Posterior corneal elevation changes and characteristic analysis 1year after corneal collagen cross-linking for keratoconus.

Jing Li,Yaohua Zhang,Jing Du,Dan Yang,Jianguo Liu,Shengsheng Wei,Yong Li,Yan Wang,Zhen Tian

doi:10.1007/s10792-021-02135-y

Abstract

To investigate the changes in posterior corneal elevations (PCEs) in the circular areas and local points after corneal collagen cross-linking (CXL) for the treatment of keratoconus. Method 1 divided the cornea into 0-2, 2-4, 4-6, and 6-8mm regions centering on the apex. Method 2 obtained other 34 PCE values of local point that were identified on the nasal, supra-nasal, sub-nasal, superior, inferior, temporal, supra-temporal, and sub-temporal sides of the circle with diameters of 2, 4, 6, and 8mm, and the apex and thinnest point. Method 1 showed a forward displacement of PCE at 1month after CXL and then a backward displacement at 3months. In Method 2, the points on the temporal side of 2mm and 4mm showed the same trend. The backward displacements of PCE on the temporal side of 2mm at 6months and on the temporal side of 4mm at 12months after CXL were both statistically different than those at 1month after CXL (P < 0.05). No significant forward displacement of PCE was found in all local points in different quadrants at 1year after CXL. The PCEs in circular areas and characteristic points of different diameters in keratoconic eyes after CXL change with time. Local point assessment of the PCE is more clinically significant. In points selected in different quadrants of the cornea, the change in temporal points was more significant after CXL.

Highlights

Keratoconus (KC) is a degenerative corneal disorder characterized by progressive thinning and cone-like protrusion of the central cornea resulting in irregular astigmatism, myopia, and scarring with decreased visual acuity [1].Conventional treatment options for KC include rigid contact lens, intracorneal ring implantation, and lamellar keratoplasty
CXL epi-on and CXL epi-off are effective in controlling the progress of KC, and CXL epi-on is preferable to CXL epi-off since CXL epion preserves the corneal thickness, improves visual acuity, and reduces postoperative ocular discomfort [7]
Changes in posterior corneal elevations (PCEs) (ΔPCE; Δ values were defined by subtracting preoperative data from postoperative data) over the annular diameters Φ0–2 mm, Φ2–4 mm, Φ4–6 mm, and Φ6–8 mm after CXL were not statistically significant over the 12-month follow-up (P = 0.244, 0.377, 0.485, and 0.115, respectively) (Fig. 4)

Summary

Introduction

Conventional treatment options for KC include rigid contact lens, intracorneal ring implantation, and lamellar keratoplasty. All these techniques only correct the refractive error of the cornea with little effect on the progression of KC. The only treatment that is considered to improve the visual acuity and prevent the progression of KC is corneal collagen cross-linking (CXL) [2, 3]. CXL epi-on and CXL epi-off are effective in controlling the progress of KC, and CXL epi-on is preferable to CXL epi-off since CXL epion preserves the corneal thickness, improves visual acuity, and reduces postoperative ocular discomfort [7]. Regardless of the surgical method, the evaluation of the postoperative effect and the monitoring of postoperative progress are important

Objectives

Methods

Results

Conclusion