Preoperative evaluation and outcome of corneal transplantation for limbal dermoids：aten-yearfollow-up study

AIM： To summarize preoperative evaluation and outcome of corneal transplantation for limbal dermoids for ten years.METHODS： Eighty-five patients diagnosed with limbal dermoids and treated with corneal transplantation were analyzed retrospectively. All patients were further divided into two groups according to absence or presence of neovascularization surrounding the dermoids in the corneal stroma. Eighty-two eyes were treated with tumor excision combined with partial lamellar sclerokeratoplasty, and the other three eyes were performed by penetrating keratoplasty. The size and location of the tumor, the associated ocular and systemic anomalies, the depth of the corneal penetration of tumor tissues, the preoperative and postoperative best-corrected visual acuity （BCVA）, graft survival and cosmetic outcome, and surgical complications were recorded respectively.RESULTS： The average age at surgery was 5.3y （range, 3mo-36y）. The mean size of dermoids was 6.1±1.6 mm. The 43.5% of eyes （37/85） were present with hair at the surface of the dermoid and 72.9% of dermoids were located inferotemporal of the eye. Amplyopia was present in 34.1% of patients （29/85） and 9.4% of patients （8/85） had lipodermoids. Eighteen patients suffered from Goldenhar’s syndrome with an accessory ear. The 75% of patients in group 1 had involvement of the corneal deep stroma down to Descemet’s membrane without involving it, but 71.4% of patients had Descemet’s membrane involvement in group 2. Preoperative BCVA ranged from counting fingers to 20/20. Postoperatively 81.1% had a BCVA of 20/800 or better. There was no significant difference between the post-surgical BCVA of the two groups （t=1.584, P〉0.05）. The grafts of 70.5% patients were present as 1＋ opacity, 21.1% as 2＋ opacity, 8.2% as 3＋ opacity and none as 4＋ opacity. Surgical complications included graft rejection, microperforation, prolonged reepithelialization, steroid glaucoma, interface neovascularization, and interface hemorrhage.CONCLUSION： The dermoids with neovascularization surrounding them in the corneal stroma invaded deeper tissues in the cornea than those with no neovascularization surrounding them in the corneal stroma. Therefore, surgeons should take care to avoid corneal perforation during the corneal transplantation operation. The majority of patients markedly improved their cosmetic appearance after surgery.

A 60-Year-Male Post Corneal Transplantation with Acute Pneumonia

Pneumonia is a common complication in organ transplantation patients. Multiple respiratory pathogens such as bacteria, viruses and fungi are potentially coexisted. A 60-year-old male with left eye post corneal transplantation developed acute severe pneumonia caused by Pneumocystis jiroveci (PJP) coinfection with Nocardia spp. and Cytomegalovirus (CMV). He was hospitalized due to acute respiratory failure. Chest radiographs and chest Computed Tomography (CT) revealed extensive ground-glass opacities. PJP was diagnosed from Bronchoalveolar Lavage Fluid (BALF). The pneumonia was persistent despite of receiving intravenous cotrimoxazole. Tracheal aspirate showed faint gram-positive filamentous beaded branching organisms. Consequently Nocardia spp. was proven. Intravenous cotrimoxazole was continued and intravenous imipenem was added. After a course of dual antibiotics, pneumonia was gradually improved. A week after, he developed the worsened acute respiratory failure. The bronchoscopy was performed. The new pathogens were not detected from BALF microbiology. The BALF cytology was unremarkable. PJP was detected by Polymerase Chain Reaction (PCR) from BALF. CMV antigenemia was detected from BALF and blood. Intravenous ganciclovir was given. This report describes PJP coinfected with Nocardia spp. and CMV in post corneal transplantation patient suffering from severe pneumonia. Multiple respiratory pathogens are common among transplantation patients representing host immunosuppression and inadequate antimicorbial prophylaxis.

