Combined Corneal Wavefront-guided Transepithelial Photorefractive Keratectomy and Accelerated Corneal Collagen Cross-linking Following Intra Corneal Ring Segment Implantation in Management of Moderate Keratoconus

Patients and Methods:

This study conducted upon 36 eyes of 36 patients with moderate keratoconus who undergoing combined corneal wavefront-guided TPRK and accelerated corneal CXL at least 3 months after ICRS implantation in the period between October, 2018 and April 2020, at the Security Forces Hospital, Ophthalmology Department, Riyadh, Kingdom of Saudi Arabia. The study was approved by SFHP ethical board committee (IRB registraion number: 18-289-54) and was adhered to the tenets of the Declaration of Helsinki as well as followed good clinical practices. All patients provided informed written consent for the study and for publication. All included patients undergoing combined corneal wavefront guided TPRK and corneal ACXL at least 3 months after ICRS implantation. Grading of keratoconus was based on the Amsler Krumeich classification. Progression was defined as one or more of the following changes over a period of 6 months: an increase of ≥1.00 diopter (D) in maximal keratometry values, an increase of ≥1.00 D in manifest cylinder, and an increase of ≥ 0.50 D in MRSE.

Examinations and measurements:- At baseline, the preoperative examination included UDVA, CDVA, manifest and cycloplegic refraction, slit lamp biomicroscopy, tonometry, Pentacam camera, tomography, and dilated fundus examination using binocular ophthalmoscopy. If patient use contact lenses it should be stopped 3 weeks before exam date, and medical history, including any systemic diseases, were recorded. After ICRS implantation (before combined TPRK and ACXL), and at 1, 3, 6, and 12 months after combined TPRK and CXL, all patients undergoing complete ophthalmic examinations, which included examinations for UDVA and CDVA with a Snellen chart, manifest refraction (MR). The corneal indices measured at the 8-mm zone using the Scheimpflug tomography system with Pentacam camera (OCULUS- Netzteil Art., Pentacam HR, Germany), and for measuring changes in corneal aberrations, including HOAs, coma, and spherical aberrations, corneal wavefront analysis implemented using corneal topographic data with tomography (Sirius, SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Root mean square (RMS) values of the corneal HOAs, with analysis up to the 7th order by expanding the set of Zernike polynomials, were calculated. Any postoperative complications, corneal haze , wound healing time were estimated. Patients overall satisfaction for the procedure were asked at last follow up and all data were recorded.

Surgical technique:-

First step procedure: