Photorefractive Intrastromal Crosslinking (PiXL) for the Treatment of Progressive Keratoconus
Condition: Keratoconus; Corneal Crosslinking; Corneal Biomechanics; Corneal Densitometry; Scheimpflug Photography; Corneal Disease; Eye Diseases
MeSH terms: Eye Diseases; Keratoconus; Corneal Diseases
Study type: Interventional

Summary: 
      The purpose of this study is to evaluate the efficacy, safety and postoperative ocular
      discomfort by comparing individually customized Photorefractive intrastromal crosslinking
      (PiXL) for progressive Keratoconus. The study compares two different protocols, PiXL with
      corneal epithelium debridement (Epi-off) and PiXL without epithelium debridement in high
      oxygen environment (Epi-on), with the hypothesis that Epi-on gives less postoperative ocular
      discomfort.
    

Detailed description: 
      The study is designed as a prospective, single-masked intraindividually comparing randomized
      clinical trial involving participants of both genders aged 18-35 years with Keratoconus
      planned for routine corneal crosslinking at the Department of Ophthalmology, Umeå University
      Hospital, Umeå, Sweden. The study includes 32 participants with bilateral Keratoconus,
      receiving Epi-off PiXL (n=32) in one eye and Epi-on PiXL in high oxygen environment (n=32) in
      the fellow eye. The participants are randomized to epi-on PiXL utilizing block randomization
      with a sample size of 16 in each block; 16 right eyes and 16 left eyes. All participants are
      informed about the procedures before consenting to participate in the study.

      At baseline, before treatment, each eye is examined with slit-lamp microscopy, subjective
      refraction, determination of uncorrected (UCVA), low contrast visual acuity at 2.5 percentage
      contrast and 10 percentage contrast and best corrected (BSCVA) visual acuities using the
      LogMAR fast protocol and intraocular pressure (IOP) using Goldmann applanation tonometry.
      Under standardized, mesopic light conditions each eye is evaluated by keratometry readings
      and central corneal thickness using Schemipflug camera measurements, Pentacam HR® (Oculus,
      Inc. Lynnwood, WA).

      Endothelial cellcount is assessed (SP-2000P, Topcon, Inc) and total ocular wavefront is
      measured with iTrace (Tracey Technologies, Inc.).

      Ocular discomfort is subjectively evaluated in each eye by a specific visual analogous rating
      scale at 4h, 8h 24h and thereafter daily up to 1 week postoperatively.

      All the above mentioned examinations are repeated at 1, 3, 6, 12 and 24 months after
      treatment. At 1 day and 1 week after treatment, solely UCVA, Auto-refractor measurements and
      slit-lamp examination are evaluated.
    

Intervention name(s): Epi-on PiXL; Epi-Off PiXL
Intervention type(s): Procedure; Procedure
Intervention description(s): Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the cornea is soaked in Riboflavin by repeated topical application during 10 minutes. For masking purposes, epithelial debridement is simulated by moving a scraping instrument in front of the cornea. A Riboflavin soaked sponge is used to lightly disrupt the epithelium tight junctions, without epithelium debridement. The cornea is illuminated with PiXL under 16:40 minutes during continuously delivery of humidified high oxygen via specific oxygen goggles. The UV-dosage is individually customized based upon Kmax; < 45D, 7.2J/cm2; 45-50D, 10J/cm2; > 50D, 15 J/cm2.; Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the corneal epithelium is debrided and the cornea is soaked in Riboflavin by repeated topical application during 10 minutes. The cornea is then illuminated with individually customized topography-guided PiXL under 16:40 minutes. The UV-dosage is individually customized based upon Kmax; < 45D, 7.2J/cm2; 45-50D, 10J/cm2; > 50D, 15 J/cm2.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Prospective, single-masked intraindividually comparing randomized controlled trial. Participants will be randomized to receive Epi-off PiXL in one eye and Epi-on PiXL in the other, which is masked to the participant. The participant can choose to treat in eye at a time or both eyes during the same visit.
Masking: Single (Participant)
Primary purpose: Treatment