Guadalupe C. Alvarez successfully brought suit against Missouri-Kansas-Texas Railroad Company (MKT) for personal injuries. On appeal, this Court reversed the judgment and remanded the cause for a new trial, holding that the wording of special issue number one constituted an impermissible comment on the weight of the evidence. Missouri-Kansas-Texas Railroad Company v. Alvarez, 670 S.W.2d 338 (Tex.App.1984). The Supreme Court re*369versed our judgment and remanded the cause to us for consideration of the remaining points of error urged by MKT. Alvarez v. Missouri-Kansas-Texas Railroad Company, 683 S.W.2d 375 (Tex.1985). We will affirm the judgment of the trial court.
MKT urges seventeen points of error. Under points one, two and three, MKT argues that the evidence established as a matter of law that it was not negligent in its application of the brakes. These points were rejected by this Court in our earlier opinion and are overruled without further discussion. Points of error five and six attack the perceived impermissible comment on the weight of the evidence set forth in special issue number one and have now been overruled by the Supreme Court.
In its remaining points of error, MKT contends that the trial court should have allowed evidence of intoxication; should have allowed MKT to amend its trial pleadings; erroneously excluded expert testimony; and finally, that there was no evidence to support the jury’s verdict pertaining to damages.
EVIDENCE OF INTOXICATION — AMENDMENT OF PLEADINGS
1. Procedural history of the case. The dispute between the parties arose out of a train-automobile collision on December 26, 1975. Suit was first filed in federal court and later removed to state court. MKT filed its original answer in state court on April 26, 1978. In this answer, MKT charged Alvarez with three specific acts of contributory negligence: accepting a ride with one known to be an untrustworthy driver; placing himself in such an alcoholic stupor that he could not take appropriate actions to protect himself; and failing to keep a proper look-out.
Almost four years passed before MKT filed its first amended original answer. This amended answer alleged certain additional affirmative defenses, but made no change in the allegations of contributory negligence.
The case was set for trial on July 27, 1982. On July 26, the trial court granted a motion in limine which, among other things, prohibited any evidence, questions, or comments concerning the fact that Guadalupe Alvarez, Antonio Ledesma and/or Antonio Tijerina had anything alcoholic to drink on the day of the accident without first obtaining the permission of the trial court.
On the day of trial, MKT requested leave of court to file a trial amendment alleging that Alvarez had failed to exercise ordinary care in exiting the automobile. Unlike MKT’s previous allegations of contributory negligence, the trial amendment challenged Alvarez’s conduct after he discovered his dangerous situation. All of MKT’s previous allegations of contributory negligence placed in issue Alvarez’s antecedent conduct — whether he was negligent in (1) accepting a ride with an untrustworthy driver; (2) placing himself in an alcoholic stupor so that he could not protect himself; and (3) failing to keep a proper look-out. Each of these allegations turns upon whether Alvarez used ordinary care in failing to guard against or appreciate the possibility of danger.
The proffered trial amendment would have placed in issue a distinctly different and even opposite theory of negligence— whether Alvarez was negligent in his reaction to a danger he actually discovered. Alvarez claimed surprise, and the trial court refused to allow the proposed amendment. MKT later unsuccessfully sought to file five similar trial amendments.
At the close of evidence, MKT submitted a special issue asking whether Alvarez failed to use ordinary care in exiting the automobile and removing himself from the path of the train. The trial court refused to submit the requested issue along with certain associated issues and instructions.
2. Evidence of Intoxication. Intoxication, in and of itself, does not constitute negligence, but evidence of intoxication is an evidentiary fact that may be considered by the trier of fact in determining whether or not a person is guilty of *370some act of contributory negligence. Benoit v. Wilson, 150 Tex. 273, 239 S.W.2d 792 (1951).
The trial court took up the question of intoxication outside the presence of the jury and determined that there was only slight evidence of intoxication while the risk of prejudicial harm was great. Under the facts of this case, we hold that the trial court properly excluded evidence of intoxication since its probative value was substantially outweighed by the danger of unfair prejudice. 2 Ray, Texas Law of Evidence, § 1481 at 167 (3rd ed. 1980); Tex.R.Evid.Ann. 403 (Supp.1985). MKT’s points of error eleven and twelve are overruled.
3. Amendment of pleadings. The seventh, eighth, ninth and tenth points of error attack the trial court’s refusal to allow a trial amendment changing MKT’s theory of contributory negligence, and the resulting refusal to allow requested special issues and instructions based on the newly alleged failure by Alvarez to exercise ordinary care in exiting the automobile. These points of error turn on a determination of whether the trial court abused its discretion in refusing to allow the requested trial amendments.
The trial court may allow pleadings to be amended during trial if an issue has been tried by consent, or if the amendment will preserve the presentation of the merits of the action and the objecting party fails to satisfy the court that the allowance of such an amendment would prejudice him in maintaining his action or defense on the merits. Tex.R.Civ.P.Ann. 66 & 67 (Supp. 1985). The decisions of the trial court granting or denying a trial amendment may not be overturned on appeal except upon a showing of abuse of discretion. Hardin v. Hardin, 597 S.W.2d 347 (Tex.1980). As in this case, the objecting party generally resists the trial amendment on the basis of surprise.
As mentioned previously, MKT’s trial amendments offered on the day of trial would have placed in issue for the first time the question whether Alvarez failed to use ordinary care in the actions he took after discovering the oncoming train. The prior allegations of contributory negligence were based solely on a theory that Alvarez failed to appreciate and guard against the possibility of danger from any source — by accepting a ride, by becoming intoxicated, and by failing to keep a proper look-out. Under the proposed trial amendments, the issue of contributory negligence would have turned instead on quite different matters — matters involving panic reaction by persons of ordinary care; milliseconds of difference in timing; and Alvarez’s age, physical condition and abilities, as they would bear upon his reaction capacity. These new allegations would require quite new and different trial preparation by Alvarez’s lawyers if they were to meet the new negligence theory.
