Clinical outcome analysis of two approaches to trypan blue dyeing for DMEK

Abstract To evaluate the clinical implications of the different trypan blue dyeing techniques used during liquid bubble (LBT) and manual peel (MPT) DMEK lenticule preparation techniques. This study retrospectively compared the degree to which endothelial cells are preserved using selective Descemet Membrane (DM) staining (LBT) versus bath-staining (MPT) when performed by a single surgeon, sourced from a single eye bank. Endothelial cell density measured after the 3-month follow-up was 1805 and 1916 cells/mm2 respectively, differing significantly (p = 0.012). A double-scroll graft formation was found and maintained until implantation in 94% of preparations with bath staining and 50% of preparations using selective DM staining. Preoperative visual acuity was comparable between preparation techniques at 0.4 logMAR as well as postoperatively, at an average of 0.1 logMAR. Reducing chemical stress on the endothelium by avoiding any contact with trypan blue allows for a significantly higher degree of cell preservation. However, achieving the often-desired double-scroll graft formation was possible less frequently. It remains unclear which factors define the differences graft scrolling behavior observed between LBT and MPT

Femtosecond-Laser Assisted Deep Anterior Lamellar Keratoplasty (F-DALK)

DALK is a demanding procedure performed by comparably few surgeons. Femtosecond-laser assisted DALK (f-DALK) potentially shortens the learning curve for surgeons, which benefits patients by reducing the invasiveness of the procedure, improving the odds against complications and by maintaining patient’s own, healthy endothelial tissue. The key advantage in using the femtosecond laser for DALK is the higher rate of successful intraoperative preparation and thus, fewer conversions to penetrating keratoplasty

Bilateral corneal perforation in Ipilimumab/Nivolumab - associated peripheral ulcerative keratitis

Purpose: To present a case of immune checkpoint inhibitor-induced bilateral peripheral ulcerative keratitis that progressed to corneal perforation requiring keratoplasty in both eyes. Observations: We describe the course of a 60-year-old man treated with a combination of Ipilimumab and Nivolumab for metastatic melanoma who presented with foreign body sensation and epiphora in both eyes.Bilateral immune-related peripheral ulcerative keratitis was refractory to topical anti-inflammatory therapy, necessitating repetitive, but unsuccessful cyanoacrylate gluing procedure followed by bilateral lamellar mini-keratoplasty. Conclusions and importance: Combined immune checkpoint inhibition revokes the corneal immune privilege and can lead to auto-immune keratitis with recalcitrant progression to ulceration and perforation

Predictive factors for re-bubbling after DMEK: focus on the posterior corneal surface

Purpose To understand whether the preoperative morphology of the posterior corneal surface influences the rate of re-bubbling after Descemet membrane endothelial keratoplasty (DMEK). Methods After retrospectively analyzing the medical records of patients undergoing DMEK, in this multicentric cross-sectional study, we performed a binomial logistic regression analysis to assess significant predictors of re-bubbling and re-transplantation after surgery. Analyzed parameters included the preoperative diagnosis, anterior and posterior surface K1/K2, central corneal thickness, posterior Q value, and other posterior corneal surface parameters evaluated on the elevation maps produced by anterior segment optical coherence tomography. Results were stratified based on the surgeons' experience. Results We included 202 eyes of 202 patients with a mean age of 69.5 +/- 12.4 years; 154 eyes were operated by a high-volume surgeon and 48 by one with less experience; 48 eyes (23.8%) underwent >= 1 re-bubbling and 14(6.9%) >= 1 re-transplantation. The presence of positive/less-negative posterior corneal irregularities and irregularities with greater absolute height had a significantly higher risk of re-bubbling in both the expert and less expert group (OR = 2.85 and 1.42, OR = 3.22 and 3.01, respectively, p < 0.05), whereas more negative posterior K1 and K2 were significant risk factors only in the former group (OR = 0.67 and 0.55, respectively, p < 0.05). Endothelial decompensation other than Fuchs and pseudophakic bullous kera-topathy, more negative posterior Q values and smaller distances between center, and the highest/lowest posterior corneal surface irregularity correlated with an increased risk of graft failure (OR 1.23, 1.21, and 1.29, respectively, p < 0.05). Conclusion Posterior corneal surface morphology significantly influences the risk of re-bubbling after DMEK

