Which of the following can lead to a significant haze after LASIK?

A significant haze after LASIK can occur when the flap created during the procedure is too thin. This is because a thin flap may not provide enough corneal bed to adequately promote healing and maintain structural integrity. The healing process can become irregular, leading to scarring and a haze that affects visual clarity. The corneal tissue needs sufficient thickness to recover properly, and when this is compromised, it can lead to complications, including haze.

In contrast, using a high-energy laser typically does not directly relate to haze formation; rather, haze is more often associated with the healing processes following the surgery. While age can influence the overall healing and corneal health, simply being over 50 does not predispose a patient to significant haze specifically. Improper post-operative care, while important for overall healing, is more likely to lead to infections or other complications than directly causing haze itself. Thus, the thinness of the flap created during the procedure is the key factor contributing to the potential for significant haze in the post-operative phase.