Undercorrection occurs much more commonly with treatment of higher degrees of ametropia. Patients with regression after treatment of their first eye have an increased likelihood of regression in their second eye. Topical mitomycin C, administered at the time of initial surface ablation, can be used to modulate the response, especially in patients with higher levels of ametropia. Sometimes the regression may be reversed with aggressive administration of topical corticosteroids. The patient may undergo a re-treatment generally no sooner than 3 months postoperatively, once the refraction has stabilized. A patient with significant corneal haze and regression after surface ablation is at higher risk after re-treatment for further regression, recurrence, or worsening of the corneal haze, as well as loss of best-corrected visual acuity (BCVA; also called corrected distance visual acuity, CDVA). It is recommended that the surgeon wait at least 6–12 months for the haze to improve spontaneously before repeating surface ablation. In patients with significant haze and myopic regression, removal of the haze with adjunctive use of mitomycin C should not be coupled with a refractive treatment, as the resolution of the haze will commonly improve the refractive outcome. Undercorrection after LASIK typically requires flap lift and laser treatment of the residual refractive error after the refraction has remained stable for at least 3 months. Cases of delayed and progressive regression, especially with concomitant development of irregular astigmatism, may suggest ectasia, or, in an older patient, refractive shift due to the development of cataract.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.