Ill. Admin. Code tit. 68, § 1320.90
b) Visual acuity.
1) Monocular.
f) Subjective refraction to best visual acuity at distance and near.
In the absence of good clinical reasons to the contrary as documented in the record, the following minimum examination shall be performed and findings recorded by an optometrist, and he/she shall keep a record for a period of 6 years:
(Source: Amended at 36 Ill. Reg. 10006, effective June 29, 2012)