What percentage of lens energy metabolism is anaerobic?

• A. Approximately 10%
• B. Approximately 70%
• C. Approximately 50%
• D. Approximately 20%

Answer: (B)

Energy metabolism in the lens is largely anaerobic because mature lens fibers lack mitochondria and operate in a relatively low-oxygen environment. Glucose from the aqueous humor is primarily processed through glycolysis, producing ATP without oxygen to support essential activities like maintaining ion gradients and transparency. The epithelial layer does have mitochondria and can perform aerobic metabolism, but its contribution to total lens energy is smaller, so most of the ATP comes from glycolysis. That makes about seventy percent of lens energy metabolism anaerobic. The other options would imply a larger or smaller role for aerobic metabolism than this tissue physiology supports.