Non-invasive quantification of corneal vascularization using anterior segment optical coherence tomography angiography

Abstract The presence of corneal vascularization (CV) interferes with the angiogenic and immune privilege of the cornea, risking rejection in eyes following keratoplasty. Pre-operative (lymph)-angioregression is a promising therapeutic approach, but objective monitoring by non-invasive CV imaging is needed. The purpose of this study was to investigate anterior-segment optical coherence tomography angiography (AS-OCTA) for CV visualization and quantification, and to show its superiority over slit-lamp photography in high-risk eyes scheduled for keratoplasty. This institutional pilot study included 29 eyes of 26 patients (51 ± 16 years, 8 female) with significant CV scheduled for keratoplasty that were imaged by slit-lamp photography (Zeiss SL 800) and AS-OCTA (Zeiss Plex Elite 9000). After manual corneal layer segmentation correction, CV maximum/relative depth was measured with the inbuilt software. Slit-lamp photographs and AS-OCTA images were compared for visualization of vascular details. Angiotool software allowed a semi-automated determination of CV-related parameters in the vascular complex of AS-OCTA images. The predominant causes of CV were the herpes simplex virus keratitis (n = 7) and chemical burn (n = 4). Visualization of vascular morphology in AS-OCTA was superior to slit-lamp photography in all except one eye. Vascular metrics including total vessel length, number of junctions/endpoints, junction density, lacunarity, and vessel area/density were defined using Angiotool, with CV depth localization despite scarring and opacification. AS-OCTA proved effective for angioregressive treatment monitoring. AS-OCTA enables non-invasive and objective three-dimensional visualization of corneal vascularization superior to slit-lamp photography, and could be a precious tool for monitoring angioregressive preconditioning prior to keratoplasty

Nonpenetrating Foldable Intrastromal Keratoprosthesis: A Review of the Literature

Purpose: To review the literature focusing on the clinical outcomes of KeraKlear (KK) (KeraMed), a foldable intrastromal keratoprosthesis. Methods: We searched 6 databases using 4 keywords: KeraKlear, Foldable Keratoprosthesis, Intrastromal Keratoprosthesis, and Non-penetrating Keratoprosthesis. Included studies had to be conducted in vivo on humans, published until January 3, 2023, and had to investigate the implantation of the KK. Eyes were considered at high risk of keratoprosthesis retention failure whenever there was an active inflammatory ocular surface disorder or in case of previous KK failure. We aimed at recording the postoperative complications, rate of prosthesis retention, and mean improvements in visual acuity. Results: We identified 144 publications, 6 of which (38 eyes) met the inclusion criteria. No randomized controlled trials were found, and some studies had significant limitations regarding sample size and follow-up duration. With a mean follow-up of 28 ± 18.8 months, postoperative complications of any kind occurred between 0% and 50% and 24% had an implant extrusion/needed a reoperation. The mean postoperative visual acuity improvement on the last follow-up was −0.83 ± 0.27 LogMAR, that is, −0.57 ± 0.3 for high-risk and −1.03 ± 0.25 for low-risk eyes, whereas 1 year after implantation, 50% of the prostheses were retained in the former and 81% in the latter group. None of the eyes developed glaucoma, endophthalmitis, or expulsive hemorrhages; none had to be eviscerated/enucleated. Conclusions: Despite the limited quality and quantity of evidence, the available literature seems to suggest the KK to be a valuable tool in the treatment of complicated corneal disorders. Because in many parts of the world, the access to corneal transplantation is limited, this prosthesis could represent a valid alternative

Graefe's Archive for Clinical and Experimental Ophthalmology / Correlation between central stromal demarcation line depth and changes in K values after corneal cross-linking (CXL)

