Longitudinal Epithelial Thickness Profile Changes 18 Months After Photorefractive Keratectomy

Abstract

Purpose: Long-term evaluation of corneal epithelial thickness (ET) profile changes after photorefractive keratectomy (PRK) using Fourier-domain anterior segment optical coherence tomography. Methods: Three hundred twenty-six eyes of 163 patients were included in this prospective observational study. The corneal epithelial map was obtained across a 9-mm diameter area of the cornea before and up to 27 months after surgery. ET was assessed in 25 sectors and 4 annular zones (central 2 mm, paracentral 2–5 mm, midperipheral 5–7 mm, and peripheral 7–9 mm). Results: There was a significant reduction in mean ET in all zones 1 month after PRK. Subsequently, ET increased in all annular zones. The change in mean ET became stable in the midperipheral and peripheral zones at 3 to 6 months and in the central zone at 12 months, and it continued to increase in the paracentral zone even after 18 months after surgery. The ET was 3.40 μm and 4.05 μm in the central and paracentral zones at 6 months, respectively. Postoperative spherical equivalent changed significantly only from 1 to 3 months (P < 0.04). There was a significant correlation between postoperative spherical equivalent at month 1 and ET change in the paracentral and midperipheral zones (P < 0.027). Conclusions: There is a significant reduction in ET 1 month after myopic PRK with a gradual thickening thereafter until it reaches stability at 12 months in the central zone. However, it continues to change even after 18 months in the paracentral zone. The greatest thickening is in the paracentral zone, followed by the central zone.

Clinical outcomes of transepithelial photorefractive keratectomy with epithelial ablation targeting actual epithelial thickness vs default laser platform values

“…5,21 Using AS-OCT, we previously reported that in normal corneas, the mean (95% CI) epithelial thickness is 53.57 mm (53.16 to 53.98) centrally, which decreases with a low gradient of 0.43 mm toward 5.0 to 7.0 mm midperiphery and 2.31 mm toward 7.0 to 9.0 mm periphery. 22,23 Very similar results have been reported by other studies. 24,25 Therefore, contrary to what was said before, the 55 mm central and 65 mm peripheral epithelial ablation profile of the SCHWIND AMARIS laser system is not refractively neutral by targeting actual epithelial profile.…”

Comparison of Vision Correction and Corneal Thickness at 180-Day Follow-Up After Femtosecond Laser-Assisted In-Situ Keratomileusis (FS-LASIK), Photorefractive Keratectomy (PRK), and Small Incision Lenticule Extraction (SMILE): A Study from a Single Center in Poland of 120 Patients with Myopia

“…Golshan et al evaluated CET changes in patients who underwent PRK [ 48 ]. They found that in the first month after the procedure, CET decreased in all zones and only gradually thickened between 3 and 18 months, depending on the zone [ 48 ]. The highest thickening was noted in the paracentral area and the least in the central site [ 48 ].…”

“…They found that in the first month after the procedure, CET decreased in all zones and only gradually thickened between 3 and 18 months, depending on the zone [ 48 ]. The highest thickening was noted in the paracentral area and the least in the central site [ 48 ]. Sedaghat et al, in a group of 52 patients (52 eyes), reported CET thinning in the first month after PRK surgery, with gradual thickening at months 3 and 6 [ 49 ].…”

Evaluation of the effect of artificial tears on corneal epithelial thickness changes after photorefractive keratectomy

“…Recent advances in imaging technologies have allowed for a detailed characterization of epithelial remodeling in response to various corneal states. Different imaging modalities such as confocal microscopy,[ 6 7 ] very high-frequency (VHF) digital ultrasound,[ 8 9 10 ] and anterior segment optical coherence tomography (AS-OCT)[ 11 12 13 14 ] have been used to evaluate the corneal epithelium. AS-OCT can provide a map of corneal epithelial thickness over a 9 mm diameter of the cornea.…”

“…Previous studies have shown significant epithelial remodeling over the ablation zone after myopic photorefractive keratectomy (PRK) surgery,[ 11 13 14 ] which is recognized as one of the reasons for postoperative refractive regression. [ 16 17 ] Several agents, such as anti-inflammatory drops and artificial lubricant tears, are routinely used after PRK to reduce the initial inflammation and alleviate patient discomfort after surgery, but little information is available on the effect of these agents on the corneal remodeling process.…”