Amniotic membrane transplantation for persistent epithelial defects with ulceration

Amniotic membrane graft (AMG) for persistent epithelial defects following infective corneal ulcers and keratitis - A systematic review

Management of nonhealing corneal ulcers is challenging as it can lead to complications such as melting, descemetocele, and perforation, which can be prevented by amniotic membrane graft (AMG). The absence of any review (English language) on AMG for corneal ulcers prompted us to conduct this review. We looked for clinical trials (randomized and controlled) on the effect of AMG combined with other treatments, through various search engines utilizing the terms amniotic membrane and corneal ulcer. All patients who received AMG and/or conventional medication were included. Risk of bias tools derived from Cochrane collaboration were used to ascertain the standard and quality of the trials. Visual acuity and epithelial healing time were the main outcome measures studied. Three trials were finally selected for analysis. AMG was noted to be associated with better uncorrected visual acuity and reduction in neovascularization. There was no difference in best corrected visual acuity, epithelial healing time, and corneal opacity. There is evidence that the use of AMG is associated with improved uncorrected visual acuity as well as reduction in neovascularization of the cornea among patients with corneal ulcers, but there was no improvement in epithelial healing time or corneal opacity. Further multicenter randomized controlled trials are needed to elicit the beneficial effects of the intervention and augment the validity of this review.

The Performance of Topical Insulin in Persistent Corneal Epithelial Defects and Persistent Corneal Ulcers - A Case Series

PURPOSE

To retrospectively describe the performance of topical insulin in persistent corneal epithelial defects (CED) and persistent corneal ulcers.

METHODS

We reviewed cases of patients treated for persistent CED and persistent corneal ulcers using topical insulin in a concentration of 25 IU per milliliter three times per day. The closure rate of CED and corneal ulcers was the main outcome measure.

RESULTS

Thirty-seven episodes of 29 patients treated with topical insulin were reviewed. There was a wide range of additionally used medication, underlying pathologies as well as ocular and systemic comorbidities in our cohort. On average, insulin drops were started after 36 days of conventional therapy (SD 59, range 0-193) and were used for 42 days (SD 38, range 3-130). Therapy success was achieved in 15 of 28 (53.5%) cases with CED and in 4 of 9 (44%) cases with corneal ulcers. While insulin generally showed a good safety profile, one patient reported intolerable discomfort related to the use of topical insulin.

CONCLUSION

Topical insulin may be considered as a treatment option in complicated cases refractory to conventional treatment, but outcomes may be less favorable than previously reported.

Management of corneal injuries in spaceflight and recommendations for planetary missions

In February 1968, NASA purchased 400 antigravity ballpoint pens from the Fisher Pen Company for the Apollo Program to prevent potential harm to astronauts and equipment. Mechanical pencils previously used in microgravity posed risks like eye injuries from floating fragments penetrating the cornea. The cornea is vulnerable to abrasions, perforations, and chemical burns in such environments, affecting crewmembers aboard the International Space Station (ISS). While they undergo extensive training for emergency situations, there are inherent complexities when faced with eye injuries. In this challenging context, adapting available medications and leveraging emergency medical training is critical for addressing ocular injuries in a high-stakes environment. This paper explores ISS medications and management strategies for corneal injuries, highlighting the need to include effective medications and countermeasures in future ISS medical kits.

Management of Diathermy-Induced Corneal Burn following Upper Eyelid Blepharoplasty with Multilayer Amniotic Membrane Transplantation: A Case Report and Review of the Literature

Introduction

Thermal injuries associated with cosmetic eyelid surgery can significantly impair corneal integrity, potentially leading to vision loss. Conventional management, including bandage contact lens use, topical steroids, lubrication, autologous serum tears, and vitamin C, plays a crucial role in preventing long-term complications. This case report explores the potential benefits of multilayer amniotic membrane transplantation (AMT) as an adjunct to standard therapy for treating diathermy-associated corneal burns. Review of the literature advocates the beneficial effects of supplementary AMT in managing thermal corneal trauma.

Case Description

A 75-year-old man presented with unilateral diathermy-associated corneal laceration superior to the visual axis following cosmetic blepharoplasty. Vision had deteriorated from his baseline 20/30 to 20/125 postoperatively. Intervention involved multilayer AMT alongside standard care, including topical steroids and antibiotics, oral doxycycline, and vitamin C. Postoperative course was monitored with anterior segment optical coherence tomography (AS-OCT) imaging. By 3 months, complete corneal healing and restoration of baseline visual acuity were achieved.

Conclusion

This is the first documented case of multilayer AMT as an effective supplement to conventional management of diathermy-associated corneal injury. While AMTs unique properties likely contributed to corneal healing and visual recovery, the results should be interpreted in the context of a multimodal therapeutic approach.

Decellularized Descemet Membrane Anterior Keratoplasty With Allogeneic Simple Limbal Epithelial Transplantation for Partial Limbal Stem Cell Deficiency Following Partial Keratolimbal Allograft Failure

PURPOSE

The purpose of this study was to describe the use of Descemet membrane anterior keratoplasty (DMAK) with modified allogeneic simple limbal epithelial transplantation to treat a case of partial limbal stem cell deficiency (LSCD) following keratolimbal allograft failure.

METHODS

Case report.

RESULTS

A 21-year-old woman with autoimmune polyglandular syndrome-related LSCD presented with pain and decreased vision. There was partial failure and recurrence of LSCD after a severe/acute keratolimbal allograft rejection that led to persistent epithelial defects refractory to conservative therapy. This was treated with a superficial keratectomy and placement of a DMAK. A modified allogeneic simple limbal epithelial transplantation was performed with an overlying amniotic membrane and temporary tarsorrhaphy. There was epithelialization of the corneal surface by 3 to 4 weeks with an improved ocular surface. Despite partial recurrence of late staining, the cornea has remained epithelized, vision has improved, and the patient has remained pain-free more than 1.5 years following the procedure.

CONCLUSIONS

DMAK may be a long-term substrate to help improve and maintain epithelization of the cornea up to 1.5 years. DMAK may be a viable alternative to using amniotic membrane as a scaffold in allogeneic simple limbal epithelial transplantation for treatment of partial LSCD. While late epithelial staining recurred in our patient, DMAK appears to prevent recurrent epithelial defects and reduce ocular surface pain, conveying an improvement in quality of life in patients at high risk of rejection/failure.

Advances and impact of human amniotic membrane and human amniotic-based materials in wound healing application

Wound healing is a complicated process, especially when surgical, traumatic, burn, or pathological injury occurs, which requires different kinds of dressing covers including hydrogels, hydrocolloids, alginates foams and films for treatment. The human amniotic membrane (hAM) is a biodegradable extracellular matrix with unique and tailorable physicochemical and biological properties, generated by the membrane itself or other cells that are located on the membrane surface. It is noted as a promising aid for wound healing and tissue regeneration due to the release of growth factors and cytokines, and its antibacterial and immunosuppressive properties. Moreover, hAM has optimal physical, biological, and mechanical properties, which makes it a much better option as a regenerative skin treatment than existing alternative materials. In addition, this layer has a structure with different layers and cells with different functions, which act as a regenerative geometry and reservoir of bioactive substances and cells for wound healing. In the present work, the structural and biological features of hAM are introduced as well as the application of this layer in different forms of composites to enhance wound healing. Future studies are recommended to detect possible further functionalization to enhance the hAM effectiveness on wound healing.

Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia

PURPOSE

To propose an ultrathin biological amniotic membrane (btAM) thinner than 10 μm as the graft to treat highly myopic macular holes (MH).

METHODS

This pilot study included 14 patients affected by refractory macular holes associated with high myopia. btAM was used as a bandage covering the holes. The best-corrected visual acuity (BCVA), fundus photography, and optical coherence tomography (OCT) before and after surgery were compared.

RESULTS

The mean MH size was 865.93 ± 371.72 μm and all the MHs achieved anatomical closure. The btAM located centrally and fully on MHs from fundus photography yet no obvious visual masking was complained. The average BCVA 1 month, 3, and 6 months after surgery were 0.95 ± 0.24, 0.92 ± 0.23, 0.92 ± 0.23 logMAR, respectively, improved significantly compared to pre-operative BCVA (1.24 ± 0.42 logMAR, all P < 0.05). Ten out of 14 (71.4%) exhibited 2C closure patterns (formally closed and no bare RPE) on OCT.

CONCLUSION

The btAM thinner showed a favorable anatomical success with less risk of parafoveal atrophy or iatrogenic injuries and shortened the dissolving time.

Neurotrophic keratopathy: General features and new therapies

Neurotrophic keratopathy is an uncommon degenerative corneal disorder characterized by compromised corneal sensory innervation resulting in the formation of epithelial defects and nonhealing corneal ulcers. Various treatment modalities are available to stabilize disease progression, improve patient well-being, and prevent vision loss. For eligible patients, medical and surgical reinnervation have emerged as pioneering therapies, holding promise for better management. We present a comprehensive review of the disorder, providing an update relevant to ophthalmologists on pathogenesis, diagnosis, treatment options, and novel therapies targeting pathophysiological pathways.

Real-life experience on the effectiveness of conjunctival flap and amniotic membrane graft in the treatment of refractory fungal corneal ulcer

PURPOSE

To evaluate and compare the results of the conjunctival flap (CF) and cryopreserved amniotic membrane graft (AMG) in the management of fungal corneal ulcers either with complications or non-responsive to medical treatment.

STUDY DESIGN

A retrospective observational study.

METHODS

Medical records of 30 patients with culture-positive fungal corneal ulcer treated with either CF or AMG (15 eyes in each group) in real world settings were retrieved for analysis. After the surgical procedure, patients were followed up on days 1, 7, 14, 21, 30, 60, 90, 120, and 180 to explore the outcomes of the operations along with complications.

RESULTS

Infecting fungi were of genus Fusarium (n = 11), Aspergillus (n = 10), Mucor (n = 4) and Penicillium (n = 10). The most common indication was resistant ulcer with perforation. After the procedure, epithelization was completed in 11(73.33%) patients in the CF, and 13 patients in the (86.67%) AMG group. Visual acuity improvement was significantly better in the latter group (CF: 1 [6.67%] vs. AMG: 7 [46.67%], p = 0.023). Flap failure occurred in 4 patients (26.67%) from the CF and 2 (13.33%) from the AMG group. No significant differences were found between the two groups regarding success rate (p = 0.651), epithelialization time (p = 0.691), healing of corneal ulcer (p = 0.651), and postoperative stability (p = 0.651) of the flaps.

CONCLUSIONS

CF and AMG are both effective for the management of refractory fungal corneal ulcers. However, AMG appears to improve visual acuity better than CF.

Comparison of the effects of preservation methods on structural, biological, and mechanical properties of the human amniotic membrane for medical applications

Amniotic membrane (AM), the innermost layer of the placenta, is an exceptionally effective biomaterial with divers applications in clinical medicine. It possesses various biological functions, including scar reduction, anti-inflammatory properties, support for epithelialization, as well as anti-microbial, anti-fibrotic and angio-modulatory effects. Furthermore, its abundant availability, cost-effectiveness, and ethical acceptability make it a compelling biomaterial in the field of medicine. Given the potential unavailability of fresh tissue when needed, the preservation of AM is crucial to ensure a readily accessible and continuous supply for clinical use. However, preserving the properties of AM presents a significant challenge. Therefore, the establishment of standardized protocols for the collection and preservation of AM is vital to ensure optimal tissue quality and enhance patient safety. Various preservation methods, such as cryopreservation, lyophilization, and air-drying, have been employed over the years. However, identifying a preservation method that effectively safeguards AM properties remains an ongoing endeavor. This article aims to review and discuss different sterilization and preservation procedures for AM, as well as their impacts on its histological, physical, and biochemical characteristics.

An important detail that is still not clear in amniotic membrane applications: How do we store the amniotic membrane best?

The use of fresh amniotic membrane (AM) is not a viable option, as it has many disadvantages. Preserving the AM reduces the risk of cross-infection and maintains its effectiveness for a long time. In order to maximize the therapeutic effects of the AM, the basic need is to preserve its vitality and the bioactive molecules it contains. However, the effect of preservation procedures on cell viability and growth factors is a still matter of debate. Optimum preservation method is expected to be cost-effective, easily-accessible, and most importantly, to preserve the effectiveness of the tissue for the longest time. However, each preservation technique has its advantages and disadvantages over the other, and each one compromises the vitality and bioactive molecules of the tissue to some extent. Therefore, the best method of preservation is still controversial, and the question of 'how to preserve the AM best?' has not yet been definitively answered.

Prevention and Treatment of Persistent Epithelial Defects After Common Refractive Surgery Procedures

PURPOSE

To discuss the prevention and treatment of persistent epithelial defects after the most common refractive surgeries-photorefractive keratectomy, laser in situ keratomileusis, or small incision lenticule extraction.

METHODS

PubMed was used to search the medical literature.

RESULTS

Persistent epithelial defects are infrequent after photorefractive keratectomy, laser in situ keratomileusis, or small incision lenticule extraction. In the authors' opinion, any persistent epithelial defect present at 1 week or beyond after surgery should be treated aggressively with a properly fit bandage contact lens, lubrication with non-preserved artificial tears, and treatment of any eyelid abnormalities, including nocturnal lagophthalmos. Consideration should be given for presumptive treatment for herpes simplex virus or varicella zoster virus infection. If the persistent epithelial defect does not close within 2 weeks, then other measures should be considered, such as autologous serum drops, topical losartan, amniotic membranes, and topical human recombinant nerve growth factor to limit corneal scarring fibrosis and microbial infection.

CONCLUSIONS

Persistent epithelial defects are among the most feared complications of refractive surgery. Timely and aggressive treatment should be instituted to close the epithelium prior to the development of scarring fibrosis and/or microbial corneal infection. [J Refract Surg. 2024;40(2):e117-e124.].