Purpose A stromal demarcation line (DL) after corneal cross-linking (CXL) has lately been suggested as a surrogate parameter for the success of CXL. The aim of this study was to investigate the correlation between depth of the central DL 1 month and the change in K values 12 months after CXL. Methods Treatment-naive subjects with keratoconus were treated using an accelerated CXL protocol [A-CXL(9*10)]. Depth of the DL/relative depth of the DL (DL%) was measured using Visante OCT imaging 1 month postoperatively (OP). Kmax/K2.5 (preOP) and change in Kmax/K2.5 (preOP12 months postOP) were assessed using corneal tomography (Pentacam HR, Oculus GmBH). Results Forty eyes were treated following the A-CXL(9*10). The mean DL depth was 20099 m (range 71 to 479)/mean DL%=42.7020.00% (range 1790). There was no statistically significant correlation between stromal depth of the DL and change in Kmax or K2.5, respectively (Spearman rho DL/Kmax 0.14 and DL/K2.5 0.14). Between DL% and the changes in maximum K values or K2.5, no statistically significant correlation was found as well (Spearman rho DL%/Kmax 0.10 and DL%/K2.5 0.19). Mean change in Kmax after 12 months was 0.682.26 diopters (D) (median 0.35 D) and 0.821.6 D (median 0.65 D) for K2.5 (p=0.07; p=0.02). Conclusions No statistically significant correlation was found between the stromal central depth of the DL and any outcome parameter for CXL after 12 months. Therefore, the interpretation of the DL as a predictive parameter for the effect of the procedure may not apply.(VLID)357508

Autophagy mediates cell cycle response by regulating nucleocytoplasmic transport of PAX6 in limbal stem cells under ultraviolet-A stress

<div><p>Limbal stem cells (LSC) account for homeostasis and regeneration of corneal epithelium. Solar ultraviolet A (UVA) is the major source causing oxidative damage in the ocular surface. Autophagy, a lysosomal degradation mechanism, is essential for physiologic function and stress defense of stem cells. PAX6, a master transcription factor governing corneal homeostasis by regulating cell cycle and cell fate of LSC, responds to oxidative stress by nucleocytoplasmic shuttling. Impaired autophagy and deregulated PAX6 have been reported in oxidative stress-related ocular surface disorders. We hypothesize a functional role for autophagy and PAX6 in LSC’s stress response to UVA. Therefore, human LSC colonies were irradiated with a sub-lethal dose of UVA and autophagic activity and intracellular reactive oxygen species (ROS) were measured by CYTO-ID assay and CM-H₂DCFDA live staining, respectively. Following UVA irradiation, the percentage of autophagic cells significantly increased in LSC colonies while intracellular ROS levels remained unaffected. siRNA-mediated knockdown (KD) of <i>ATG7</i> abolished UVA-induced autophagy and led to an excessive accumulation of ROS. Upon UVA exposure, LSCs displayed nuclear-to-cytoplasmic translocation of PAX6, while ATG7KD or antioxidant pretreatment largely attenuated the intracellular trafficking event. Immunofluorescence showing downregulation of proliferative marker PCNA and induction of cell cycle regulator p21 indicates cell cycle arrest in UVA-irradiated LSC. Abolishing autophagy, adenoviral-assisted restoration of nuclear PAX6 or antioxidant pretreatment abrogated the UVA-induced cell cycle arrest. Adenoviral expression of an ectopic PAX gene, PAX7, did not affect UVA cell cycle response. Furthermore, knocking down PAX6 attenuated the cell cycle progression of irradiated ATG7KD LSC by de-repressing p21 expression. Collectively, our data suggest a crosstalk between autophagy and PAX6 in regulating cell cycle response of ocular progenitors under UVA stress. Autophagy deficiency leads to impaired intracellular trafficking of PAX6, perturbed redox balance and uncurbed cell cycle progression in UVA-stressed LSCs. The coupling of autophagic machinery and PAX6 in cell cycle regulation represents an attractive therapeutic target for hyperproliferative ocular surface disorders associated with solar radiation.</p></div