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Sidney J. Sousa, Liliane Ventura, Victor Lincoln; Transmittance of the UV Light Through Deepithelized Cadaver Cornea During the Cross-linking Procedure. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5208.
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© ARVO (1962-2015); The Authors (2016-present)
To study the transmittance of the UV light through deepithelized cadaver cornea during the cross-linking procedure.
The study included 20 human corneas preserved in Optisol-GS for 3 to 11 days (mean: 6 days). The corneas were washed with saline and laid on top of the lid of a Chiron Ophthalmics corneal storage chamber. About 10cm under this lid a 600 µm core diameter optical fiber connected to a spectrometer (USB 2000 Ocean Optics) received the UV transmitted through the mounting. After the complete deepithelization, one drop of riboflavin 0.1%, 400 mOsm, was instilled on the cornea, every 5 minutes, totaling 12 instillations. The UV treatment (365±5 nm, 3 mW/cm2, 1.51 mW, 5.405 J/cm2, 8mm spot, 45mm distance) started only after the 7th instillation. All measurements were collected 4 minutes after each instillation. The average time taken to collect each spectrum was 2 seconds. The thickness of the naked corneas ranged from 464 to 657µm (mean: 570 µm).
The average transmittance of the cornea with no riboflavin instillation was 62% (95% CI: 59 to 65%); after the 6th drop yet with no irradiation it was 32% (95% CI: 28 to 36). The UV irradiation started and after the 7th, 8th, 8th, 9th, 10th,11th and 12th drop the average transmittance was respectively 30% (95% CI: 26 to 34), 28% (95% CI: 24 to 32), 26% (95% CI: 22 to 30), 24% (95% CI: 20 to 28), 22% (95% CI: 19 to 26) and 21% (95% CI: 17 to 25).
The average transmittance in terms units of energy after the 7th, 8th,9th,10th ,11th and 12th drop were respectively 0.915 , 0.841, 0.793, 0.731, 0.687, 0.643 mW/cm2. All these results are above the assumed endothelium safety limit of toxicity of 0.35 mW/cm2.
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