Debulking corneal biopsy with tectonic amniotic membrane transplantation in refractory clinically presumed fungal keratitis

The treatment of fungal keratitis (FK) is challenging due to the subacute indolent course, and initial misdiagnosis. In this retrospective case series, we highlight both the diagnostic and therapeutic roles of corneal biopsy together with amniotic membrane transplantation (AMT) in patients with refractory clinically presumed FK. Debulking biopsy and tectonic AMT were performed during the initial presentation. Biopsy specimens were sent for KOH smears and cultures. After KOH smears confirmed the presence of fungal elements, topical voriconazole 1% was prescribed for the first 72 h then tailored according to the clinical response and the culture results. The outcome measures were complete resolution of infection and restoration of corneal integrity. Cases associated with culture proven bacterial keratitis were excluded. Twelve cases were included in the study. KOH smears confirmed the presence of fungal growth in all specimens. Cultures grew Aspergillus in 6/12 cases, sensitive to voriconazole (5/6) and amphotericin (3/6); Fusarium (4/12), sensitive to both voriconazole and amphotericin; and no growth in 2/12 cases. Amphotericin 0.15% eye drops were added to the 7 cases with proven sensitivity and to the remaining 2 culture negative cases. Gradual resolution of infection was seen in all cases after 35.6 ± 7.8 days. In FK, a debulking biopsy simultaneously with AMT help decrease the microbial load, suppress the inflammatory process, support the corneal integrity, confirm the presence of fungal pathogen.

Application of the Human Amniotic Membrane as an Adjuvant Therapy for the Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related morbidity and mortality worldwide. Current therapeutic approaches suffer significant side effects and lack of clear understanding of their molecular targets. Recent studies reported the anticancer effects, immunomodulatory properties, and antiangiogenic effects of the human amniotic membrane (hAM). hAM is a transparent protective membrane that surrounds the fetus. Preclinical studies showed pro-apoptotic and antiproliferative properties of hAM treatment on cancer cells. Herein, we present the latest findings of the application of the hAM in combating HCC tumorigenesis and the underlying molecular pathogenies and the role of transforming growth factor-beta (TGFβ), P53, WNT/beta-catenin, and PI3K/AKT pathways. The emerging clinical applications of hAM in cancer therapy provide evidence for its diverse and unique features and suitability for the management of a wide range of pathological conditions.

Human Amniotic Membrane Graft in the Management of Peripheral Hypertrophic Subepithelial Corneal Degeneration: A Case Report

Introduction

In this report, we describe the case of peripheral hypertrophic subepithelial corneal degeneration (PHSCD), managed with surgical excision and a human amniotic membrane (hAM) graft.

Case Presentation

A 45-year-old female Caucasian patient presented with decreased vision, itching, and burning in both eyes, and a presence of pseudopterygium in the right eye, causing visual decline. Routine ocular exams and anterior segment OCT led to the diagnosis of PHSCD, after a careful differential diagnosis with other similar clinical occurrences. Subsequently, the patient was successfully managed with surgical intervention and an amniotic membrane graft placement.

Conclusion

PHSCD is a rare disease, which in advanced cases can be successfully managed with hAM graft. No recurrence of the lesions was observed at 1-year follow-up in our patient.

Modulating Growth Factor Receptor Signaling to Promote Corneal Epithelial Homeostasis

The corneal epithelium is the first anatomical barrier between the environment and the cornea; it is critical for proper light refraction onto the retina and prevents pathogens (e.g., bacteria, viruses) from entering the immune-privileged eye. Trauma to the highly innervated corneal epithelium is extremely painful and if not resolved quickly or properly, can lead to infection and ultimately blindness. The healthy eye produces its own growth factors and is continuously bathed in tear fluid that contains these proteins and other nutrients to maintain the rapid turnover and homeostasis of the ocular surface. In this article, we review the roles of growth factors in corneal epithelial homeostasis and regeneration and some of the limitations to their use therapeutically.

New developments in the management of persistent corneal epithelial defects

A persistent epithelial defect (PED) is a corneal epithelial defect that failed to heal after 2weeks. It is a condition that carries much morbidity, and our understanding of PED remains poor, with current treatment methods often having unsatisfactory outcomes. With PEDs becoming more prevalent, more efforts are required to establish reliable treatment modalities. Our reviews describe the causes of PEDs and the different approaches developed to manage them, as well as their associated limitations. Emphasis is placed on understanding various advances in the development of new treatment modalities. We have also described a case of a woman with a background of graft-versus-host disease on long-term topical corticosteroids who developed complicated PED involving both eyes. The current approach to managing PEDs generally involves exclusion of an active infection, followed by treatment modalities that aim to encourage corneal epithelial healing. Success rates, however, remain far from desirable, as treatment remains challenging due to multiple underlying etiologies. In summary, advances in the development of new therapies may be able to facilitate progress in the understanding and treatment of PED.

Clinical outcomes, time span for healing of various ocular surface disorders with amniotic membrane: A prospective, an Indian study

Purpose

To study the clinical outcomes, time span of healing of various ocular surface disorders with amniotic membrane graft.

Methods

A total of 41 patients, presenting to cornea clinic were included in the study and divided into five groups depending on the type of diagnosis: Group 1, with either >2 weeks of Persistent epithelial defect following cataract/retinal/glaucoma surgeries or Shield ulcers, Group 2 with >4 weeks of Non healing corneal ulcers, Group 3 with chemical injuries, Group 4 with Epithelial defects following keratoplasty, and Group 5 is the miscellaneous group.

Results

The mean age of the study subjects was 50.0 years. Overall mean duration between clinical presentation and AMT was 23.59 (30.7) days, a median 16 days (IQR; 2-26 days). Failure rate was high in Group 5 (n = 3: 30.0%) and Group 2 (n = 3: 27.3%). Time taken for epithelial closure was slower in groups 1 and 5 patients. The average time taken for reabsorption of AMG was 14.98 days. The complications included repeat AMG was in four eyes (9.75%), and graft displacement was noted in four eyes (9.75%) required resuturing, three eyes required TPK (7.31%), and one eye underwent evisceration (2.43%) following severe corneal melt secondary to neurotropic ulcer. The mean log MAR visual acuity improved from 1.52 to 1.26 at the 3 months.

Conclusion

Understanding on timespan for healing of ocular surface disorders with AMG is needed to assess the prognosis of the disease, preoperative counselling for repeat procedures, and the compliance with regard to follow up.

Healing of Chemical Injury-Related Persistent Corneal Epithelial Defects With Topical Insulin

PURPOSE

The purpose of this study was to evaluate the effectiveness of insulin eye drops for treating refractory persistent epithelial defects (PEDs).

METHODS

A prospective, single-center, case series was performed from March 2020 to September 2021. All patients were prescribed insulin eye drops for refractory PEDs that failed on maximum standard medical treatment (including serum eye drops). The drops were used 4 times/day. Patients were followed up at 2 weekly intervals with full slitlamp examination and serial anterior segment photography. The primary end point was resolution of the epithelial defect.

