Corneal stromal lenticule transplantation for the treatment of congenital optic disc pit maculopathy : a case report and review.

BACKGROUND: Congenital optic disc pit (ODP) is a relatively uncommon congenital anomaly of the optic disc, which seriously affects the patient's vision when combined with optic disc pit maculopathy(ODP-M). Currently, the treatment of ODP-M remains a clinical challenge and a focus of research. CASE PRESENTATION: A boy had a pit in the inferotemporal segment of the optic disc with ODP-M. Optical Coherence Tomography(OCT) showed ODP and serous retinal detachment. He was treated with pars plana vitrectomy(PPV), followed by Corneal Stromal Lenticule (CSL) sealing and C3F8 tamponade. In the end, significant anatomical improvement was achieved, and the Best Corrected Visual Acuity(BCVA) was improved. CONCLUSIONS: The CSL transplantation may be a viable therapeutic option for improving ODP-M with stable anatomical and functional result. However, more cases and longer follow-up are needed to confirm the safety and effectiveness of the technology.

Clinical outcomes of femtosecond laser-assisted corneal allogenic intrastromal ring segment (CAIRS) in the treatment of keratoconus.

BACKGROUND: To evaluate the results of corneal allogenic intrastromal ring segment (CAIRS) implantation in keratoconus. METHODS: The medical records of patients with keratoconus who underwent CAIRS implantation were reviewed. The CAIRS, prepared by trephination from the donor cornea, was implanted into a tunnel created using the femtosecond laser. The depth of the tunnel was 200 µ; the inner diameter of the tunnel was 4.5 mm; and the outer diameter was 7 mm. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry, minimum corneal thickness (CT), endothelial cell density (ECD), and high order aberration values were recorded preoperatively and at the 1st, 3rd, and 6th months postoperatively. RESULTS: A total of 23 eyes of 23 patients were included in the study. Preoperative UCVA (0.08 ± 0.01) and BCVA (0.25 ± 0. 11) values improved postoperatively and reached 0.40 ± 0.05 and 0.68 ± 0.09, respectively, at the end of the 6-month follow-up period (p1 < 0.001, p2 = 0.016; respectively). A statistically significant flattening of all keratometric values was observed in the postoperative period compared to preoperatively (p < 0.001 for all). There were no statistical differences between CT and ECC values at the preoperative and postoperative visits (p1 = 0.654, p2 = 0.769; respectively). In addition, coma aberration values were lower than the preoperative values at all postoperative visits (p < 0.05 for all). CONCLUSIONS: These results suggest that CAIRS implantation is a safe treatment option with good visual and keratometric outcomes for suitable patients with keratoconus.

SMILE lenticule versus amniotic membrane graft (AMG) augmented with platelet-rich plasma (PRP) for the treatment of perforated corneal ulcer.

PURPOSE: To evaluate the safety and efficacy of stromal lenticule obtained from small-incision lenticule extraction (SMILE) surgery versus amniotic membrane graft (AMG) augmented with platelet-rich plasma (PRP) for the treatment of perforated corneal ulcers and compare the results between the two groups. PATIENTS AND METHODS: This is a comparative retrospective study that included 40 eyes with medium-sized corneal perforations, which were classified into two equal groups of 20 eyes each; group (A) was treated with SMILE lenticule graft and group (B) was treated with AMG augmented with PRP. Pre- and postoperative evaluations were carried out using both slit-lamp (SL) examination and anterior segment optical coherence tomography (AS-OCT), including closure of perforation, complete healing, and best corrected visual acuity (BCVA). RESULTS: Complete closure of the perforation was achieved in both groups. However, healing was faster in the SMILE lenticule group than in the AMG with PRP group (P < 0.05). Complete healing was achieved in both groups: 100% in SMILE lenticule group and 95% in AMG with PRP group (P > 0.05). Both groups had few insignificant complications (30% in each), which were managed. CONCLUSION: Both methods achieved adequate healing of corneal perforations within few weeks without significant complications. However, the stromal lenticule obtained from small-incision lenticule extraction (SMILE) surgery tended to be safer with faster healing than AMG with PRP.

Rejection of Acellular Porcine Corneal Stroma Transplantation During Coronavirus Disease 2019 Pandemic.

