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Comparative Study of Riboflavin-UVA Cross-linking and “Flash-linking” Using Surface Wave Elastometry

2008; Slack Incorporated (United States); Volume: 24; Issue: S2 Linguagem: Inglês

10.3928/1081597x-20080901-20

1938-2391

Karolinne Maia Rocha, Jerome C. Ramos-Esteban, Ying Qian, Satish Herekar, Ronald R. Krueger,

Ocular Surface and Contact Lens

Purpose To investigate comparative stiffness values in porcine corneas after standard cross-linking and a new, rapid method of cross-linking (flash-linking) using surface wave elastometry. Methods Ten porcine eyes were treated using an ultraviolet A (UVA) double diode light source with a wavelength of 370 nm and delivering an irradiance of 4.2 mW/cm 2 at a distance of 1.2 cm while applying 0.1% riboflavin-5-phosphate drops to the central cornea every 5 minutes as a photosensitizer for 30 minutes (riboflavin-UVA group). The next 10 porcine corneas were treated with a single application of a customized photoactive cross-linking agent and 30 seconds of UVA light at the same power and wavelength (flash-linking group). Following treatment, the Sonic Eye system (PriaVision Inc) was used to measure ultrasound surface wave propagation time between two fixed-distance transducers applied to the cornea along central horizontal and vertical positions. Intraocular pressure was continuously monitored. Results Mean surface wave velocity was determined from the last 5 of 10 sequential measurements for each eye, and was 90.87±15.26 m/s for all eyes with a mean standard deviation (SD) of 2.34 m/s among each eye in the riboflavin-UVA group versus 83.66±12.30 m/s with a mean SD of 2.69 m/s among each eye in the flash-linking group before treatment and 109.2±21.76 m/s with a mean SD of 2.15 m/s among each eye (riboflavin-UVA group) versus 109.2±18.42 m/s with a mean SD of 2.26 m/s among each eye (flash-linking group) after cross-linking. The mean surface wave velocity increased by 18.3 units from 90.87 to 109.2 m/s ( P =.003) after cross-linking with riboflavin-UVA, and by 25.5 m/s from 83.66 to 109.2 m/s ( P =.0001) after flash-linking. Surface wave velocity was noted to increase after both cross-linking techniques, but the differences observed did not reach statistical significance ( P =.74). Conclusions A new, rapid method of cross-linking (flash-linking) is introduced by the use of a customized photoactive cross-linking agent. The method demonstrates similar efficacy in stiffening the cornea (when measured with surface wave elastometry) in comparison to standard cross-linking, but requires only 30 seconds of UVA exposure. [ J Refract Surg . 2008;24:S748–S751.]