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Mohit N. Parekh, Stefano Ferrari, Enzo Di Iorio, Vanessa Barbaro, Davide Camposampiero, Diego Ponzin, Gianni Salvalaio; A New Device To Measure The Objective Values For Transparency Of The Donor Cornea. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3071.
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© ARVO (1962-2015); The Authors (2016-present)
We have developed a portable device for the objective measurement for transparency of the donor corneas which is currently performed subjectively, for use by the eye banks and surgeons in evaluation prior to transplantation.
The transparency device (TD) is built ensuring 0% transmittance of surrounding light. The amount of light passed from the source is detected by a probe viewed digitally on a meter. The device has an opening on the top for light source, detachable system for insertion of petri plate (pp) & cornea, and a base helpful for transmitting the unabsorbed light to the probe. A new contact lens is used as a ‘Control’. Light emitted from the empty pp is noted as ‘Blank’. The cornea must be placed in the center of the pp under sterile conditions without any solution after a gentle wash with sterile PBS to ensure all the light emitted from the cornea is captured by the probe referred as ‘Sample’. The final % of light emitted by the cornea is calculated (S X 100 / B) and referred as % transparency. Blank reading must be performed before every sample.
20 corneas with intact epithelial layer were evaluated. Each cornea was submitted to 2 evaluation methods: subjective classification of transparency obtained by 2 different experts (exp 1 and 2) & untrained eye bank personnel (exp 3 - to find evaluation by eye banks without experts) and measurement of transparency with TD. Every cornea underwent subjective evaluation considering parameters like intact epithelial layer, physical defect/damage, presence of folds and clarity check. The correlation between expert 1, 2 and 3 to TD was 0.9886, 0.9796 and 0.9622. The standard error between all the 3 experts was 0 ± 5%. The mean standard deviation by expert 1, 2, 3 and TD was 1.023467, 1.026074, 2.198915 and 0.211126 and the p-Value for expert 1, 2 and 3 to TD was 0.739086, 0.81333 and 0.345935.
The device has a reasonable reproducibility and is portable, efficient, quick to use, cheap and does not require any previous preparation or correction of the instrument or sample. > 90% transparency was only found in new contact lens which is difficult to obtain in a normal cornea due to different layers and thickness of the cornea. It is also useful to understand the relation of thickness to transparency of cornea, research purposes and to study the difference in transparency of corneas at various stages of preservation prior to transplantation. It permits evaluation of the entire corneal region and so is particularly dedicated to eye banks in order to standardize the routine evaluation of the donated corneas, with respect to its transparency. It could also be used in pharmaceutical research to measure changes regarding clarity of grafts after therapy and to evaluate the strength of a new media formulation.
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