title: Vital dyes and light sources for chromovitrectomy: comparative assessment of osmolarity, pH, and spectrophotometry.
abstract: OBJECTIVE
  To investigate the in vitro pH, osmolarity, spectral, and photostability properties of nine vital dyes for vitreoretinal surgery.
  
  
  METHODS
  Nine dyes-indocyanine green (ICG), trypan blue (TB), brilliant blue (BriB), bromophenol blue (BroB), Congo red (CR), light green (LG), fast green (FG), indigo carmine (IC) and Evans blue (EB)-diluted in three solvents (saline solution, glucose 5%, and water) were tested for osmolarity and pH. Spectrophotometry was used to determine absorbance properties of 27 solutions. Irradiance emission spectra of seven endoillumination light sources and fiber-optics were compared with dye absorbance curves.
  
  
  RESULTS
  Dye osmolarity in saline solution and glucose 5% varied widely (257-385 mOsm) and was lower (0-54 mOsm) when dyes were dissolved in water. Dyes diluted in three solvents showed pH values varying from 2.6 to 9.85. ICG, LG, TB, BroB, CR, and IC demonstrated different absorbances, depending on the solvent. BriB and FG showed similar absorbance curves with different solvents. Spectrophometric analysis showed that all dyes except ICG had remarkable spectral overlap with the light sources. Among endoillumination fiber-optics, overlap was greatest with dual-output illumination with an integrated laser pathway and least with a mercury vapor lamp.
  
  
  CONCLUSIONS
  Vital dyes showed variable osmolarity and pH, which also depended on the solvent used. Interaction of light from endoillumination source and vital dye may increase or decrease the risk for toxicity, making appropriate selection of both a desirable way to minimize the risk for phototoxic effects.
authors.affiliation: Department of Ophthalmology, Vision Institute (IPEPO), Federal University of São Paulo, São Paulo, Brazil. elaine68@terra.com.br
authors.forename: Elaine de Paula Fiod
authors.initials: Ede P
authors.lastname: Costa
authors.forename: Eduardo B
authors.initials: EB
authors.lastname: Rodrigues
authors.forename: Michel Eid
authors.initials: ME
authors.lastname: Farah
authors.forename: Eduardo
authors.initials: E
authors.lastname: Dib
authors.forename: Fernando
authors.initials: F
authors.lastname: Penha
authors.forename: Octaviano
authors.initials: O
authors.lastname: Magalhães
authors.forename: Bruno Albuquerque
authors.initials: BA
authors.lastname: Furlani
authors.forename: Acácio A S
authors.initials: AA
authors.lastname: Lima Filho
authors.forename: Antônio
authors.initials: A
authors.lastname: de Miranda
authors.forename: Mauricio
authors.initials: M
authors.lastname: Maia
mesh_terms: D004396:Coloring Agents / Q000737:chemistry* / Q000528:radiation effects*; D004355:Drug Stability; D019773:Epiretinal Membrane / Q000175:diagnosis / Q000601:surgery; D006863:Hydrogen-Ion Concentration; D008027:Light; D009883:Ophthalmic Solutions / Q000737:chemistry / Q000528:radiation effects; D009994:Osmolar Concentration; D013056:Spectrophotometry, Ultraviolet; D013194:Staining and Labeling / Q000379:methods; D014821:Vitrectomy
chemical_list: D004396:Coloring Agents; D009883:Ophthalmic Solutions