Translation between two foreign languages (or “cross-translation”) is a practice as old as the hills, and yet only now are professionals rediscovering it. As it has never before been investigated, the present paper intends to provide readers with an experiment-driven theoretical and descriptive analysis of quality in specialised cross-translation from French into English performed by native Italian translators. The data analysed comprise 4 translations by native English speakers and 4 by native Italian speakers on trabeculoplasty. Thanks to an assessment grid, idiomaticity and usability as predictive factors of quality in translation have been evaluated. The findings are further corroborated by a focus group made up of the 4 native Italian translators, as well as by a questionnaire to ascertain the attitude towards cross-translation among professional translators. The combination of these three approaches suggests that translation between two foreign languages is a widespread phenomenon that can be qualitatively assessed through usability, and whose deliverables should always undergo revision for a better result. Moreover, as idiomaticity appears to be consistent across the translations performed by both native and non-native speakers of English, the author of this study deems it unfit to predict quality in translation.