In Vivo Confocal Microscopic Observation of Lamellar Corneal Transplantation in the Rabbit Using Xenogenic Acellular Corneal Scaffolds as a Substitute

Background： The 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. Methods： Fresh 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, lmmunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft. Results： Decellularized xenogenic corneal matrix remained transparent for about l-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. Conclusions： Xenogenic 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.

The lived experiences of patients undergoing acellular porcine corneal stroma transplantation

To explore the lived experiences of patients undergoing acellular porcine corneal stroma（APCS）transplantation,a descriptive,qualitative design was performed.A purposive sample of 13 patients who underwent APCS transplantation to treat progressive infectious keratitis were enrolled in the semi-structured,open-ended interviews.The taped and transcribed interviews were analyzed using a thematic analysis approach.Alterations in the transparency of APCS grafts were accompanied by a gradual improved visual acuity（before surgery：1.38±0.91 logMAR;3mo postoperatively ：0.40±0.24 logMAR, respectively）.Accordingly,in terms of lived experiences,the patients generally reported＂negative＂experiences before the operation and during the early postoperative period,but this was greatly improved 3mo after surgery.Four main themes were derived：anxiety and fear,stigma,lifestyle change,and gratitude and insights. Conclusively,health care professionals should provide holistic care for patients,proactively promoting patients’physical and mental health.

Corneal transplantation outcomes after the extrusion of an intrastromal keratoprosthesis:a pilot study

This short report includes 5 eyes of 5 patients(mean age 63.2±12 years)who underwent a tectonic keratoplasty[deep anterior lamellar keratoplasty(DALK)or penetrating keratoplasty(PK)]in order to rehabilitate the eye after the extrusion of the non-perforating keratoprosthesis(Kpro)KeraKlear(KeraMed,USA).The non-perforating Kpro was extruded after a mean period of 21.4±21.8 months due to melting.In two cases,the keratoplasty was performed the same day of the non-perforating Kpro removal due to a severe melting,while in the other three cases it was performed one to 3 months later.Two eyes received a DALK,but in 3 eyes a macroscopic Descemet membrane perforation forced the conversion into a PK.The mean follow-up period after the keratoplasty was 16.8±6.6 months.No cases of rejection were recorded.All the 5 eyes achieved“anatomical success”(transparent graft,with no signs of infection or inflammation).Two eyes showed limited“functional success”because the achievement of the best visual potential was prevented by the development of glaucomatous optic atrophy during the follow-up period.In conclusion,this short report presents an unexpected success of a keratoplasty performed with a tectonic purpose after the extrusion of the non-perforating Kpro because the corneal graft remained transparent,without neovascularization or scarring during the follow-up period.This initial evidence shows some encouraging results regarding graft survival rate and the achievement of a useful visual rehabilitation with keratoplasty after a nonperforating Kpro failure instead of repeating the Kpro implantation.

Tocilizumab promotes corneal allograft survival in rats by modulating Treg-Th17 balance

AIM: To examine the therapeutic effects of tocilizumab on experimental corneal transplantation and its effect on Treg/Th17 balance. METHODS: Allograft corneal graft was performed between host Sprague Dawley and Wistar donor rats.The rats were randomly divided into four groups: normal,autograft, allograft, and allograft treated with tocilizumab.Kaplan-Meier was performed to draw the survival curve.The protein levels of interleukin-17A(IL-17A), vascular endothelial growth factor(VEGF), and forkhead box protein3(Foxp3) were measured by immunohistochemistry.The mRNA levels of IL-17A, VEGF, retinoid-related orphan receptor gammat(RORγt), interleukin-6(IL-6) and Foxp3 were detected by reverse transcription real-time polymerase chain reaction(RT-PCR). The Treg and Th17 cells were investigated by flow cytometry. RESULTS: The survival time of tocilizumab group was(24±1.27 d) longer than that of allograft group(10±0.55 d).Moreover, immunohistochemical examination revealed that IL-17A and VEGF protein levels in the allograft group were significantly higher than that of tocilizumab group(P<0.01),while Foxp3 levels in the allograft group was significantly lower than that of the tocilizumab treated group(P<0.001).Flow cytometry showed that the number of Th17 cellsin allograft group was significantly higher than that in tocilizumab group(P<0.001). Meanwhile, the number of Tregs was significantly lower than in tocilizumab group(P<0.001). Simultaneously, Foxp3 m RNA expression level in corneal tissues of tocilizumab treated group was significantly higher than other groups(P<0.001). CONCLUSION: These findings suggest that tocilizumab may promote corneal allograft survival, possibly by modulating Treg-Th17 balance.

