Optical measurement of dioptric power and transparency of cornea stored in an innovative bioreactor

Abstract

Purpose: Quantification of dioptric power (DP) and transparency (T) of stored corneas remain almost unmet in daily eye bank practice. Complementary to T, DP could help screening donors having had refractive surgery and selecting the best donor/recipient refractive matching. During the development of an innovative corneal bioreactor (patented) for preclinical research and long-term storage, we took into account the possibility to integrate devices to perform these new quality controls. Aim: to present an original device, named “frontofoco-graft-meter” (FGM) able to quantify DP and T of corneas in the bioreactor.

Methods: Measurement of DP was based on the principle of magnification measurement and for T on the transmitted light over incoming light ratio. The FGM comprised a light source + specific chart made of parallel black lines + digital camera. Human corneas in the bioreactor were pressurised at 15 mmHg, with medium circulation in endothelial chamber, whereas epithelial chamber was filled with air during measurements. DP was compared to the power map provided by OCT (Tomey, Casia SS-1000, Japan), and T measures to results provided by our previous device called ‘transparometer’ (based on the analysis of modulation transfer function). Measurements were done by 3 operators in a masked fashion.

Results: For DP, agreement with OCT was good (within ±1 Dioptry). For T, measurements were comparable with both devices. Inter-rater agreement was good for DP and T. FGM took a limited place and could easily be integrate in eye banks.

Conclusions: The new FGM provides objective and reproducible quality controls of DP and T of corneas placed in the corneal bioreactor.

Keywords: 483 cornea: storage • 480 cornea: basic science • 733 topography