title: Smoothness assessment of corneal stromal surfaces.
abstract: OBJECTIVE
  To assess the accuracy of the scanning electron microscopy (SEM) and present alternative approaches to quantify surface roughness based on numerical analysis.
  
  
  METHODS
  Department of Ophthalmology, Maisonneuve-Rosemont Hospital, University of Montreal, Montreal, Quebec, Canada.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Lamellar stromal cuts were performed on human corneas using a femtosecond laser or a microkeratome. The photodisrupted stromal surfaces were processed for SEM, and images were acquired at ×1000 magnification. First, images were evaluated by independent observers. Second, images were analyzed based on first-order and second-order statistics of gray-level intensities. Third, 3-dimensional (3-D) surface reconstructions were generated from pairs of SEM images acquired at 2 angles.
  
  
  RESULTS
  Results show that traditional assessment of roughness based on evaluating SEM images by independent observers can be replaced by computer-image texture analysis; an algorithm was developed to avoid subjective and time-consuming observations. The 3-D reconstructions allowed additional characterization of surface properties that was not possible with SEM images alone. Significant fluctuations in surface height were lost, although they could be retrieved using 3-D reconstructions.
  
  
  CONCLUSIONS
  Image texture analysis allowed objective and repeatable assessment of stromal surface roughness; however, full assessments of surface-height fluctuations required 3-D reconstruction. These complementary methodologies offer a more comprehensive assessment of corneal surface roughness in clinical applications.
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: Anca
authors.initials: A
authors.lastname: Marian
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada; The Ophthalmology Department Ain Shams University, Cairo, Egypt.
authors.forename: Ossama
authors.initials: O
authors.lastname: Nada
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Légaré
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Meunier
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Vidal
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Roy
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Brunette
authors.affiliation: From the Maisonneuve-Rosemont Hospital Research Center (Marian, Nada, Brunette, Costantino), the Department of Mathematics and Statistics (Meunier, Roy), University of Montreal, and the Department of Ophthalmology (Meunier, Brunette, Costantino), University of Montreal, Montreal, Quebec, and the Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications (Marian, Légaré, Vidal), Varennes, Quebec, Canada. Electronic address: santiago.costantino@gmail.com.
authors.forename: Santiago
authors.initials: S
authors.lastname: Costantino
mesh_terms: D003319:Corneal Stroma / Q000601:surgery* / Q000648:ultrastructure*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D053685:Laser Therapy; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D014019:Tissue Donors