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SOT Maxime, Julie FRANCOIS, Marie-Soline LUC, François Tortuyaux, YAHIA Rekia, Charlotte JAUD, Nadia ouamara, Christophe Goetz, Jean-Marc Perone; Visual acuity gain after cross linking (CXL) cases : role of cone excentration.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5676.
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© ARVO (1962-2015); The Authors (2016-present)
Although it isn't the first aim of cross linking (CXL), it was reported that some patients have shown improved best corrected visual acuity (BCVA) after a cross linking procedure. The aim of this study is to evaluate the proportion of BCVA improvement after cross linking, and trying to find explanation to this phenomenon in analyzing cone excentration evolution.
All consecutive patients treated with CXL between march 2014 and May 2016 were included. They all underwent the same procedure: accelerated-CXL protocole (De-epithelialization, 30 minutes Riboflavin impregnation followed by 10 minutes UVA irradiation at 9 mW/cm2 intensity). Irradiation device : IROC UV-X™ 2000, Medeuronet. The indication of all these CXL was a progressive keratoconus. Patients were divided into two groups. First group was composed of patients with BVCA improvement after CXL. The second group consisted in patients whose BCVA remained steady or was lower after CXL procedure. Visual acuity was assessed before CXL, and 6 months after CXL. Cone excentration evolution,(defined as the difference between conus excentration before CXL and six months after CXL), using OCULUS Pentacam. These characteristics were compared using a Student test.
80 patients (90 eyes) who underwent CXL were included. Mean age was 26 (SD=10 )years. 33 % were female. 40 eyes were included in the first group, 50 eyes in the second group : 44,4 % of eyes who underwent CXL procedure had BVCA improvement. BCVA mean variation after CXL procedure was -0,22 logMar (SD=0,19) in the first group. BCVA mean variation after CXL procedure was 0,08 logMar (SD=0,12) in the second group. The cone excentration was decreased of 0,03mm (SD=0,22) in the first group. The cone excentration was decreased of 0,01mm (SD=0,38) in the second group. There was no significant difference in the two groups concerning conus excentration evolution (student test : p= 0,75).
Although some cases had a decreased excentration of the cone associated to a BCVA gain, our study did not show any difference of conus excentration variation between patients with BCVA improvement, compared to those whose BCVA remained stable or went lower. There might exist other factors that influence visual acuity gain after CXL procedure that still need to be found out.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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