Copenhagen 2016 Registration Programme Exhibitor Information Virtual Exhibition Satellite Meetings Glaucoma Day 2016 Hotel Star Alliance

10 - 14 Sept. 2016, Bella Center, Copenhagen, Denmark

This Meeting has been awarded 27 CME credits


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Comparison of the demarcation line on ASOCT after simultaneous LASIK and different protocols of accelerated collagen cross-linking: a bilateral eye randomised study

Poster Details

First Author: A. Ng HONG KONG

Co Author(s):    T. Chan   S. Kwok                 

Abstract Details


To compare the early corneal morphological changes of two different protocols of simultaneous laser in-situ keratomileusis (LASIK) and accelerated collagen crosslinking (LASIK Xtra) in the treatment of myopia.


Hong Kong Laser Eye Center, Hong Kong SAR


23 patients receiving bilateral LASIK Xtra were included. After femtosecond LASIK, while the LASIK flap was still lifted, the corneal stroma was soaked with 0.22% riboflavin solution for 90 seconds. After the flap was re-positioned, one eye was randomized to receive either 18 mW/cm2 of UVA irradiation for 120 seconds (total energy 2.16 J/cm2) or for 180 seconds (total energy 3.24 J/cm2), while the fellow eye received the other treatment protocol. The demarcation line was measured with an anterior-segment OCT (Optovue Inc, Fremont, USA) at postoperative 1 month. The grading of corneal haze on slit lamp was also compared.


The average age was 29.0 ± 8.2. There was no statistical difference in the preoperative spherical equivalent refraction (p>0.05). At postoperative 1 month, a well-defined demarcation line was visible in 74% and 70% in the 2-and 3-minute groups respectively. The demarcation line depth was 282 ± 51 µm and 284 ± 43 µm respectively (p = 1.00), and the ratio of the demarcation line depth to the postoperative central corneal thickness was 0.69 ± 0.13 and 0.72 ± 0.10 (p = 0.61). There was no difference in the percentage of eyes with grade 1 or 2 corneal haze either (p=0.76).


The depth of the demarcation line was the same with either 2.16 or 3.24 J/cm2 LASIK Xtra protocols. The amount of early postoperative corneal haze was also similar. This suggested that the early morphological change or the amount of tissue cross-linked was similar using the two different protocols. Since the UVA irradiation was given after repositioning of the LASIK flap, the intact corneal epithelium could have acted as a barrier limiting the penetration of the UVA despite a 50% difference in the irradiation duration.

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