I would like to read or download this ARVO Journal's article, but I just cannot find any button on the website with this functionality: https://jov.arvojournals.org/article.aspx?articleid=2139676 I have already registered and logged on, but the situation has not changed. Could you please help me find a way?
The paper you are linking to is an abstract presented on the Vision Sciences Society Annual Meeting of 2011. Study abstracts are submitted to the conference organizers and often appear in the conference program and/or on the conference web site. They describe the work that will be/has been presented as an oral or poster presentation on a conference. Often the abstract is the only written record that remains of a conference prezzo. In other words, the abstract you are seeing is the paper itself, there is no further material to be downloaded, which explains the absence of the download button. If you click on the specific 2011 issue, you'll see hundreds of prezzo abstracts listed there, including yours. On the website of VSS there's unfortunately only information about the last conference held, I believe in May 2020.
You can contact the study authors and ask if they are willing to share the poster or the slides of the prezzo. In my experience, authors are often happy to share their research. Perhaps the results have been published in a journal paper in the meantime.