ABSTRACT: To report 2 successfully managed cases of graft rejection with acellular porcine corneal stroma (APCS) transplantation in patients with fungal corneal ulcer. Two patients were diagnosed with fungal corneal ulcer and received APCS transplantation. Graft rejection developed due to the lost follow-up during the period of coronavirus disease 2019 outbreak. Amniotic membranes transplantation and cauterization of neovascularization was performed, respectively. The graft failure resolved successfully after the procedure. To the best of our knowledge, amniotic membranes transplantation and cauterization of new vessels are the firstly reported in treating APCS graft failure. Amniotic membranes transplantation or cauterization of neovascularization appear to be a safe and costeffective method for treating graft failure.

The use of acellular porcine corneal stroma xenograft (BioCorneaVet™ ) for the treatment of deep stromal and full thickness corneal defects: A retrospective study of 40 cases (2019-2021).

OBJECTIVE: To document the effectiveness and outcome of corneal grafting using acellular porcine corneal stroma (APCS) for veterinary use (BioCorneaVet™ ) to restore corneal integrity in dogs. METHODS: A review of medical records of patients that underwent keratoplasty with APCS graft to repair deep corneal defects, descemetoceles, and perforations between 2019 and 2021 was carried out. Only animals with intact dazzle reflex, consensual PLR before the surgery and a minimum follow-up of four weeks were considered for the study, with forty dogs (1 eye each) meeting the inclusion criteria. RESULTS: Brachycephalic breeds were the most frequently represented, and 20 right eyes and 20 left eyes were affected with 25 perforations, 8 descemetoceles, and 9 deep stromal defects (1 eye had both perforation and descemetocele). Most of the patients had concurrent ocular diseases or had undergone previous surgery on the other eye. Two different thickness of xenograft was used (300 or 450 µm), and the diameter ranged from 3 to 10 mm. Postoperative complications included mild to severe corneal vascularization, partial dehiscence, melting, and glaucoma. Follow-up time ranged from 28 to 797 days (mean: 233 days). Ocular integrity was maintained in 37/40 cases (92.5%), and vision was preserved in 36 cases (90%). CONCLUSION: The use of APCS (BioCorneaVet™ ) is an effective surgical treatment for deep stromal defects, descemetocele, and perforations in dogs, providing a good tectonic support and preserving anatomical integrity and vision. The cosmetic appearance was considered good in all the cases and continued to improve with time.

Penetrating Keratoplasty in Dogs using Acellular Porcine Corneal Stroma (BioCorneaVet™): A prospective pilot study of five cases.

OBJECTIVE: This prospective pilot study was conducted to evaluate the outcome of a commercially available corneal stroma substitute, Acellular Porcine Corneal Stroma (APCS), in dogs undergoing penetrating keratoplasty (PK) to restore corneal integrity after having deep ulcers. METHOD: Five dogs (1 eye in each dog) underwent a PK using APCS (BioCorneaVet™) as a graft. The surgical procedure and peri- and postoperative treatment were standardized. All cases required a minimum 6 months follow-up. Ease of keratoprosthetic tissue handling, graft survival, anterior chamber stability, corneal opacity, neovascularization and re-epithelialization were noted. Presence of secondary uveitis was investigated. RESULTS: BioCorneaVet™ was easy to handle and, at all-time points, provided adequate tectonic support. Graft survival was achieved in all 5 cases. A minimum follow-up period of 10 months was available for the five eyes (22 months maximum). Degree and area of corneal graft opacity progressively improved resulting in minimal to moderate loss of transparency in all cases but one, where it was severe. Neovascularization degree was most severe 0.5-1 month after surgery and fully resolved 4-6 months post-surgery. Re-epithelialization was complete in the majority of grafts in 1 month. Secondary uveitis was not detected at any time in 4 of 5 dogs. CONCLUSION: BioCorneaVet™ seems to be an effective graft for PK in the dog. In this case series, APCS was convenient to handle during surgery and provided excellent tectonic support. The material showed good tissue biocompatibility and resulted in the majority of cases in minimal to moderate graft opacity, that ameliorates with time.

Two-year observation of morphologic and histopathologic changes in the monkey cornea following small incision allogenic lenticule implantation.

