title: Effect of the eyelid speculum on pachymetry during corneal collagen crosslinking in keratoconus patients.
abstract: OBJECTIVE
  To compare central corneal thickness (CCT) with and without using an eyelid speculum during corneal collagen crosslinking (CXL).
  
  
  METHODS
  University Medical Center Utrecht, Utrecht, the Netherlands.
  
  
  METHODS
  Prospective nonrandomized comparative study.
  
  
  METHODS
  Eyes with progressive keratoconus were treated by CXL and consecutively divided into 2 groups. In Group A, an eyelid speculum remained in place throughout the entire CXL procedure. In Group B, the eyelids remained closed during the 30-minute riboflavin instillation. Intraoperative ultrasound pachymetry measurements were performed at different timepoints. The visual acuity, refraction, keratometry, pachymetry, and endothelium were evaluated 6 months after CXL. The main outcome measures were intraoperative CCT measurements and the clinical CXL effect after 6 months.
  
  
  RESULTS
  Fifty-two eyes (50 patients) were treated. After riboflavin instillation, a statistically significant difference in CCT reduction was found between the 2 groups (P<.001), with a mean CCT decrease of 62 μm±53 (SD) (13%±11%) in Group A and 11±35 μm (2%±8%) in Group B. No statistically significant between-group differences were found after epithelial removal or ultraviolet-A (UVA) irradiation. Six months after CXL, no statistically significant between-group difference was found in the visual acuity, refraction, keratometry, pachymetry, or endothelium.
  
  
  CONCLUSIONS
  Avoidance of an eyelid speculum during riboflavin instillation resulted in less CCT reduction during CXL. This finding could increase the chance of attaining the required pachymetry safety margin for applying UVA and thus decrease the chance of premature CXL treatment termination.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Utrecht Cornea Research Group (Soeters, van Bussel, van der Valk, Van der Lelij), Department of Ophthalmology, University Medical Center Utrecht, Utrecht, and Zonnestraal Eye Hospital (Tahzib), Amersfoort, the Netherlands. Electronic address: n.soeters@umcutrecht.nl.
authors.forename: Nienke
authors.initials: N
authors.lastname: Soeters
authors.affiliation: From the Utrecht Cornea Research Group (Soeters, van Bussel, van der Valk, Van der Lelij), Department of Ophthalmology, University Medical Center Utrecht, Utrecht, and Zonnestraal Eye Hospital (Tahzib), Amersfoort, the Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: van Bussel
authors.affiliation: From the Utrecht Cornea Research Group (Soeters, van Bussel, van der Valk, Van der Lelij), Department of Ophthalmology, University Medical Center Utrecht, Utrecht, and Zonnestraal Eye Hospital (Tahzib), Amersfoort, the Netherlands.
authors.forename: Rikkert
authors.initials: R
authors.lastname: van der Valk
authors.affiliation: From the Utrecht Cornea Research Group (Soeters, van Bussel, van der Valk, Van der Lelij), Department of Ophthalmology, University Medical Center Utrecht, Utrecht, and Zonnestraal Eye Hospital (Tahzib), Amersfoort, the Netherlands.
authors.forename: Allegonda
authors.initials: A
authors.lastname: Van der Lelij
authors.affiliation: From the Utrecht Cornea Research Group (Soeters, van Bussel, van der Valk, Van der Lelij), Department of Ophthalmology, University Medical Center Utrecht, Utrecht, and Zonnestraal Eye Hospital (Tahzib), Amersfoort, the Netherlands.
authors.forename: Nayyirih G
authors.initials: NG
authors.lastname: Tahzib
mesh_terms: D000293:Adolescent; D000328:Adult; D002452:Cell Count; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000000981:diagnostic imaging; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004728:Endothelium, Corneal / Q000473:pathology; D005143:Eyelids; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D012256:Riboflavin / Q000627:therapeutic use; D014463:Ultrasonography; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin