Amniotic membrane transplantation for persistent epithelial defects with ulceration

Fibrin glue-assisted augmented amniotic membrane transplantation for the treatment of large noninfectious corneal perforations

PURPOSE

To evaluate and report the efficacy of fibrin glue (FG)-assisted augmented amniotic membrane transplantation (AMT) in patients with large corneal perforations.

METHODS

In a retrospective case series, 10 patients with corneal perforations more than 2 mm in diameter were treated with "FG-assisted augmented AMT." A 5- or 7-ply "augmented amniotic membrane" (AM) was constructed by applying FG to each sheet of AM to repair the corneal perforation. The augmented AM was designed 0.5 mm larger than the diameter of the perforation. The augmented AM was transplanted onto the perforation site with 10-0 nylon suture. If needed, additional overlay AM was sutured on top.

RESULTS

The mean ulceration diameter was 2.7 +/- 0.95 mm (range, 2-5 mm). All patients retained their own globes after the procedure and had well-formed deep anterior chambers, and 90% of patients showed complete epithelialization over the AM. The mean reepithelialization time was 14.9 +/- 4.9 days (range, 10-24 days). No eyes showed evidence of infection or recurrent corneal melting during the follow-up period.

CONCLUSIONS

FG-assisted augmented AMT was easily performed for repairing large corneal perforations. This surgical method was very helpful in stabilizing the wound in the early postoperative period.

The influence of various storage conditions on cell viability in amniotic membrane

Up to now freeze-dried, gamma-sterilised or glycerol-preserved amniotic membranes (AMs) have widely been used in the field of ophthalmology and wound care (e.g. leg ulcers, burns). After some preservation processes in use, like freeze-drying or glycerol-preserving, the cells in the AM are no longer viable. Within this study we evaluated the influence of different short-term and long-term storage conditions on cell viability in AM. Therefore AMs from cesarean section placentae were washed and biopsied to evaluate the microbiological status and to determine the viability of the tissue. Additionally, viability under various storage conditions was examined by assessment of mitochondrial activity. Preservation included temperatures above and below 0 degrees C as well as various media compositions. As expected, cell viability in amnion decreases during storage, in fact the effect was more pronounced when stored frozen, but the higher viability of amnion obtained by storage above 0 degrees C with medium is associated with the limitation to a short period of storage of about 28 days. The evaluated preservation methods are the basis for future non-clinical in-vivo studies in which the possible benefit of amnion as a viable biomaterial in wound healing will be investigated.

Application of amniotic membrane as xenograft for urethroplasty in rabbit

OBJECTIVES

Uroepithelium repair has always been the subject of discussion in urology surgeries. Using human amniotic membrane allograft has already proved to be useful in other fields. In this study, we use amniotic membrane to repair uroepithelium injuries in rabbits.

METHODS

Twenty healthy rabbits underwent surgery to induce a 10-mm incision, 10 mm from the meatus on ventral part of the urethra. Then a 5 x 10 mm patch of amniotic membrane was sutured to the incised urethra. All of the rabbits were catheterized for a week and then the patches were removed. The rabbits were studied for a month for any signs of infection and fistula formation.

RESULTS

All samples revealed complete re-epithelialization of reconstructed urethra by transitional epithelium. There was one case of infection and following fistula (5%). There were two cases of urethral strictures (10%).

CONCLUSION

The result from this study suggests that amniotic membrane is an inexpensive, easy, and biodegradable graft with very little antigen effect which seems to be the ideal solution for urethroplasty.

The effect of amniotic membrane preparation method on its ability to serve as a substrate for the ex-vivo expansion of limbal epithelial cells

Human amniotic membrane (HAM) is employed as a substrate for the ex-vivo expansion of limbal epithelial cells (LECs) used to treat corneal epithelial stem cell deficiency in humans. The optimal method of HAM preparation for this purpose is unknown. This study evaluated the ability of different preparations of stored HAM to serve as substrates for LEC expansion ex-vivo. The effect of removing the amniotic epithelial cells (decellularisation) from HAM prior to seeding of LECs, the effect of glycerol cryopreservation and the effect of peracetic acid (PAA) sterilization and antibiotic disinfection were evaluated using different HAM test groups. Human LECs were cultured on each preparation and the following outcomes were assessed: confluence of growth, cell density, cell morphology and expression of the putative LESC markers deltaN-p63alpha and ABCG2. Removing amniotic epithelial cells prior to seeding of LECs resulted in a higher percentage of confluence but a lower cell density than intact HAM suggesting that decellularisation does not increase proliferation, but rather that it facilitates migration of LECs resulting in larger cells. Decellularisation did not affect the percentage of cells expressing the putative LESC markers deltaN-p63alpha (< or =4% in both intact and acellular groups) and ABCG2 (< or =3% in both intact and acellular groups). Glycerol cryopreservation of HAM resulted in poor morphology and a low proportion of cells expressing deltaN-p63alpha (< or =6%) and ABCG2 (< or =8%). HAM frozen at -80 degrees C in Hank's Balanced Salt Solution (HBSS) was superior, demonstrating excellent morphology of cultured LECs and high levels of deltaN-p63alpha (< or =68%) and ABCG2 (< or =62%) expression (p<0.001). The use of PAA or antibiotics to decontaminate HAM does not appear to affect this function. The variables affecting the ability of HAM to serve as a substrate for LEC expansion ex-vivo are poorly understood. The use of glycerol as a cryoprotectant impairs this ability whereas simple frozen HAM appears to work extremely well for this purpose.

The role of allogenic amniotic membrane in burn treatment

Amniotic membrane (AM) has been used in burns for nearly 100 years. The purpose of this article is to give a comprehensive review of the English literature published in the last two decades (1987--2007) to present the current state of this therapy form. Three medical databases (PubMed, Medline, The Cochrane Library) and specific burn journals were electronically screened for relevant articles using carefully selected retrieval strategies and keywords (AM, amnion grafts, burns, wound dressing, amnion banking). Bibliographies of relevant articles were analyzed for additional pertinent publications. After exclusion of articles which referred to the use of AM in reconstructive and ophthalmologic surgery, the inquiry yielded 31 relevant articles in English language dealing with AM and burns. There was no publication fulfilling the criteria of evidence level I, 6 articles had evidence level II, 10 had evidence level III, 6 had evidence level IV, and 9 were merely narrative (level V). The review testifies to--in view of good tissue practice--heightened use of processed AM in burns, especially in the last decade. Randomized clinical trials favored the use of amnion in burns in the first place for promotion of wound healing and in the second place for its comfortable and less dressing changes. Antimicrobial effects, pain relief, reduction of fluid, and scar formation were demonstrated additionally.

