title: [Cholesterol, alpha-tocopherol, and retinoid concentrations in silicone oil used as a vitreous substitute].
abstract: OBJECTIVE
  To verify the existence of organic lipophylic compounds in silicone oil extracted from human eyes following its use for previous retinal detachment, and to determine the intraocular permanence time of these substances in the oil.
  
  
  METHODS
  Concentrations of retinoic acid, retinol, retinal, cholesterol and alpha-tocopherol were detected by HPLC in 23 samples of silicone oil extracted from patients with complicated retinal detachments. The time interval between the time of injection of the silicone oil and the subsequent assessment varied from 3 to 50 months (the permanence time).
  
  
  RESULTS
  All tested compounds were found in the samples, but these were most commonly cholesterol and less frequently alpha-tocopherol. There was an inverse relationship between retinoic acid concentration and age (p=0.023), and a direct relationship between cholesterol concentration and permanence time (p=0.0008) at least up to 20 months.
  
  
  CONCLUSIONS
  These findings confirm that silicone oil is not an inert substance but is capable of extracting lipophylic compounds from the intraocular tissues. There is a clear linear elevation of cholesterol levels with increased intraocular permanence time. This finding could be used to further establish a safe permanence time for intraocular silicone oil used in ophthalmologic surgery. More studies with larger samples are warranted to evaluate this further.
authors.affiliation: Instituto Universitario de Oftalmobiología Aplicada, Servicio de Oftalmología, Hospital Clínico, Universidad de Valladolid, Spain. pastor@ioba.med.uva.es
authors.forename: J C
authors.initials: JC
authors.lastname: Pastor
authors.forename: M J
authors.initials: MJ
authors.lastname: Del Nozal
authors.forename: P
authors.initials: P
authors.lastname: Marinero
authors.forename: O
authors.initials: O
authors.lastname: Díez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002784:Cholesterol / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013508:Ophthalmologic Surgical Procedures / Q000009:adverse effects / Q000379:methods; D012163:Retinal Detachment / Q000601:surgery; D012176:Retinoids / Q000032:analysis*; D012827:Silicone Oils / Q000737:chemistry*; D014822:Vitreous Body / Q000737:chemistry / Q000601:surgery; D024502:alpha-Tocopherol / Q000032:analysis*
chemical_list: D012176:Retinoids; D012827:Silicone Oils; D002784:Cholesterol; D024502:alpha-Tocopherol