Surprise is not the only basis for denying a trial amendment in this case. The question of diligence on the part of the party offering the trial amendment should also be addressed by the court. Westinghouse Electric Corp. v. Pierce, 153 Tex. 527, 271 S.W.2d 422 (1954); Sanchez v. Matthews, 636 S.W.2d 455 (Tex.App.1982, writ ref’d n.r.e.). In view of the procedural history of this case set forth above, the trial court’s refusal to allow MKT's proposed trial amendments may be justified both on the basis of surprise and on the basis of lack of diligence by MKT. The seventh, eighth, ninth and tenth points of error are overruled.
EXCLUSION OF EXPERT TESTIMONY
MKT apparently planned to call Jerry Simmons, an employee of the Texas Rehabilitation Commission, as an expert witness to rebut proof by Alvarez of loss of future earning capacity. The trial court excluded Simmons’ testimony.
In its brief on appeal, MKT states that the trial court excluded Simmons’ testimony because he had not been disclosed as an expert witness at least fourteen days before trial in supplementation of defendant’s answers to plaintiff’s interrogatories. *371MKT admits that under Tex.R.Civ.P.Ann. 168 as amended in 1981 and in effect at the time of trial, the trial court was authorized to exclude testimony from an expert witness whose name had not been previously disclosed in response to an appropriate interrogatory. However, MKT argues that in this case no such interrogatory had been filed by Alvarez.
On July 22, 1982, five days before the trial of this case, MKT filed what is styled “Supplemental Answers to Plaintiff’s Interrogatories Previously Filed in Federal Court.” Interrogatory number 61(c) specifically asked “... whether the defendant retained or specifically employed for any purpose any expert not identified in response to prior interrogatories ...” In its supplement to this interrogatory, MKT stated: “Defendant may call Jerry Simmons ... as a vocational rehabilitation expert to testify on Mr. Alvarez’s employability and earning capacity.” Further, in a July 14, 1982, letter to the attorney for Alvarez, MKT stated: “Supplementing our answers to interrogatories previously filed in this cause, please be advised that defendant may call Jerry Simmons, ... as a vocational rehabilitation expert ...” While the interrogatories being supplemented do not appear as part of the record, it is clear from the material before us that MKT was responding to one or more “appropriate interrogatories” in listing Simmons as an expert witness whose name had not been previously disclosed. We hold under Rule 168 that Simmons was an undisclosed expert witness properly excluded by the trial court.
After Simmons was disqualified from giving opinion testimony concerning Alvarez’s employability and loss of future earning capacity, MKT urged that he be permitted to testify as a “fact witness” concerning certain related matters: (1) services supplied by the Texas Rehabilitation Commission; (2) jobs and rates of pay available to a man with Alvarez’s handicap; and (3) rates of pay for oil field and construction employment. The distinction between an “expert witness” and a “fact witness” suggested by MKT is not a real one, for it is readily apparent that testimony concerning the three subjects in question could only be opinion inferences drawn from hearsay information. While Simmons no doubt possessed, by virtue of his special skill, knowledge or experience, a capacity to draw better inferences than an ordinary person, this is only to say that he was an “expert” relative to such matters. See Moore v. Grantham, 599 S.W.2d 287 (Tex.1980). The trial court properly determined that Simmons would be testifying in an expert capacity even though called as a “fact witness.” Since Simmons was disqualified as an expert, the disqualification encompassed all matters about which he would testify by giving his expert opinion.
MKT did call Simmons as an expert witness by bill of exceptions. While Simmons testified to some pay rates substantially lower than the expert witness for the plaintiff, he also testified to an hourly rate of pay for oil-field workers substantially in excess of the hourly rate of pay testified to by the expert witness for Alvarez. Taking Simmons’ testimony as a whole, it is clear that the exclusion of this evidence, if error, was not such an error as was “reasonably calculated to cause ... the rendition of an improper judgment ...” and was therefore harmless. Tex.R.Civ.P. 434 (1985). Points of error thirteen and fourteen are accordingly overruled.
LACK OF EVIDENCE TO SUPPORT LOSS OF FUTURE EARNING CAPACITY
In points of error fifteen and sixteen, MKT argues that there was no evidence, and alternatively, insufficient evidence to support the jury’s findings concerning loss of future earning capacity.
In reviewing a no-evidence point, we must consider only the evidence favorable to the answer by the jury and disregard all evidence or inferences to the contrary. In considering an insufficient evidence point, we must review and weigh all of the evidence, including any evidence contrary to *372the jury’s answer. Calvert, “No Evidence” and “Insufficient Evidence” Points of Error, 38 Texas L.Rev. 361 (1960).
MKT contends that when Alvarez’s actual position, interest and goals are taken in account, there was clearly no loss of earning capacity after the accident. However, in a personal injury case the measure of damages is the diminished earning power or capacity of the plaintiff, not his actual lost earnings. Greyhound Lines, Inc. v. Craig, 430 S.W.2d 673 (Tex.Civ.App.1968, writ ref’d n.r.e.). The record on appeal is filled with evidence of a diminution in earning capacity following the 1975 injury, and this Court will not hold as a matter of law that a one-legged laborer has the same earning capacity as a man possessed of all his limbs. Points of error fifteen and sixteen are overruled.
The judgment of the trial court is affirmed.