Conventional corneal transplantation, in the form of penetrating keratoplasty (PK), involves full-thickness replacement of the cornea, and is a highly successful procedure. However, the cornea is anatomically a multi-layered structure. Pathology may only affect individual layers of the cornea, hence selective lamellar surgical replacement of only the diseased corneal layers whilst retaining unaffected layers represents a new paradigm shift in the field. Recent advancements in surgical techniques and instrumentation have resulted in several forms of manual, microkeratome and femto-second laser-assisted lamellar transplantation procedures. Anterior lamellar keratoplasty (ALK) aims at replacing only diseased or scarred corneal stroma, whilst retaining the unaffected corneal endothelial layer, thus obviating the risk of endothelial allograft rejection. Posterior lamellar keratoplasty/endothelial keratoplasty (PLK/EK) involves the replacement of the dysfunctional endothelial cell layer only. Whilst significant technical and surgical challenges are involved in performing lamellar micro-dissection of a tissue which is only 0.5 mm thick, the benefits of a more controlled surgical procedure and improved graft survival rates have resulted in a shift away from conventional PK. This review details the current advances in emerging lamellar corneal surgical procedures and highlights the main advantages and disadvantages of these new lamellar corneal procedures.
Contraindications ; Corneal Transplantation ; methods ; trends ; Humans

BACKGROUNDThe limiting factor to corneal transplantation is the availability of donors. Research has suggested that xenogenic acellular corneal scaffolds (XACS) may be a possible alternative to transplantation. This study aimed to investigate the viability of performing lamellar corneal transplantation (LCT) in rabbits using canine XACS.

METHODSFresh dog corneas were decellularized by serial digestion, and LCT was performed on rabbit eyes using xenogeneic decellularized corneal matrix. Cellular and morphological changes were observed by slit-lamp, light, and scanning electron microscopy at 7, 30 and 90 days postoperatively. Immunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft.

RESULTSDecellularized xenogenic corneal matrix remained transparent for about 1-month after LCT. The recipient cells were able to survive and proliferate into the grafts. Three months after transplantation, grafts had merged with host tissue, and graft epithelialization and vascularization had occurred. Corneal nerve fibers were able to grow into the graft in rabbits transplanted with XACS.

CONCLUSIONSXenogenic acellular corneal scaffolds can maintain the transparency of corneal grafts about 1-month and permit growth of cells and nerve fibers, and is, therefore, a potential substitute or carrier for a replacement cornea.

Animals ; Cornea ; surgery ; Corneal Stroma ; surgery ; Corneal Transplantation ; methods ; Dogs ; Microscopy, Confocal ; Rabbits ; Tissue Engineering

A myxoma is a benign tumor found in the heart and in various soft tissues; however, a corneal myxoma is rare. A mucinous mass of unknown etiology was observed on the left cornea of a 32-year-old male patient. We performed deep anterior lamellar keratoplasty using acellular corneal tissue and concurrent amniotic membrane transplantation. Hematoxylin and eosin staining revealed vacuolation of the parenchyma and myxoid change in the corneal tissue that occurred in the anterior half of the corneal parenchyma. We identified a myxoid stroma by Alcian blue staining and observed collagen fibers with denatured stroma by Masson trichrome staining. The patient's visual acuity improved from light perception to 20 / 200, and the intraocular pressure remained within the normal range for one year after surgery. The transplanted cornea survived successfully with well-maintained transparency, and recurrence was not observed one year after surgery.
Adult ; *Cornea ; Corneal Stroma/cytology/*transplantation ; Corneal Transplantation/*methods ; Eye Neoplasms/diagnosis/*surgery ; Humans ; Male ; Myxoma/diagnosis/*surgery

A myxoma is a benign tumor found in the heart and in various soft tissues; however, a corneal myxoma is rare. A mucinous mass of unknown etiology was observed on the left cornea of a 32-year-old male patient. We performed deep anterior lamellar keratoplasty using acellular corneal tissue and concurrent amniotic membrane transplantation. Hematoxylin and eosin staining revealed vacuolation of the parenchyma and myxoid change in the corneal tissue that occurred in the anterior half of the corneal parenchyma. We identified a myxoid stroma by Alcian blue staining and observed collagen fibers with denatured stroma by Masson trichrome staining. The patient's visual acuity improved from light perception to 20 / 200, and the intraocular pressure remained within the normal range for one year after surgery. The transplanted cornea survived successfully with well-maintained transparency, and recurrence was not observed one year after surgery.
Adult ; *Cornea ; Corneal Stroma/cytology/*transplantation ; Corneal Transplantation/*methods ; Eye Neoplasms/diagnosis/*surgery ; Humans ; Male ; Myxoma/diagnosis/*surgery