Amniotic membrane transplantation in severe ocular surface disorders

PURPOSE

Amniotic membrane transplantation is currently being used as an alternative approach to treat severe corneal surface disorders refractory to medical therapy. The authors report complications of corneal surface disorders after successful amniotic membrane transplantation.

METHODS

Case series.

RESULTS

Twenty-eight patients with corneal surface disorders due to severe chemical burns, corneal ulceration, or persistent epithelium defects were treated with amniotic membrane transplantation. Four of these patients showed a spontaneous perforation and three patients developed a descemetocele within 6 weeks after the amniotic membrane transplantation.

CONCLUSIONS

In this case series, descemetocele and corneal perforation occurred in 25% of the patients after amniotic membrane transplantation. This might be due to the severity of the underlying disease or to the impact of amniotic membrane on corneal fibroblasts and collagenases. The risk of corneal thinning and perforation should be considered in the decision of treatment with amnion and follow-up regimen.

In vivo laser confocal microscopy findings of cryopreserved and fresh human amniotic membrane

BACKGROUND AND OBJECTIVE

Recently, the cornea-specific in vivo laser confocal microscope has become available. The objective of the current study was to obtain laser confocal images of fresh and cryopreserved human amniotic membrane.

MATERIALS AND METHODS

Fresh and cryopreserved amniotic membranes from different donors were examined using the in vivo laser scanning confocal microscope (Heidelberg Retina Tomograph II Rostock Cornea Module [HRT II-RCM]; Heidelberg Engineering GmbH, Dossenheim, Germany).

RESULTS

In all samples of both fresh and cryopreserved amniotic membranes, the HRT II-RCM resolved four distinct layers: the epithelium, a basement membrane, a cell-rich stromal layer (fibroblast layer), and a spongy stromal layer. In a posterior aspect of the basement membrane layer (facing the fibroblast layer), microfolds were more prominent in fresh amniotic membranes than in cryopreserved amniotic membranes. For the cell-rich stromal layer, mesenchymal cells were observed more distinctively in fresh amniotic membranes than in cryopreserved amniotic membranes.

CONCLUSION

These baseline laser confocal images can be used for future investigation of in vivo remodeling after amniotic membrane transplantation.

Amniotic membrane transplantation: indications and results

PURPOSE

To describe amniotic membrane transplantation indications and results at the authors' institution.

METHODS

In this study, chart review of 108 patients who underwent amniotic membrane transplantation between January 2002 and April 2006 was performed. The survival rate of corneal integrity was compared, using Kaplan-Meier survival analysis, as a measure of success rate.

RESULTS

The mean age of the patients was 55.2+/-20.1 (6-87 years, 75 female, 51 male). The patients underwent amniotic membrane transplantation for six different diagnoses: nontraumatic corneal perforation (32 eyes, Group 1), persistent epithelial defect (29 eyes, Group 2), aphakic/pseudophakic bullous keratopathy (18 eyes, Group 3), infectious ulcer resistant to treatment (14 eyes, Group 4), necrotizing keratitis secondary to endophthalmitis (10 eyes, Group 5), and caustic injury (5 eyes, Group 6). The mean survival of corneal integrity was similar in all groups (p=0.156).

CONCLUSIONS

Amniotic membrane transplantation is a successful adjunctive method in achieving corneal epithelization in the study indications.

[OCT Visante observation of the progression of a perforated neurotrophic cornea ulcer treated with amniotic membrane grafts]

INTRODUCTION

The optical coherence tomography (OCT) Visante provides easy, high-resolution observation free of contact with the cornea and anterior segment. We present the progression of a neurotrophic corneal ulcer treated with amniotic membrane grafts studied with this system.

METHODS

A 71-year-old patient with facial nerve paresis secondary to vestibular schwannoma surgery presented with a neurotrophic perforated corneal ulcer. Since medical treatment had failed, we performed an amniotic membrane graft. The OCT Visante was used for follow-up for 2 months.

RESULTS

Progression was slow but the perforation eventually closed. Cicatrization of the corneal ulcer was followed with the OCT Visante to document the healing process and corneal thickness.

CONCLUSION

Optical coherence tomography Visante provides easy visualization and high-resolution documentation with no contact with the healing corneal ulcerations.

Cryopreserved human amniotic membrane for soft tissue repair in rats

Fresh amniotic membrane has been used in medicine since 1910. The reconstruction of immunologic privileged ocular surfaces with cryopreserved amniotic membrane was introduced in the 1990s. The aim of this study was to analyze the use of cryopreserved human amniotic membrane (HAM) as a surgical patch in immunologic unprivileged anatomic sites. In part I of the investigation, the abdominal wall muscle of 36 rats was covered with mono- and multilayered HAM. After 3, 14, and 28 days, respectively, these grafts were evaluated macro- and microscopically. Multilayer samples displayed slower degradation and less inflammation compared with monolayer coverage. In part II of the study, abdominal wall closure with multilayer HAM and with polypropylene mesh was conducted in 20 rats. All rats showed sufficient closure after 21 days, but significantly lower intraabdominal adhesion formation was observed in the HAM rats. The results of this study might pave the way for the use of cryopreserved HAM as graft material in reconstructive surgery.

Amniotic membrane transplantation for persistent corneal epithelial defects in eyes after penetrating keratoplasty

PURPOSE

To determine the primary success and recurrence rate of amniotic membrane transplantation (AMT) for the treatment of persistent corneal epithelial defects (PEDs) in eyes after penetrating keratoplasty (PK).

DESIGN

Retrospective, non-randomized, observational case series.

METHOD

AMT was performed in 24 eyes of 24 patients with erosions (n=6) or ulcers (n=18), which were resistant to medical therapy. All eyes had undergone one (42%) or more PKs before AMT. After the removal of epithelium and pannus (if present), one or more layers of AM ('graft' (n=3), 'patch' (n=5), 'sandwich'=combination of graft/patch (n=16)) were transplanted. Main outcome measures included 'surgical success' (epithelium closed within 4 weeks after AMT), and 'recurrence' (new epithelial defect developing during follow-up after surgical success).

