Purchase this article with an account.
I. Pentari, H. S. Ginis, A. Pennos, G. D. Kymionis, I. G. Pallikaris; Controlling Corneal Pachymetry Using Dextran Solutions: In vitro vs. in vivo Study. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6204.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Intraoperative variation of corneal hydration is the leading factor that may influence the laser-cornea interaction and particularly the ablation rate and post ablation surface quality in corneal refractive surgery. Although dextran solutions are described in the literature for controlling corneal hydration, it was the purpose of this study to identify a dextran concentration that is effective in maintaing physiological hydration in the living eye at the presence of the endothelial function and normal intraocular pressure.
Corneal epithelium was removed from 10 living rabbit eyes by means of a rotating brush. Ultrasound pachymetry (Sonogage Ohio, USA) was performed immediately after epithelium removal. The surface of each cornea was rinsed with Dextran solutions with concentrations ranging from 1 to 7% for a time interval of 2 minutes. Ultrasound pachymetry was performed immediately after rinsing. The Dextran concentration corresponding to zero change in pachymetry was determined by linear regression. In a different series of experiments, in vivo corneas were overhydrated by means of rinsing with saline. Following this acute change in hydration, the corneas were rinsed with the previously determined iso-osmotic concentration for 2 minutes. The changes in pachymetry were recorded after each step. Additionally, deepithelialized corneal discs, 8mm in diameter, were placed in individual beakers containing solutions of dextran (500kDa) in BSS at different concentrations for 3 hours. Corneal thickness was measured before and after immersion in the solutions.
In accordance to previous studies, the Dextran concentration that maintained physiological hydration in vitro was the 20%. However, a different concentration (3.9%) was determined for the in vivo corneas. Rinsing with the iso-osmotic concentration regulated pachymetry whithin 2% of the original value.
Corneal pachymetry (and therefore hydration) can be regulated intraoperatively by means of appropriate Dextran solutions for experimental procedures and for corneal refractive surgery. In cases where corneal hydration is different from normal this may contribute to increased accuracy of laser refractive procedures.
This PDF is available to Subscribers Only