RESULTS

Eleven eyes of 10 patients were treated with insulin eye drops. The mean age of the cohort was 45.4 + 25 years with a mean follow-up of 195.7 + 114.3 days after re-epithelization. The most common causative condition was chemical injury (n = 5, 60%). Mean baseline PED defect was 41.3 + 55.2 mm 2 . Nine of 11 eyes (82%) fully re-epithelized within a mean time of 62.3 + 34.6 days (range 14-112). In 2 patients who did not achieve re-epithelization, one had a reduction in size from 12.25 mm 2 to 4.5 mm 2 and the other had no response. No recurrence in defect was observed in the group that had fully re-epithelized.

CONCLUSIONS

This study showed that the use of topical insulin eye drops led to a successful resolution of PED in 9 of 11 cases. We demonstrate the use of insulin for closure of PEDs in chemical eye injury. Larger controlled studies are required to further evaluate this novel therapy.

Quantification of Analgesic and Anti-Inflammatory Lipid Mediators in Long-Term Cryopreserved and Freeze-Dried Preserved Human Amniotic Membrane

The aim of this study was to compare concentrations of endogenous N-acylethanolamine (NAE) lipid mediators-palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and anandamide (AEA)-in fresh, decontaminated, cryopreserved, and freeze-dried amniotic membrane (AM) allografts, thereby determining whether AM's analgesic and anti-inflammatory efficiency related to NAEs persists during storage. The concentrations of NAEs were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. Indirect fluorescent immunohistochemistry was used to detect the PEA PPAR-α receptor. The concentrations of PEA, OEA, and AEA were significantly higher after decontamination. A significant decrease was found in cryopreserved AM compared to decontaminated tissue for PEA but not for OEA and AEA. However, significantly higher values for all NAEs were detected in cryopreserved samples compared to fresh tissue before decontamination. The freeze-dried AM had similar values to decontaminated AM with no statistically significant difference. The nuclear staining of the PPAR-α receptor was clearly visible in all specimens. The stability of NAEs in AM after cryopreservation was demonstrated under tissue bank storage conditions. However, a significant decrease, but still higher concentration of PEA compared to fresh not decontaminated tissue, was found in cryopreserved, but not freeze-dried, AM. Results indicate that NAEs persist during storage in levels sufficient for the analgesic and anti-inflammatory effects. This means that cryopreserved AM allografts released for transplant purposes before the expected expiration (usually 3-5 years) will still show a strong analgesic effect. The same situation was confirmed for AM lyophilized after one year of storage. This work thus contributed to the clarification of the analgesic effect of NAEs in AM allografts.

Influence of Storage Conditions on Decellularized Porcine Conjunctiva

Porcine decellularized conjunctiva (PDC) represents a promising alternative source for conjunctival reconstruction. Methods of its re-epithelialization in vitro with primary human conjunctival epithelial cells (HCEC) have already been established. However, a long-term storage method is required for a simplified clinical use of PDC. This study investigates the influence of several storage variants on PDC. PDC were stored in (1) phosphate-buffered saline solution (PBS) at 4 °C, (2) in glycerol-containing epithelial cell medium (EM/gly) at −80 °C and (3) in dimethyl sulfoxide-containing epithelial cell medium (EM/DMSO) at −196 °C in liquid nitrogen for two and six months, respectively. Fresh PDC served as control. Histological structure, biomechanical parameters, the content of collagen and elastin and the potential of re-epithelialization with primary HCEC under cultivation for 14 days were compared (n = 4–10). In all groups, PDC showed a well-preserved extracellular matrix without structural disruptions and with comparable fiber density (p ≥ 0.74). Collagen and elastin content were not significantly different between the groups (p ≥ 0.18; p ≥ 0.13, respectively). With the exception of the significantly reduced tensile strength of PDC after storage at −196 °C in EM/DMSO for six months (0.46 ± 0.21 MPa, p = 0.02), no differences were seen regarding the elastic modulus, tensile strength and extensibility compared to control (0.87 ± 0.25 MPa; p ≥ 0.06). The mean values of the epithelialized PDC surface ranged from 51.9 ± 8.8% (−196 °C) to 78.3 ± 4.4% (−80 °C) and did not differ significantly (p ≥ 0.35). In conclusion, all examined storage methods were suitable for storing PDC for at least six months. All PDC were able to re-epithelialize, which rules out cytotoxic influences of the storage conditions and suggests preserved biocompatibility for in vivo application.

Recurrence of perforation and overall patient survival after penetrating keratoplasty versus amniotic membrane transplantation in corneal perforation

PURPOSE

The following is a comparative analysis on the treatment outcomes of corneal perforations using amniotic membrane transplantation (AMT) or penetrating keratoplasty (PK).

METHODS

This monocentric retrospective study was performed at the Department of Ophthalmology, University Hospital Ulm, Germany. A total of 78 eyes of 78 patients were included. Thirty-nine eyes received an AMT, and 39 patients were treated with a PK. Primary outcome was recurrence of perforation. Secondary outcomes were patient mortality and visual acuity.

RESULTS

No statistically significant difference was observed with regard to a recurrence of perforation between the two groups (26% in AMT vs 23% in PK, p > 0.99). The time of recurrences was within the first two years and did not differ statistically (p = 0.97). In addition, a proportional hazards model with cox regression regarding recurrent perforation showed no significant differences (p = 0.5). After AMT, 41% and after KP, 28% of the patients died during follow-up (p = 0.2), respectively. The Charlson Comorbidity Index (p < 0.0001) and the age at the time of surgery (p = 0.0002) were statistically significantly higher in those who were deceased. A mean follow-up of 485 ± 517 days was recorded.

CONCLUSION

Both surgical methods show good results and no statistically significant difference regarding recurrent perforation rate. About a third of the patients died during the follow-up period. The decision regarding the appropriate method should therefore be based on a combination of all factors.

Biological properties and surgical applications of the human amniotic membrane

The amniotic membrane (AM) is the inner part of the placenta. It has been used therapeutically for the last century. The biological proprieties of AM include immunomodulatory, anti-scarring, anti-microbial, pro or anti-angiogenic (surface dependent), and tissue growth promotion. Because of these, AM is a functional tissue for the treatment of different pathologies. The AM is today part of the treatment for various conditions such as wounds, ulcers, burns, adhesions, and skin injury, among others, with surgical resolution. This review focuses on the current surgical areas, including gynecology, plastic surgery, gastrointestinal, traumatology, neurosurgery, and ophthalmology, among others, that use AM as a therapeutic option to increase the success rate of surgical procedures. Currently there are articles describing the mechanisms of action of AM, some therapeutic implications and the use in surgeries of specific surgical areas, this prevents knowing the therapeutic response of AM when used in surgeries of different organs or tissues. Therefore, we described the use of AM in various surgical specialties along with the mechanisms of action, helping to improve the understanding of the therapeutic targets and achieving an adequate perspective of the surgical utility of AM with a particular emphasis on regenerative medicine.