RESULTS

The rate of surgical success was 70% and was found to be inversely proportional to the number of previous PKs. Defects limited only to the centre of the graft had a higher success rate (central: 100%, non-central: 61%). A total of 44% successful eyes (erosions: 75% vs ulcers: 33%) had a recurrence after a mean follow-up of 16+/-13 months. The rate of surgical success was highest (81 vs 67 vs 25%) and the rate of recurrence was lowest (38 vs 90 vs 100%) with the sandwich technique in contrast to the graft or patch techniques used alone.

CONCLUSIONS

AMT may be beneficial in the treatment of PEDs after PK, especially when applying the sandwich technique. Recurrences seem to be more frequent, if PK preceded AMT.

Sterilization and preservation influence the biophysical properties of human amnion grafts

The introduction of amniotic membrane (AM) transplantation in ophthalmic surgery holds great promise and in many clinical situations it offers an alternative to existing management options. The purpose of this study was to examine the influence of established sterilization and preservation procedures on biophysical and histological properties of AM grafts. Amnion was sterilized by peracetic acid/ethanol sterilization [PES] and preserved by air-drying (sterile laminar flow) [AD] or in glycerol [GLYC]. Unsterilized AM were preserved at -80 degrees C [-80 degrees C] and served as an experimental control. Amnion allografts were characterized by the determination of their thickness, moisture vapour permeability (MVP), oxygen permeability (OPERM), tensile strength and sulphur content. Immunostaining for tissue-specific and basement membrane-related proteins was performed. Differences in biophysical parameters were found between the unsterilized allografts and the sterilized, air-dried or glycerol-preserved allografts. [PES/AD] showed the highest MVP and OPERM, the highest tensile strength and the lowest sulphur content and thickness. [PES/GLYC] exhibited the lowest OPERM and the highest thickness compared to [-80 degrees C] and [PES/AD]. Collagen types V and VII were preserved the best in the control group. Sterilization and preservation affect biophysical properties important for the use of AM as allogenic grafts. It has to be determined if any change, as noted, has a clinical impact.

Sutureless amniotic membrane transplantation for ocular surface reconstruction with a chemically defined bioadhesive

The purpose of this study was to evaluate the efficiency and safety of a sutureless amniotic membrane transplantation (AMT) for ocular surface reconstruction with a chemically defined bioadhesive (CDB). The CDB was synthesized from aldehyded polysaccharides and epsilon-poly(L-lysine), two kinds of medical and food additives, as starting materials. Biocompatibility assay indicated that the CDB showed excellent biocompatibility with in vitro and in vivo ocular surface tissues and most of the CDB was histologically degraded within 4 weeks. Sutureless AMT using the CDB was safely and successfully performed onto a rabbit scleral surface. Transplanted amniotic membrane (AM) evaluated by histological, electron microscopic- and immunohistochemical examination indicated that the CDB did not affect normal differentiation of the cells or the integrity of the surrounding tissue. Thus, this newly developed CDB was found to be very useful for sutureless AMT for ocular surface reconstruction, without considering the risk of infection. It has the ability to fix AM to the ocular surface for a long time-period without additional inflammation, scarring, or damage to the surrounding tissues.

Human amniotic membrane transplantation with fibrin glue in management of primary pterygia: a new tuck-in technique

PURPOSE

To report the use of fibrin glue for attaching the human amniotic membrane graft with a tuck-in technique after primary pterygium excision.

METHODS

Twelve patients with primary pterygium (grade 2 or 3) underwent pterygium excision. The bare sclera was covered with an oversized human amniotic membrane graft by using fibrin glue for graft adherence. The edges of the graft were tucked underneath the adjacent free margin of conjunctiva on 3 sides. Various parameters such as operative time, patient's postoperative comfort, graft adherence, time of graft epithelialization, and recurrence of pterygium were assessed.

RESULTS

The amniotic membrane graft adhered successfully in 11 patients. Average surgical time was 15.5 minutes (range, 13-21 minutes). The postoperative period was generally comfortable. Epithelialization of the graft was rapid, occurring within 7 days in 11 eyes. In 1 patient, the graft was found dislodged partially on the first postoperative day. Eleven eyes showed no recurrence at the end of 1-year follow-up.

CONCLUSIONS

Use of fibrin glue for attaching human amniotic membrane graft in primary pterygium surgery is effective. It not only reduces the surgical time but also minimizes postoperative discomfort and complications.

Hypopyon iritis after primary fresh amniotic membrane transplantation

PURPOSE

To report the occurrence of hypopyon iritis after primary, fresh amniotic membrane transplant (AMT).

METHODS

A case report of a 65-year-old man who underwent AMT along with placement of hydrophilic contact lens for symptomatic relief of pseudophakic bullous keratopathy for the first time. The amniotic membrane (AM) transplanted was obtained freshly after an elective cesarean section.

RESULTS

The patient developed hypopyon on the second postoperative day. Culture of remnants of AM and contact lens were negative. Hypopyon did not respond to periocular antibiotics but disappeared with periocular steroids. Hypopyon was noticed again at 1-week follow-up because of poor compliance of the patient. It again responded to periocular steroids. At 1-year follow-up, the patient is asymptomatic with 20/600 vision.

CONCLUSIONS

Sterile hypopyon iritis appeared after primary AMT with fresh AM, and it disappeared with periocular steroids.

Transplante de membrana amniótica canina criopreservada para cicatrização de córnea com deficiência de células límbicas em coelhos

Avaliaram-se as alterações relacionadas à deficiência das células límbicas precursoras do epitélio corneano de coelhos e o efeito da membrana amniótica sobre sua cicatrização. A lesão, induzida com n-heptanol associado à peritomia conjuntival em 360°, foi recoberta com membrana amniótica canina, suturada à episclera perilímbica, criopreservada em meio para congelação de embrião ou em meio próprio, ambos com glicerol a 50% e mantida a -80°C. O grupo-controle não foi tratado com a membrana. As avaliações histológicas foram realizadas ao sétimo, 15º e 30º dias. Todos desenvolveram deficiência de células germinativas do limbo, denominada conjuntivalização, com presença de neovascularização, inflamação e defeitos epiteliais recorrentes, caracterizada na histopatologia pela presença de neovasos, edema, leucócitos e células caliciformes. O transplante de membrana amniótica não foi eficiente para o tratamento desta deficiência, entretanto auxiliou o processo de cicatrização da córnea.

