A recent review article investigated the importance of hyaluronic acid chain lengths in eye drops for the physical as well as physiological performance of the drops. The classification according to average molecular weight was proposed: LMW HA (low molecular weight hyaluronic acid: < 1.5 MDa), MMW HA (medium molecular weight hyaluronic acid: 1.5 – 2.3 MDa), HMW HA (high molecular weight hyaluronic acid: 2.4 – 2.9 MDa), Hylan A (very high molecular weight hyaluronic acid: > 3.0 MDa).
This month the results of a randomized clinical study involving 11 centers in eight countries were published. The therapeutic efficacy of Comfort Shield® 0.15% Hylan A eye drops was compared with a control group treated with other tear substitutes. Only patients suffering from severe dry eye symptoms (ocular surface disease index OSDI > 33) and, simultaneously, strong corneal fluorescein staining (CFS > 3 Oxford grade) were included. By the time of inclusion all patents were treated with their individual best therapy. The control group continued their therapy, whereas, in the Comfort Shield group the tear substitutes used until inclusion were replaced by Comfort Shield® eye drops. At the beginning of the study, after four weeks and after eight weeks the patients were subject to extensive diagnostic testing.
After eight weeks the symptoms of patients treated with Comfort Shield® eye drops had improved significantly as compared to the control group (difference in OSDI 13.5; p-value 0.001). Both discomfort/pain and visual stability were significantly ameliorated.
Within the study the testing centers had the option to submit images of the subbasal corneal nerve plexus taken by confocal laser scanning microscopy to a masked reading center for evaluation. Four of the testing centers provided the nerve images of their patients (eight each of the Comfort Shield group and the control group). The reading center found in the Comfort Shield group 51% growth of the total nerve fiber length (p-value 0.031) and no growth in the control group.
The authors of the study conclude that Comfort Shield® eye drops grant a holistic approach in the treatment of dry eye disease, simultaneously addressing the various and complex interacting pathomechanisms of the disease: lubrication, hydration, stabilization of the glycocalyx and barrier function, downregulation of inflammation, trophic support of corneal nerves, increasing goblet cell counts and expression of MUC5AC, support of aqueous tear production, and reduction of pain.