Ipsilateral Lymphadenectomy to Inhibit Corneal Allograft Rejection in Rats

In order to investigate the ipsilateral lymphadenectomy for inhibiting rejection in rat corneal transplantation, corneal allogenic transplantation models were established in rats. Eighteen female Wister rats were used as donors, and 36 Sprague Dawley rats as recipients. After penetrating corneal transplantation, recipients were randomly divided into 3 groups: group A (control group); group B, the ipsilateral lymphadenectomy group; group C, the bilateral lymphadenectomy group. Among 12 rats in each group, the corneas of 2 rats in each group were used for pathological study at day 14 after the transplantation, and the remaining 10 rats were used for studying corneal rejection by a slit lamp. The time points when allograft rejection occurred were recorded and mean survival time (MST) was compared. The results showed that MST in groups B and C was 46 30±9 464 days and 44 43±7 604 days, respectively, which was significantly prolonged as compared with that in group A (10 71±1 567 days, P<0.01). There was no significant difference in MST between groups B and C (P>0.05). It was concluded that both bilateral and ipsilateral lymphadenectomy therapies could effectively inhibit the corneal allograft rejection. Ipsilateral lymphadenectomy is a less complex surgical procedure and is just as effective in preventing rejection.

Lymphocyte infiltration and activation in iris-ciliary body and anterior chamber of mice in corneal allograft rejection

AIM: To investigate the infiltration and activation of lymphocyte in iris-ciliary body and anterior chamber after allogenic penetrating keratoplasty (PK), for further revealing the role of iris-ciliary body in corneal allograft immune rejection. METHODS: In the mice models of PK, BALB/C mice received orthotopic isografts (n =35) or C57BL/6 donor allografts (n=25). Grafts were examined daily for 3 weeks by slit-lamp microscopy and scored for opacity. The infiltration of CD4(+) T lymphocyte in iris-ciliary body and anterior chamber was examined by immunohistology and the mRNA of CD80 and CD86 in both cornea graft and iris-ciliary body by RT-PCR was analyzed in allograft recipient at days 3, 6, 10 and the day when graft rejection occurred. Isograft recipients were examined as control at the corresponding time points. Transmission electron microscope was used to study the ultrastructure, especially cell infiltration, of iris-cilary body and corneal graft at day 3, 7 and the day when rejection occurred after allogenic PK. RESULTS: Rejection was observed in all the allograft recipients followed more than 10 days, at a median time of 15 days (range 12-18 days), but not in any of isografts. CD4(+) T cells were first detected at day 6 after transplantation in limbus and Ciliary body, and then in the stroma of recipient, iris, anterior chamber and corneal allograft with an increased number until graft rejection occurred. CD80 and CD86 mRNA were detected under RT-PCR examination in both graft and iris-ciliary body of allograft recipient, but not in any of isograft recipient. Three days after operation, lymphocytes and monocytes macrophages were visible in iris blood vessels and the anterior chamber, and vascular endothelial cell proliferation and activation were significant under transmission electron microscopy examination. At day 7, corneal endothelial cells became thinner. Lymphocytes and mononuclear macrophages were found with great number in the anterior chamber and adhered to the corneal endothelium. Blood vessels in iris increased and were filled with lymphocytes. And lymphocytes were detected to migrate through endothelial cell gap out of vessels. When allograft rejection occurred, macrophages attached to endothelial cells with large number of lymphocytes and macrophages infiltrating in iris. CONCLUSION: Lymphocyte infiltration and activation occurred in iris-ciliary body after allogenic PK, and the lymphocytes could migrate from iris blood vessel to the anterior chamber, which might play an important role in corneal allograft immune rejection.

