Long-term graft survival after penetrating keratoplasty

A Predictive Model for Graft Failure in Femtosecond Laser-Assisted Penetrating Keratoplasty Among Chinese Patients: A 2-Year Study

INTRODUCTION

Graft failure is a major challenge in femtosecond laser-assisted penetrating keratoplasty (Fs-PKP). This study focuses on the development and validation of a clinical predictive model aimed at identifying the risk of graft failure in individuals undergoing Fs-PKP in China, offering a tailored approach to improve surgical outcomes.

METHODS

This retrospective cohort study at Nanjing First Hospital involved 238 patients and followed the TRIPOD statement. The cohort was divided into a training set (n = 166) and a validation set (n = 72) in a 7:3 ratio. It analyzed 23 predictor variables related to recipient, donor, and surgical factors, defining graft failure as "visually significant and irreversible corneal stromal edema, haze, or scarring." A comprehensive nomogram was created using univariate and multivariate Cox regression analyses and assessed by concordance index (C-index), time-dependent receiver operating characteristics (ROC) curve, calibration plots, and decision curve analysis (DCA).

RESULTS

Five critical risk factors were identified: recipients' history of systemic autoimmune disorders, ocular trauma, prior penetrating keratoplasty (PKP) history, donors' diabetes history, and the endothelial cell density of the donor cornea. The nomogram showed a C-index of 0.72 (95% CI 0.65-0.79) in the training group and 0.66 (95% CI 0.55-0.76) in the validation group, indicating robust predictive accuracy. Time-dependent ROC curves, calibration plots, and DCA consistently validated the model's reliability, predictive power, and clinical utility across both training and validation cohorts.

CONCLUSIONS

Our study developed and validated a model incorporating five key factors, enhancing preoperative prediction and management for Chinese patients with Fs-PKP graft failure.

Risk factors for corneal graft rejection after penetrating keratoplasty for keratoconus

PURPOSE

To evaluate the association between donor-related factors and the risk of rejection in patients undergoing penetrating keratoplasty (PKP) for keratoconus.

METHODS

A retrospective review was performed of keratoconus patients with no corneal neovascularization who underwent PKP from November 2014 to December 2016 and completed at least two years of follow-up. Preoperative, donor, operative, and postoperative data were collected and analyzed to identify factors leading to corneal graft rejection.

RESULTS

A total of 201 eyes (of 201 patients) that underwent PKP for keratoconus were included. Of these, 22.9% (95% CI 17.6-29.2%) had an episode of graft rejection. The overall graft survival rate was 98.5%. Receipts with a history of corneal transplant in the fellow eye (IRR 1.69, 95% CI 1.01, 2.80; p = 0.044) and those with postoperative stromal neovascularization (IRR 2.51, 95% CI 1.49, 4.21; p = 0.001) had a significantly higher incidence of rejection than those without these features. In univariate analysis, death-to-surgery time and death-to-excision time (DET) showed a weak association with graft rejection (p 0.05 and 0.08 respectively); However, in the multivariable analysis, this significance was lost. Grafts with a death-to-excision time (DET) greater than 8 h had a 0.53X lower risk of rejection compared with grafts with DET within 8 h or less (p = 0.05). Rejection was higher in patients receiving grafts with a preservation time within 7 days or less compared with preservation time greater than 7 days (30.6% vs. 21.2%, respectively, p = 0.291).

CONCLUSION

In the multivariable analysis, none of the donor-related factors were significantly associated with graft rejection; however, short death-to-surgery time may be associated with rejection after PKP. Recipients with a history of PKP in the fellow eye and those who developed corneal neovascularization were also at increased risk of developing rejection after keratoplasty.

A Detailed Analysis of Individuals Having Graft Failure After Corneal Transplantation

PURPOSE

To describe demographic and clinical characteristics of patients with graft failure after keratoplasty, determine the cause of graft failure and outcomes.

METHODS

The charts of patients between 2008-2013 in the Cornea Service at Wills Eye Hospital with a history of a corneal transplant before the end of 2012 were retrospectively reviewed. Included were patients who had graft failure after corneal transplantation and had at least one year of follow-up after transplantation. Penetrating keratoplasty (PK) and Descemet's stripping endothelial keratoplasty (DSEK) patients were analyzed separately.

