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Omkar C Thaware, David Huang; Enrichment of oxygen concentration over corneal surface through non-contact oxygen delivery device.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2581.
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© ARVO (1962-2015); The Authors (2016-present)
To enrich oxygen concentration during corneal collagen crosslinking (CXL) with a noncontact device.
An oxygen delivery device was tested in a laboratory mockup. The device comprises a clear polycarbonate tube of 14 cm in length and 15.8 cm inner diameter (Figure 1). Compressed oxygen gas (99% purity) is delivered to the tube from a side opening through a flow regulator. The oximeter was attached to a sampling tube of 1.50 mm inner diameter at 3 mm above the apex of a scleral lens that simulates the cornea. During each experimental run, the oximeter reading was recorded manually at every 30 seconds for 4.5 minutes after the regulator was opened to the preset flow rate. Three flow rates of 0.25 L/min, 0.50 L/min and 1 L/min were tested with all three cornea-tube distances of 8 mm, 10 mm and 14 mm.
The baseline oxygen concentration was 20.9%. The oxygen concentration reached plateau levels after 2.0 to 2.5 minutes. Oxygen measurements were averaged over the five time points in the plateau phase between 2.5 to 4.5 minutes. Atmospheric oxygen concentration above the simulated corneal surface was found to be strongly dependent on the oxygen flow rate up to 1 L/min flow rate (Figure 2). At the 1 L/min flow rate, 99% concentration was achieved at 8-10 mm of cornea-tube distances, and drops to 93% at 14 mm.
Atmospheric oxygen concentration can be boosted to greater than 90% using a noncontact device. This could potentially improve the effectiveness of accelerated CXL by boosting oxygen transport more than 4 folds and avoid stromal oxygen depletion.
This is a 2020 ARVO Annual Meeting abstract.
Photograph of the setup to measure oxygen concentration through transparent plastic tube. Scleral contact lens (simulating the cornea) is placed below the O2 delivery tube, aligning its apex to the center of the tube opening.
Oxygen enrichment as a function of oxygen flow rates and distances between cornea and tubing. Oxygen measurements were averaged over the five time points in the plateau phase between 2.5 to 4.5 minutes. Error bars represent the standard deviation of the three trials.
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