Effects of CTLA4-Ig Gene-modified Dendritic Cells on the Corneal Allografts

In order to investigate the effects of mouse CTLA4Ig gene-modified dendritic cells （DCs） on the survival of the corneal allografts in rats, the plasmid PG／CTLA4Ig was transfected into DCs of F344 rats mediated by Lipofectamine^TM 2000. The expression of CTLA4Ig was detected by immunofluorescent microscopy. The effects of donor DCs on the proliferation of T cells in Lewis rats （recipients） were tested by by CCK8. Corneal transplantation was performed from F344 rats to Lewis rats. The DCs modified with CTLA4Ig gene were injected into the Lewis rats on the day 0 and 3 after transplantation. The movement of the DCs after modification in vivo was observed by immunofluorescent microscopy, and the survival of corneal allografts was evaluated by Holland criterion. The results showed that the CTLA4Ig-modified DCs could restrain the proliferation of allogenetic T cells. The CTLA4Ig-modified DCs prolonged survival of corneal allografts. （P〈0.01）. It was suggested that the injection of CTLA4Ig gene-modified DCs could obviously inhabit the allograft rejection and prolong the survival of corneal allografts.

Evaluation of corneal graft survival in mice model

·AIM: To investigate the characteristics and criterion of graft rejection in mice model. ·METHODS: C57BL/6 or BALB/c mice corneal grafts were grafted onto BALB/c hosts. Each group was divided into two subgroups according to the corneal opacity scores 12d after transplantation. The characteristics of opacity and neovascularization were observed. Mice of the 12 th , 50 th day after transplantation, the grafts biopsy of mice in allogeneic group 1, which opacity score exceed 3, were prepared for histological observation and those restore transparent were endothelial stained. ·RESULTS: There was no difference of corneal opacity score on the 7 th and 12 th day after operation; the histological results had no disparity between syngeneic group and allogeneic group. On the 12 th day after surgery, the turbidity curve was apparent in grafts with opacity score 【2. Mononuclear cells were shown in grafts with opacity score reached 3 in allogeneic group 1. Different rejection performance was observed in tissue sections on the 50 th day after surgery. ·CONCLUSION: Grafts, opacity score exceeds 3 from the 7 th to the 12 th day after operation could not be judged as a rejection. We should pay more attention to the variation of grafts opacity since 12d after corneal transplantation.·

Comparison of contrast sensitivity and visual acuity between deep anterior lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

AIM: To evaluate postoperative visual acuity and contrast sensitivity results following deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus (KC). METHODS: All the patients’ records with KC who had PK or DALK surgery between May 2010 and May 2011 were retrospectively reviewed. Sixty patients who underwent successful corneal transplantation for KC: 30 eyes underwent DALK and 30 eyes underwent PK were included in this study. Preoperative and postoperative mean logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity (UCVA), logMAR best spectacle-corrected visual acuity (BSCVA) and intraocular pressure (IOP) were evaluated. Contrast sensitivity tests (CS) were done preoperative and 2 months after all sutures had removed. All surgeries were performed under regional anesthesia (retrobulbar anesthesia) by 1 surgeon (B.K.) who was experienced in penetrating and lamellar keratoplasty techniques. RESULTS: The mean age of the DALK group was 29.67±4.95 (range 18-40) years and the PK group was 28.7±3.53 (range 18-39) years. Preoperatively there was no significant difference in the logMAR UCVA, logMAR BSCVA and IOP between the DALK (1.281±0.56; 0.97±0.85; 12.07±2.12mmHg) and PK (1.34±0.21; 0.98±0.21; 13±2.12mmHg) groups. One-year after surgery there was no significant difference in the mean logMAR UCVA and IOP between the DALK (0.46±0.37; 11.73±2.1mmHg) and PK (0.38±0.21; 12±2.12mmHg) groups. The mean contrast sensitivity was evaluated by CC-100 Topcon LCD at 1.5, 2.52, 4.23, 7.10 and 11.91 cycles per degree (cs/deg) spatial frequencies before and 2 months after the all sutures had removed. CONCLUSION: All patients with keratoconus in both DALK and PK groups performed good visual function postoperatively. The mean contrast sensitivity increased considerably at all spatial frequencies compared with preoperative levels in the DALK and PK groups. The mean post-operative evaluation of contrast sensitivity measurements was not significantly different between the two groups.

