@article {1307459,
	title = {Quantitative analysis of corneal stromal riboflavin concentration without epithelial removal},
	journal = {J Cataract Refract Surg},
	volume = {44},
	number = {2},
	year = {2018},
	month = {2018 Feb},
	pages = {237-242},
	abstract = {PURPOSE: To compare the corneal stromal riboflavin concentration and distribution using 2 transepithelial corneal crosslinking (CXL) systems. SETTING: Absorption Systems, San Diego, California, USA. DESIGN: Experimental study. METHODS: The stromal riboflavin concentration of 2 transepithelial CXL systems was compared in rabbit eyes in\&nbsp;vivo. The systems were the Paracel/Vibex Xtra, comprising riboflavin 0.25\% solution containing TRIS and ethylenediaminetetraacetic acid and an isotonic solution of riboflavin 0.25\%, (Group 1) and the CXLO system (Group 2). Manufacturers{\textquoteright} Instructions For Use were followed. The intensity of riboflavin fluorescence by slitlamp observation 10, 15, and 20\&nbsp;minutes after instillation was graded on a scale of 0 to 5. The animals were humanely killed and the corneal stromal samples analyzed with liquid chromatography and mass spectrometry. RESULTS: The mean riboflavin fluorescence intensity grades in\&nbsp;Group 1 (4 eyes) were 3.8, 4.8, and 4.8 at 10, 15, and 20\&nbsp;minutes, respectively. The mean grades in Group 2 (3 eyes) were 2.0, 2.3, and 2.0, respectively. The riboflavin distribution was uniform in Group 1 but not in Group 2. The mean riboflavin concentration by liquid chromatography and mass spectrometry was 27.0\&nbsp;μg/g stromal tissue in Group 1 and 6.7\&nbsp;μg/g in Group 2. A stromal riboflavin concentration theoretically adequate for CXL, 15\&nbsp;μg/g, was achieved in all eyes in Group 1 and no eyes\&nbsp;in Group 2. Slitlamp grading correlated well with liquid\&nbsp;chromatography and mass spectrometry concentration (R\&nbsp;=\&nbsp;0.940). CONCLUSIONS: The system used in Group 1 produced corneal riboflavin concentrations that were theoretically adequate for effective transepithelial CXL (>=15\&nbsp;μg/g), while the system in Group 2 did not. Slitlamp grading successfully estimated the corneal riboflavin concentration and can be used to ensure an adequate concentration of riboflavin in the cornea for transepithelial CXL.},
	issn = {1873-4502},
	doi = {10.1016/j.jcrs.2018.01.010},
	author = {Rubinfeld, Roy S and Stulting, R Doyle and Gum, Glenwood G and Talamo, Jonathan H}
}