PURPOSE: To observe the morphologic and histopathologic changes of femtosecond laser assisted small incision allogenic intrastromal lenticule implantation (AILI) in monkey corneas. METHODS: 6 healthy adult monkeys were included. One eye of two monkeys and both eyes of one monkey received femtosecond lenticule extraction with a -4.0 diopter (D) correction. Each extracted refractive donor lenticule was immediately allogeneically transplanted into a corneal stromal pocket created by a femtosecond laser in another monkey's eye. A postoperative two-year follow-up was performed with slit lamp microscopy, corneal topography, anterior segment optical coherence tomography and in vivo confocal microscopy. All eyes were enucleated for Hematoxylin-Eosin staining and transmission electron microscopy (TEM) observation. RESULTS: No complications were observed in the follow-up period. At postoperative 2 years, the corneas remained clear and the lenticules were integrated with the surrounding tissue under slit lamp microscopy. Nerve fiber regeneration was detected in the lenticule layer as observed through confocal microscopy. Corneal power was increased by 1.83 ± 1.36 D after 2 years, which was less than at 6 months (3.27 ± 1.2 D). Disordered fibers and decreased keratocytes in the implanted lenticules could be detected under light microscopy and TEM, with a clear boundary between the lenticules and the surrounding tissue. CONCLUSIONS: Small incision AILI is feasible and safe for reshaping the cornea. Corneal healing remained stable while refraction showed a moderate regression within postoperative 2 years.

Healing characteristics of acellular porcine corneal stroma following therapeutic keratoplasty.

BACKGROUND: Acellular porcine corneal stroma (APCS) has proven to be a promising alternative to traditional corneal grafts. This prospective case series was conducted to further investigate the healing characteristics of APCS following keratoplasty. METHODS: Twenty-seven patients undergoing APCS implantation to treat infectious keratitis were included. The patients were followed up for 12 months after surgery. The main outcome measures included visual acuity, corneal transparency, graft thickness, and cellular and nerve regeneration. RESULTS: In the operated eyes, the best-corrected visual acuity (BCVA, in logarithm of the minimal angle of resolution [logMAR] units) increased from 1.23 ± 0.95 logMAR before surgery to 0.23 ± 0.18 logMAR at 12 months after surgery (P < .001). The contrast sensitivity was still evidently reduced, especially at higher spatial frequencies. Gradual transparency improvement was observed in APCS grafts post-operatively. After implantation, the APCS graft thickness initially increased (day 1 = 592.41 ± 52.69 µm) but then continuously decreased until 3 months after surgery (1 month = 449.26 ± 50.38 µm; 3 months = 359.63 ± 34.14 µm, P < .001). Graft reepithelialization was completed within 1 week. In the in vivo confocal microscopy scans, host keratocytes began to repopulate the APCS grafts between 3 and 6 months post-operatively; subbasal nerve regeneration was only noted in 18.52% (5/27) of the eyes by 12 months after surgery. CONCLUSIONS: Acellular porcine corneal stroma functions as an effective alternative to human corneal tissue in lamellar keratoplasty. However, APCS is somewhat different from fresh human cornea in term of the post-operative healing process, which warrants the attention of both clinicians and patients.

Risk factors influencing survival of acellular porcine corneal stroma in infectious keratitis: a prospective clinical study.

BACKGROUND: A worldwide lack of donor corneas demands the bioengineered corneas be developed as an alternative. The primary objective of the current study was to evaluate the efficacy of acellular porcine corneal stroma (APCS) transplantation in various types of infectious keratitis and identify risk factors that may increase APCS graft failure. METHODS: In this prospective interventional study, 39 patients with progressive infectious keratitis underwent therapeutic lamellar keratoplasty using APCS and were followed up for 12 months. Data collected for analysis included preoperative characteristics, visual acuity, graft survival and complications. Graft survival was evaluated by the Kaplan-Meier method and compared with the log-rank test. RESULTS: The percentage of eyes that had a visual acuity of 20/40 or better increased from 10.3% preoperatively to 51.2% at 12 months postoperatively. Twelve patients (30.8%) experienced graft failure within the follow-up period. The primary reasons given for graft failure was noninfectious graft melting (n = 5), and the other causes included recurrence of primary infection (n = 4) and extensive graft neovascularization (n = 3). No graft rejection was observed during the follow-up period. A higher relative risk (RR) of graft failure was associated with herpetic keratitis (RR = 8.0, P = 0.046) and graft size larger than 8 mm (RR = 6.5, P < 0.001). CONCLUSIONS: APCS transplantation is an alternative treatment option for eyes with medically unresponsive infectious keratitis. Despite the efficacy of therapeutic lamellar keratoplasty with APCS, to achieve a good prognosis, restriction of surgical indications, careful selection of patients and postoperative management must be emphasized. Trial registration Prospective Study of Deep Anterior Lamellar Keratoplasty Using Acellular Porcine Cornea, NCT03105466. Registered 31 August 2016, ClinicalTrails.gov.

