Disclaimer. Simpson Optics LLC does not provide medical advice, and neither does this website. If you have concerns about your vision, you should see a specialist, such as an Ophthalmologist or an Optometrist.
"Far peripheral vision" is at very large visual angles (above 60 degrees), and it appears to be a visual region where there has been very little direct research. A recent review summarizes the information that is readily available: Simpson MJ. Mini-review: Far Peripheral Vision. Vision Research 140C (2017) pp. 96-105
The topic is included on this website because "Negative Dysphotopsia" is a visual phenomenon that is occasionally seen by some users of intraocular lenses (IOLs) in the far peripheral vision region. This has led in turn to the new questions that are discussed in the review paper.
A Special Interest Group (SIG) also reviewed "Far Peripheral Vision" at ARVO in Baltimore, MD, May 2017. Observations from that meeting were included in the review paper.
May/June 2018. See link for free download of JCRS paper about the iris on the Negative Dysphotopsia page.