Evaluation of visual acuity and color vision in normal human eyes with a sutureless temporary amniotic membrane patch

PURPOSE

To evaluate how sutureless amniotic membrane patches may affect visual functions in normal human eyes.

DESIGN

Prospective intervention study.

METHODS

Ten sets of sutureless amniotic membrane patch manufactured as PROKERA were inserted in one eye of six normal patients. Four sets (one each) were inserted in four patients, while six sets (three each) were inserted in two patients. Uncorrected distant and near visual acuities, color vision, amniotic membrane thickness measured by pachymetry, and total symptom scores were compared before and after insertion.

RESULTS

Within 30 minutes after insertion, mean distant visual acuities decreased from -0.22 +/- 0.06 to 0.92 +/- 0.45 logarithmic minimum angle of resolution (logMAR). Among 10 sets of PROKERA inserted, the largest optotype (1.0 logMAR) of the near vision chart could not be recognized in five, but color vision evaluated by Panel D-15 was still preserved in all. Total symptom scores increased to 47.8 +/- 9.1 points (maximum, 100 points). Among symptoms, total scores for foreign body sensation (17.8 +/- 3.6) and blurred vision (17.8 +/- 4.4) were high. Loss of distant visual acuity and increases of symptom scores were not correlated with amniotic membrane thickness, of which the mean was 67.6 +/- 25.2 mum. However, amniotic membrane that was less opaque tended to provide relatively good visual acuities.

CONCLUSION

Because of the relative non-transparency of sutureless amniotic membrane patches in PROKERA, distant and near visual acuities decreased in normal human eyes. The foreign body sensation noted after insertion is primarily derived from the rigid supporting skirt.

The potential of amniotic membrane/amnion-derived cells for regeneration of various tissues

Regenerative medicine is a new field based on the use of stem cells to generate biological substitutes and improve tissue functions, restoring damaged tissue with high proliferability and differentiability. It is of interest as a potential alternative to complicated tissue/organ transplantation. Recently, amnion-derived cells have been reported to have multipotent differentiation ability, and these cells have attracted attention as a cell source for cell-transplantation therapy. The amnion possesses considerable advantageous characteristics: the isolated cells can differentiate into all three germ layers; they have low immunogenicity and anti-inflammatory functions; and they do not require the sacrifice of human embryos for their isolation, thus avoiding the current controversies associated with the use of human embryonic stem cells. Moreover, we developed human amniotic cell-sheets using a novel culture surface coated with a noncytotoxic, temperature-responsive elastic protein-based polymer. We also generated a "hyper-dry-amnion", which has already been applied clinically in the ophthalmological field. Compared to cryopreserved fresh amnion, "hyper-dry-amnion" is easy to handle and has started to bring good results to patients. These materials from the amnion are also expected to open a new field in tissue engineering. Thus, amnion, which had been discarded after parturition, has started to be appreciated as an attractive material in the field of regenerative medicine. In this review, the most recent and relevant clinical and experimental data about the use of amniotic membrane and cells derived from it are described.

The expression of TIMPs in cryo-preserved and freeze-dried amniotic membrane

PURPOSE

To investigate the change of tissue inhibitor of metalloproteinase (TIMP) in cryopreserved amniotic membranes (AM) according to preservation time, and to evaluate the expression of TIMP in freeze-dried AM.

METHODS

Cryopreserved or fresh AMs were incubated in dispase II for two hours at 37 degrees C and their epithelial cells were scraped with a cell scraper. Remaining stromal AM was minced and frozen in liquid nitrogen, and then treated with 0.1% diethyl pyrocarbonate. The mRNA levels of TIMP-1 and -2 were determined by reverse transcription-polymerase chain reaction (RT-PCR) in epithelial and stromal cells of fresh AM, AMs cryopreserved for 6 and 12 months, and freeze dried AM, respectively. Western blot analysis and immunohistochemical staining were performed to assess the expression of TIMP-1 in fresh, cryopreserved, and freeze dried AMs.

RESULTS

RT-PCR revealed that mRNAs of TIMP-1 and -2 were expressed in the amniotic epithelial cells of both fresh and cryopreserved AMs, while the stromal cells of fresh or cryopreseved AMs and freeze-dried AM showed higher expression of TIMP-1 than TIMP-2 mRNA. On Western blot analysis, the level of TIMP-1 was more in fresh AMs than in cryopreserved or freeze-dried AM, but it was not statistically significant.

CONCLUSION

TIMP-1 was expressed in cryopreserved AMs until 12 months, and the amount of expression was comparable to that in fresh AMs.

Amniotic membrane transplantation for intraoperative conjunctival repair during trabeculectomy with mitomycin C

PURPOSE

To describe the use of amniotic membrane (AM) transplantation for the repair of conjunctival buttonholes during trabeculectomy with mitomycin C.

METHODS

Four eyes of 3 patients with thin conjunctiva, precluding watertight conjunctival closure at the incision site with suturing, underwent intraoperative AM grafts over the leaking areas.

RESULTS

In all eyes, a functional, nonleaking bleb was achieved. At the latest follow-up (8 to 30 mo), all eyes had intraocular pressures of 12 mm Hg or less without medications.

CONCLUSIONS

AM transplantation was effective in the intraoperative closure of conjunctival buttonholes which developed at the incision line in 4 eyes. This intervention may be a useful addition to the glaucoma surgeon's repertoire of surgical techniques.

On the influence of neutrophils in corneas with necrotizing HSV-1 keratitis following amniotic membrane transplantation