Short-term results of acellular porcine corneal stroma keratoplasty for herpes simplex keratitis.

BACKGROUND: Corneal transplantation is a common surgical intervention for restoring vision loss due to corneal damages. However, for cultural reasons, there is a huge shortage of donor corneas in China. Acellular porcine corneal stromas (APCSs) can be used as corneal substitutes in lamellar keratoplasty for corneal ulcers. This study was conducted to analyze the results of APCS use for herpes simplex keratitis (HSK). METHODS: The study involved HSK patients who underwent keratoplasty with APCSs from February 2016 to October 2017 in the second affiliated hospital of Zhejiang University. Patient data were collected at 7 days, 1 month, 3 months, 6 months, and at the last follow-up (7-25 months) postoperative. The corneal transparency, neovascularization, visual acuity, and graft stability were observed. RESULTS: Thirteen patients with HSK including five patients with corneal perforation were included in this study, nine patients underwent deep anterior lamellar keratoplasty (DALK) and five perforation patients underwent double lamellar keratoplasty. There were nine men and four women with an average age of 62.5 ± 5.6 years old (ranging from 52 to 70 years old). The mean postoperative follow-up duration was 15.1 ± 5.8 months (ranging from 7 to 25 months). At the last visit, visual acuity improved in nine patients (69.2%) compared with preoperative (P = 0.008).The grafts of seven individuals (53.8%) were completely transparent or slightly opaque; their corneal transparency score had improved significantly compared with before the surgery (P = 0.010). Various degrees of neovascularization were present in 11 of the 13 patients (84.6%), most neovascularization gradually stabilized. Graft dissolution occurred in three eyes (23.1%) during the observation period, two underwent regrafting, the other one became stable after treatment. Three patients underwent second allograft transplantation, two of which encountered APCS graft dissolution and one of the patients requested a human donor allograft transplantation due to transparency issues despite the absence of adverse issues. CONCLUSION: Acellular porcine corneal stroma seems to be effective in the treatment of HSK and can be used in HSK with corneal perforation by using double lamellar keratoplasty in an emergency.

A comparative study: deep anterior lamellar keratoplasty for corneal dystrophies using two different donor stromal tissues.

PURPOSE: This study aimed to present a comparison of early postoperative results of deep anterior lamellar keratoplasty (DALK) surgery performed using the two different corneal graft sources. MATERIALS AND METHODS: This retrospective clinical study included the surgery performed on 26 eyes of 26 patients who underwent DALK for the stromal dystrophies. At the time of surgery, donor stromal tissue for DALK was sourced using the two different preparatory techniques. For 14 cases (Group 1), the donor grafts were prepared quickly by removing the descemet's membrane (DM) without much care after the exposure of the bare DM in the recipient cornea. For 12 cases (Group 2), the grafts for DALK surgery had already been prepared during a previous descemet's membrane endothelial keratoplasty (DMEK). RESULTS: The groups differed statistically regarding the blue staining of the grafts at the time of surgery and on the first day post-DALK. The first day after surgery, 14 (100%) grafts were clear in Group 1, while eight (66.7%) grafts were clear and four (33.3%) were edematous in Group 2 (p = 0.019). Bubbling was performed in three (25.0% of Group 2) of the four cases on the first day post-DALK, while none of the patients in Group 1 underwent this procedure (p = 0.47). The postoperative increase in visual acuity was higher in Group 1 in the early postoperative period (p = 0.012). CONCLUSION: During the early postoperative period, complications (as graft edema, detachment, re-bubbling) were observed more frequently in the DALK operations performed with stromal tissue having blue stain remaining from the DMEK performed on the same day and in the same session.

Stromal lenticule transplantation for management of corneal perforations; one year results.

