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Phototherapeutic epithelial-guided keratectomy (PTEK): a novel trans-epithelial OCT-guided phototherapeutic keratectomy protocol combined with corneal collagen cross-linking – post-LASIK ectasia outcomes

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Session Details

Session Title: Presented Poster Session: Cornea IV

Venue: Poster Village: Pod 3

First Author: : A.Davidson UK

Co Author(s): :    J. Than   R. Cann   E. Trocme   F. Allen   A. Barsam  

Abstract Details


Post-LASIK ectasia is an uncommon laser refractive surgery complication resulting in progressive myopia and irregular astigmatism, secondary to central and inferior corneal steepening. Collagen cross-linking has been successfully used to stabilise progressive disease. Combination with transepithelial phototherapeutic keratectomy (PTK) prior to CXL, versus mechanical epithelial debridement, has shown superior outcomes in other keratectatic conditions e.g. keratoconus. However, this protocol fails to account for population heterogeneity in epithelial thickness, risking over-ablation of stroma, compromising structural integrity. We propose a novel protocol utilising anterior segment OCT to adapt transepithelial PTK depth to individual epithelial profiles, before CXL, to improve post-LASIK ectasia outcomes.


Ophthalmic private practice, London, United Kingdom


Patients with post-LASIK ectasia, minimum corneal thickness ≥400μm, and no prior corneal surgery barring LASIK underwent PTEK. Anterior segment OCT was performed and trans-epithelial PTK ablation depth set at the thinnest epithelial depth within a 5mm radius of the central cornea + 20±5μm in order to achieve effective apical stromal smoothing and peripheral de-epithelialisation. PTEK was then performed using an excimer laser (Wavelight Alegretto, Alcon, Texas, USA) and subsequent CXL performed according to modified Dresden protocol. BCVA, Kmax, refraction, and corneal astigmatism measures were taken pre-operatively and 1 week, 6 weeks, 6, 12, and 18 months post-operatively.


4 eyes of 4 patients met inclusion criteria for PTEK and were recruited. Mean length of follow-up was 18 months. At latest follow-up, mean BCVA improved from logMAR equivalent 0.23 to 0.01 (p<0.05). Mean Kmax improved from 59.03 to 53.6D, and mean magnitude of astigmatism improved from 3.15 to 2.55D, but these changes lacked statistical significance. Spherical equivalent worsened by a mean 0.83D. No intra-operative complications were noted. Post-operative complications included sterile punctate epithelial erosions in 1 eye and slight corneal haze in 3 eyes.​


PTEK followed by CXL is a novel protocol for treatment of progressive post-LASIK ectasia, with theoretical benefits versus present protocols. This audit demonstrates its safety and efficacy in stabilising BCVA, Kmax, refraction, and magnitude of astigmatism in such patients. Further work is required to compare its efficacy versus current protocols and establish long-term outcomes.

Financial Disclosure:


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