Amniotic membrane attenuates heterotopic ossification following high-dose bone morphogenetic protein-2 treatment of segmental bone defects

Treatment of large bone defects with supraphysiological doses of bone morphogenetic protein-2 (BMP-2) has been associated with complications including heterotopic ossification (HO), inflammation, and pain, presumably due to poor spatiotemporal control of BMP-2. We have previously recapitulated extensive HO in our rat femoral segmental defect model by treatment with high-dose BMP-2 (30 μg). Using this model and BMP-2 dose, our objective was to evaluate the utility of a clinically available human amniotic membrane (AM) around the defect space for guided bone regeneration and reduction of HO. We hypothesized that AM surrounding collagen sponge would attenuate heterotopic ossification compared with collagen sponge alone. In vitro, AM retained more BMP-2 than a synthetic poly(ε-caprolactone) membrane through 21 days. In vivo, as hypothesized, the collagen + AM resulted in significantly less heterotopic ossification and correspondingly, lower total bone volume (BV), compared with collagen sponge alone. Although bone formation within the defect was delayed with AM around the defect, by 12 weeks, defect BVs were equivalent. Torsional stiffness was significantly reduced with AM but was equivalent to that of intact bone. Collagen + AM resulted in the formation of dense fibrous tissue and mineralized tissue, while the collagen group contained primarily mineralized tissue surrounded by marrow-like structures. Especially in conjunction with high doses of growth factor delivered via collagen sponge, these findings suggest AM may be effective as an overlay adjacent to bone healing sites to spatially direct bone regeneration and minimize heterotopic ossification.

Challenges and concepts in the diagnosis and management of ocular graft-versus-host disease

Graft-versus-host disease (GVHD) is characterized by tissue inflammation in the host following an allogeneic hematopoietic cell transplantation (HCT). The pathophysiology is complex and only incompletely understood yet. Donor lymphocyte interaction with the histocompatibility antigens of the host plays a crucial role in the pathogenesis of the disease. Inflammation may affect multiple organs and tissues, e.g., the gastrointestinal tract, liver, lung, fasciae, vaginal mucosa, and the eye. Subsequently, alloreactive donor-derived T and B lymphocytes may lead to severe inflammation of the ocular surface (i.e., cornea and conjunctiva) and the eyelids. Furthermore, fibrosis of the lacrimal gland may lead to severe dry eye. This review focuses on ocular GVHD (oGVHD) and provides an overview of current challenges and concepts in the diagnosis and management of oGVHD. Ophthalmic manifestations, diagnostic procedures, grading of severity and recommendations for ophthalmic examination intervals are provided. Management of ocular surface disease with lubricants, autologous serum eye drops, topical anti-inflammatory agents and systemic treatment options are described based on the current evidence. Ocular surface scarring and corneal perforation are severe complications of oGVHD. Therefore, ophthalmic screening and interdisciplinary treatment approaches are highly relevant to improve the quality of life of patients and to prevent potentially irreversible visual loss.

The progress in techniques for culturing human limbal epithelial stem cells

In vitro culture of human limbal epithelial stem cells (hLESCs) is crucial to cell therapy in the treatment of limbal stem cell deficiency, a potentially vision-threatening disease that is characterized by persistent corneal epithelial defects and corneal epithelium conjunctivalization. Traditionally, hLESCs are cultivated based on either limbal tissue explants or single-cell suspensions in culture media containing xenogenous components, such as fetal bovine serum and murine 3T3 feeder cells. Plastic culture dishes and human amniotic membranes are classical growth substrates used in conventional hLESC culture systems. The past few decades have witnessed considerable progress and innovations in hLESC culture techniques to ensure a higher level of biosafety and lower immunogenicity for further cell treatment, including complete removal of xenogenous components from culture media, the application of human-derived feeder cells, and the development of novel scaffolds. Three-dimensional artificial niches and three-dimensional culture techniques have also been established to simulate the real microenvironment of limbal crypts for better cell outgrowth and proliferation. All these progresses ensure that in vitro cultured hLESCs are more adaptable to translational stem cell therapy for limbal stem cell deficiency.

Modified Continuous Suturing Technique for Amniotic Membrane Fixation after Chemical Corneal Injury: An Octagonal Graft

This case report aims to describe a modified continuous suturing technique for firm fixation of a human amniotic membrane graft in a patient with persistent epithelial defect (PED) after a chemical eye injury. As a result of this technique, the amniotic membrane (AM) was firmly fixed to the corneal surface with eight continuous and locked episcleral sutures that resembled an octagon graft. This technique was performed in a 14-year-old patient with PED after a chemical corneal burn. Three weeks after the surgery, the PED was completely healed. This simple continuous suturing technique can allow firm and stable fixation of AM grafts on the ocular surface in cases of PED after chemical burn. It may prevent early loss of the graft and facilitate corneal epithelial wound healing.

Surgical Management of Peripheral Ulcerative Keratitis: Update on Surgical Techniques and Their Outcome

Peripheral ulcerative keratitis (PUK) is an inflammatory, necrotic condition in the peripheral cornea which may end in corneal perforation and visual morbidity if not treated adequately. PUK can occur due to infectious or non-infectious causes. Early cases need medical therapy, both locally and systemically (for some cases). However, advanced PUK may necessitate surgical removal of inciting cause of the pathology and maintaining tectonic stability. Such surgical treatment, including corneal transplantations, may be used in an emergency setting or for visual rehabilitation following preliminary stabilization of the affected cornea. The outcome of these surgeries need to be analyzed to understand the long-term visual prognosis of such eyes. This is an attempt to analyze surgical modalities in the management of PUK and their outcomes.

New Devitalized Freeze-Dried Human Umbilical Cord Amniotic Membrane as an Innovative Treatment of Ocular Surface Defects: Preclinical Results

A preclinical study was performed to investigate the efficacy and safety of a new viral inactivated, devitalized, freeze-dried and gamma-sterilized human umbilical cord amniotic membrane (lhUC-AM) for the treatment of deep scleral and corneal defects with or without perforation. Firstly, lhUC-AM was investigated on experimental deep sclerectomy in rabbit eyes (n = 12) and compared to autograft (n = 4) on cross section histology. Secondly, lhUC-AM was studied on a selected series of uncontrolled cases of corneal defects (n = 18) with or without perforation, in dogs and cats. lhUC-AM tolerance, reconstruction of the deep corneal lesion and recovery of the structural aspect of the tissue were followed post-surgery. In experimental deep sclerectomy, histology showed that the lhUC-AM was well tolerated and degraded completely in 45 days while allowing an overall quality and kinetic of scleral regeneration, similar to autograft. In the clinical situations, lhUC-AM was well tolerated, with ocular inflammatory signs quickly decreasing after surgery. Mean follow-up was 16.40 ± 11.43 months. In 15 out of 18 cases, lhUC-AM allowed ocular surface wound healing. The ocular surface was fully reconstructed three months after surgery. This study suggests a good safety and efficacy profile of lhUC-AM in the treatment of deep corneal or scleral defect in animals. This new tissue should now facilitate the treatment of severe ocular surface diseases in humans.

