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

Poster Details

First Author: J.Than UK

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

Abstract Details


Keratoconus is an ectatic disorder affecting approximately 1 in 1000 people, resulting in progressive myopia and irregular astigmatism secondary to conical protrusion and apical thinning of the cornea. Collagen cross-linking is the gold standard treatment for progressive disease. Combination with transepithelial phototherapeutic keratectomy (PTK) prior to cross-linking, versus mechanical epithelial debridement, has shown superior outcomes. However, this protocol fails to account for population heterogeneity in epithelial thickness, risking over-ablation of stroma and consequent reduced structural integrity. We propose a novel protocol utilising anterior segment optical coherence tomography to adapt transepithelial PTK depth to individual epithelial profiles to improve patient outcomes.


Ophthalmic private practice, London, United Kingdom


Patients with progressive keratoconus, minimum corneal thickness ≥400μm, and no prior corneal surgery underwent PTEK. Anterior segment OCT was performed and trans-epithelial PTK ablation depth was 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.


9 eyes of 7 patients met inclusion criteria for PTEK and were recruited. Mean length of follow-up was 14 months. At latest follow-up, mean BCVA improved from logMAR equivalent 0.093 to 0.04. Mean Kmax improved from 56.2 to 52.6D. Mean magnitude of astigmatism changed from 2.53 to 2.81D. Spherical equivalent improved by a mean 0.26D. These changes lacked statistical significance. No intra-operative or post-operative complications were noted.


PTEK followed by CXL is a novel protocol for treatment of progressive keratoconus, with theoretical benefits versus present protocols. This audit demonstrates its safety and efficacy in improving BCVA and stabilising 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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