Necrotizing herpetic stromal keratitis (HSK) in mice rapidly improved after amniotic membrane transplantation (AMT). In this study we determined the fate of polymorphonuclear neutrophils (PMN) after AMT. AMT or tarsorrhaphy (T) was performed in BALB/c mice with ulcerative HSK. After 2 days, corneas were studied histologically and by transmission electron microscopy (TEM). CD11b, Gr-1, and TUNEL-positive cells were identified. Macrophages were depleted by subconjunctival injection of dichloromethylene-diphosphonate-liposomes (Cl(2)MDP-LIP) before AMT. Corneas were studied for interleukin (IL)-1alpha, IL-2, interferon (IFN)-gamma, CXCL1, CXCL2, and tumor necrosis factor (TNF)-alpha production by ELISA. PMN-enriched cell preparations co-cultured with amniotic membrane (AM) or with AM and such recombinant (r) cytokines as rIL-1alpha, rIL-2, and rTNF-alpha or supernatants from activated lymphocytes were investigated by flow cytometry (Annexin-V/7-AAD and TUNEL), and a dimethylthiazolyl-diphenyltetrazolium-bromide (MTT)-viability assay. Corneas in the AMT mice had less inflammation, fewer PMN-like cells and fewer CD11b+, and Gr-1+ cells (P<0.01), but a higher ratio of apoptotic to viable PMN-resembling cells (P<0.01) than the T mice. Phagocytic removal of apoptotic PMN-like cells by macrophages was evident in the AMT group. After Cl(2)MDP-LIP treatment, the corneas had more cell debris and apoptotic cells with PMN-like morphology. The concentrations of IL-1alpha, IL-2, CXCL1, and TNF-alpha were reduced in corneas of the AMT group as compared to that of the T group, while the concentration of CXCL2 was increased. Apoptosis of PMN-resembling cells was detected following cocultivation with AM, even when proinflammatory cytokines were present. Resolution of corneal inflammation in mice with necrotizing HSK after AMT is associated with increased apoptosis of PMN-like cells, reduction of pro-inflammatory cytokines, an increase of CXCL2, and increased removal of apoptotic PMN-like cells by macrophages.

How does amniotic membrane work?

Transplantation of amniotic membrane as a temporary or permanent graft promotes epithelial wound healing and exerts potent anti-inflammatory and anti-scarring effects on the ocular surface. These actions depend on the killing of allogeneic amniotic cells and preservation of the cytokine-containing matrix during the preparation of the amniotic membrane. This review describes how these actions inherently operate in utero and how amniotic membrane transplantation aims to recreate such a fetal environment to exert these actions by insulating the surgical site from the host environment. These actions also render the amniotic membrane a unique niche capable of expanding both epithelial and mesenchymal progenitor cells ex vivo, while maintaining their normal cell phenotypes. As a result, the amniotic membrane becomes an ideal substrate for engineering different types of ocular surface tissues for transplantation. Further studies investigating the exact molecular mechanism by which the amniotic membrane works will undoubtedly unravel additional applications in reconstruction and engineering of both ocular and nonocular tissues in the burgeoning field of regenerative medicine.

Use of Autologous Platelet-Rich Plasma in the Treatment of Dormant Corneal Ulcers

PURPOSE

To investigate the potential role of autologous platelet-rich plasma in promoting healing in dormant corneal ulcers.

DESIGN

Prospective, consecutive, interventional, noncomparative, nonrandomized, observational study.

PARTICIPANTS

Forty eyes of 38 patients with dormant corneal ulcers.

METHODS

Autologous platelet-rich plasma was used in a total of 40 eyes with dormant corneal ulcers divided into 2 groups: group I, 26 eyes treated with topical eyedrops of autologous platelet-rich plasma (12 neurotrophic, 9 herpetic, and 5 immunological ulcers), and group II, 14 eyes treated surgically with a solid clot of autologous platelet-rich plasma combined with amniotic membrane transplantation in perforated corneas or with impending perforation. The treatment was used in patients with chronic nonhealing ulcers (mean, 2 years of evolution) that had been unresponsive to conventional topical therapy. Autologous blood from each patient was obtained by venipuncture, and platelet-rich plasma was prepared from each blood sample without additives.

MAIN OUTCOME MEASURES

Ulcer size, inflammation, healing, visual acuity, and patient's subjective symptoms.

RESULTS

Autologous platelet-rich plasma promoted healing of ulcers. In group I, 13 eyes healed, 11 eyes improved significantly, and 2 eyes showed no change. In group II, 10 eyes healed and 4 eyes improved significantly. Inflammation and subjective symptoms, particularly pain, improved in all patients. Vision remained stable or improved in all cases.

CONCLUSION

Autologous platelet-rich plasma promoted healing of dormant corneal ulcers even in eyes threatened by corneal perforation and was accompanied by a reduction in pain and inflammation.

Amniotic membrane as a carrier for lacrimal gland acinar cells

BACKGROUND

The secretion of the lacrimal gland provides 95% of the aqueous tears, which are essential for lubrication, nutrition and protection of the ocular surface. Long-term studies of acinar lacrimal gland cells in vitro are complicated by low proliferation rate and fast loss of cell function on plastic. Aim of this study was to evaluate the growth pattern and the secretory function of lacrimal gland acinar cells on amniotic membrane (AM) in a rabbit model.

METHODS

Lacrimal gland acinar cells from Chinchilla Bastard and New Zealand White rabbits of both sexes were isolated and cultured on denuded amniotic membrane. Cells were analysed by light and electron microscopy. Secretory function was tested by measuring the beta-hexosaminidase activity.

RESULTS

Three days after seeding to the amniotic membrane, the acinar cells had attached to each other and formed small cluster. Cell clusters consisted of 2-5 cell layers, and the cells showed fine granulation in their cytoplasm, typical for secreting cells. Between days 7 and 14 cell clusters increased in size, and acini-like structures with a central lumen were found. Cells showed polarity, with a basal nucleus and apical secretory granules. Between days 21 and 28 acini-like structures were still found inside the cell clusters. Accumulation of secretory material in the central lumen and desmosome formation connecting the apical cell structures was frequently evident. However, the number of cytoplasmatic granules decreased, and on parts of the AM, cell morphology changed to flat, spindle-shaped cells with a small nucleus. Stimulation with carbachol showed a strong beta-hexosaminidase release until day 7, with a decreasing secretory function detectable until day 21.

CONCLUSION

Acinar lacrimal gland cells can be successfully cultured on amniotic membrane up to 28 days, with a secretory response to carbachol up to 21 days. This model may be used for further experimental work, to elucidate cellular mechanisms in normal and diseased lacrimal tissue.

[Advantages of amniotic membrane transplantation in eye surface diseases]

Amniotic membrane transplantation is now a widely adopted technique in the field of eye surface diseases. Depending on the indication, the amniotic membrane can be used as either a graft or a patch. When used as a graft, the amniotic membrane serves as a substrate for regrowth of deficient epithelium; the aim is to integrate this membrane. The basal membrane reinforces the adhesion and differentiation of the corneal epithelial cells, facilitates their migration, and prevents their apoptosis. When used as a patch, the amniotic membrane is sutured epithelium-down so as to maximize the concentration of biological factors delivered by this membrane: the membrane covers the diseased cornea and acts as a biological bandage and analgesic. The best indications for amniotic membrane grafts are acute chemical burns and trophic corneal ulcers refractory to all medical treatment. When these ulcers are perforated or in the early stages of perforation, it is best to use multiple layers of amniotic membrane, restoring the thickness of the cornea. In cases of confirmed limbal deficiency, amniotic membrane grafts may be a useful complement to the necessary limbal stem cell grafts. In the future, amniotic membranes will provide an indispensable support for the expansion of cultured stem cells. Amniotic membrane grafts may also be used to reconstruct the conjunctiva following the exeresis of symblepharons or conjunctival tumors. However, the use of this technique is currently limited to diseases with little inflammation and no extensive fibrosis.

