TY - CHAP M1 - Book, Section TI - Chapter 8. Lens A1 - Harper, Richard A. A1 - Shock, John P. A2 - Riordan-Eva, Paul A2 - Cunningham, Emmett T. PY - 2011 T2 - Vaughan & Asbury's General Ophthalmology, 18e AB - The crystalline lens is a remarkable structure that contributes to focusing of images on the retina. It is positioned just posterior to the iris and is supported by zonular fibers arising from the ciliary body and inserting onto the equatorial region of the lens capsule (see Figure 1–12). The lens capsule is a basement membrane that surrounds the lens substance. Epithelial cells near the lens equator divide throughout life and continually differentiate into new lens fibers, so that older lens fibers are compressed into a central nucleus; younger, less-compact fibers around the nucleus make up the cortex. Because the lens is avascular and has no innervation, it must derive nutrients from the aqueous humor. Lens metabolism is primarily anaerobic owing to the low level of oxygen dissolved in the aqueous. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=55782574 ER -