Blue light (~400-470nm) is considered potentially detrimental to the retina but is present in natural environmental light. Mitochondrial density is highest in the retina, and they exhibit a prominent optical absorption around 420nm arising from the Soret band of their porphyrins, including in cytochrome-c-oxidase in their respiratory chain. We examine the impact of continuous 420nm at environmental energy levels on retinal mitochondrial metabolism and haemodynamics in vivo in real time using broadband near-infrared spectroscopy. 1h environmental exposure to 420nm induces significant metabolic instability in retinal mitochondria and blood signals, which continues for up to 1h post blue exposure. Porphyrins are important in mitochondrial adenosine triphosphate (ATP) production and cytochrome-c-oxidase is a key part of the electron transport chain through which this is achieved. Hence, environmental 420nm likely restricts respiration and ATP production that may impact on retinal function. This article is protected by copyright. All rights reserved