PURPOSE: To study application of stromal lenticules extracted by femtolaser small incision lenticule extraction (SMILE) surgery as a surgical adjuvant to seal corneal perforations. METHODS: Corneal stromal lenticules obtained through SMILE surgery with central thickness 100 µm or more were fixed over corneal perforation sites using 10-0 nylon interrupted stitches with an overlying single layer of amniotic membrane. Seven patients who had been followed up for a minimum of 12 months were assessed using slit-lamp biomicroscopy, fluorescein stain, tonometry, and best spectacle-corrected visual acuity (BSCVA) measurements. Postoperative complications were recorded throughout the follow up period. RESULTS: Corneal perforations had successfully been sealed in all 7 patients; 3 patients (42.9%) exhibited improved postoperative BSCVA. During the follow-up period of one year, no signs of re-perforation or infections were detected in any patient. CONCLUSIONS: These early findings suggest that the use of corneal stromal lenticules could be a safe and efficient surgical adjuvant for corneal perforation closure with potential clinical application, together with amniotic membrane, as relatively simple and low cost temporary measures to prepare perforated corneas for further definitive procedures.

Construction of Anterior Hemi-Corneal Equivalents Using Nontransfected Human Corneal Cells and Transplantation in Dog Models.

Tissue-engineered human anterior hemi-cornea (TE-aHC) is a promising equivalent for treating anterior lamellar keratopathy to surmount the severe shortage of donated corneas. This study was intended to construct a functional TE-aHC with nontransfected human corneal stromal (ntHCS) and epithelial (ntHCEP) cells using acellular porcine corneal stromata (aPCS) as a carrier scaffold, and evaluate its biological functions in a dog model. To construct a TE-aHC, ntHCS cells were injected into an aPCS scaffold and cultured for 3 days; then, ntHCEP cells were inoculated onto the Bowman's membrane of the scaffold and cultured for 5 days under air-liquid interface condition. After its morphology and histological structure were characterized, the constructed TE-aHC was transplanted into dog eyes via lamellar keratoplasty. The corneal transparency, thickness, intraocular pressure, epithelial integrity, and corneal regeneration were monitored in vivo, and the histological structure and histochemical property were examined ex vivo 360 days after surgery, respectively. The results showed that the constructed TE-aHC was highly transparent and composed of a corneal epithelium of 7-8 layer ntHCEP cells and a corneal stroma of regularly aligned collagen fibers and well-preserved glycosaminoglycans with sparsely distributed ntHCS cells, mimicking a normal anterior hemi-cornea (aHC). Moreover, both ntHCEP and ntHCS cells maintained positive expression of their marker and functional proteins. After transplantation into dog eyes, the constructed TE-aHC acted naturally in terms of morphology, structure and inherent property, and functioned well in maintaining corneal clarity, thickness, normal histological structure, and composition in dog models by reconstructing a normal aHC, which could be used as a promising aHC equivalent in corneal regenerative medicine and aHC disorder therapy.

Acellular human corneal matrix sheets seeded with human adipose-derived mesenchymal stem cells integrate functionally in an experimental animal model.

PURPOSE: To evaluate the in vivo biocompatibility of grafts composed of sheets of decellularized human corneal stroma with or without the recellularization of human adipose derived adult stem cells (h-ADASC) into the rabbit cornea. METHODS: Sheets of human corneal stroma of 90 µm thickness were decellularized, and their lack of cytotoxicity was assayed. The recellularization was achieved by the injection of 2 × 10(5) labeled h-ADASC in the graft followed by five days of cell culture. The grafts were implanted in vivo into a stromal pocket at 50% depth. After a triple-masked three-month follow-up, the animals were euthanized and the biointegration of the graft, the viability of the stem cells and the expression of keratocan (human keratocyte-specific protein) were assessed. RESULTS: The decellularized stromal sheets showed an intact extracellular matrix with a decellularization rate of 92.8% and an excellent recellularization capacity in vitro with h-ADASC. A complete and stable graft transparency was observed during the full follow-up, with absence of any clinical sign of rejection. The postmortem analysis demonstrated the survival of the transplanted human stem cells inside the graft and their differentiation into functional keratocytes, as assessed by the expression of human keratocan. CONCLUSIONS: We report a new model of lamellar keratoplasty that requires only a simple and safe procedure of liposuction and a donor allogeneic cornea to provide an optically transparent autologous stromal graft with excellent biocompatibility and integration into the host tissue in a rabbit model.

Biomechanical Modeling of Femtosecond Laser Keyhole endokeratophakia Surgery.

