Vital dyes and light sources for chromovitrectomy: comparative assessment of osmolarity, pH, and spectrophotometry.
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.
Costa
Elaine de Paula Fiod
Ede P
Department of Ophthalmology, Vision Institute (IPEPO), Federal University of São Paulo, São Paulo, Brazil. elaine68@terra.com.br
Rodrigues
Eduardo B
EB
Farah
Michel Eid
ME
Dib
Eduardo
E
Penha
Fernando
F
Magalhães
Octaviano
O
Furlani
Bruno Albuquerque
BA
Lima Filho
Acácio A S
AA
de Miranda
Antônio
A
Maia
Mauricio
M
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
D004396:Coloring Agents; D009883:Ophthalmic Solutions