Public Defence: Andreas Thorsrud Andreas Thorsrud at Institute of Clinical Medicine will be defending the thesis “Corneal collagen crosslinking: Studies on a treatment modality for progressive corneal ectasia” for the degree of PhD (Philosophiae Doctor).

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Photo: Geir Aksel Qvale

Trial Lecture – time and place

See Trial Lecture.

Adjudication committee

  • First opponent: Senior Consultant Anders Ramløv Ivarsen, Aarhus University, Denmark
  • Second opponent: Professor Anders Behndig, Umeå University, Sweden
  • Third member and chair of the evaluation committee: Associate Professor G. Cecilie Alfsen, Faculty of Medicine, University of Oslo

Chair of the Defence

Professor Emeritus Odd Geiran, Faculty of Medicine, University of Oslo

Principal Supervisor

Professor II Liv Drolsum, Faculty of Medicine, University of Oslo


Corneal ectasia is a group of progressive eye diseases causing the cornea to bulge into a cone-like shape. This shape results in visual impairment and disturbances such as monocular diplopia, glare and light sensitivity. Corneal collagen crosslinking (CXL) is a treatment for stabilizing keratoectasia. The aim of this thesis was to examine safety and efficacy of CXL treatment.

At the Eye department, Oslo University Hospital, we have carried out both in-vitro and in-vivo research on CXL. First, in-vitro CXL on the limbus showed a toxic effect in an experimental study. Therefore, avoiding the limbus during CXL was advocated for safety reasons.

Different measuring methods of the CXL demarcation line depth in-vivo were studied in a prospective case series. Two different confocal microscopy methods and an optical coherence tomography method all showed good correlation and are useful for different purposes.

In the last two trials, different CXL protocols were compared. A randomized controlled trial showed deeper CXL demarcation line in the conventional protocol than in a new accelerated protocol. In a comparative case series, we compared methylcellulose to dextran as the main riboflavin supplement. We found thicker corneas during CXL, deeper demarcation lines and more corneal flattening when using methylcellulose than dextran. Thus, different treatment depths imply a distinct safety and efficacy profile of each CXL protocol.

In conclusion, the CXL protocol may be adjusted to the individual patient to optimize safety and efficiacy of CXL treatment.

Additional information

There will be a light reception for all audiences in the Library, 3. floor, after the disputation

Contact the research support staff.


Published Nov. 11, 2019 10:30 PM - Last modified Nov. 22, 2019 2:35 PM