Tex. Labor Code § 408.151

(a) On or after the second anniversary of the date the commissioner makes the initial award of supplemental income benefits, an insurance carrier may not require an employee who is receiving supplemental income benefits to submit to a medical examination more than annually if, in the preceding year, the employee's medical condition resulting from the compensable injury has not improved sufficiently to allow the employee to return to work.

(b) If a dispute exists as to whether the employee's medical condition has improved sufficiently to allow the employee to return to work, the commissioner shall direct the employee to be examined by a designated doctor chosen by the division. The designated doctor shall report to the division. The report of the designated doctor has presumptive weight, and the division shall base its determination of whether the employee's medical condition has improved sufficiently to allow the employee to return to work on that report unless the preponderance of the other medical evidence is to the contrary.