Late-Onset Haze and Severe Corneal Flattening after Combined Corneal Collagen Cross-Linking and Photorefractive Keratectomy (CXL Plus): A Case Report.

Introduction: Significant corneal flattening and haze are important complications that can occur after combined corneal collagen cross-linking (CXL) and photorefractive keratectomy (PRK) procedures (CXL Plus). Case Presentation: We present a 24-year-old man who underwent combined standard CXL and PRK. The patient experienced satisfactory vision for approximately 4 years after the surgery. However, after this period, he began to complain of visual blurring. Subsequent examination revealed significant corneal haze, excessive flattening in both eyes, and thinning (thinnest point 227 μm in the right eye, 244 μm in the left eye) 4 years postoperatively. Upon presentation, the corrected distance visual acuity (CDVA) was 20/200 in the right eye and 20/400 in the left eye. The presenting refraction was +2.50 sph, -3.50 cyl *114 in the right eye and +11.5 sph, -9.75 cyl *81 in the left eye. With rigid gas permeable contact lenses, the corrected visual acuity was 20/50 in both eyes. Before the CXL Plus surgery, initial refraction and CDVA were 20/50 in the right eye (-5.50 sph, -3.00 cyl *175) and 20/30 in the left eye (-5.50 sph, -2.75 cyl *175). The patient was treated by penetrating keratoplasty. The CDVA reached 20/30 at the final follow-up. Conclusion: Our report highlights significant corneal haze and flattening that occurred 4 years after combined CXL and PRK treatment. These findings suggest that this procedure might not be safe in suspected patients of keratoconus. Further long-term follow-up research is necessary to evaluate the safety of combined CXL and PRK procedures.