PURPOSE: To report two cases of femtosecond laser-assisted small incision deep lamellar endothelial keratoplasty (DLEK) for patients with corneal endothelial decompensation by Fuchs dystrophy and glaucoma METHODS: Femtosecond laser (IntraLase(R); IntraLase Corp., Irvine, CA) with 15 kHz of repetition rate, was used for a 9.5 mm diameter by 400 micrometer thickness donor corneal lamellar dissection. RESULTS: In Case 1, the graft was clear and compact without interface haze, Orbscan showed smooth and regular corneal surface, specular microscopy was unremarkable without sign of corneal endothelial damage, and Optical coherence tomography showed uniform graft well attached to recipient stroma with minimal interface reflection at 2 months postoperation. In Case 2, the graft was clear and compact with minimal interface haze at 1 month postoperation. Femtosecond laser-assisted small incision DLEK was safe and technically feasible in our cases; however, further evaluation is required to determine long-term effects.
Aged ; Aged, 80 and over ; Corneal Edema/*surgery ; Corneal Surgery, Laser/*methods ; Corneal Topography ; Corneal Transplantation/*methods ; Endothelium, Corneal/*transplantation ; Female ; Fuchs' Endothelial Dystrophy/*surgery ; Humans ; Male ; Tomography, Optical Coherence ; Visual Acuity

PURPOSE: To report two cases of femtosecond laser-assisted small incision deep lamellar endothelial keratoplasty (DLEK) for patients with corneal endothelial decompensation by Fuchs dystrophy and glaucoma METHODS: Femtosecond laser (IntraLase(R); IntraLase Corp., Irvine, CA) with 15 kHz of repetition rate, was used for a 9.5 mm diameter by 400 micrometer thickness donor corneal lamellar dissection. RESULTS: In Case 1, the graft was clear and compact without interface haze, Orbscan showed smooth and regular corneal surface, specular microscopy was unremarkable without sign of corneal endothelial damage, and Optical coherence tomography showed uniform graft well attached to recipient stroma with minimal interface reflection at 2 months postoperation. In Case 2, the graft was clear and compact with minimal interface haze at 1 month postoperation. Femtosecond laser-assisted small incision DLEK was safe and technically feasible in our cases; however, further evaluation is required to determine long-term effects.
Aged ; Aged, 80 and over ; Corneal Edema/*surgery ; Corneal Surgery, Laser/*methods ; Corneal Topography ; Corneal Transplantation/*methods ; Endothelium, Corneal/*transplantation ; Female ; Fuchs' Endothelial Dystrophy/*surgery ; Humans ; Male ; Tomography, Optical Coherence ; Visual Acuity

To evaluate the efficacy of amniotic membrane in the management of painful bullous keratopathy secondary to the intractable glaucoma and in preventing exposure of drainage devices, we inserted Ahmed valve with amniotic membrane patch graft over the implant itself, and debrided corneal epithelium with amniotic membrane graft over the exposed stroma as a single operation. During the follow-up periods, we monitored vision, intraocular pressure (IOP), presence of ocular pain, and postoperative complications associated with the implants. The mean follow up period was 8.4+/-3.2 months. IOP was well controlled after the intervention. The preoperative mean IOP was measured as 43.9+/-9.0 mmHg and lowered to 16.1+/-1.8 mmHg at the last visit and no complications associated with the implants were noted. Even though the improvement in vision was not prominent, the ocular surface stabilized rapidly and ocular pain associated with bullous keratopathy disappeared soon after surgery. Conclusively the use of amniotic membrane in conjunction with Ahmed valve implantation is an effective way to relieve ocular pain and lessen the chances of complications associated with the implant in patients with intractable glaucoma and bullous keratopathy.
Retrospective Studies ; Middle Aged ; Male ; Humans ; *Glaucoma Drainage Implants ; Glaucoma/complications/surgery ; Female ; Epithelium, Corneal/pathology/surgery ; Corneal Transplantation/*methods ; Corneal Diseases/etiology/pathology/*surgery ; Amnion/*transplantation ; Aged