Clinical Results of the Use of Amniotic Membrane Transplantation Alone or in Combination with Adjuvant Therapies in Conjunctival Fornix Reconstruction

Objectives:

To evaluate the clinical results of amniotic membrane transplantation alone or in combination with adjuvant therapies in conjunctival fornix reconstruction.

Materials and Methods:

The clinical results of patients who presented to our clinic between 2002 and 2016 due to conjunctival fornix obliteration and underwent amniotic membrane transplantation alone or in combination with additional treatments were retrospectively analyzed. The Foster and Mondino classifications were used to grade fornix obliteration. In all cases, the area of conjunctival defect formed after symblepharon lysis was covered with amniotic membrane. In advanced fornix obliteration, amniotic membrane transplantation was combined with 0.04% mitomycin-C (MMC), oral mucosal transplantation, fornix formation (anchoring) sutures, symblepharon ring, eyelid surgery, fibrin glue, and limbal autograft. Deep and scarless restoration of the fornix was considered surgical success.

Results:

Twenty-two men and 5 women with a mean age of 45.54±4.17 years were included in the study. The etiology of fornix obliteration was mechanical trauma in 16 cases, chemical burn in 6 cases, recurrent pterygium in 3 cases, thermal burn in 1 case, and recurrent chalazion surgery in 1 case. Indications for amniotic membrane transplantation were socket insufficiency in 12 cases, cosmetic reasons in 4 cases, keratoplasty preparation in 3 cases, ptosis in 3 cases, entropion in 2 cases, strabismus in 2 cases, and diplopia in 1 case. The mean follow-up period was 45.04±8.4 months. Twenty-four of 27 cases (88.8%) were successful, while 3 (12.2%) failed due to recurrence of symblepharon.

Conclusion:

Amniotic membrane transplantation is a successful method when used alone in the reconstruction of early-stage conjunctival fornix obliteration and provides safe and effective results in advanced-stage fornix obliteration when performed in combination with topical 0.04% MMC, oral mucosal transplantation, and limbal autograft surgeries.

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.

Cultivated Autologous Limbal Epithelial Cell Transplantation: New Frontier in the Treatment of Limbal Stem Cell Deficiency

PURPOSE

Taking into consideration prior human experience with treating limbal stem cell deficiency (LSCD) with cultivated limbal epithelial cells (CLEC) from other countries, we have set a goal to optimize and standardize the techniques of CLEC preparation (called CALEC by our group) for the clinical trial in the United States.

METHODS

We performed an extensive literature review of all human trials, case series, and reports involving autologous cultivated limbal epithelial cell transplantation. Allogeneic cultivated limbal epithelial cell transplantations were reported only when combined with autologous studies. We also searched prior animal data aiding in detailing regulatory toxicology requirements.

RESULTS

Between 1997 and 2020, the analysis of human trials revealed 21 studies on autologous grafts, and 13 studies analyzing both autologous grafts and allogeneic grafts. Of a total of 34 studies, 6 studies used good manufacturing process (GMP) facilities, and 11 studies had no animal-derived products or murine feeder layers, whereas only 1 study had both. Overall, the treatment with autologous CLEC grafts was 68.9% successful. In total there were 6 preclinical studies using rabbits, serving as surrogate studies to assess the safety and toxicity of cultivated limbal epithelial cells for human trials. Based on prior human experience, we further optimized the manufacturing conditions with GMP-grade and serum and animal-free reagents, and developed cell characterization assays for the CALEC product release.

CONCLUSIONS

These data were used to develop a novel and consistent manufacturing process using only qualified and validated reagents for performing the first clinical trial on CALEC transplantation to treat LSCD in the United States.

Clinical and instrumental assessment of the corneal healing in moderate and severe neurotrophic keratopathy treated with rh-NGF (Cenegermin)

PURPOSE

To evaluate corneal healing in patients with moderate and severe neurotrophic keratitis (NK) treated with topical rh-NFG (Cenegermin).

METHODS

Twenty-one patients (12F and 9M) aged from 21 to 93 years (62.5 ± 19.4) with moderate and severe NK were enrolled in the study. The patients were divided into 2 groups accordingly to the severity of the disease. The underlying causes of NK were determined. The VAS questionnaire was dispensed. The ocular examination comprised slit lamp evaluation, ocular surface assessment with Keratograph 5M (Oculus, Germany), corneal sensitivity with Cochet-Bonnet esthesiometer (Lunneaux, France) and corneal thickness measurement with AC-OCT (DRI, Triton, Topcon, Japan). The drops of Cenegermin 0.002% were administrated 6 times daily for 8 weeks. All participants were evaluated at baseline, after 4 and 8 weeks of the treatment. The area of corneal defect with maximum diameter less than 0.5 mm was considered as healed. The main outcome measures were corneal healing, corneal sensitivity recovery and corneal thickness in the ulcer group.

RESULTS

The herpetic keratitis was the most common cause of NK. Thirteen eyes were affected by severe grade of NK with corneal ulcer and 8 eyes presented a moderate grade. After 8 weeks a complete healing of the corneal defects was registered both in moderate and severe NK. Significant increase of the corneal sensitivity and thickness were registered.

CONCLUSIONS

The rh-NGF (Cenegermin) resulted effective in the treatment of the severe and moderate NK with significant recovery of the corneal sensitivity and healing of the corneal defects in both groups.

Cryopreservation of human amniotic membrane for ocular surface reconstruction: a comparison between protocols

PURPOSE

To compare the effects on adhesive and structural properties of newer preservation conditions to those obtained with an established, standardized protocol (dimethyl sulfoxide at -180 °C). In attempt to simplify and enhance the safety of the procedure, we tested dextran-based freezing medium and a dry condition (no medium) at temperatures of -80 °C.

METHODS

Five patches of human amniotic membrane were obtained from three different donors. For each donor, five preservation condition were tested: dimethyl sulfoxide at -180 °C, dimethyl sulfoxide at -80 °C, dextran-based medium at -180 °C, dextran-based medium at -80 °C and dry freezing at -80 °C (no medium). At the end of four months storage period, adhesive properties and structure were analyzed.

RESULTS

None of the newer preservation protocols showed differences in adhesive and structural properties of the tissues. The stromal layer always kept its adhesiveness, while both structure and basement membrane were not altered by any the preservation protocol.

CONCLUSIONS

Switching from liquid nitrogen cryopreservation to -80 °C would reduce manipulation, simplify the procedure, making it also cheaper. The use of dextran-based freezing medium or no medium at all (dry condition) would avoid the potential toxicity of the dimethyl sulfoxide-based freezing media.

