The 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." The existence and extent of permanent impairment must be determined by a doctor. Claimants with injuries that occurred in 1992 or before may be eligible for additional benefits, beyond lost time and payment of medical, just for permanent impairment. However, as of January 1, 1993, the Legislature abolished that separate entitlement. Since then, permanent impairment is used as a threshold for determining whether claimants with partial incapacity are eligible for lost time benefits beyond 520 weeks. The threshold level varies depending on the date of injury. If permanent impairment is rated below the threshold, then lost time benefits are "capped" at 520 weeks. If permanent impairment is rated above the threshold, lost time benefits are not capped, however they are not guaranteed for any set amount of time beyond the cap either, but rather only for "the duration of disability," meaning the insurance company reserves the right to challenge the extent of your disability in the future. As of January 1, 2013, the threshold jumped from 12% to 18%, making it more difficult for claimants with permanent, partial injuries to continue to receive lost time benefits past the 520-week cap. Importantly, permanent impairment has no impact on the duration of entitlement to lost time benefits for claimants who are totally incapacitated as a result of the work injury.