The first try at using computers in the study of old Slavic language happened in August 1980 at the University of Nijmegen, where a team made a system of indexing manuscripts titled

Producing Codicological Catalogues with the Aid of Computers

This was developed over the years since, including adding a Cyrillic character set for MS-DOS, but nothing comprehensive came of the project.

Since then various stabs at catalogs and indexes have been made, and for the purposes of our story, this led to the rather lengthily named

First International Conference on the Application of Computer Technology to the Study of Mediæval Slavonic Manuscripts

in 1995, where one of the conference organizers noted a plethora of systems for trying to render Slavic manuscripts, but no coordination with those working in other systems (Latin, Greek, Hebrew) leading to a lack of cross-communication.

Unicode became a way to form a common thread; for example, the Medieval Unicode Font Initiative (founded 2001) was on medieval texts using Latin alphabets, and eventually made a 2006 "Proposal to add medievalist characters to the UCS" with a 2015 follow-up.

For Slavic medievalists, the UC Berkeley Script Encoding Initiative came up with a 2007 "Proposal to encode additional Cyrillic characters in the BMP of the UCS" where the character in the question occurs. But to be particular, it is one of several, all used in words with a root of 'eye'; the singular has one dot in each of the circles, representing single eyes, whereas the dual has two. The multi-eyed seraphim is just one of the inclusions in the proposal, and while the latter is only known to occur in one manuscript, the others occur in several. So it is a special case, but related to ones that were common enough to justify their inclusion.

(As far as why historically the Os as part of eyes got the rare ornamental touch, there is at least some evidence of belief in mystical power of letters themselves. The monk Khrabr in the 9th century wrote the treatise On Letters defending the local language and opining about the power of each letter in Glagolitic, a custom Slavic alphabet devised by Saint Cyril who found that the languages of the Slavic tribes did not translate easily to Greek or Latin letters. Glagolithic influenced the development of Cyrillic. Going later to the 12th century, Kirik of Novgorod contemplated if it was a sin to step on letters. As the historian Simon Franklin writes, "an alphabet can be an amulet" -- although he cautions that this theorizing perhaps did not apply too much in real practice.)

One might ask why the ornaments were included at all; could we not write ocular Os as regular Os? (The Old Church Slavonic Digital Hub does not, incidentally, differentiate ocular Os.) And this gets into a "lumper" vs. "splitter" debate in paleography, that being just how much should different "forms" of a letter get merged? These are all different forms of E; should each one be written separately? If not, which ones are merged? Merging makes it easier to search for similarity, but splitting theoretically maintains more information. There becomes a point where a slightly askew E is not meaningfully another letter, but just a particular quirk of a scribe.

...

Franklin, S. (2002). Writing, society and culture in Early Rus, c. 950–1300. Cambridge University Press.

Leich, H. (2019). Libraries in Open Societies: Proceedings of the Fifth International Slavic Librarians' Conference. United Kingdom: Taylor & Francis.