A comprehensive review on methods for promotion of mechanical features and biodegradation rate in amniotic membrane scaffolds

Amniotic membrane (AM) is a biological tissue that surrounds the fetus in the mother's womb. It has pluripotent cells, immune modulators, collagen, cytokines with anti-fibrotic and anti-inflammatory effect, matrix proteins, and growth factors. In spite of the biological characteristics, some results have been released in preventing the adhesion on traumatized surfaces. Application of the AM as a scaffold is limited due to its low biomechanical resistance and rapid biodegradation. Therefore, for using the AM during surgery, its modification by different methods such as cross-linking of the membrane collagen is necessary, because the cross-linking is an effective way to reduce the rate of biodegradation of the biological materials. In addition, their cross-linking is likely an efficient way to increase the tensile properties of the material, so that they can be easily handled or sutured. In this regard, various methods related to cross-linking of the AM subsuming the composite materials, physical cross-linking, and chemical cross-linking with the glutraldehyde, carbodiimide, genipin, aluminum sulfate, etc. are reviewed along with its advantages and disadvantages in the current work.

Cryopreservation in a Standard Freezer: −28 °C as Alternative Storage Temperature for Amniotic Membrane Transplantation

Human amniotic membrane (hAM) is usually stored at −80 °C. However, in many regions, cryopreservation at −80 °C is not feasible, making hAM unavailable. Therefore, the possibility of cryopreservation at −28 °C (household freezer) was investigated. hAMs (n = 8) were stored at −80 °C or −28 °C for a mean time of 8.2 months. hAM thickness, epithelial integrity and basement membrane were assessed histologically. The collagen content, concentration of hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) were determined. Elastic modulus and tensile strength were measured. The mean thickness of hAM stored at −28 °C was 33.1 ± 21.6 µm (range 9.7–74.9); thickness at −80 °C was 30.8 ± 14.7 µm (range 13.1–50.7; p = 0.72). Mean collagen content, epithelial cell number and integrity score showed no significant difference between samples stored at −28 °C or −80 °C. Basement membrane proteins were well preserved in both groups. Mean tensile strength and elastic modulus were not significantly different. Concentration of bFGF at −28 °C was 1063.2 ± 680.3 pg/g (range 369.2–2534.2), and 1312.1 ± 778.2 pg/g (range 496.2–2442.7) at −80 °C (p = 0.11). HGF was 5322.0 ± 2729.3 pg/g (range 603.3–9149.8) at −28 °C, and 11338.5 ± 6121.8 pg/g (range 4143.5 to 19806.7) at −80 °C (p = 0.02). No microbiological contamination was detected in any sample. The cryopreservation of hAM at −28 °C has no overt disadvantages compared to −80 °C; the essential characteristics of hAM are preserved. This temperature could be used in an alternative storage method whenever storage at −80 °C is unavailable.

Comment on "Cornea Classic Article: Kim JC and Tseng SCG: Transplantation of Preserved Amniotic Membrane for Surface Reconstruction in Severely Damaged Rabbit Corneas (Cornea 1995;14:473-484)"

ABSTRACT

Following identification of limbal stem cells, efforts have been devoted to restore and/or replace these essential progenitors of the corneal epithelium. Limbal stem cell deficiency, commonly a consequence of ocular chemical injury, results in clinically compromised vision consequent to corneal conjunctivalization. The insight of Kim and Tseng provided experimental proof of the concept that even in the presence of total limbal stem cell deficiency, amnion membrane overlay grafts can promote limbal recovery as a means of ocular surface reconstruction.

Applications of the amniotic membrane in tissue engineering and regeneration: the hundred-year challenge

The amniotic membrane (Amnio-M) has various applications in regenerative medicine. It acts as a highly biocompatible natural scaffold and as a source of several types of stem cells and potent growth factors. It also serves as an effective nano-reservoir for drug delivery, thanks to its high entrapment properties. Over the past century, the use of the Amnio-M in the clinic has evolved from a simple sheet for topical applications for skin and corneal repair into more advanced forms, such as micronized dehydrated membrane, amniotic cytokine extract, and solubilized powder injections to regenerate muscles, cartilage, and tendons. This review highlights the development of the Amnio-M over the years and the implication of new and emerging nanotechnology to support expanding its use for tissue engineering and clinical applications.

Clinical Outcomes of In-office Sutureless Amniotic Membrane Transplantation in Persistent Epithelial Defect

Purpose

To investigate the efficacy of outpatient clinic-based sutureless amniotic membrane transplantation (AMT) along with therapeutic contact lens (T-lens) application in eyes with persistent epithelial defects (PED).

Methods

Nine eyes of nine patients (mean age: 71.7 ± 5.2 years) diagnosed with PED and treated with in-office sutureless AMT combined with T-lens application were retrospectively reviewed. Demographics, systemic diseases, PED etiology, corneal epithelial defect (ED) size, visual acuity, corneal scraping culture results, and clinical course were evaluated.

Results

Among nine eyes with PED, three had neurotrophic keratopathy, four had infectious keratitis (three with fungal keratitis, one with bacterial keratitis), one had limbal deficiency, and one had marginal keratitis. The mean ED size (calculated as an average of the horizontal and vertical diameters) was 3.13 ± 1.42 mm, and the mean duration from AMT to epithelial healing was 30.1 ± 10.5 days (range: 14-51 days) in successful trials. The success rates were 77.8% (7/9) per patient and 66.7% (8/12) per trial. The causes of failure in two patients were AMT displacement and uncontrolled infection.

Conclusions

Our results demonstrate that in-office sutureless AMT combined with T-lens application can be used in patients with PED who are refractory to medications. It will be especially helpful for elderly patients because of its easy-to-use method. To achieve successful outcomes with AMT, an appropriate periocular environment as well as infection control need to be considered.

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.

Sutureless "Contact Lens Sandwich" Technique for Amniotic Membrane Therapy of Central Corneal Ulcers

PURPOSE

To describe a new technique for sutureless and glue-free amniotic membrane transplantation (AMT) and to investigate its effectiveness to treat corneal persistent epithelial defects (PEDs), compared to bandage contact lens (BCL) application alone.

METHODS

We performed AMT with "contact lens sandwich technique" (CLS-AMT) in 8 consecutive patients with central/para-central (up to 4.00 mm from the geometrical centre) PED/ulceration and we retrospectively compared the results with 11 BCL procedures.

RESULTS

The procedures were performed successfully with no complications.CLS-AMT showed significantly shorter healing time than BCL (24.0  ±  19.1 vs 42.9  ±  14.6 days; P < 0.05, Mann-Whitney test). Recurrence rates were 12% and 27% for CLS-AMT and BCL, respectively.

CONCLUSION

CLS-AMT technique, based on the suction effect due to the superposition of a bandage contact lens on the AM-ring complex, represents a quick, low cost, easy to perform and nearly non-invasive AMT technique. This approach is able to provide adequate fixation of AM, and it seems to be a safe and effective treatment for patients with PEDs.

Assessment of Antimicrobial Activity of Dehydrated Amniotic Membrane in Infectious Keratitis: A Small Retrospective Case Series and In Vitro Study

PURPOSE

To describe a small case series of infectious keratitis with poor visual outcomes after amniotic membrane (AM) placement and to prospectively evaluate whether AM demonstrates antibacterial activity in vitro against pathogens commonly isolated from infectious corneal ulcers.

