Efficacy of fixation of the amniotic membrane on a symblepharon ring with continuous suturing in acute ocular chemical burn patients

Development of a new plasma rich in growth factors membrane with improved optical properties

PURPOSE

The aim of the present work was to develop a fibrin membrane using plasma rich in growth factors (PRGF) technology with improved optical properties to be used for the treatment of ocular surface diseases.

BASIC PROCEDURES

Blood was drawn from three healthy donors, and the volume of PRGF obtained from each donor was divided into two main groups: i) PRGF or ii) platelet-poor plasma (PPP). Each membrane was then used pure or diluted to 90 %, 80 %, 70 %, 60 % and 50 %. The transparency of each of the different membranes was evaluated. The degradation and morphological characterization of each membrane was also performed. Finally, a stability study of the different fibrin membranes was performed.

MAIN FINDINGS

The transmittance test showed that the fibrin membrane with the best optical characteristics was obtained after removal of platelets and dilution of fibrin to 50 % (50 % PPP). No significant differences (p > 0.05) were observed between the different membranes in the fibrin degradation test. The stability test showed that the membrane at 50 % PPP retains its optical and physical characteristics after storage at - 20 °C for 1 month compared to storage at 4 °C.

PRINCIPAL CONCLUSIONS

The present study describes the development and characterization of a new fibrin membrane with improved optical characteristics while maintaining mechanical and biological characteristics. The physical and mechanical properties of the newly developed membrane are preserved after storage for at least 1 month at - 20 °C.

Clinical Benefits of Amniotic Membrane Contact Lens

Purpose: To investigate the clinical efficacy of MS-Amnion amniotic membrane contact lenses.Methods: MS-Amnion amniotic membrane contact lenses were placed for 1 week in patients with severe superficial punctate keratitis or corneal epithelial defects that did not respond to medical treatment. Eighteen eyes followed-up for ≥3 months were evaluated in terms of the best-corrected visual acuity, tear break-up time, and corneal sensation and opacity before and after application of the MS-Amnion amniotic membrane contact lens. The success and recurrence rates, and complications during follow-up, were recorded.Results: Out of 18 eyes, 15 (83.3%) healed within 2 weeks without any treatment other than the amniotic membrane; three eyes (16.7%) were unresponsive, and thus underwent temporary amniotic membrane transplantation. Recurrence developed in three eyes (20%). The amniotic membrane contact lens dropped out in five eyes (27.8%) and folded over in two (11.1%). The mean best-corrected visual acuity improved from 0.89 to 0.27 logarithm of the minimal angle of resolution after 3 months, while the mean corneal opacity decreased from 0.38 to 0.11 after 3 months; the changes were statistically significant. The tear break-up time and corneal sensation also improved, but they were not statistically significant. We encountered no significant complications.Conclusions: The MS-Amnion amniotic membrane contact lenses can heal the amniotic membrane and do not require suturing when applied in the outpatient clinic. This may be beneficial for patients with intractable ocular surface disorders.

Amniotic Membrane Transplantation for Persistent Epithelial Defects and Ulceration due to Pseudomonas Keratitis in a Rabbit Model

Purpose

The use of amniotic membrane has been suggested in the treatment of infectious keratitis for its intrinsic anti-infective properties probably mediated by its anti-inflammatory effects. The aim of this study was to investigate the effect of amniotic membrane transplantation (AMT) along with ciprofloxacin to cure the primary stages of Pseudomonas keratitis.

Methods

In total, 28 rabbits were selected and divided in four groups as follows: group 1 as control, group 2 with amniotic membrane, group 3 with ciprofloxacin, and group 4 with amniotic membrane combined with ciprofloxacin. About 0.05 cc suspension of Pseudomonasaeruginosa, 27853 ATCC was injected into corneal stroma.

Results

The results showed groups of AMT, AMT + ciprofloxacin, and ciprofloxacin had 0% perforation while the control group had 85.6%. Average infiltration of 5.5 mm was observed in ciprofloxacin group, 5 mm in AMT + ciprofloxacin group, 24 mm in AMT group, and finally 23.75 mm for control. Amniotic membrane showed to be effective in prevention of cornea perforation as well as remission of Pseudomonas keratitis. There was no significant difference between ciprofloxacin groups in comparison with ciprofloxacin + AMT group. However, regarding the anti-inflammatory effect, the process of improvement of inflammation in ciprofloxacin + AMT group was faster.

