The purpose of this study was to investigate the effect of high molecular weight hyaluronan (HMWHA) eye drops on subbasal corneal nerves in patients suffering from severe dry eye disease (DED) and to evaluate the damage of subbasal corneal nerves associated with severe DED. Designed as an international, multicenter study, 16 patients with symptoms of at least an Ocular Surface Disease Index (OSDI) score of 33, and corneal fluorescein staining (CFS) of at least Oxford grade 3, were included and randomized into two study arms. The control group continued to use their individual optimum artificial tears over the study period of eight weeks; in the verum group, the artificial tears were substituted by eye drops containing 0.15% HMWHA. At the baseline visit, and after eight weeks, the subbasal nerve plexus of 16 patients were assessed by confocal laser scanning microscopy (CSLM). The images were submitted to a masked reading center for evaluation. Results showed a significant increase of total nerve fiber lengths (CNFL) in the HMWHA group (p = 0.030) when compared to the control group, where the total subbasal CNFL did not significantly change from baseline to week 8. We concluded that in severe DED patients, HMWHA from topically applied eye drops could cross the epithelial barrier and reach the subbasal nerve plexus, where it exercised a trophic effect.

Cystinosis is a rare lysosomal storage disease characterised by cystine crystal formation within cells. In the eyes, crystals accumulate in the cornea causing photophobia, loss of visual acuity, and corneal complications. Strict adherence to topical cysteamine treatment is the only therapy that reduces corneal crystal accumulation. Cystinosis, a crystallopathy, is also a disease of inflammation. As the disease progresses the inflammatory processes have a greater impact on the ocular manifestations. The age at which inflammation becomes increasingly significant is dependent on the adequacy of early patient management and adherence with therapy. As patients are living longer with cystinosis, optimising ocular management is increasingly important. No clinical guidelines addressing the long-term ocular management of cystinosis exist. Similarly, there is little recognition in the literature of how to address the inflammatory component of the disease. This paper presents management guidelines, linked to the 3C Classification of severity, used at our centre that provides a framework for optimising care. Adoption of these can help preserve the sight of cystinosis patients. The paper also hypothesises the molecular pathway leading to corneal inflammation.