The Department of Education may employ any person, otherwise qualified, who has retired for service under either the Public Employees' Retirement System or the State Teachers' Retirement System as a substitute in a position requiring certification qualifications at the California School for the Blind; provided, that the total of such service and any service rendered pursuant to Section 23919 shall not exceed 90 teaching days in any one fiscal year.
Ca. Educ. Code § 59113