Visual Acuity and Number of Amniotic Membrane Layers as Indicators of Efficacy in Amniotic Membrane Transplantation for Corneal Ulcers: A Multicenter Study

Outcomes and success of amniotic membrane transplantation for the treatment of corneal diseases

PURPOSE

The amniotic membrane (AM), the inner layer of the placenta, is a semitransparent, avascular, and thin tissue that is useful due to its structure. Amniotic membrane transplantation (AMT) avoids the need for keratoplasty to prevent corneal perforating. The purpose of the study was to evaluate the visual (gain of or no change in visual acuity) and corneal outcomes (closure of the ulcer or corneal healing) of AMT in patients with ocular surface diseases.

MATERIALS AND METHODS

This was a retrospective case control study (success or failure of the surgery). It was undertaken at a single academic center. The study cohort consisted of subjects with ocular surface diseases. Patients were treated with AMT for refractory ocular surface diseases. They were divided into five subgroups according to the preoperative diagnosis. The technique of AMT used was the onlay method with two layers of AM. Primary outcome measures included best corrected visual acuity (BCVA), the number of AMTs, and reepithelization of the corneal epithelium at the end of the treatment. Two weeks to six months were given to consider epithelial closure. Treatment success was defined as corneal healing within 6 months.

RESULTS

A total of the 66 eyes of 66 patients (39 male/27 female) with a mean age of 44 ± 23 years (range 1-88 years) were included in the study. A single AMT procedure achieved epithelial closure in 74.2% (n = 49) of the eyes (53% in <15 days, 19.6% in 15-30 days, and 1.5% in 1-6 months). The fastest reepithelization occurred in neurotrophic keratopathy, 76.9% of which cases occurred within 15 days after the AMT procedure. Treatment failure was observed in five patients (7.5%), four with keratitis and one with neurotrophic keratopathy. The highest closure rates were found in persistent epithelial defects, graft-versus-host disease (GvHD), and bullous keratopathy, although there was no statistically significant difference in BCVA. Pairwise comparisons were made of neurotropic keratoplasty versus bullous keratopathy (P = 0.025), neurotrophic keratopathy versus keratitis (P = 0.004), GVHD versus keratitis (P = 0.003), and lastly, GvHD versus bullous keratopathy (P = 0.023).

CONCLUSIONS

AMT is a safe, valuable, and fast treatment technique to treat corneal epithelial defects stemming from different etiologies that are refractory to conventional treatment.

The application of a 4D-printed chitosan-based stem cell carrier for the repair of corneal alkali burns

BACKGROUND

Corneal alkali burns can lead to ulceration, perforation, and even corneal blindness due to epithelial defects and extensive cell necrosis, resulting in poor healing outcomes. Previous studies have found that chitosan-based in situ hydrogel loaded with limbal epithelium stem cells (LESCs) has a certain reparative effect on corneal alkali burns. However, the inconsistent pore sizes of the carriers and low cell loading rates have resulted in suboptimal repair outcomes. In this study, 4D bioprinting technology was used to prepare a chitosan-based thermosensitive gel carrier (4D-CTH) with uniform pore size and adjustable shape to improve the transfer capacity of LESCs.

METHODS

Prepare solutions of chitosan acetate, carboxymethyl chitosan, and β-glycerophosphate sodium at specific concentrations, and mix them in certain proportions to create a pore-size uniform scaffold using 4D bioprinting technology. Extract and culture rat LESCs (rLESCs) in vitro, perform immunofluorescence experiments to observe the positivity rate of deltaNp63 cells for cell identification. Conduct a series of experiments to validate the cell compatibility of 4D-CTH, including CCK-8 assay to assess cell toxicity, scratch assay to evaluate the effect of 4D-CTH on rLESCs migration, and Calcein-AM/PI cell staining experiment to examine the impact of 4D-CTH on rLESCs proliferation and morphology. Establish a severe alkali burn model in rat corneas, transplant rLESCs onto the injured cornea using 4D-CTH, periodically observe corneal opacity and neovascularization using a slit lamp, and evaluate epithelial healing by fluorescein sodium staining. Assess the therapeutic effect 4D-CTH-loaded rLESCs on corneal alkali burn through histological evaluation of corneal tissue paraffin sections stained with hematoxylin and eosin, as well as immunofluorescence staining of frozen sections.

RESULTS

Using the 4D-CTH, rLESCs were transferred to the alkali burn wounds of rats. Compared with the traditional treatment group (chitosan in situ hydrogel encapsulating rLESCs), the 4D-CTH-rLESC group had significantly higher repair efficiency of corneal injury, such as lower corneal opacity score (1.2 ± 0.4472 vs 0.4 ± 0.5477, p < 0.05) and neovascularization score (5.5 ± 1.118 vs 2.6 ± 0.9618, p < 0.01), and significantly higher corneal epithelial wound healing rate (72.09 ± 3.568% vs 86.60 ± 5.004%, p < 0.01).

CONCLUSION

In summary, the corneas of the 4D-CTH-rLESC treatment group were similar to the normal corneas and had a complete corneal structure. These findings suggested that LESCs encapsulated by 4D-CTH significantly accelerated corneal wound healing after alkali burn and can be considered as a rapid and effective method for treating epithelial defects.

Self-Retained, Sutureless Amniotic Membrane Transplantation for the Management of Ocular Surface Diseases

Amniotic membrane (AM) has anti-inflammation, anti-fibrotic, and regenerative effects. Sutureless cryopreserved AM transplantation, ProKera® (Bio-Tissue, Inc., Miami, FL, USA), is easily applied by ophthalmologists in the treatment of ocular surface diseases. This retrospective study included patients with ocular surface diseases who received ProKera® between January 2022 and May 2023. Six patients (9 eyes) with a mean age of 56.8 ± 20.8 years old (range 25-74) and a mean follow-up period of 7.8 ± 4.1 months (range 1-12) were included, including 2 of recurrent conjunctival tumors with limbal and corneal involvement (cases 1-2), 1 of pterygium with marked astigmatism (case 3) and 3 of Stevens-Johnson syndrome (SJS, cases 4-6). ProKera® was inserted after the lesion excision and deep keratectomy in cases 1-3, and no recurrence or corneal complication was noted. Cases 4-5 were discharged from the intensive care unit and presented with severe chronic SJS. Most ocular manifestations improved significantly after symblepharon release and ProKera® insertion, except for corneal conjunctivalization in 1 eye (case 5). Case 6 involved early ProKera® use at the bedside during acute SJS, resulting in complete resolution. We concluded that the adjunctive application of ProKera® can be effective for ocular surface reconstruction and provides options to intervene earlier for outpatients or patients unstable for invasive surgical intervention.

AmnioClip-Plus as Sutureless Alternative to Amniotic Membrane Transplantation to Improve Healing of Ocular Surface Disorders

The medicinal benefits of amniotic membrane transplantation for ocular surface disorders are well accepted worldwide. Even in high-risk keratoplasties, the concomitant use of amniotic membrane has demonstrated its value in improving graft survival. However, its seam-associated application can lead to an additional trauma. The AmnioClip ring system, into which the amniotic membrane is clamped (AmnioClip-plus, AC+), was developed to avoid this surgical intervention. The AC+ is placed on the cornea, similar to a contact lens, under local anesthesia and can therefore be applied repeatedly. Clinical practice demonstrates the easy handling, good compatibility, and efficacy of this minimally invasive method.