Conclusion

Transplantation of amniotic membrane in the primary stages of Pseudomonas keratitis treatment remarkably prevents the disease and it can be used to control its process.

Various administration forms of decellularized amniotic membrane extract towards improving corneal repair

Amniotic membrane (AM) transplantation is often used as a treatment for corneal repair, but AM is prone to dissolving and shedding after surgery; multiple transplants will cause pain and financial burden. In this work, human amniotic membrane was firstly decellularized to obtain an AM extracellular matrix (dAM). This dAM was homogenized and extracted to obtain the dAM extract (simplified as dAME). Different forms of administration for corneal injury were performed as liquid drops (diluted dAME), in situ gels (using temperature-dependent Poloxamer 407 as the matrix), and tablets (poly(vinyl alcohol) as the matrix). The cytocompatibility of dAME was evaluated using corneal epithelial cells, corneal stromal cells and fibroblasts as cell models. The results showed that dAME is biocompatible to all these cells. Cells exhibited normal morphology and growth state at a dAME concentration of up to 160 μg mL^-1. In vivo, dAME exhibited increased wound healing efficiency in severe corneal injury, being characterized with a shorter healing time for epithelium and a faster recovery for stromal opacity and thickness, compared with those of the control eyes. Different forms of administration have different effects on corneal repair; among them, in situ gels achieved the best therapeutic efficiency. Their biological mechanism was detected via quantitative real-time polymerase chain reaction (qRT-PCR) technology. It was confirmed that dAME plays important roles in promoting the mRNA expression of leucine-rich and immunoglobulin-like domains 1 (LRIG1) and in inhibiting the mRNA of transforming growth factor-β1 (TGF-β1).

Surgical Management and Recent Advances in Chemical Injury: A 5-year Review

Purpose: To review the surgical management options in ocular chemical burn, including newer advances.Methods: Online literature search of published articles over last 5 years on surgical management of ocular chemical burn and newer advances were performed on December 30, 2020.Results: Following literature search and screening using adequate filters, 67 review articles on surgical management of ocular chemical burns were retrieved. The review talks about the surgical management options starting from Debridement in acute stage to various visual rehabilitative procedures in the chronic stage. The review also highlights the evolving surgical advances in this field.Conclusion: It is imperative to choose adequate surgical tool wherever applicable; current review discusses the role of each surgical option at different clinical stages in detail.

Evaluation and ultrastructural changes of amniotic membrane fragility after UVA/riboflavin cross-linking and its effects on biodegradation

This study aims to evaluate the changes of fragility and ultrastructure of amniotic membrane after cross-linking by UVA/riboflavin.Forty-nine fresh amniotic membranes were randomly divided into 3 groups. Eighteen were in group A (CX group) and immersed in 0.1% riboflavin solution for 10 min for UVA/riboflavin cross-linking. Sixteen were in group B (B2 group), soaked for 10 min with 0.1% riboflavin. After soaking, membranes in group A and B were transferred into corneal preservation solution. Fifteen pieces were in group C, directly into corneal preservation solution. The biomechanical and ultrastructural changes of the amniotic tissue before and after cross-linking were examined (CX group = 13, B2 group = 11, C group = 15). The amniotic membrane tissue of group A (n = 5) and B (n = 5) was transplanted into 16 eyes of the rabbits, respectively, and the dissolution time of the amniotic membrane tissue was investigated.After cross-linking, compared with the control group, the elastic modulus of the low-stress area of the amniotic membrane (Elow) was higher, while the elastic modulus of the high-stress area of the amniotic membrane (Ehigh) was lower, with no significant difference in the tensile strength. Also, the collagen fibers showed coarse and bamboo-like changes. In group A, amniotic membranes began to dissolve 4 weeks after conjunctiva transplantation, and all amniotic membranes were dissolved and absorbed 6 weeks after conjunctiva transplantation. In group B, some amniotic membrane tissues were still visible 6 weeks after conjunctiva transplantation.This study suggested that after amniotic membrane cross-linking, the brittleness was increased, the hardness was enhanced, and the morphology of the collagen fiber was changed. The cross-linked amniotic membrane showed resistance to tissue dissolution.