Donor cornea quality used for penetrating keratoplasty vs deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.

Structural analysis of processed corneas

Background:Disruption of the microstructure in corneal stroma can lead to the loss of transparency.The lack of a characterization method for the microstructure prevents such scaffolds to be implemented in tissue transplantation.The non-invasive,three-dimensional(3D)rendering multiphoton microscopy(MPM)poses the potential to solve this problem.Methods:MPM images and data analyses were performed with three kinds of samples with known and different quality.Isosurfaces(ISOs)were constructed for the evaluation of void volume and collagen distribution.Results:The differences in the microstructures of these samples were revealed with clear indications and links to their behaviours in rehydration and possible transparency.According to this analysis,the scaffold with the highest void space ratio amongst the three presented the highest successful rates to be thoroughly rehydrated.Conclusions:Such a method can be developed for assessing the quality of tissue engineered corneas,or donated corneas,and be useful as a powerful research tool in cornea related research.

Corneal Endothelial Cell Loss in Femtosecond Laser-assisted Descemet＇s Stripping Automated Endothelial Keratoplasty： A 12-month Follow-up Study

Background：Descemet＇s stripping automated endothelial keratoplasty （DSAEK） surgery offers a more standardized approach and reliable method to create corneal grafts with an instrument such as a microkeratome.With the development of Descemet＇s membrane endothelial keratoplasty,an excellent clinical outcome is seen in the treatment of corneal endothelial dysfunctions,which indicates that thinner corneal graft results in better clinical outcome.With the recent development of the femtosecond laser,ultrathin corneal graft preparation has become possible.This study aimed to report corneal graft endothelial cell loss （ECL） in a large series of cases undergoing DSAEK with femtosecond laser-assisted corneal graft preparation within a 12-month period.Methods：This study was designed as a prospective,noncomparative,interventional case series.Totally 126 consecutive eyes with endothelial failure of 120 patients,who had corneal endothelial decompensation and underwent femtosecond-assisted DSAEK using the VisuMax femtosecond laser system,were included in the study.Central endothelial cell density （ECD） was recorded postoperatively at 2 weeks （n =126）,1 month （n =126）,3 months （n =110）,6 months （n =101）,and 12 months （n =71） and then compared with the preoperative eye bank measurements.Pre-and postoperative central ECDs were evaluated using Heidelberg retina tomography-Ⅲ confocal microscopy.ECL was calculated for each postoperative time point.Graft thickness was examined using anterior segment-optical coherence tomography.Results：Mean preoperative cell count was 3383 ± 350 cells/mm^2.Mean postoperative cell counts were 2382 ± 707 cells/mm^2,2179 ± 685 cells/mm^2,2074 ± 688 cells/mm^2,1884 ± 662 cells/mm^2,and 1723 ± 624 cells/mm^2 at 2 weeks,1,3,6,and 12 months,respectively;these represented the ECL of 29.7 ± 19.7%,35.4 ± 19.5%,38.6 ± 19.8%,44.3 ± 18.9%,and 48.9 ± 18.4% at the each corresponding time point.The mean corneal graft thickness after surgery was 142 ± 48 μm,118 ± 41 μm,108 ± 37 μm,100 ± 32 μm,and 99 ± 32 μm at each corresponding study visit,respectively.There was no correlation between corneal graft thickness and corneal ECL （R =0.039）.Conclusions：Corneal ECL remained relatively stable up to 12 months after femtosecond laser-assisted ultrathin DSAEK in a large case series.No correlation between cell loss and corneal graft thickness was found,which indicated that corneal graft preparation by the femtosecond laser was safe.ECL was faster within the first 6 months and relatively stable thereafter.

