Thank you all for your helpful responses! Interesting to hear what others have been using and what's been working. Seems like it probably comes down to what my district policy says.
Some resources I've come across regarding vision screenings that mostly apply to CA:
https://www.cde.ca.gov/ls/he/hn/documents/visionreport.pdf--"for students with special needs who are unable to use the optotype test with letters, use other appropriate optotype tests. - Illiterate “E” Charts - Blackbird - HOTV with crowding bars - Lea symbols"
https://higherlogicdownload.s3.amazonaws.com/NASN/3870c72d-fff9-4ed7-833f-215de278d256/UploadedImages/PDFs/Practice Topic Resources/vision_screening_table.pdf