RESULTS

A total of 186 eyes of 170 patients with graft failure after a PK (156) or DSEK (30) procedures were identified. The baseline characteristics included 100 female and 70 male patients with an age between 0 and 90 years (median 63 years). At the time of surgery, 38% had three or more systemic diseases and 68% were using three or more systemic medicines. Mean follow up time for PK was nearly four times of DSEK. Only 2 DSEK eyes (7%) underwent a 3rd DSEK graft, while 47 (30%) PK eyes underwent a 3rd PK and 15 (10%) PK eyes underwent more than three PK procedures.

CONCLUSIONS

Most DSEK failures occurred in 1st year, while graft failure in PKs is scattered over years. Failure in DSEK is mostly due to graft or surgical risk factors but in PK mostly due to factors in the host. DSEK does not appear to be as affected by the patients' demographic and clinical characteristics as much as PK.

Long-Term Outcomes of Keratoprosthesis With Biological Haptic: A Review of 25 Years of Single-Center Surgeries

PURPOSE

To study the outcome of eyes that underwent surgery for keratoprosthesis with a biological haptic, osteo-odonto-keratoprosthesis (OOKP) or tibia keratoprosthesis, by a single surgeon over a time span of more than 25 years.

METHODS

One hundred thirty eyes that had received a keratoprosthesis with a biological haptic between 1994 and 2022 by a single surgeon were included in this retrospective analysis. Main outcome parameters were postoperative best corrected visual acuity, postoperative refractive error, postoperative complications, anatomical and functional survival of the prosthesis as well as comparison of subgroups of the 2 different types (OOKP n = 78; tibia keratoprosthesis n = 52) of keratoprostheses, and subgroup analysis of different indications for surgery. Patients were examined every 6 months.

RESULTS

The longest follow-up was 25.8 years. Reasons for implantation were graft-vs-host disease (6.9%), vascularized corneas and dry eye (22.9%), physical or chemical burns (29.8%), Stevens-Johnson syndrome (9.9%), and ocular cicatricial pemphigoid (30.5%). The functional success rate with postoperative visual acuity of better than 0.7 log MAR was achieved by 56.9%. The OOKP subgroup showed a better mean visual outcome. 14 keratoprostheses (10.7%) had to be explanted over the whole time span. In the time leading to explantation, refraction showed a statistically significant myopic shift when compared with the non-explanted prosthesis. Anatomical survival rates were better for the OOKP in the first 12 years after implantation.

CONCLUSIONS

The study shows that keratoprosthesis with a biological haptic has favorable long-term outcomes. The retention rate stayed very high with excellent functional outcomes.

Descemetic Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty in Advanced Keratoconus: Comparison of Visual and Refractive Outcomes

Purpose

To assess and contrast the visual and refractive results of Descemetic deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in the treatment of advanced keratoconus.

Design

Retrospective, comparative, interventional study.

Methods

This study enrolled eyes affected by keratoconus with preoperative mean keratometry ≥60 diopters (D) that were treated with either Descemetic DALK (30 eyes) or PK (29 eyes) by using always the same corneal diameters (8.00mm recipient; 8.25mm donor cornea) and the same suture technique (10-0 nylon double-running 12-bites continuous suture). The outcome measures were postoperative uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), subjective refractive astigmatism (SRAst), and keratometric astigmatism at 3mm area (SimK), spherical equivalent (SEq).

Results

Postoperative visual acuity significantly improved in both groups. Mean CDVA was higher in the DALK group 3 months (DALK 0.61, PK 0.42, p<0.05), 6 months (DALK 0.69, PK 0.44, p<0.05), and 12 months (DALK 0.72, PK 0.45, p<0.05) postoperatively. However, 6 months after suture removal, CDVA was not statistically different between the two groups (DALK 0.71, PK 0.75, p>0.05). Final SRAst and SimK also were comparable between the two groups (respectively DALK 2.97, PK:2.81, p>0.05; DALK 3.91, PK 2.37, p>0.05). No significant statistical differences were noted for UCVA and SEq data during the entire follow-up period between the two groups.

Conclusion

Both methods of corneal transplantation resulted in a notable enhancement of visual and refractive outcomes in eyes afflicted by advanced keratoconus. Descemetic DALK demonstrated superior visual acuity before suture removal, whereas DALK and PK exhibited comparable results in terms of visual acuity, refractive correction, and keratometric astigmatism after suture removal.