METHODS

A retrospective case series and in vitro study of antibacterial activity of dehydrated AM using disk diffusion and measurement of inhibitory zones for bacterial assessment and inverted microscopy analysis for Acanthamoeba sp. growth.

RESULTS

Three cases of known etiology infectious keratitis are described where the clinical presentation worsened after treatment with AM. In vitro analysis of dehydrated AM, with and without a soft contact lens, demonstrated no inhibition of growth against Pseudomonas aeruginosa or Streptococcus pneumoniae. There was minimal growth inhibition of Staphylococcus aureus, although these zones of inhibition were much smaller than that surrounding the positive control. For Acanthamoeba sp., solubilized, dehydrated AM did not alter cyst density.

CONCLUSIONS

In an in vitro analysis, dehydrated AM did not provide evidence for a potentially clinically meaningful antibacterial effect against organisms commonly isolated from corneal ulcers.

Corneal Epithelial Stem Cells-Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.

[Surgical management of infectious keratitis]

Infectious keratitis is one of the most common causes of blindness worldwide. Despite the existence of a wide arsenal of quite effective antimicrobial drugs, some forms of bacterial and viral keratitis are resistant. Advanced acanthamoeba and mycotic lesions of the cornea, as well as mixed forms of infection usually do not respond well to conservative treatment. In the absence of positive dynamics from the applied etiotropic therapy with observed further progression of the microbial process, there is a risk of corneal perforation and spread of infection to the sclera or deep ocular structures with a high probability of irreversible functional disorders or anatomical death of the eye. In such cases, a timely transition to surgical treatment is necessary in order to maintain structural integrity of the eyeball. For this purpose, corneal crosslinking, microdiathermocoagulation, tissue adhesive, autoconjunctival plasty, amniotic membrane, corneoscleral flap coating, various combinations of these methods, as well as therapeutic keratoplasty are used most often in clinical practice. The choice depends on the etiology, size and depth of the lesion, its localization, prognosis of visual outcomes, somatic status of the patient. Therapeutic keratoplasty is the most radical and effective method of surgical intervention that allows eradication of the infectious focus and best possible restoration of the structural integrity of the eyeball. However, in some cases due to inaccessibility of donor material or high risks of the surgery and non-transparent graft engraftment, it is advised to use alternative surgical approaches, and keratoplasty, if necessary, should be carried out for optical purposes at a further, "quiet" period.

Safety and feasibility of subconjunctival injection of mesenchymal stem cells for acute severe ocular burns: A single-arm study

PURPOSE

To investigate the safety and feasibility of topical injection of bone marrow derived mesenchymal stem cells (BM-MSCs) in acute severe ocular burns.

METHODS

In this open-label，single-arm study, subconjunctival injection of allogenic BM-MSCs combined with standard treatment was given to 16 patients with acute severe ocular burns (Dua's grade IV to VI) within 2 weeks after injury. The primary outcome was efficacy rate which referred to the proportion of complete corneal epithelialization patients without perforation. The secondary outcome was safety, visual acuity, the number of symblephara, and elevated intraocular pressure.

RESULTS

One patient was lost to follow-up. During the follow-up period, no corneal perforation was developed. Complete corneal epithelialization was noted 8 (ranged 4-10 weeks) weeks after treatment in 13 eyes (81.3%). The efficacy rate was 87.5% (95% confidence interval, CI: 61.7-98.4). Hypopyon was detected and later well controlled in 1 eye. Partial or total limbal stem cell deficiency (LSCD) was noted in all eyes. Improvement of visual acuity was achieved in 5 out of 16 eyes (31.3%). Seven eyes' visual acuity was reached 0.1. Symblepharon with varied severity was noted in 5 eyes. Two eyes had elevated intraocular pressure.

CONCLUSIONS

This study confirms the safety of subconjunctival injection of BM-MSCs as an innovative and convenient procedure in ocular burns. The overall result is promising considering the absence of perforation, the low severity of symblepharon and visual acuity improvement.

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

BACKGROUND

To evaluate new indicators in the efficacy of amniotic membrane transplantation (AMT) for non-healing corneal ulcers (NHCUs).

METHODS

Retrospective, multicenter study. In total, 223 AMTs for NHCU in 191 patients were assessed. The main outcomes studied were the success rate of AMT (complete re-epithelization), postoperative visual acuity (VA) gain, and number of AM layers transplanted.

RESULTS

The overall AMT success rate was 74.4%. In 92% of our patients VA stability or improvement. Postoperative VA was significantly higher than preoperative VA in the entire cohort (p < 0.001) and in all etiological groups of ulcers (post-bacterial, p ≤ 0.001; post-herpetic, p ≤ 0.0038; neurotrophic ulcers, p ≤ 0.014; non-rheumatic peripheral, p ≤ 0.001; and ulcers secondary to lagophthalmos and eyelid malposition or trauma, p ≤ 0.004). Most participants (56.5%) presented a preoperative VA equal to or less than counting fingers (≤0.01). Of these, 13.5% reached a postoperative VA equal to or better than legal blindness (≥0.05) after AMT. A higher success rate was observed in the monolayer than in the multilayer AMT (79.5% and 64.9%, respectively; p = 0.018). No statistically significant values were found between the number of layers transplanted and VA gain (p = 0.509).

CONCLUSION

AMT is not only beneficial in achieving complete re-epithelialization in NHCUs but also in improving postoperative VA; these improvements are independent of etiologies of ulcers. Furthermore, the use of monolayer AMT seems to be a more appropriate option than multilayer AMT for NHCU since the multilayer AMT did not present better outcomes (success rate and VA gain) compared to monolayer AMT in the different types of ulcers studied.

Chronic Wound Healing by Amniotic Membrane: TGF-β and EGF Signaling Modulation in Re-epithelialization

The application of amniotic membrane (AM) on chronic wounds has proven very effective at resetting wound healing, particularly in re-epithelialization. Historically, several aspects of AM effect on wound healing have been evaluated using cell models. In keratinocytes, the presence of AM induces the activation of mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK) pathways, together with the high expression of c-Jun, an important transcription factor for the progression of the re-epithelialization tongue. In general, the levels of transforming growth factor (TGF)-β present in a wound are critical for the process of wound healing; they are elevated during the inflammation phase and remain high in some chronic wounds. Interestingly, the presence of AM, through epidermal growth factor (EGF) signaling, produces a fine-tuning of the TGF-β signaling pathway that re-conducts the stalled process of wound healing. However, the complete suppression of TGF-β signaling has proven negative for the AM stimulation of migration, suggesting that a minimal amount of TGF-β signaling is required for proper wound healing. Regarding migration machinery, AM contributes to the dynamics of focal adhesions, producing a high turnover and thus speeding up remodeling. This is clear because proteins, such as Paxillin, are activated upon treatment with AM. On top of this, AM also produces changes in the expression of Paxillin. Although we have made great progress in understanding the effects of AM on chronic wound healing, a long way is still ahead of us to fully comprehend its effects.