How does long wavelength light exposure improve vision?

There was a 2021 study published in Nature Scientific reports (Shinhmar et al.) which demonstrated the following about one-time exposures restoring vision in aging patients.

We show here that single 3 min 670 nm exposures, at much lower energies than previously used, are sufficient to significantly improve for 1 week cone mediated colour contrast thresholds (detection) in ageing populations (37–70 years) to levels associated with younger subjects.

Additionally, the results of this study are being used by a UK-based company (eye-power.co.uk) as scientific backing for their product which is promoted to “slow retinal aging”. 

Figure: “eyepower red” product sold by “eyepower” as detailed on their website https://eye-power.co.uk/product/eyepower-red/
 

Bounty details: I'm offering 2500 RSC for information about the cellular/molecular mechanisms behind the claims to slow retinal aging. 

Optional Bounty: Additionally, I will award an additional 2500 RSC for commentary on the suggested regimen of using the eyepower-red “just 3 minutes every few days” as it relates to the information found in literature.