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Mohit Parekh, Gianni Salvalaio, Stefano Ferrari, Marie-Claude Amoureux, Cecile Albrecht, Denis Fortier, Diego Ponzin; A quantitative approach to evaluate the overall quality of cornea used in a comparative study between two hypothermic storage media. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3066.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate and validate a new evaluation technique for calculating the overall quality (OQ) of the donor cornea and to check its efficacy in a comparative study for corneas preserved in Optisol-GS and Cornea Cold®.
24 pairs of corneas suitable for research with intact epithelial layer and good endothelial morphology were selected. 12 Right and 12 left corneas and vice versa were placed in each medium for a 4 week comparative study. The study was divided into 4 phases where phase 1 was open and the rest were blinded (masked observers). Endothelium was stained with trypan blue and cells were counted under a light microscope with a grid to check the mortality and endothelial cell density (ECD) manually. The ECD and the mortality were incorporated together to measure the viable endothelial cell density (VECD). Difference between epithelial and endothelial layer (using a grid on the knob) was evaluated microscopically for thickness measurement which was also confirmed using OCT. A transparency device was used for calculating the degree of transparency. Epithelium was stained using trypan blue to check the integrity, morphology and viability. All the above subjective parameters were converted to numerical values (range) for determining the OQ of the cornea. Statistical analysis was used to confirm the significant difference.
The conversion to numerical values helped to evaluate the quality of corneas at different time intervals of preservation in different media. Students t-test showed statistically better results (p<0.05) for thickness (from week 3), transparency (from week 2), morphology and VECD (from week 1) for the corneas that were preserved in Cornea Cold® rather than in Optisol-GS. OQ was statistically significantly better (p<0.05) from week 2 in Cornea Cold®. Epithelial quality was similar regardless of the medium.
The OQ evaluation of cornea presented here is efficient, consistent and easy. This technique could be used for comparative studies, to value corneas for eye-banks, bio-banks, research and transplantation purposes to standardize communication between cornea users. Cornea Cold® is a promising corneal preservation medium for hypothermic storage with preservation time of ≤21 days. This permits higher flexibility, evaluation accuracy, surgical manipulation and ease of transportation.
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