Purpose:
Hydrofluoric acid burn up to now is evaluated by experiments derived from heuristic expositions of different types. The use of high resolution optical coherence tomography (OCT) to visualize penetration kinetics during the initial phase of chemical eye burns has been demonstrated recently for sodium hydroxide. We use this method to evaluate the penetration characteristics and the decontamination of HF from the ex vivo rabbit cornea within the ex vivo eye irritation assay (EVEIT).
Methods:
Corneas of each 3 ex vivo rabbit eyes were exposed to 50µl 2.5% HF solution for 20 sec. OCT recordings of high resolution corneal trans-sections were taken every 30 sec. Each 3 corneas were treated without rinsing, with each 5 minutes of water, Hexafluorine (Anti Flußsäure-Lösung) and 1% calcium gluconate solution. We recorded the opacity of the cornea and the propagation within the corneal layers during and after decontamination by rinsing.
Results:
Corneal burns with 2.5 % HF are complete within 120 seconds after exposures resulting in an increase in reflectivity throughout the whole cornea. With water rinsing and calcium gluconate rinsing optical density of the cornea itself was less intense as in untreated eyes. With Hexafluorine we found only 50% of the cornea of higher density and the deep corneal stroma remained clear. All corneas except water rinsed corneas shrinks in thickness to nearby half of the initial size. This was not the case for rinsed healthy eyes except Hexafluorine. We interpret the shrinkage as result of osmolar changes and loss of water binding capacity with shrinkage after HF burn.
Conclusions:
OCT can provide new and valuable information on kinetics of HF penetration into the cornea. The changes in thickness are directly accessible by means of OCT. The efficiency of decontamination can be demonstrated by means of OCT resulting in good decontamination of HF by Hexafluorine.
Keywords: ocular irritancy/toxicity testing • drug toxicity/drug effects • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)