Optical and Tectonic Corneal Transplant Outcomes in a Tertiary Hospital in Singapore within the Singapore Corneal Transplant Registry

<p><b>INTRODUCTION</b>This study aimed to describe and compare corneal graft survival and optical outcomes following deep anterior lamellar keratoplasty (DALK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) with penetrating keratoplasty (PK), and to document tectonic success of patch grafts.</p><p><b>MATERIALS AND METHODS</b>This was a retrospective, non-randomised, comparative and descriptive cohort study. A total of 139 eyes that underwent primary keratoplasty between 2000 and 2016 were included, and the following data was extracted: demographics, clinical diagnosis and primary indication, pre- and intraoperative risk factors, postkeratoplasty outcomes, and complications. Optical success was defined as good graft clarity and best corrected visual acuity (BCVA) of 6/12 or better. Graft failure was defined as irreversible corneal oedema and loss of clarity. Tectonic success in patch grafts was defined as tectonic integrity with no repeat tectonic surgical procedure required in the postoperative period.</p><p><b>RESULTS</b>The mean follow-up duration was 3.24 ± 3.47 years in the PK group (n = 16), 1.89 ± 0.86 years in the DALK group (n = 37), 2.36 ± 1.24 years in the DSAEK group (n = 53), and 2.17 ± 1.09 years in the patch graft group (n = 33). The 3-year probabilties of survival for PK, DALK, DSAEK and patch graft were 60.9%, 94.1%, 89.9%, and 67.1%, respectively. The overall percentage of complications was significantly higher for PK (81.3%), compared to DALK (48.6%), DSAEK (49.1%), and patch graft (21.2%). In the PK and DALK groups, 100% achieved DSAEK (49.1%), and patch graft (21.2%). In the PK and DALK groups, 100% achieved BCVA of 6/12 or better, while in the DSAEK group, 96.43% achieved BCVA of 6/12 or better.</p><p><b>CONCLUSION</b>From a similar study cohort of Asian eyes, graft survival was superior and complications were reduced for DALK and DSAEK compared to PK, but optical outcomes were comparable. Graft survival for patch graft was expectedly lower, but the incidence of complications was low.</p>

Human limbal progenitor cell characteristics are maintained in tissue culture

<p><b>INTRODUCTION</b>To determine the differentiation of human limbal epithelial cells in tissue culture.</p><p><b>MATERIALS AND METHODS</b>Epithelial cells from the human limbus (n = 29) were isolated and cultured in supplemental hormonal epithelial medium (SHEM) in the presence of mitomycin C-treated 3T3 feeder layer. Confluent cells were airlifted to form multiple layers. The expression of cytokeratin 3 (K3), cytokeratin 12 (K12), involucrin, connexin 43 (Cx43), proliferation cell nuclear antigen (PCNA) and p63 was studied in normal and airlifted cells by immunohistochemistry. Expression levels of K3 and K12 mRNA were examined by real-time polymerase chain reaction (PCR).</p><p><b>RESULTS</b>The colony-forming efficiency of primary cultured (P0) cells was about 19.35 +/- 6.46% (mean +/- SD, n = 7). Real-time PCR analysis showed that the transcription level of K3 and K12 in cultured cells was lower than in freshly isolated limbal cells or cells from central cornea (P <0.01). Few cells were positive for K3 in P0 or P1 cells [(1.99 +/- 1.27)% (n = 7, P0) and (3.96 +/- 1.35)% (n = 4, P1), P = 0.046]. More cells at all levels were found to stain positive for PCNA and p63 as compared to K3, K12 and involucrin. After air-lifting, cell sheets of 3 to 5 epithelial cell layers formed. Involucrin showed positive staining in suprabasal layers of the cell sheets while connexin 43 was only observed in the basal layer. Staining of K3 remained sparse.</p><p><b>CONCLUSIONS</b>Human limbal cells isolated from cadaveric tissues were able to proliferate in vitro and exhibited a phenotype with characteristics similar to that of the limbal stem or progenitor cells.</p>