Epithelial and stromal profiles of post-laser vision correction ectasia by OCT.

Purpose: To investigate changes in the epithelium and stroma in patients with post-laser vision correction (LVC) ectasia using spectral-domain optical coherence tomography (SD-OCT) and to compare these changes with those observed in post-LVC stable eyes.

Setting: Eye Hospital of Wenzhou Medical University, Wenzhou, China.

Designs: Retrospective case-control study.

Methods: Scheimpflug tomography and SD-OCT were performed on post-LVC stable and ectasia eyes. The postoperative remodeling pattern of epithelium and stroma was described. All SD-OCT machine-derived parameters were evaluated based on their receiver operating characteristic (ROC) curves, area under the curve (AUC), sensitivity, and specificity to discriminate between post-LVC stable and ectasia eyes.

Results: 111 eyes from 111 post-LVC stable patients (41 post-trans-photorefractive keratectomy [transPRK] eyes, 34 post-laser in situ keratomileusis [LASIK] eyes, and 36 post-small incision lenticule extraction [SMILE] eyes) and 23 eyes from 23 post-LVC ectasia patients (1 post-transPRK ectasia eye, 1 post-sub-Bowman keratomileusis ectasia eye, 1 post-laser-assisted subepithelial keratomileusis ectasia eye, and 20 post-LASIK ectasia eyes). The unique epithelium remodeling pattern was observed in both post-LVC stable and ectasia eyes, in the latter as a "horseshoe"-like pattern. The top 3 ranked AUC ROC SD-OCT parameters were all derived from epithelium, including epithelium 5 mm superior-inferior (cutoff value = -0.675, AUC = 0.956), epithelium 5 mm inferior (cutoff value = 52.41, AUC = 0.937), and epithelium thickness range (cutoff value = -23.685, AUC = 0.936).

Conclusions: The characteristic remodeling pattern and the machine-derived SD-OCT parameters describing the epithelium remodeling of post-LVC ectasia could potentially be used for its diagnosis.