Predicting Long-Term Endothelial Cell Loss after Preloaded Descemet Membrane Endothelial Keratoplasty in Fuchs' Endothelial Corneal Dystrophy: A Mathematical Model

(1) Background: This study offers a biexponential model to estimate corneal endothelial cell decay (ECD) following preloaded "endothelium-in" Descemet membrane endothelial keratoplasty (DMEK) in Fuchs' endothelial corneal dystrophy (FECD) patients; (2) Methods: A total of 65 eyes undergoing DMEK alone or combined with cataract surgery were evaluated. The follow-up period was divided into an early phase (first 6 months) and a late phase (up to 36 months). Endothelial cell count (ECC) and endothelial cell loss (ECL) were analyzed; (3) Results: The half time of the ECD was 3.03 months for the early phase and 131.50 months for the late phase. The predicted time-lapse interval to reach 500 cells/mm2 was 218 months (18.17 years), while the time-lapse interval to reach 250 cells/mm2 was 349 months (29.08 years). There was no statistically significant difference between the ECL in DMEK combined with cataract extraction and DMEK alone at 24 months (p ≥ 0.20). At the late phase, long-term ECL prediction revealed a lower ECC half time in patients undergoing DMEK combined with cataract surgery (98.05 months) than DMEK alone (250.32 months); (4) Conclusions: Based on the mathematical modeling, a predicted average half-life of a DMEK graft could reach 18 years in FECD. Moreover, combining cataract extraction with DMEK could result in excessive ECL in the long term.

Comparison of repeat penetrating keratoplasty, DSAEK and DMEK for the management of endothelial failure of previous PK

PURPOSE

To compare the clinical outcomes of repeat PK, DSAEK-on-PK or DMEK-on-PK for the management of endothelial failure of previous penetrating keratoplasty.

DESIGN

Retrospective, interventional consecutive case series.

PARTICIPANTS

104 consecutive eyes of 100 patients requiring a second keratoplasty for endothelial failure of their primary penetrating keratoplasty performed between September 2016 and December 2020.

INTERVENTION

Repeat keratoplasty.

MAIN OUTCOME MEASURES

Survival and visual acuity at 12 and 24 months, rebubbling rate and complications.

RESULTS

Repeat PK was performed in 61/104 eyes (58.7%), DSAEK-on-PK was performed in 21/104 eyes (20.2%) and DMEK-on-PK was performed in 22/104 eyes (21.2%). Failure rates in the first 12 and 24 months were 6.6% and 20.6% for repeat PKs compared to 19% and 30.6% for DSAEK and 36.4% and 41.3% for DMEK. For those grafts surviving 12 months, the chances of surviving to 24 months were greatest for DMEK-on-PK at 92% vs 85% each for redo PK and DSAEK-on-PK. Visual acuity at one year was logMAR 0.53 ± 0.51 in the redo PK group, 0.25 ± 0.17 for DSAEK-on-PK and 0.30 ± 0.38 for DMEK-on-PK. 24-month outcomes were 0.34 ± 0.28, 0.08 ± 0.16, and 0.36 ± 0.36 respectively.

CONCLUSIONS

DMEK-on-PK has a greater failure rate in the first 12 months than DSAEK-on-PK which has a greater failure rate than redo PK. However, the 2-year survival rates in our series for those already surviving 12 months were greatest for DMEK-on-PK. There was no significant difference in visual acuity at 12 or 24 months. Careful patient selection is needed by experienced surgeons to determine which procedure to offer to patients.

Demographic and Socioeconomic Determinants of Penetrating Keratoplasty Outcomes

PURPOSE

The aim of this study was to determine possible associations between demographic and socioeconomic factors and graft survival after penetrating keratoplasty (PK).

METHODS

This study was a retrospective chart review of patients undergoing PK at a tertiary-care corneal practice at Wills Eye Hospital between May 1, 2007, and September 1, 2018. The first PK of the first eye was included. The primary outcome measure was graft failure, defined as irreversible and visually significant graft edema, haze, or scarring. Demographic and socioeconomic factors included yearly average adjusted gross income (AGI) based on residential zip code, age, sex, and race. Two income groups were created: 1) individuals from neighborhoods with the lowest 10% of AGI (N = 82, AGI=$32,100 ± 4000) and 2) the remaining 90% of individuals (N = 740, AGI=$86,900 ± 52,200). Logistic regression analysis was performed to identify factors predictive of graft prognosis.