Human Amniotic Membrane as a Delivery Matrix for Articular Cartilage Repair

The purpose of this study is to evaluate the feasibility of human amniotic membrane (HAM) as a chondrocyte carrier by assessing cell proliferation and maintenance of phenotype in vitro and cartilage regeneration in vivo. Intact HAM was treated with 0.1% trypsin-ethylenediaminetetraacetic acid (EDTA) for 15 min and the epithelial cells removed to make a denuded HAM. Rabbit articular chondrocytes were then seeded on three different HAM substrates: the epithelial side of intact HAM (IHE), basement side of denuded HAM (DHB), and stromal side of denuded HAM (DHS). These cell-substrate specimens were cultured for up to 4 weeks, and cell proliferation rate and phenotypic stability were examined at weeks 1 and 4. While chondrocytes grew in monolayer fashion on the surface of IHE and DHB substrates, the cells seeded in DHS penetrated and spread into the whole thickness of the stromal layer. The proliferating activity of chondrocytes in DHB was continuously up-regulated. A similar proliferating activity was observed in DHS in the first week, which remained stable for up to 4 weeks. The expression of type II collagen gradually increased with time in the DHS group, while it gradually decreased in the DHB group or was not detected at all in the IHE group. These results suggested that denuded HAM was able to support chondrocyte proliferation and maintenance of phenotype in vitro, seemingly more favorable when DHS was used. Based on this data, the DHS with chondrocytes was used to cover rabbit osteochondral defect with the stromal side facing in. The defect area was successfully regenerated with hyaline cartilage in the Safranin-O stain and International Cartilage Repair Society (ICRS) scoring after 8 weeks of implantation. In conclusion, our findings suggest that denuded HAM could be one of the ideal cell carrier matrices for cartilage regeneration.

Measurement of Light Transmission of Human Limbal Epithelial Cells Cultured on Human Amniotic Membranes

PURPOSE

To measure the light transmission properties of human limbal epithelial cell sheets (LECSs) cultured on human amniotic membranes (AMs) and compare them with those of AMs with and without amniotic epithelium.

METHODS

Total light transmission of 3 kinds of tissue (LECSs, intact AMs, denuded AMs) was measured in the 250- to 800-nm range by using a spectrophotometer.

RESULTS

The percent transmission of each kind of tissue decreased gradually and continually throughout the spectrum as the wavelength shortened and dropped rapidly at 300 nm to less than 20% at 250 nm. All tissues transmitted more than 70% of light in the wavelength region greater than 400 nm and more than 90% in that greater than 600 nm. The percent transmission spectrum of all tissues showed identical curves in the visible light and UV-A regions. However, the percent transmission of LECSs was lower than that of either intact or denuded AMs in the UV-B and UV-C regions.

CONCLUSIONS

In the visible and UV-A light region, the percent transmission profiles of amnion-related tissues (LECSs, intact AMs, denuded AMs) are not altered by the presence of either amniotic epithelium or multilayered limbal corneal epithelium. However, the presence of multilayered limbal corneal epithelium, but not amniotic epithelium, on amniotic stroma reduced UV-B and -C transmission significantly. Further study concerning light transmission and other physical properties of LECSs is necessary to fully understand the ocular physiology of eyes grafted with such newly developed bioengineered tissues.

Amniotic membrane transplantation combined with antiviral and steroid therapy for herpes necrotizing stromal keratitis

PURPOSE

To evaluate therapeutic effect of multilayer amniotic membrane transplantation (AMT) in conjunction with antiviral and corticosteroid therapy on herpes necrotizing stromal keratitis.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Fifteen patients (15 eyes) with herpes necrotizing stromal keratitis, persistent corneal inflammation, and impending ulcer, despite topical and systemic antiviral treatment for over 2 weeks.

METHODS

Multilayer AMT was performed in the 15 eyes. Antiviral medications and appropriate corticosteroids were administered after surgery. Remodeling of amniotic membrane (AM) and growth of epithelial cells were detected by confocal microscopy.

MAIN OUTCOME MEASURES

Visual acuity and corneal status (ulceration, edema, and opacification).

RESULTS

Follow-up ranged from 7 to 13 months (mean +/- standard deviation, 8.9+/-1.8). Visual acuity improved by > or =2 lines in 14 eyes. Central corneal ulcers healed completely at 2.0+/-0.6 weeks, and paracentral ulcers at 2.1+/-0.6 weeks (t = 0.314, P = 0.759). Corneal stromal thickness was restored in eyes with central ulcers at 2.4+/-1.2 weeks and in those with paracentral ulcers at 2.6+/-0.7 weeks (t = 0.425, P = 0.678). Superficial epithelial cells, together with small basal epithelial cells, gradually migrated to the surface of AM on postoperative weeks 1 to 3. There were corneal nebulae in 11 eyes, corneal maculae in 3 eyes, and a corneal leukoma in 1 eye at the end of follow-up. No recrudescence occurred in any eye.

CONCLUSION

Multilayer AMT combined with antiviral and corticosteroid therapy appears effective in treating herpes necrotizing stromal keratitis. It provides patients with marked scars and visual impairment an opportunity for subsequent keratoplasty by arresting the inflammatory response and reducing the graft bed diameter.