PURPOSE: To apply a finite element model to endokeratophakia and evaluate anterior and posterior corneal surface changes. METHODS: Spatial elevation data (Pentacam HR; Oculus, Wetzlar, Germany) were obtained for the front and back corneal surfaces of an eye prior to undergoing an endokeratophakia procedure. These were used to warp a spherical template finite element model of the cornea to create a patient-specific finite element mesh and the initial stress distribution was computed with an iterative approach. The finite element model (Optimeyes; Integrated Scientific Services, Biel, Switzerland) included non-linear elastic characteristics of the stroma. The endokeratophakia procedure was recreated in the model: a donor lenticule (-10.50 diopters [D], 5.75-mm zone, 127-µm thick) was inserted into a lamellar pocket (180-µm deep, 6.25-mm diameter) and two 2-mm small incisions were made at 150° and 330°. Anterior and posterior surfaces, computed by the finite element model, were compared to clinical data to assess accuracy and reliability of finite element modeling. RESULTS: The postoperative axial curvature produced by the model closely resembled the patient data; average curvature was 48.01 D clinically and 48.23 D in the simulation, and corneal astigmatism was 3.01 D clinically and 2.88 D in the simulation. The posterior best-fit sphere elevation map also matched the patient data, replicating inward bulging of the posterior surface by approximately 40 µm. Stress distribution modeling predicted a stress increase by 159.94% ± 73% in the cap and a stress decrease by 32.41% ± 21% in the stromal bed. CONCLUSIONS: Finite element modeling of the cornea reproduced the clinically observed anterior and posterior corneal surface changes following an endokeratophakia procedure. This case sets the stage for further study to refine and yield predictive finite element modeling for the evaluation of corneal refractive surgical procedures.

The Safety and Predictability of Implanting Autologous Lenticule Obtained by SMILE for Hyperopia.

PURPOSE: To evaluate the safety, effectiveness, stability, and predictability of implanting autologous lenticules obtained from small incision lenticule extraction for the treatment of hyperopia. METHODS: Five patients (10 eyes) with one myopic eye and one hyperopic eye were enrolled. The myopic eye was treated with small incision lenticule extraction; a lenticule was extracted and subsequently implanted in the hyperopic eye. Follow-up was at 1 day, 1, 3, 6, and 9 months, and 1 year postoperatively. Patients received a complete ophthalmologic examination at each visit, including uncorrected distance visual acuity, corrected distance visual acuity, anterior segment optical coherence tomography, and corneal topography. RESULTS: There were no complications in any eye during follow-up. Compared with preoperative levels, at the last follow-up visit the eyes with lenticule implantation showed mean spherical equivalent reduced by 5.53 diopters (residual spherical equivalent was +1.13 to -2.63 diopters), mean uncorrected distance visual acuity increased approximately two lines (approximately 20/63 to 20/40 Snellen), and corrected distance visual acuity in 4 (80%) eyes gained one line, 2 (40%) eyes gained two lines, and 1 (20%) eye gained more than two lines. There was no significant difference (P > .05) in spherical equivalent compared with 1 day postoperatively and the last follow-up visit. Corneal topography showed that the lenticule was uniform and located well; anterior segment optical coherence tomography images showed that the lenticule was transparent and the demarcation line was visible. CONCLUSIONS: Implanting an autologous lenticule obtained by small incision lenticule extraction for hyperopia might be safe, effective, and stable, but its predictability should be improved in the future.

[Treatment of large corneal perforations with acellular multilayer of corneal stromal lenticules harvested from femtosecond laser lenticule extraction].

OBJECTIVE: To describe a novel surgical technique for the treatment of large corneal perforations by using acellular multilayer of corneal stromal lenticules. METHODS: Prospective study. The acellular tissue used for the repair was harvested from myopic patients during the femtosecond laser (FS) refractive surgery. Informed consent, blood test and donor eligibility were obtained in each case. Three or four layers of lenticules were stacked up and stored at -80°C in pure sterile glycerin. The diameter is 6.0 to 6.5 mm and central thickness was 300 to 400 µm. If the diameter of the corneal ulcer perforation was larger than 3 mm and corneal grafts were not available, we used this kind of patches to seal the perforations. It was a retrospective case series study. Five cases of corneal ulcer perforation were enrolled in this study. One was neuropathic keratitis, one was atopic keratoconjunctivitis, and the other three were fungal keratitis. Acellular multilayer of stromal lenticules were used in these cases for emergent therapy. RESULTS: The sealing of the perforation and the re-establishment of the anterior chamber were achieved successfully in all the cases. For the pericentral perforations, visual recovery was achieved. And efficient palliative management was done for the central perforations. CONCLUSIONS: The reported technique seems to represent a good alternative emergency procedure for the management of large corneal perforations. It is a very useful method for Chinese hospitals where the shortage of cornea donors is a very serious problem and the amount of FS surgeries are increasing.

