In Vivo Confocal Microscopy Automated Morphometric Analysis of Corneal Subbasal Nerve Plexus in Patients With Dry Eye Treated With Different Sources of Homologous Serum Eye Drops

Purpose: To investigate the comparative effect of allogeneic peripheral blood serum (allo-PBS) and cord blood serum (CBS) eye drops on the status of the corneal subbasal nerve plexus in patients with dry eye disease by using an automated analysis system of in vivo confocal microscopy images. Methods: This prospective, randomized, double-blind study included 30 patients with severe dry eye disease assigned to receive allo-PBS (group 1) or CBS (group 2) eye drops 8 times a day for 30 days. The following in vivo confocal microscopy parameters were calculated with ACCMetrics before (visit 1 [V1]) and after treatment (visit 2 [V2]): corneal nerve fiber density, corneal nerve branch density, corneal nerve fiber length, corneal nerve total branch density, corneal nerve fiber area, corneal nerve fiber width, and corneal nerve fractal dimension (CNFrD). Results: In overall patients, the values of corneal nerve fiber density, corneal nerve fiber length, and CNFrD significantly increased, whereas the value of corneal nerve fiber width signif- icantly decreased at V2 compared with V1 (respectively, 20.4 6 7.9 vs. 17.4 6 10.1 n/mm2; 13.5 6 4.0 vs. 12.0 6 5.1 mm/mm2; 1.466 6 0.046 vs. 1.475 6 0.033; and 0.022 6 0.002 vs. 0.023 6 0.002; all P , 0.05). In the subanalysis according to the treatment type, the increase of CNFrD value from V1 to V2 was higher in group 2 compared with group 1 (respectively, from 1.455 6 0.041 to 1.471 6 0.030 and from 1.479 6 0.050 to 1.481 6 0.035; P = 0.030). Conclusions: Overall, both treatments significantly improved corneal subbasal nerve plexus parameters, and in particular, nerve density, length, width, and fractal dimension. Treatment with CBS eye drops was associated with a higher increase of CNFrD compared with allo-PBS.