In Vivo Cartilage Tissue Engineering Using a Cell-Derived Extracellular Matrix Scaffold

We have observed in our previous study that a cell-derived extracellular matrix (ECM) scaffold could assure the growth of a cartilage tissue construct in vitro. The purpose of the present study was to evaluate the feasibility of a chondrocyte-seeded cell-derived ECM scaffold by implanting it in vivo in nude mouse. A porous cell-derived ECM scaffold was prepared with a freeze-drying protocol using porcine chondrocytes. Rabbit articular chondrocytes were seeded onto the scaffold and cultured for 2 days in vitro, and then implanted into the nude mouse subcutaneously. They were retrieved at 1, 2, and 3 weeks postimplantation. Under macroscopic analysis, the cartilage-like tissue formation matured with time and developed a smooth, white surface. Contrary to the control (in which no cells were seeded), the size of the neocartilage tissue increased slightly by the third week and remained more stable. Total glycosaminoglycan (GAG) content and the GAG/DNA ratio increased significantly with time in the chemical analysis. The histology exhibited a sustained accumulation of newly synthesized sulfated proteoglycans. Immunohistochemistry, Western blot, and reverse transcriptase-polymerase chain reaction (RT-PCR) clearly identified type II collagen at all time points. Compressive strength of in vivo neocartilage increased from 0.45 +/- 0.06 MPa at 1 week to 1.18 +/- 0.17 MPa at 3 weeks. In conclusion, this study demonstrated that the cell-derived ECM scaffold could provide chondrocytes with favorable in vivo environment to produce a hyaline-like cartilage tissue.

Plasticity of epidermal adult stem cells derived from adult goat ear skin

Here we report the isolation and characterization of pluripotent stem cells from adult goat skin. We found that these primary cells have the properties of embryonic stem cells (ESC), including the expression of appropriate immunological markers and the capability of forming embryoid bodies. The subcultured cells also show the characteristics of stem cells, such as the expression of CK19, beta(1-)integrin, P63, and formation of holo-clones in culture. Therefore, we termed these cells epidermal adult stem cells (EpiASC), although their origin was not identified. We have shown that clones of individual EpiASC proliferate and differentiate in culture to produce neurons, cardiomyocytes, osteoblasts, and occytes. Further, we cultivated EpiASC on bioengineered dermis and denuded human amniotic membrane (HAM), to reconstruct artificial skin and corneal epithelium. We successfully transplanted those artificial tissues in goats with acute full-thickness skin defect (AFTSD) and limbal stem cell deficiency (LSCD), respectively. Our results showed that indeed EpiASC reconstructed the skin (hair was observed in restored areas), and repaired the damaged cornea of goats with total LSCD. These data confirm that EpiASC can differentiate into different functional cell types in vivo or in vitro. Due to their high degree of inherent plasticity, and to their easy accessibility for collection from the skin, EpiASC are excellent candidate sources for diverse cell therapies.

Amniotic membrane transplantation for ocular disease: a review of the first 233 cases from the UK user group

BACKGROUND

Amniotic membrane transplantation (AMT), as a new tool in the armamentarium of therapies available for ocular surface problems, became widely available in the UK in 1998. This study evaluates the indications for treatment, the surgical procedures used, and the results of a subset of the first AMT cases carried out by the group using this nationally available supply. This user group model provides data which is different from that obtained from uncontrolled case series, or clinical trials, and may be more representative of the outcomes that can be expected when a procedure becomes widely available.

METHODS

The first 233 AMTs, performed by the UK user group, were evaluated by audit and outcomes were assessed at 3 months.

RESULTS

Of the 233 transplants, there were 126 (54.1%) valid outcome returns: the outcome for persistent epithelial defects was a healed and stable surface in 11/35 (31.4%, 95% CI 16.9 to 49.3); for chemical/thermal injuries, a healed uninflamed eye with clear cornea in 5/18 (27.8%, 95% CI 9.7 to 53.4); for bullous keratopathy a pain-free, stable surface without bullae in 4/18 (22.2%, 95% CI 6.4 to 47.6); for ocular surface reconstruction, an epithelialised uninflamed conjunctiva without scarring in 12/23 (52.2%, 95% CI 30.6 to 73.2); and for limbal stem cell deficiency, a corneal phenotype in 4/7 (57.1%). The operative technique least associated with failure was use of a bandage contact lens at the end of the procedure (OR 0.19, 95% CI 0.06 to 0.59, p = 0.004). Previous treatment with topical steroids was significantly associated with failure (OR 5.70, 95% CI 1.77 to 18.43, p = 0.004).

CONCLUSION

Although the outcome criteria used in this study were stringent, and the follow-up duration was short, the results of AMT by this user group were generally less favourable than those of previously reported case series. Controlled clinical trials would improve the quality of evidence for use of amniotic membrane in ocular disease.

Immunohistochemical observation of amniotic membrane patching on a corneal alkali burn in vivo

PURPOSE

To investigate by immunohistochemical observation the effects of amniotic membrane (AM) patching on myofibroblastic differentiation and matrix metalloproteinase (MMP) expression in the corneal stroma after an alkali burn in vivo.

METHODS

A corneal alkali burn was made by placing a circular piece of filter paper containing 1 N NaOH on the central cornea of rabbits. Burning was done unilaterally in each rabbit. Immediately after the wounding, in the AM group, AM was sutured onto the cornea and removed on day 1. Rabbits with no AM patching were controls. On day 14, corneas were excised and immunohistochemical observation was carried out using antibodies against alpha-smooth muscle actin (alpha-SMA), vimentin, MMP-1, MMP-2, MMP-9, and membrane-type1 (MT1)-MMP. Observation after Masson trichrome staining was also performed.

RESULTS

In the AM group, alpha-SMA positive cells were noticeably fewer, and MMP-2, MMP-9, and MT1-MMP expression was clearly inhibited. Also, collagen fibers were more regularly arranged than in control eyes. The more proximate the cells were to the epithelial side, the fewer alpha-SMA-positive cells were observed in the AM group.

CONCLUSIONS

AM patching suppressed myofibroblastic differentiation and MMP expression in the stroma after an alkali burn. An inhibition gradient suggests that AM may release unknown soluble factors possessing some antiscarring capability.

Vascularization is more delayed in amniotic membrane graft than conjunctival autograft after pterygium excision

PURPOSE

To monitor the development of graft vascularization by indocyanine green angiography (ICGA) after pterygium excision with limbal-conjunctival autograft transplantation (LCAT) and amniotic membrane transplantation (AMT).

DESIGN

Randomized prospective interventional case series.

METHODS

Anterior segment ICGA findings at one, seven, and 30 days after surgery were evaluated in eyes with primary pterygium treated by excision and LCAT (14 eyes of 14 patients) or AMT (13 eyes of 13 patients), and the results for graft vascularization were compared.

RESULTS

All conjunctival autografts showed early vascularization from underlying episcleral vascular bed as multiple hyperfluorescent foci at the graft margin on postoperative day 7; graft vascularization was complete on postoperative day 30. In contrast, all grafts in AMT group showed no graft vascularization at any stage after pterygium surgery. This delay of vascularization with AMT persisted until one month after surgery.

