In patients with dry eye disease (DED), treatment with self-retained cryopreserved amniotic membrane (CAM)—present in PROKERA Slim (PKS) (Bio-Tissue, Inc., Miami, FL)—may be efficacious in achieving corneal nerve regeneration and rapid ocular surface health recovery, according to study results published in the Journal of Ophthalmology.
“This prospective randomized controlled clinical trial demonstrates that self-retained CAM through the placement of PKS can accelerate the recovery of corneal surface health that lasts for at least three months in patients with moderate and severe DED,” wrote these authors, led by Thomas John, MD, Department of Ophthalmology, Loyola University at Chicago, and the Thomas John Vision Institute, Tinley Park, IL.
Dr. John and fellow researchers conducted this study to assess the efficacy of self-retained CAM—currently used to treat DED with ocular surface involvement due to its potent anti-inflammatory properties1—in aiding corneal nerve regeneration as well as improving corneal sensitivity in patients with DED. They randomized 17 patients with DED to CAM (study group) or conventional maximum treatment (control group), and evaluated changes in signs and symptoms, corneal sensitivity, topography, and in vivo confocal microscopy (IVCM) at baseline, 1, and 3 months.
These researchers found significant increases in corneal nerve density in subjects who received CAM, from 12,241 µm/mm2 at baseline, to 16,364 µm/mm2 at 1 month, and 18,827 µm/mm2 at 3 months (P=0.015). They found no difference, however, in control subjects.
Also in the study group treated with CAM, the improvement in corneal nerve density coincided with a significant increase in corneal topography and corneal sensitivity, from 3.25 cm at baseline to 5.2 cm at 1 month, and ultimately, 5.6 cm at 3 months (P < 0.001).
In addition to anti-inflammatory properties, CAM is rich in neurotrophic factors, especially nerve growth factor (NGF). It may be that because of this, CAM promotes corneal nerve regeneration.
“For the first time, we demonstrate that such a therapeutic efficacy is correlated with corneal nerve regeneration as evidenced by a significant increase in sub-basal corneal nerve density and corneal sensitivity. We thus surmise that the lasting effect of a single placement of PKS for treating DED may be attributed to corneal nerve regeneration,” noted the authors.
“This interpretation is supported by the fact that corneal nerves play a vital role in epithelial regeneration and tear film stability through reflex tearing and blinking. It also explains why the aforementioned corneal nerve regeneration can restore corneal surface as evidenced by resolution of corneal punctuate staining and improvement of tear film stability (ie, lengthened tear film breakup time [TFBUT]), despite that the Schirmer I test did not show significant changes,” they concluded.
Dr. John is a consultant for Bio-Tissue, Inc. This study was supported in part by a research grant from TissueTech, Inc., Miami, FL.
1. AM Cheng, D Zhao, R Chen, et al. “Accelerated restoration of ocular surface health in dry eye disease by self-retained cryopreserved amniotic membrane.” The Ocular Surface. 2016;14:56–63.