title: Increase in lens capsule stiffness caused by vital dyes.
abstract: OBJECTIVE
  To assess potential changes in lens capsule mechanical properties after staining with brilliant blue, indocyanine green (ICG), and trypan blue.
  
  
  METHODS
  Department of Ophthalmology and Applied Physics and Center for NanoScience, Ludwig-Maximilians-University, Munich, Germany.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Fifteen unstained lens capsules were dissected into 7 wedge-shaped parts. Three fragments were stained with brilliant blue 0.025%, ICG 0.05%, and trypan blue 0.06%, respectively, for 1 minute. Another 3 specimens were additionally illuminated using a standard light source. The seventh part served as an untreated control. All specimens were analyzed using atomic force microscopy (AFM) in contact mode with a scan rate of 0.6 Hz. Two scan regions of 10 μm × 10 μm were chosen, and stiffness was determined using AFM in a force spectroscopy mode. The force curves were performed with a data rate of 5000 Hz.
  
  
  RESULTS
  Staining of the samples resulted in an increase in tissue stiffness (brilliant blue: P<.001; ICG: P<.01; trypan blue: P<.05). Additional illumination after staining further increased tissue stiffness, but not significantly. Mean increase in the relative elasticity values were 1.61 ± 0.15 (SD) for brilliant blue, 2.04 ± 0.21 for brilliant blue with illumination, 1.63 ± 0.22 for ICG, 2.01 ± 0.22 for ICG with illumination, 1.23 ± 0.11 for trypan blue, and 1.39 ± 0.11 for trypan blue with illumination. In relation to unstained tissue, the relative elasticity of the stained tissue increased 1.2-fold after illumination.
  
  
  CONCLUSIONS
  Staining significantly increased the mechanical properties of the human lens capsule.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Department of Ophthalmology (Haritoglou, Schumann, Wolf, Kernt) and the Department of Applied Physics and Center for NanoScience (Mauell, Benoit), Ludwig-Maximilians-University, Munich, Germany; the Department of Ophthalmology (Henrich), University Hospital Basel, Basel, Switzerland. Electronic address: christos.haritoglou@med.uni-muenchen.de.
authors.forename: Christos
authors.initials: C
authors.lastname: Haritoglou
authors.forename: Stephan
authors.initials: S
authors.lastname: Mauell
authors.forename: Ricarda G
authors.initials: RG
authors.lastname: Schumann
authors.forename: Paul B
authors.initials: PB
authors.lastname: Henrich
authors.forename: Armin
authors.initials: A
authors.lastname: Wolf
authors.forename: Marcus
authors.initials: M
authors.lastname: Kernt
authors.forename: Martin
authors.initials: M
authors.lastname: Benoit
mesh_terms: D002387:Cataract Extraction; D004396:Coloring Agents / Q000633:toxicity*; D004548:Elasticity / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D007208:Indocyanine Green / Q000633:toxicity; D007903:Lens Capsule, Crystalline / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D018625:Microscopy, Atomic Force; D012394:Rosaniline Dyes / Q000633:toxicity; D013194:Staining and Labeling; D014343:Trypan Blue / Q000633:toxicity
chemical_list: D004396:Coloring Agents; D012394:Rosaniline Dyes; D014343:Trypan Blue; D007208:Indocyanine Green; C004692:coomassie Brilliant Blue