Regarding lens energy metabolism, which statement is correct?

Regarding lens energy metabolism, which statement is correct?

• A. All metabolism is aerobic
• B. There is no metabolism in the lens
• C. Approximately 70% is anaerobic and 20% is aerobic
• D. Most energy comes from active transport unrelated to oxygen

Answer: (C)

The main idea here is that the lens relies largely on anaerobic glycolysis for its ATP because it is avascular and experiences low oxygen levels. The epithelial cells do have mitochondria and perform some oxidative phosphorylation, but many mature lens fibers lack mitochondria, so most energy production happens through glycolysis. This combination yields a distribution where the majority of energy comes from anaerobic metabolism, with a meaningful but smaller contribution from aerobic metabolism in the more metabolically active regions. The commonly cited breakdown—about 70% anaerobic and 20% aerobic—captures this reality. This energy supports essential ion pumps like Na+/K+-ATPase to maintain lens homeostasis and transparency. The other statements imply there is no metabolism, or that energy comes mainly from active transport unrelated to oxygen, which don’t fit the lens’s physiology, since energy production via glycolysis is central to its function and is closely tied to oxygen availability.

The main idea here is that the lens relies largely on anaerobic glycolysis for its ATP because it is avascular and experiences low oxygen levels. The epithelial cells do have mitochondria and perform some oxidative phosphorylation, but many mature lens fibers lack mitochondria, so most energy production happens through glycolysis. This combination yields a distribution where the majority of energy comes from anaerobic metabolism, with a meaningful but smaller contribution from aerobic metabolism in the more metabolically active regions. The commonly cited breakdown—about 70% anaerobic and 20% aerobic—captures this reality. This energy supports essential ion pumps like Na+/K+-ATPase to maintain lens homeostasis and transparency. The other statements imply there is no metabolism, or that energy comes mainly from active transport unrelated to oxygen, which don’t fit the lens’s physiology, since energy production via glycolysis is central to its function and is closely tied to oxygen availability.