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Long-term outcomes following primary versus secondary Boston keratoprosthesis type 1 implantation
  1. Taylor Nayman1,2,
  2. Cristina Bostan1,2,
  3. Andrei-Alexandru Szigiato1,2,
  4. Mona Harissi-Dagher1,2
  1. 1Department of Ophthalmology, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
  2. 2Department of Ophthalmology, University of Montreal, Montreal, Quebec, Canada
  1. Correspondence to Dr Taylor Nayman, Department of Ophthalmology, Centre Hospitalier de l'Université de Montréal, Montreal, QC H2X 3E4, Canada; taylornayman{at}


Background/aims To compare long-term outcomes of primary versus secondary (postgraft failure) Boston keratoprosthesis type 1 (KPro) implantation.

Methods Medical records of patients at the Centre hospitalier de l’Université de Montréal having undergone KPro implantation between 2008 and 2017 were reviewed and included if they had a preoperative Snellen best-corrected visual acuity (BCVA) of 20/100 or worse and a minimum of 5 years of follow-up. Eighty-two eyes were separated into two cohorts (40 primary, 42 secondary KPro) and BCVA, complications and device retention were evaluated between groups.

Results BCVA improved from baseline in both groups at each year; this was significant at all five postoperative years in the primary group and the first 3 years in the secondary group (p<0.05). Mean BCVA was similar between groups at 5 years (logarithm of minimal angle resolution 1.3±0.8 in the primary group vs 1.5±0.8 p<0.05). Idiopathic vitritis, choroidal detachment and new glaucoma occurred more after primary KPro (n=7, 17.5% vs n=1, 2.4%; n=11, 27.5% vs n=3, 7.14% and n=14, 35% vs n=6, 14%, respectively; p<0.05). Primary KPro had lower retention (n=28, 70% vs n=38, 91%, p<0.05) at final follow-up. There was more aniridia in the primary group (n=19, 48% vs n=6, 14%, p<0.01). Within each group, 50% of removals occurred in aniridic eyes.

Conclusion Primary KPro yielded favourable long-term visual outcomes but had more complications and lower retention rates than secondary KPro, likely explained by preoperative indications. Primary device implantation represents a favourable option for patients for whom grafts are likely to fail.

  • cornea
  • prosthesis
  • ocular surface
  • treatment surgery

Statistics from


  • CB and A-AS contributed equally.

  • Contributors TN and A-AS performed a literature review. TN, CB and A-AS collected data. TN, CB and A-AS analysed the data. TN drafted the manuscript. TN, CB and MH-D edited and revised the manuscript critically for important intellectual content.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the local Institutional Review Board and respects the principles of the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. Data involve deidentified participant information and related statistical analyses. They are available from TN (ORCID: 0000-0002-5888-8968) on request.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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