Late-Onset Unilateral Corneal Ectasia After Prk With Mitomycin-C: Case Report Ina Low-Risk Patient

To describe a paradigm-challenging case of late-onset, unilateral corneal ectasia occurring 3 years after bilateral photorefractive keratectomy (PRK) with intraoperative mitomycin-C in a patient deemed low risk by standard preoperative tomography, and to emphasize that apparently “normal” screening results do not fully exclude individual biomechanical susceptibility. This report aims to reinforce the need for sustained postoperative vigilance and to highlight the current limits of tomographic-only risk stratification.

Tertiary cornea and refractive surgery referral service at a specialized ophthalmology center, where the patient was investigated using Scheimpflug corneal tomography (Pentacam) and subsequently characterized with dynamic corneal biomechanical assessment (Corvis ST). Management included standard cross-linking and intrastromal ring implantation for stabilization and visual rehabilitation.

A 32-year-old man underwent bilateral PRK in 2020 with intraoperative mitomycin-C 0.02% for 40 seconds for myopia/astigmatism correction. Preoperative screening suggested low ectasia risk: no focal thinning (CCT 558 µm OD, 569 µm OS), no significant elevation abnormalities, Belin/Ambrósio display within normal limits, and only mild inferior–superior asymmetry in the right eye (1.4–1.6 D). Kmax was slightly elevated but symmetric (46.2 D OD; 45.8 D OS). Surgery used a 6.5-mm optical zone, vertex-centered ablation with eye tracking, standard aspheric profile, and 85% stromal preservation. Early outcome was excellent, with UDVA 20/20 bilaterally by month 3 and stability through year 2.

In 2023, the patient reported progressive monocular blur in the right eye. Repeat tomography demonstrated marked inferior steepening and ectatic pattern with Kmax rising to 61.1 D and thinning to 478 µm OD; the left eye remained stable (Kmax 46.4 D). Corvis ST revealed reduced biomechanical stability in the affected eye (total biomechanical index 0.40). After excluding alternative causes, unilateral post-PRK ectasia was diagnosed. The patient underwent corneal cross-linking (Dresden protocol). Once topographic stability was achieved, an asymmetric Ferrara ICRS (150/250 µm; 180° arc) was implanted to address residual irregular astigmatism, resulting in CDVA improvement to 20/25, stable corneal curvature, and no further progression at 6 months.

Ectasia can develop after PRK with mitomycin-C even when preoperative tomography and Belin/Ambrósio indices are within accepted “normal” limits and classic risk factors are absent. A subtle, borderline asymmetry may be the only early warning sign, and unilateral progression does not preclude future risk to the fellow eye. Clinicians should avoid overreassurance based on tomographic-only screening, consider adding biomechanical assessment whenever available, and maintain long-term follow-up after surface ablation—particularly when patients report new monocular blur years after surgery.