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PTK or PRK with corneal collagen cross-linking: chasing superior outcomes!

Poster Details

First Author: S.Holland CANADA

Co Author(s):    D. Lin   J. Hogden   N. Davey   S. Mosquera           

Abstract Details


To compare a statistically case-matched cohort of keratoconic patients undergoing combined topographic guided photorefractive keratectomy (TG-PRK) or phototherapeutic keratectomy (PTK) in combination with corneal collagen cross-linking (CXL). Our study is the first of its kind, to our knowledge, and we believe the outcomes will further assist clinicians in discussing the therapeutic and refractive treatment options available to keratoconic patients.


A retrospective pre-operatively statistically case-matched cohort study was performed based on 18 patients, 10 in the PRK arm and 8 in the PTK arm. All patients underwent treatment with the Schwind Amaris 1050 laser platform, with SmartSurfACE technology employed for the TG-PRK patients.


A retrospective pre-operatively statistically case-matched cohort study. Pre-operative and post-operative data analyzed: spherical correction, cylinder correction, spherical equivalent error, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), average keratometry, maximum keratometric readings (Kmax) and central corneal thickness. Patient follow-up ranged from 3 to 18 months. SmartSurfACE treatments (TG PRK) were prepared using the SCHWIND custom ablation manager based on the total manifest and refraction. PTK was performed with the primary target being ablation of the keratoconic segment and removal of epithelium to facilitate CXL therapy. The surgeries were all performed at the Pacific Laser Eye Centre, Vancouver, Canada.


Post-operatively there was a statistically significant reduction in cylinder post-operatively in the TG-PRK cohort of patients (PTK: -2.55 D and TG-PRK: -0.91D, P=0.1). There was also a statistically significant improvement in both UDVA and CDVA in the TG-PRK treatment cohort. TG-PRK cohort gained 7 lines UDVA versus 2 lines gained for PTK (p= 0.005). TG-PRK patients on average also gained 2 lines CDVA versus no improvement for PTK cohort (p=0.01). Expectantly there was statistically significantly less tissue removed for PTK versus TG-PRK (57�Â�µm versus 115�Â�µm, p=0.001).


It is our finding in this pre-operatively statistically matched cohort study that the TG-PRK CXL therapy was statistically superior to PTK CXL in terms of cylinder correction, UDVA and CDVA. The improvements in vision and astigmatism do however come at the cost of more ablated tissue and this must be considered, in terms of safety, when pre-operative keratoconic patients requiring CXL are evaluated. Our study highlights the importance of discussing both refractive and therapeutic options when considering CXL therapy in keratoconic patients and suggests superior visual outcomes with TG-PRK CXL therapy in appropriate cases.

Financial Disclosure:

is employed by a for-profit company with an interest in the subject of the presentation, travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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