What portion of metabolism occurs aerobically in the lens?

• A. Approximately 60%
• B. Approximately 40%
• C. Approximately 80%
• D. Approximately 20%

Answer: (D)

Energy production in the lens is dominated by anaerobic glycolysis rather than oxidative phosphorylation. Mature lens fibers lose their mitochondria to stay transparent, so the regions where mitochondria remain are limited to the anterior epithelium. Because oxygen diffusion into the deeper lens is restricted, only a small fraction of metabolism can occur aerobically. Therefore, roughly 20% of the lens’s metabolism is aerobic, with about 80% carried out anaerobically via glycolysis.