Enrichment of Oxygen Concentration Over Simulated Corneal Surface Through Noncontact Oxygen Delivery Device

To demonstrate a noncontact device to enrich oxygen concentration during corneal cross-linking (CXL).

An oxygen delivery device was tested in a laboratory mock-up. The device comprises a clear polycarbonate tube of 14 cm in length and 1.58 cm inner diameter. Compressed oxygen gas is delivered to the tube from a side opening. The oximeter was attached to a sampling tube 3 mm above the apex of a scleral lens that simulates the cornea. The lens was mounted on a mannequin face. During each experimental run, the oximeter reading was recorded manually every 30 seconds for 4.5 minutes after the flow regulator was opened to the preset flow rate. Three flow rates of 0.25, 0.50, and 1 L/min were tested with all three cornea-tube distances of 8, 10, and 14 mm.

The baseline oxygen concentration was 20.9%. The oxygen concentration reached plateau levels after 2 to 3.5 minutes. Oxygen measurements were averaged over the three time points in the plateau phase between 3.5 and 4.5 minutes. Atmospheric oxygen concentration above the simulated cornea was found to be strongly dependent on the oxygen flow rate up to 1 L/min. At the 1 L/min flow rate, 99% concentration was achieved at 8 to 10 mm of cornea-tube distances, and dropped to 90% at 14 mm.

Atmospheric oxygen concentration can be boosted to more than 90% using a noncontact device. This could potentially improve the effectiveness of accelerated CXL by boosting oxygen transport more than fourfold. [J Refract Surg. 2020;36(9):613-616.].