Joe Bostic brings this appeal from his conviction of aggravated assault following the denial of his motion for a new trial.

1. The trial court did not err in overruling the defendant's objection and allowing the victim to testify that the loss of the vision in his right eye was a result of being shot in the head by the defendant. The court ruled that he could testify as to whether or not any incident caused him to be blind. Such testimony was admissible as an observation. Van Gundy v. Wilson, 84 Ga. App. 429 (6) (66 SE2d 93) (1951). Appellant did not deny that he seriously wounded the witness in the head with a gun, but claimed that he acted in self-defense. We, therefore, do not see how the witness' answer to the question could have been harmful to him.

2. The general grounds are also without merit. As appellant claimed that he acted in self-defense when the witness attacked him with a "hawk-bill" knife and a police officer testified that he did not find a knife at the scene of the crime, the issue of the credibility of the witnesses is entirely within the province of the jury. Redd v. State, 154 Ga. App. 373 (268 SE2d 423) (1980). The evidence was clearly sufficient for a rational trier of fact to find that the defendant was guilty beyond a reasonable doubt. Black v. State, 154 Ga. App. 441 (268 SE2d 724) (1980).