RESULTS

The 822 patients (822 eyes) included had a mean age of 57.1 ± 22.1 years at the time of PK. Over an average of 4.2 ± 3.1 years of follow-up, graft failure occurred in 35.3%. Age, sex, and follow-up duration were comparable between income groups (all P > 0.05). Black race was disproportionately represented in the lower-income group (50.0% vs. 11.5%, P < 0.001). Multivariable analysis identified predictors of graft failure including residing in a lower-income neighborhood [hazard ratio (HR) = 2.27, 95% confidence interval (CI) = 1.24-4.19, P = 0.008], younger age (HR = 0.99, 95% CI = 0.98-1.00, P = 0.046), and Black race (HR = 1.63, 95% CI = 1.03-2.56, P = 0.035).

CONCLUSIONS

Individuals with a lower income, younger age, and Black race may be more vulnerable to graft failure after PK. Further studies are warranted to identify reasons for these associations.

Effects of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) on mild-to-moderate and advanced keratoconus

PURPOSE

To compare the outcomes of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) for mild-to-moderate keratoconus (KC) and advanced KC.

METHODS

Prospective case series study. Sixty-three eyes of 56 patients with progressive KC underwent FL-MILK were divided into group 1 [mean keratometry (Kmean) ≤ 53D] and group 2 (Kmean > 53D). Best spectacle-corrected visual acuity (BSCVA), Kmean, maximum keratometry (Kmax), anterior central corneal elevation (ACE), stiffness parameter A1 (SP-A1) and deformation amplitude (DA) were evaluated preoperatively and up to 24 months postoperatively.

RESULTS

Mean BSCVA improved from 0.34 ± 0.13 logMAR preoperatively to 0.25 ± 0.13 logMAR at 24 months postoperatively in group 1 (F = 10.10, P < .0001), and from 0.54 ± 0.31 logMAR to 0.40 ± 0.26 logMAR (F = 9.06, P = .0002) in group 2. Group 2 showed an average Kmax reduction of 10.9 D and an average Kmean reduction of 3.9 D at 24 months postoperatively (both P < .0001), whereas no significant change was observed in group 1. Average ACE decreased from 19.2 ± 10.0 to 5.2 ± 8.4 at 24 months postoperatively in group 1 (F = 28.5, P < .0001), and from 46.2 ± 16.3 to 19.1 ± 9.0 (F = 49.6, P < .0001) in group 2; SP-A1 increased from 53.8 ± 12.7 mmHg/mm to 95.9 ± 20.2 mmHg/mm in group 1 (F = 70.0, P < .0001), and from 38.6 ± 13.4 mmHg/mm to 89.3 ± 18.2 mmHg/mm (F = 96.9, P < .0001) in group 2; DA decreased from 1.30 ± 0.14 mm to 1.17 ± 0.13 mm in group 1 (F = 14.0, P < .0001), and from 1.40 ± 0.16 mm to 1.18 ± 0.10 mm (F = 27.6, P < .0001) in group 2.

CONCLUSIONS

FL-MILK can stabilize progressive KC in mild-to-moderate cases and advanced cases at 24-month follow-up. Steeper corneas are more likely to undergo flattening after FL-MILK.

CLINICAL TRIAL

Date of registration: July 16, 2017. The title of the trail: www.

CLINICALTRIALS

gov Trial registration number: NCT03229239. The name of the trial registry: ClinicalTrials.gov.

Outcomes of Pre-Descemet Endothelial Keratoplasty for Failed Therapeutic Penetrating Keratoplasty

PURPOSE

The aim of this study was to analyze the outcomes of pre-Descemet endothelial keratoplasty (PDEK) for failed therapeutic penetrating keratoplasty.

METHODS

This was a retrospective, interventional study that involved 12 eyes of 12 patients with failed therapeutic penetrating keratoplasty that underwent PDEK. All cases had a minimum follow-up of 12 months. The main outcome measures were best-corrected visual acuity, graft clarity, endothelial cell density loss, and graft survival. Corneal clarity was graded on a scale from 0 to 4, where grade 4 denoted an absolutely clear cornea and grade 0 denoted a totally opaque cornea. Three cases underwent PDEK, 6 cases PDEK with phacoemulsification, and 3 cases underwent PDEK with pupilloplasty.