CONCLUSIONS

Anterior segment ICGA is useful to monitor graft vascularization after pterygium surgery. Graft health after LCAT may be demonstrated by early graft vascularization and perfusion; however, there is a delay in graft vascularization after AMT that may be related to the antiangiogenic effects of the membrane. Further study is needed to demonstrate the relationship between this delay of graft perfusion and early postoperative pterygium recurrence.

Effect of limbal explant orientation on the histology, phenotype, ultrastructure and barrier function of cultured limbal epithelial cells

PURPOSE

To compare the histology, phenotype, ultrastructure and barrier function of cultured limbal epithelial cells using two explant culture protocols.

METHODS

Epithelial cells were cultured for 16 days from limbal explants, positioned with either the stromal side (stromal group) or the epithelial side (epithelial group) on intact amniotic membranes. The cultured epithelium (n = 56) was examined using light microscopy, immunohistochemistry for K3, Cx43, ABCG2 and p63 expression, Western blot analysis of DeltaNp63alpha, transmission electron microscopy, a horseradish peroxidase (HRP) permeability assay and scanning electron microscopy.

RESULTS

The epithelial group demonstrated a significantly higher expression of p63-positive cells (85.7 +/- 4.2%) than the stromal group (75.3 +/- 8.9%), and Western blots showed a stronger band of DeltaNp63alpha. K3 and ABCG2 were not detected in either group, whereas Cx43 displayed moderate immunostaining in the suprabasal layer. The number of cell layers, the desmosome number and the undulation length in the epithelial group were not significantly different from those in the stromal group. In both groups, HRP accumulated on the apical surface of the superficial cells, and scanning electron microscopy demonstrated tightly apposed superficial cells.

CONCLUSIONS

Our findings indicate that limbal explants positioned epithelial side down may give rise to cultured epithelia with higher expression of p63 and DeltaNp63alpha.

[Diseases of the adnexa in the tropics: amnion membrane transplantation for noninfectious trachoma-associated corneal ulcers]

BACKGROUND

Corneal ulcers with fornix shortening associated with late stages of cicatrizing trachoma contribute significantly to blindness in many developing countries. We report on the outcome of ocular surface and fornix reconstruction using amnion membrane transplantation.

PATIENTS AND METHODS

From 2001 to 2005, cryopreserved human amnion membrane without mitomycin C was grafted to 25 eyes of 17 patients with trophic corneal ulcers and symblepharon (cicatrizing trachoma: 19 eyes of 14 patients, Stevens-Johnson syndrome: 4 eyes of 2 patients, alkali burns: 2 eyes of 1 patient) in a controlled case series. Follow-up was done up to 6 months.

STATISTICS

Fischer's exact probability test.

RESULTS

Of 25 eyes, 9 of 19 eyes with trachoma, 3 of 4 eyes with Stevens-Johnson syndrome, and 2 of 2 eyes with chemical burns showed complete reepithelialization and stromal recovery after 28-35 days (mean: 31+/-2.3 days). The primary success rate of trachoma eyes was not significantly different from the other indications (p=0.256). At 6 months post-op, 15 of 19 trachoma eyes (79%) compared to 2 of 6 non-trachoma eyes (33.3%) had developed a recurrence of symblephara (p=0.0592), and 13 of 15 eyes (86.6%) with a cicatricial trachoma compared to 1 of 6 with non-trachoma diagnosis experienced a recurrence of corneal vascularization (difference nonsignificant: p=0.1752). Persistent long-term reepithelialization was observed only in 1 of 19 trachoma eyes (5.3%) versus 4 of 6 non-trachoma eyes (66.7%, p=0.005); 3 of 19 trachoma eyes with a recurrence of ulcers had perforated after 6 months.

CONCLUSIONS

Human amnion membrane without mitomycin C can be used for ocular surface reconstruction in selected patients with cicatrizing trachoma. Its efficacy in the long-term rehabilitation of cicatrizing trachoma seems to be limited due to the progressive scarring.

Rate of epithelialisation and re-operations in corneal ulcers treated with amniotic membrane transplantation combined with botulinum toxin-induced ptosis

OBJECTIVE

To examine the efficacy of amniotic membrane transplantation (AMT) and/or botulinum toxin type A-induced ptosis (Dysport) in the treatment of corneal ulcerations of different entities.

METHODS

Retrospective evaluation of 137 cases of corneal ulcers which have been treated with AMT, botulinum toxin type A and perforating keratoplasty (pKP). Regarding corneal ulcerations the patients were divided into three groups: group A, patients initially having received an AMT (92 eyes eventually followed by AMT or pKP as a second intervention); group B, patients initially having received an AMT (32 eyes followed by botulinum toxin type A injection in the upper lid as a second intervention); group C, patients initially treated only by botulinum toxin type A injection (13 eyes followed occasionally by AMT or pKP or additional botulinum toxin type A injection). Additionally, we analysed the complete epithelialisation rate of the ocular surface in respect to different ocular and systemic diseases and compared the frequency of re-operations in each group.

RESULTS

The overall follow-up was 14.2 (+/-14.7 months; range from 1 to 60 months). The total frequency of re-operations was 45.3% (overall time until complete epithelialisation 12.7 (+/-6.1) days). If the patient was initially treated with an AMT (group A), the re-operation rate was 44.6%. Treating affected eyes in this group with a subsequent amniotic membrane resulted in a reduction of re-operation rate to 30.4%. In cases with induced ptosis by injecting botulinum toxin type A in the M. levator palpebrae (group B), the re-operation frequency could be reduced to 34.4% with similar times of epithelialisation [group A: 12.0 (+/-6.5) days and group B: 11.7 (+/-5.5) days]. In group C, with botulinum toxin type A alone initially, the re-operation rate of 69.2% was the highest one compared with groups A and B; this rate could be drastically reduced by a following AMT to 23.1%. Surprisingly, in the few successful cases with botulinum toxin type A alone a quite low epithelialisation time of 6.5 (+/-1.3) days was achieved, but turned out to be similar after additional interventions if compared with the other groups (botulinum toxin type A + AMT: 15.7 (+/-4.9) day).

CONCLUSION

AMT alone and combined with botulinum toxin type A-induced ptosis is an effective surgical approach for managing severe corneal ulcerations by promoting wound healing and stabilizing ocular surface homeostasis.