Deep anterior lamellar keratoplasty for keratoconus: a review.

Deep anterior lamellar keratoplasty (DALK) is a surgical technique that involves the removal of pathological corneal stroma down to Descemet membrane and replacing it with a donor cornea. Over the last decade, there has been a paradigm shift in the surgical techniques of DALK, which has made it safer with visual outcomes comparable with penetrating keratoplasty. This review aims to discuss the existing popular techniques of DALK, their advantages and limitations. We will also describe techniques of DALK that are useful in special situations.

Donut-shaped Corneal Allogeneic Intrastromal Segment as an Alternative to Deep Anterior Lamellar Keratoplasty in Advanced Keratoconus.

PURPOSE: The aim of this study was to describe a new technique of selective corneal stromal transplantation for keratoconus treatment, donut-shaped CAIRS (corneal allogeneic intrastromal ring segment). METHODS: A donut-shaped corneal graft is obtained using a double-bladed trephine. Descemet membrane, endothelium, and epithelium are all removed from the graft. Only stromal tissue is transplanted. A wide 360-degree intrastromal tunnel is created using the femtosecond laser, with a 30-degree angulation. The diameter is from 5.4 mm to 8 mm optical zone. After dehydration, the corneal graft is inserted into the tunnel. We report the clinical and tomographic outcomes after the procedure in 3 patients. RESULTS: The mean follow-up time after donut-shaped CAIRS was 6.01 ± 1.02 months. In case 1, best spectacle-corrected visual acuity improved from 20/150 to 20/40. In case 2, it improved from 20/400 to 20/40, and in case 3 from 20/200 to 20/40. The mean preoperative K was 57.3 ± 4.5 D and reduced to 44.2 ± 2.5 D after donut-shaped CAIRS. The mean spherical equivalent decreased from -9.8 ± 3.2 preoperatively to -3.2 ± 2.2 postoperatively. No intraoperative or postoperative complications were observed. Anterior segment OCT showed a mid-stroma implant, fusiform in shape, equidistant from the epithelium and endothelium. CONCLUSIONS: Donut-shaped CAIRS is a variation of the traditional CAIRS technique and showed to be an alternative option for keratoconus treatment, especially in moderate to advanced cases with a central clear cornea without scars. The technique is minimally invasive, and the visual axis remains untouched.

A Technique of Multiple Corneal Allogeneic Ring Segments Prepared From a Single Corneal Graft: A Case Series.

PURPOSE: To describe a novel technique for preparing multiple corneal allogeneic ring segments (CAIRS) from a single corneal graft using femtosecond laser technology. METHODS: This is a case series of 10 eyes from 10 patients with keratoconus who underwent FS-assisted CAIRS implantation using corneas from 4 donors at the Hospital Foundation Adolphe de Rothschild-Noémie de Rothschild institute. A preoperative and postoperative examination was performed at 1 day, 1 week, and 1 month. Anterior segment OCT and corneal tomography with aberrometric and pachymetric analyses were performed at each visit. Visual, refractive, and topographic parameters were extracted. The thickness and width of implanted CAIRS were analyzed. RESULTS: Patients were classified according to keratoconus severity: group A (maximal keratometry Kmax <75D) and group B (Kmax >75D). At 1 month postoperatively, both groups A and B showed a significant decrease in mean keratometry by 4.78 ± 1.57D and 12.87 ± 4.62D, respectively. Total and higher order aberrations decreased by 5.66 ± 4.55 and 0.65 ± 1.54 in group A and by 9.45 ± 9.15 and 0.49 ± 1.39 in group B, respectively. The corrected distance visual acuity improved by 4.8 ± 1.7 lines in group A. Visual improvement was not significant in group B. One eye in group B exhibited acute rejection and required explantation. CONCLUSIONS: FS-assisted multiple CAIRS implantation using a single corneal graft maximizes the utilization of viable corneal tissue. CAIRS implantation is an effective and biocompatible therapeutic alternative, particularly in cases of moderate to advanced keratoconus with Kmax <75D.