Phase I/II randomized, double-masked, placebo-controlled study of processed amniotic fluid drops after PRK

Amniotic Fluid as a Potential Treatment for Vocal Fold Scar in a Rabbit Model

OBJECTIVES/HYPOTHESIS

Vocal fold (VF) injury and chronic inflammation can progress to scarring, which is notoriously difficult to treat. Human amniotic fluid (AF) has potential for VF wound healing in a rabbit model, and we hypothesized that AF would demonstrate wound healing properties superior to hyaluronic acid (HA) over time.

STUDY DESIGN

Randomized, controlled trial.

METHODS

In this pilot study, 60 New Zealand white rabbits (10 rabbits in each of six groups) received unilateral VF biopsy and immediate injection treatment of AF, HA, or saline (SA). The contralateral VF served as an uninjured control. Rabbits were sacrificed and VFs removed at 4 or 10 weeks postinjury. Rheology and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) were employed to assess viscoelastic properties and inflammation, respectively.

RESULTS

Rheology differences were seen between four and 10 weeks postinjury in treatment groups but not in controls. Values for the AF treatment group differed from the SA and HA groups at week 10 (elastic P = 0.0002, viscous P < 0.0001). RT-qPCR: AF and HA had higher levels of inflammatory cytokines than SA at week 4 [TNFα: SA4 < HA4 (P = 0.0086), SA4 < AF4 (P = 0.0112)]. Presumptive inflammation was still present at 10 weeks in all treatment groups [IL-1β: AF control < AF (P = 0.0002), SA control < SA (P = 0.0212); IL-6: HA control < HA (P = 0.0312)]. AF demonstrated reduced inflammation at 10 weeks compared with SA [IL-6: SA > AF (P = 0.0141)]. AF was the only treatment group that had significant reductions in inflammation at 10 versus 4 weeks [IL-1β: AF4 > AF10 (P = 0.0249)].

CONCLUSIONS

The main finding from this pilot study was that AF demonstrated wound healing effects over time compared with HA and SA by reducing inflammation and improving VF viscoelastic properties. Continued research to further investigate the use of AF in VF wound healing over longer periods of time is necessary before translation to human VFs.

One-Year Results of a Phase I/II Randomized, Double-Masked, Placebo-Controlled Study of Processed Amniotic Fluid Drops After PRK

PURPOSE

The aim of this study was to evaluate the 1-year outcomes of using processed amniotic fluid (pAF) postoperatively after photorefractive keratectomy (PRK).

METHODS

Sixty-one participants were randomized to receive either placebo or pAF drops. The drops were instilled 4 times daily for 1 week after PRK along with routine postoperative medications. The primary outcome measures included uncorrected visual acuity, topographic corneal irregularity measurement, and surface staining over 1 year.

RESULTS

A statistically significant difference in uncorrected distance visual acuity between the placebo and treatment groups was seen at 1 month post-PRK, with a visual advantage evident in the pAF group. A suggestive difference in corneal irregularity measurement was also seen between the placebo and treatment groups at 1 month postsurgery, with less irregularity noted in the pAF group. No differences in uncorrected distance visual acuity or corneal irregularity measurement were found at 3, 6, and 12 months. There was also no significant difference in corneal staining scores between the 2 groups at any of the measured time points.

CONCLUSIONS

This 1-year study evaluating the safety and efficacy of pAF as an additional postoperative topical medication after PRK demonstrated that pAF offered a mild visual advantage at 1 month post-PRK. There were no late adverse events, and the intervention proved safe at 1 year.