To study corneal lymphangiogenesis after corneal transplantation, corneal allogenic transplantation models were established in rats. 8 female Wister rats were used as donors, and 16 Sprague Dawley (SD) rats were used as recipients and 2 SD served as controls. Corneal lymphangiogenesis and hemangiogenesis was examined by electron microscopy 1 and 2 weeks after corneal penetrating transplantation, and the expression of lymphatic vessel endothelial receptor (LYVE-1) was examined 1, 3, 7, 14 days after the transplantation respectively. In addition, 19 allograft failed human corneas were examined by 5'-nase-alkaline phosphatase (5'-NA-ALP) double-enzyme-histochemistry staining to detect corneal lymphangiogenesis and hemangiogenesis. By immunohistochemistry for LYVE-1, it was found that blown lymphatics were localized in the stroma 3 days after the corneal transplantation. With electron microscopy, new lymphatic vessels and blood vessels were found 1 and 2 weeks after the corneal transplantation. By 5'-NA-ALP enzyme-histochemistry, corneal hemangiogenesis was found in all allograft failed human corneas and 5 of 19 (26.3 %) cases had developed corneal lymphangiogenesis. It is concluded that corneal lymphangiogenesis is present after corneal transplantation, which may play an important role in allograft rejection.
Cornea/*blood supply ; Cornea/chemistry ; Cornea/ultrastructure ; Corneal Neovascularization/etiology ; Corneal Neovascularization/metabolism ; Corneal Transplantation/adverse effects ; Corneal Transplantation/*methods ; Immunohistochemistry ; Lymphangiogenesis ; Microscopy, Electron ; Rats, Sprague-Dawley ; Rats, Wistar ; Vesicular Transport Proteins/biosynthesis

We report our experience with corneal epithelium, grown in vivo, transplantation in three patients with persistent epithelial defect (PED). The three patients had ocular surface disease unresponsive to standard treatments and were therefore chosen for transplantation. They underwent transplantation of epithelial sheets, grown in vivo, to the most affected eye. In vivo cultivation was carried out in the cornea of a living related donor. After epithelialization was completed, the epithelium grown on an amniotic membrane was harvested gently; it was then transplanted into the patient's eye after debridement of fibrovascular tissue. The cultivated epithelium was completely epithelialized by 2 weeks; it was well-differentiated with well-formed hemidesmosome. On immunohistochemical staining, p63, connexin 43, and Integrin beta4 were expressed in the cells on the epithelial sheet. The PED was covered completely and maintained for 4 weeks in all cases. However, corneal erosion recurred after 5 weeks in two cases. This novel technique demonstrates the corneal epithelial cells can be expanded in vivo successfully on denuded amniotic membrane of a healthy cornea and harvested safely. A corneal epithelial sheet, grown in vivo, can be transplanted to treat eye with a severe ocular surface disease, such as total limbal deficiency.
Adult ; Cell Culture Techniques ; Cells, Cultured ; Corneal Diseases/etiology/pathology/*surgery ; Corneal Transplantation/*methods ; Epithelial Cells/cytology/*transplantation ; Epithelium, Corneal/cytology/*transplantation ; Eye Burns/complications ; Humans ; Limbus Corneae/*pathology ; Male ; Middle Aged ; Stem Cells/*pathology ; Stevens-Johnson Syndrome/complications

PURPOSE: To compare outcomes of femtosecond laser-enabled deep anterior lamellar keratoplasty (IE-DALK) versus manual trephine using deep anterior lamellar keratoplasty (Manual DALK, M-DALK). METHODS: Seventeen eyes from 17 patients underwent manual deep anterior lamellar keratoplasty, and femtosecond laser-enabled deep anterior lamellar keratoplasty was performed in 13 eyes of 13 patients. Postoperative clinical outcomes such as best corrected visual acuity, refractive astigmatism, keratometric astigmatism, endothelial cell density were compared between the two groups. RESULTS: The mean log MAR best spectacle-corrected visual acuity (BSCVA) was 0.31 +/- 0.17, 0.23 +/- 0.15, 0.18 +/- 0.14 in the IE-DALK group, and 0.55 +/- 0.41, 0.45 +/- 0.28, 0.35 +/- 0.22 (p = 0.056, p = 0.025, p = 0.313) in the M-DALK group at postoperative 2, 4, and 6 months respectively. The mean keratometric cylinder was 5.35 +/- 1.57, 4.24 +/- 1.97, 3.65 +/- 1.31 in the IE-DALK, 8.32 +/- 2.75, 6.80 +/- 2.50, 4.54 +/- 1.25 (p = 0.031, p = 0.041, p = 0.370) in the M-DALK group at postoperative 2, 4, and 6 months respectively. Endothelial cell counts in the two groups did not differ significantly at postoperative 6 months. CONCLUSIONS: The IE-DALK showed better results in BSCVA and keratometric astigmatism in the early postoperative period, in comparison with the M-DALK, and can be considered as a valuable method in deep anterior lamellar keratoplasty.
Astigmatism ; Corneal Transplantation* ; Endothelial Cells ; Humans ; Methods ; Postoperative Period ; Visual Acuity