Anatomy of the Human Eye

The vertebrate retina contains two classes of light-sensitive receptor cells called rods and cones. The rod is an elongated cylindrical cell containing several hundred thylakoids which support the visual pigment. The pigment system in the rod is confined to internal membranes situated close to the outer membrane of the cell. In the other type of visual receptor, the cone, the pigment is situated in the external membrane itself. In the cone the external 

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FIGURE 38.1 Anatomy of the eye. Diagram of the human eye, labeled with the structures involved in ocular toxicity following exposure to CWAs. Source Image modified with permission from National Eye Institute, National Institutes of Health, reference number NEA04. 

In order to research and develop an effective ophthalmic delivery system, a good understanding of the anatomy and physiology of the eye (the globe) is necessary. Figure 1 shows a cross section through the human eye. This chapter will mainly focus on the precorneal area and the transport barriers present in the eye. 

Vesalius, Andreas (1514-1564) Flemish anatomist who portrayed human anatomy with unprecedented accuracy, visible light The fraction of the electromagnetic spectrum that is visible to the human eye. The visible region is bracketed by wavelengths of 400 nanometers (nm, violet) and 780 nm (red) and contains all wavelengths in between. 

Physical man has himself become the object of a separate science, anatomy, which in its ordinary meaning includes physiology, that science which had been retarded by a superstitious respect for the dead, profited from the general enfeeblement of prejudice and successfully undermined the support that it received from powerful men who were interested in its preservation. Its progress seems somehow to have come to a stop, and to await the discovery of improved instruments and new methods. And it now seems to be almost reduced to the study of the comparisons between the parts of animals and those of men, the organs common to different species, and the manner in which similar functions are exercised, in its search for those truths which are at the moment not open to human observation. Almost everything which the eye of the observer has been able to discover with the aid of a microscope is already unveiled. The future development of anatomy seems to depend on the possibility of experiment which has proved so useful to the progress of other sciences. But this necessary means of improvement has been denied to anatomy by the very nature of its subject. 

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