title: A technique to visualize corneal incision and lamellar dissection depth during surgery.
abstract: OBJECTIVE
  To describe a surgical technique to visualize the depth of corneal incisions and lamellar stromal dissections during surgery.
  
  
  METHODS
  In porcine cadaver eyes, the aqueous was exchanged by air. Thus an air-to-endothelium interface (i.e., a useful optical surface) was created at the posterior corneal surface. The air-to-endothelium interface was used as a reference plane to visualize the corneal thickness and the relative depth of corneal incisions and dissections. Freehand peripheral corneal incisions, tangential keratotomy incisions, and lamellar stromal dissections were made at an intended corneal depth of 60, 80, and 99%. Light microscopy was used to measure the relative depth of the incisions and dissections.
  
  
  RESULTS
  Achieved depth for peripheral corneal incisions averaged 65.2+/-5.3%, 78.8+/-5.1%, and 93.4+/-6.0%, respectively (p<0.05); and for tangential keratotomy incisions, 68.2+/-7.3%, 83.2+/-4.4%, and 95.8+/-3.6%, respectively (p<0.05). Achieved depth for lamellar stromal dissections averaged 58.3+/-9.4%, 81.1+/-3.4%, and 94.4+/-1.5%, respectively (p<0.05). Microperforations occurred with three incisions made at 99% intended depth.
  
  
  CONCLUSIONS
  During surgery, the depth of incisions and lamellar dissections relative to the corneal thickness can be visualized by filling the anterior chamber with air (i.e., by creating an optical interface at the posterior corneal surface).
authors.affiliation: Cornea Service, Rotterdam Eye Hospital, The Netherlands. melles@oogziekenhuis.nl
authors.forename: G R
authors.initials: GR
authors.lastname: Melles
authors.forename: F J
authors.initials: FJ
authors.lastname: Rietveld
authors.forename: W H
authors.initials: WH
authors.lastname: Beekhuis
authors.forename: P S
authors.initials: PS
authors.lastname: Binder
mesh_terms: D000388:Air; D000818:Animals; D000867:Anterior Chamber / Q000033:anatomy & histology; D003315:Cornea / Q000033:anatomy & histology* / Q000601:surgery*; D066298:In Vitro Techniques; D007646:Keratotomy, Radial / Q000379:methods*; D013537:Sutures; D013552:Swine