topical, parenteral, and oral) are available for both therapeutic and diagnostic use. Medications play a key role in the management of chronic dry-eye, diabetic retinopathy, glaucoma, infection, inflammation, and macular degeneration.
The structural anatomy of the eye makes pharmacological treatment a unique challenge. The cornea consists of multiple layers comprised of hydrophobic and hydrophilic properties which can alter topical drug absorption. Although systemic absorption of ophthalmic agents can occur (mentioned in topics below), it is generally minimal as the eye is isolated from systemic vascular access due to the blood-retinal, blood-aqueous, and blood-vitreous barriers.
Figure from: http://slideplayer.com/slide/3862142/ Figure 15.4a Internal Structure of the Eye (sagittal section). Marieb & Hoehn 9th ed. Chapter 15 The Special Senses. Pearson Education, Inc. 2013