Femtosecond laser-assisted laser in situ keratomileusis versus photorefractive keratectomy: Effect on ocular surface condition

Purpose: To compare ocular surface characteristics in eyes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Setting: Centro de Oftalmologia Barraquer, Barcelona, Spain. Design: Prospective comparative observational study. Methods: Patients with myopia who had femtosecond laser assisted LASIK or PRK were included. Tear osmolarity, the Ocular Surface Disease Index questionnaire, Schirmer I, corneal sensitivity, tear breakup time (TBUT), and corneal fluorescein staining were evaluated preoperatively and 3, 6, and 12 months postoperatively. The Wilcoxon signed-rank test was used for temporal intragroup analysis, and the Mann-Whitney U test was used for intergroup comparisons. Results: The study comprised 44 patients (44 eyes) with myopia. Comparison of the parameters between the femtosecond laser-assisted LASIK group (22 eyes) and the PRK group (22 eyes) showed a similar temporal progression postoperatively. Compared with the preoperative evaluation, corneal sensitivity decreased after 3 months (P = .002 and P = .02, respectively) and 6 months (P = .03 and P = .04, respectively). The TBUT reached the highest mean value after 12 months (P = .01 and P = .04, respectively), and tear osmolarity was slightly increased after 1 year, although the mean values remained within the normal range (P = .01 and P = .04, respectively). The only difference between the 2 groups was lower corneal sensitivity in the femtosecond laser-assisted LASIK group after 3 months (P = .02). The ocular surface condition could be considered clinically unaltered after 1 year in both groups. Conclusion: Femtosecond laser-assisted LASIK and PRK techniques seemed to be safe for the ocular surface condition and to have a similar effect on it.Postprint (author's final draft

Femtosecond laser-assisted laser in situ keratomileusis versus photorefractive keratectomy: Effect on ocular surface condition

Purpose: To compare ocular surface characteristics in eyes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Setting: Centro de Oftalmologia Barraquer, Barcelona, Spain. Design: Prospective comparative observational study. Methods: Patients with myopia who had femtosecond laser assisted LASIK or PRK were included. Tear osmolarity, the Ocular Surface Disease Index questionnaire, Schirmer I, corneal sensitivity, tear breakup time (TBUT), and corneal fluorescein staining were evaluated preoperatively and 3, 6, and 12 months postoperatively. The Wilcoxon signed-rank test was used for temporal intragroup analysis, and the Mann-Whitney U test was used for intergroup comparisons. Results: The study comprised 44 patients (44 eyes) with myopia. Comparison of the parameters between the femtosecond laser-assisted LASIK group (22 eyes) and the PRK group (22 eyes) showed a similar temporal progression postoperatively. Compared with the preoperative evaluation, corneal sensitivity decreased after 3 months (P = .002 and P = .02, respectively) and 6 months (P = .03 and P = .04, respectively). The TBUT reached the highest mean value after 12 months (P = .01 and P = .04, respectively), and tear osmolarity was slightly increased after 1 year, although the mean values remained within the normal range (P = .01 and P = .04, respectively). The only difference between the 2 groups was lower corneal sensitivity in the femtosecond laser-assisted LASIK group after 3 months (P = .02). The ocular surface condition could be considered clinically unaltered after 1 year in both groups. Conclusion: Femtosecond laser-assisted LASIK and PRK techniques seemed to be safe for the ocular surface condition and to have a similar effect on it

Bacterial nanocellulose as a corneal bandage material: a comparison with amniotic membrane

Corneal trauma and ulcerations are leading causes of corneal blindness around the world. These lesions require attentive medical monitoring since improper healing or infection has serious consequences in vision and quality of life. Amniotic membrane grafts represent the common solution to treat severe corneal wounds. However, amniotic membrane's availability remains limited by the dependency on donor tissues, its high price and short shelf life. Consequently, there is an active quest for biomaterials to treat injured corneal tissues. Nanocellulose synthetized by bacteria (BNC) is an emergent biopolymer with vast clinical potential for skin tissue regeneration. BNC also exhibits appealing characteristics to act as an alternative corneal bandage such as; high liquid holding capacity, biocompatibility, flexibility, natural – but animal free-origin and a myriad of functionalization opportunities. Here, we present an initial study aiming at testing the suitability of BNC as corneal bandage regarding preclinical requirements and using amniotic membrane as a benchmark. Bacterial nanocellulose exhibits higher mechanical resistance to sutures and slightly longer stability under in vitro and ex vivo simulated physiological conditions than amniotic membrane. Additionally, bacterial nanocellulose offers good conformability to the shape of the eye globe and easy manipulation in medical settings. These excellent attributes accompanied by the facts that bacterial nanocellulose is stable at room temperature for long periods, can be heat-sterilized and is easy to produce, reinforce the potential of bacterial nanocellulose as a more accessible ocular surface bandage.Authors acknowledge financial support from the Spanish Ministry of Science and Innovation through the RTI2018-096273-B-I00, project, the ‘Severo Ochoa’ Programme for Centers of Excellence in R&D (SEV-2015-0496) and the PhD scholarship of I. A. S. (BE-2017-076734) and the Generalitat de Catalunya with the 2017SGR765 and the 2019LLAV00046 projects. Authors also thank María Jesús Sánchez-Guisadofor for her assistance with the endotoxin study. The ICMAB technical services (TGA and X-Ray) and Marcos Rosado from the ICN2 electron microscopy service are acknowledged. The ICMAB members (IAS, AL, AR) participate in the CSIC Interdisciplinary Platform for Sustainable Plastics towards a Circular Economy, SUSPLAST and in the Aerogels COST ACTION (CA 18125). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe