Workers’ Compensation Act defines permanent impairment as “any anatomic or functional abnormality or loss existing after the date of maximum medical improvement that results from the injury.” 39-A M.R.S.A. §102(1b). Permanent impairment is determined by a doctor. An injured worker’s entitlement to permanent impairment benefits is based on the law in effect at the time of the injury. Prior to 1992, the Act provided additional benefits for permanent impairment. When the Legislature revised the Act, it abolished this separate entitlement. Since 1992, permanent impairment is used as a threshold for determining the duration of benefits in cases involving partial incapacity. If the permanent impairment rating is below the threshold, benefits are “capped” at 520 weeks (10 years). If it is above the threshold, benefits may continue for the duration of the disability. When the Legislature revised the Act again in 2012, it raised the permanent impairment threshold from 12% to 18%, making it harder for partially incapacitated workers to stay on benefits past 10 years. Permanent impairment has no impact on the duration of entitlement to benefits for total.