Immunological studies on the cellular phenotype involved in corneal allograft rejection

Objective To investigate the cellular phenotype involved in corneal allograft rejection using wholemounts analysis.Methods Corneal transplantation was performed between Sprague Dawley (SD) and Wistar rats. Corneal wholemounts were prepared from control rats and those after corneal transplantation on day 7 and 12. Immunohistochemical stain was performed on these wholemounts using monoclonal antibodies to transforming growth factor β1(TGF β1), CD3, CD4, CD8, B lymphocytes, macrophages, dendritic cells and major histocompatibility complex (MHC) class Ⅱ antigen.Results Corneal allograft rejection started on day 7 and reached its maximum from 10 to 14 days after corneal transplantation. Presence of TGF β1 , CD3 , CD4 , CD8 , MHC class Ⅱ positive cells, macrophages and dendritic cells were noted at the limbus of both SD rats and Wistar rats. No positive cell was present in the central cornea of normal rats. All positive cells but B lymphocyte were noted in large numbers in the cornea after corneal allograft transplantation. Marked staining for TGF β1 was noted during graft rejection.Conclusion The corneal wholemounts technique provides a good visualization for the cellular phenotype involved in corneal allograft rejection. A variety of cells including TGF β1, CD3, CD4, CD8, MHC class Ⅱ antigen positive cells, macrophages and dendritic cells are involved in corneal allograft rejection. TGF β1 positive cell might be an important immunosuppressive factor after corneal transplantation and also involved in the induction of fibrosis.

Interleukin-1 receptor antagonist eye drops promoting high-risk corneal allografts survival in rats

Background Immune rejection is the main reason of grafts failure after corneal transplantation. This study was to determine whether interlerkin-1 receptor antagonist (IL-1ra) eye drops could prolong corneal allografts survival in high-risk corneal orthotopic allotransplantation in rat model and to study the effect of IL-1ra on the expression of CD 1-positive cells in the grafts Methods For all experiments, the Sprague-Dawley (SD) rats' corneas were transplanted into Wistar rats' eyes High-risk transplants included those that had been sutured into Wistar recipient beds with corneal neovascularization induced by placement of three interrupted sutures in the host cornea 7 days earlier All the animals were divided, in a masked fashion, into three treatment groups and one control group Each treatment group received IL-1ra eye drops of different concentrations (1 mg/ml, 3 mg/ml, or 5 mg/ml, respectively) four times a day for 30 days The control group received 0 9% normal saline (NS) eye drops in the same way as the treatment groups All allografts were evaluated for signs of rejection from the first day after surgery Ten days later, corneal specimens were processed to examine the expression of CD 1-positive cells and histopathological changes Results The survival time of the transplants was 5 80±0 79, 5 89±1 05, 6 78±0 83, and 9 00±2 36 days respectively in the control or three treatment groups Compared with the control group, 1 mg/ml IL-1ra eye drop did not prolong the survival time of the allografts ( t =0 210, P >0 05) However, 3 mg/ml and 5 mg/ml IL-1ra eye drop did prolong the survival time of the grafts ( t ≥2.627, P <0 05), with the latter showing more obvious effect Immunohistochemical examinations showed a significant decrease in inflammatory cell and CD 1-positive cell infiltration in IL-1ra treated groups compared with the control group Conclusions IL-1ra can promote corneal allograft survival in a dose-dependant manner by reducing the infiltration of CD 1-positive cells in high-risk corneal transplantation

Corneal surgery in keratoconus: which type, which technique, which outcomes?

