**5. Conclusions**

This is the first evidence that topically applied HMWHA eye drops induced a significant neurotrophic effect on the subbasal nerve plexus in humans. When applied after any kind of ocular surgery, HMWHA eye drops may serve to support the recovery of damaged nerves. Moreover, HMWHA eye drops offered a new therapeutic option in preventing and treating ocular surface disease, in particular diseases associated with nerve damage like diabetic keratopathy and all forms of neuropathic keratopathy. Future research will focus on the question if patients with diabetic keratopathy and other forms of neuropathic keratopathy could benefit from HMWHA eye drops. HMWHA eye drops provide a holistic approach while simultaneously addressing different interacting pathomechanisms of DED.

**Author Contributions:** B.D., S.A.T., B.S., and H.R. were the investigators taking IVCM images of their patients within the HYLAN M study; R.F.G. provided advice during the design of the HYLAN M study investigation plan and in the interpretation of the results of IVCM; O.S. provided the precise work instruction for IVCM and served as masked reading center for the IVCM images; K.W. performed the digital assessment of the images; G.-B.v.S. served as the coordinating investigator of the HYLAN M study; W.G.K.M.-L. had an overall responsibility for the HYLAN M study design, organization, regulatory compliance, monitoring, and study report; O.S., K.W., G.-B.v.S., J.H.-W., and W.G.K.M.-L. prepared the manuscript of this publication. All authors have read and agreed to the published version of the manuscript.

**Funding:** The HYLAN M study received unrestricted funding from i.com medical GmbH, Munich, Germany.

**Conflicts of Interest:** The study director Wolfgang G.K. Müller-Lierheim is also the CEO of the company i.com medical GmbH, Munich, Germany. The remaining authors declare no conflict of interest.
