title: Efficacy of ophthalmic viscosurgical devices in maintaining corneal epithelial hydration and clarity: in vitro assessment.
abstract: OBJECTIVE
  To determine the efficacy of hydroxypropyl methylcellulose (HPMC) and hyaluronic acid (HA) in maintaining corneal hydration and optical clarity.
  
  
  METHODS
  Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  In porcine autopsy eyes, the effect of 13 ophthalmic viscosurgical devices (OVDs) (5 formulations of HPMC; 8 formulations of HA) in maintaining corneal hydration and optical clarity was tested. The main outcome variables were the time to reach optical clarity of the cornea during dissipation of the OVD and duration of corneal hydration. These variables were assessed after the first application of the OVD, after balanced salt solution application to rehydrate the gel matrix, and after the second application of OVD on top of the first layer.
  
  
  RESULTS
  The study used 57 porcine eyes. High-molecular-weight HA 1.5% (zero shear viscosity [ZSV] 55,122 millipascal seconds [mPa.s]) took a significantly shorter time to reach optical clarity than HA 1.4% (ZSV 36,882 mPa.s) (P=.04). Hyaluronic acid 1.4% and HA 1.5% maintained corneal hydration significantly longer than HPMC 2.0% (P<.001).
  
  
  CONCLUSIONS
  For corneal hydration during short-lasting surgical procedures such as cataract surgery, the results suggest using HPMC because it distributes quickly and provides an adequate duration of sufficient corneal hydration. For corneal hydration during prolonged surgical procedures, such as vitreoretinal surgery, results suggest using HA 1.5% in the formulation because it provides long-lasting corneal hydration.
  
  
  BACKGROUND
  Dr. Prinz has a proprietary interest in Croma Pharma GmbH, Leobendorf, Austria. Dr. Findl is a scientific advisor to Croma Pharma GmbH. No other author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: Department of Ophthalmology, Hietzing Hospital, Vienna, Austria.
authors.forename: Ana
authors.initials: A
authors.lastname: Prinz
authors.forename: Carina
authors.initials: C
authors.lastname: Fennes
authors.forename: Wolf
authors.initials: W
authors.lastname: Buehl
authors.forename: Oliver
authors.initials: O
authors.lastname: Findl
mesh_terms: D000818:Animals; D002387:Cataract Extraction; D019573:Epithelium, Corneal / Q000187:drug effects*; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000008:administration & dosage / Q000031:analogs & derivatives*; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D012029:Refraction, Ocular / Q000502:physiology*; D013552:Swine; D014783:Viscosity; D055675:Viscosupplements / Q000008:administration & dosage*; D017155:Wettability; D014906:Wetting Agents / Q000008:administration & dosage
chemical_list: D009883:Ophthalmic Solutions; D055675:Viscosupplements; D014906:Wetting Agents; D065347:Hypromellose Derivatives; D006820:Hyaluronic Acid; D008747:Methylcellulose