Keratoconus is a disease characterized by progressive thinning,bulging,and distortion of the cornea.Advanced cases usually present with loss of vision due to high irregular astigmatism.A majority of these cases require surgical intervention.This review provides an update on the current treatment modalities of corneal surgery available for the management of advanced corneal ectasias.

Cellular therapy of the corneal stroma: a new type of corneal surgery for keratoconus and corneal dystrophies

Cellular therapy of the corneal stroma,with either ocular or extraocular stem cells,has been gaining a lot of interest over the last decade.Multiple publications from different research groups are showing its potential benefits in relation to its capacity to improve or alleviate corneal scars,improve corneal transparency in metabolic diseases by enhancing the catabolism of the accumulated molecules,generate new organized collagen within the host stroma,and its immunosuppressive and immunomodulatory properties.Autologous extraocular stem cells do not require a healthy contralateral eye and they do not involve any ophthalmic procedures for their isolation.Mesenchymal stem cells have been the most widely assayed and have the best potential to differentiate into functional adult keratocytes in vivo and in vitro.While embryonic stem cells have been partially abandoned due to ethical implications,the discovery of the induced pluripotent stem cells(iPSC)has opened a new and very promising field for future research as they are pluripotent cells with the capacity to theoretically differentiate into any cell type,with the special advantage that they are obtained from adult differentiated cells.Cellular delivery into the corneal stroma has been experimentally assayed in vivo in multiple ways:systemic versus local injections with or without a carrier.Encouraging preliminary human clinical data is already available although still very limited,and further research is necessary in order to consolidate the clinical applications of this novel therapeutic line.

Knowledge and attitudes toward corneal donation among Singaporean youth: a cross-sectional study

Background:To assess the knowledge of Singaporean youth regarding corneal donation and gauge their willingness to donate their corneas.Methods:We conducted a cross-sectional study among 500 students from five tertiary institutions in Singapore.All students answered self-administered questionnaires which included seven questions that tested knowledge and three questions that determined willingness to donate corneas.Results:Among 500 Singaporean youth aged 18 to 25,most students(73.2%)answered 3 or fewer of the 7 questions about corneal donation correctly.With regards to the willingness to donate,155(31%)were willing to donate their corneas,111(22.2%)were not willing to donate their corneas,and 234(46.8%)were undecided.Willingness to donate corneas was associated with an older age group(21 to 25 years old),those who are non-Muslims,and have good basic knowledge.Particularly,students with good basic knowledge were 1.71 times more likely to willingly donate their corneas.Conclusion:The knowledge of the Singaporean youth regarding corneal donation and transplantation is poor.Since insufficient information was cited as the most common reason for being undecided in regards to corneal donation,specific and tailored programs to increase knowledge and awareness are needed to convince the youth to support corneal donation.

Management of cytomegalovirus corneal endotheliitis

Background:Cytomegalovirus(CMV)can manifest as corneal endotheliitis in immunocompetent individuals.Early diagnosis is prudent to prevent endothelial cell loss,which could ultimately lead to corneal decompensation.CMV DNA was first detected in an eye with corneal endotheliitis in 2006;since then,clinical evidence from numerous case reports and case series have accumulated.Main text:In this narrative review,we identified several drugs,including ganciclovir,valganciclovir,and their combination in oral,intravenous,intravitreal,and topical forms in different concentrations,together with the judicious use of topical steroids,have reported variable success.There has yet to be any prospective comparative study evaluating the efficacy and safety of these assorted forms of treatment;clinical evidence is based on case reports and case series.CMV endotheliitis presenting with corneal edema can masquerade as other corneal diseases and thus poses a great challenge especially in post-keratoplasty eyes.Heightened awareness is needed before and after keratoplasty to start prompt prophylaxis and treatment.Conclusion:There is no consensus on the management of CMV endotheliitis.Further studies are much needed to elucidate the optimal treatment modality,regime,and duration in the treatment and prophylaxis of CMV endotheliitis.