RESULTS

The mean follow-up period for all cases was 18.5 ± 4.9 months. The mean preoperative and postoperative best-corrected visual acuity (in Snellen decimal equivalent) was 0.02 ± 0.01 and 0.54 ± 0.17, respectively, at the last follow-up. Postoperatively, corneal clarity grade 4 was present in 9 eyes, grade 3 in 2 eyes, and grade 2 in 1 eye. Mild subepithelial haze was noted in 2 eyes. The percentage of endothelial cell density loss was 28.2% ± 10.6%. No correlation was observed between the postoperative graft clarity and preoperative specular count (r = -0.021, P = 0.512). Rebubbling was performed for 1 eye that developed partial graft detachment in the first postoperative week. One patient had an episode of rejection that was managed with systemic and topical steroids.

CONCLUSIONS

In patients with failed therapeutic penetrating keratoplasty, PDEK can be a useful alternative for visual rehabilitation as it demonstrates favorable visual outcomes with a good graft survival rate.

[Corneal transplantation at the beginning of the 21th century]

Corneal transplantation (keratoplasty) is necessary when various disorders result in corneal opacities with severe visual loss that cannot be treated conservatively, or the regular structure and curvature of the cornea is distorted, and its function is lost. Among human transplantation, keratoplasty is the most successful surgical procedure. In recent decades, penetrating keratoplasties have been increasingly replaced by lamellar techniques, where only the abnormal layer of the cornea is transplanted. The anterior form is deep anterior lamellar keratoplasty (DALK), recommended mainly for keratoconus. The main forms of posterior lamellar keratoplasty are Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK). The indications are bullous keratopathy after cataract surgery with endothelial destruction and Fuchs endothelial dystrophy. Lamellar keratoplasty has several advantages over penetrating surgery. Postoperative visual acuity is better, wound healing, patient rehabilitation are faster and the course of any immune rejection is milder and can be better managed. Orv Hetil. 2023; 164(28): 1087-1093.

Recurrent Keratoconus: Corneal Transplants for Keratoconus Develop Tomographic Ectatic Changes

PURPOSE

The purpose of this study was to evaluate postoperative Scheimpflug imaging changes during the first 5 years after penetrating keratoplasty (PK) in patients with keratoconus (KC).

METHODS

This retrospective, interventional case series includes 31 eyes of 31 patients who underwent their first PK with a history of KC. Postoperative Scheimpflug imaging was performed 3 months after the removal of the last suture (baseline) and then repeated 3 and 5 years after the PK. Demographic data, donor and host trephination diameter, and Scheimpflug imaging (Pentacam HR, Oculus, Germany) parameters indicative of ectasia were analyzed to evaluate postoperative graft changes that occur after PK.

RESULTS

The maximal keratometry (Kmax) progressed significantly between baseline (53.5 ± 6.1 D) and postoperative year 3 and year 5 [56.5 ± 6.1 diopter (D) and 58.8 ± 7.9 D, P < 0.001]. Significant changes were also observed for the anterior best fit sphere and posterior best fit sphere ( P < 0.001 for 3 and 5 years compared with baseline). Kmax increased by at least 2 Ds for 74.2% of patients and up to 7 Ds or more for 25.8% of the patients. A significant inverse correlation was observed for host trephine size and progression of Kmax (r = -0.52, P = 0.01), which indicated that larger host trephination size was associated with a smaller increase in postoperative Kmax.

CONCLUSIONS

Tomographic graft changes indicative of ectasia were observed within 3 to 5 years after PK in patients with KC. These changes were observed more frequently and sooner after corneal transplants than previously reported.

Long-term Outcomes After Lamellar Endothelial Keratoplasty Compared With Penetrating Keratoplasty for Corneal Endothelial Dysfunction: A Systematic Review

PURPOSE

The purpose of this study is to evaluate long-term outcomes of endothelial keratoplasty (EK) compared with penetrating keratoplasty (PK) for corneal endothelial dysfunction [Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK)].

METHODS

In this systematic review, we searched PubMed, the Cochrane Library, and Embase up to May 2022 and considered all types of studies addressing our objective. Graft survival at 5, 10, and 15 years was the main outcome.

RESULTS

Fifty cohort studies were included. At 5 years, in FECD and BK, graft survival seemed higher after EK than PK. Two comparative studies showed either a higher 5-year graft survival after EK than PK or no significant differences. Including noncomparative studies, in FECD, the 5-year graft survival ranged from 0.69 to 0.98 for PK, from 0.93 to 1.00 for DSEK, and from 0.93 to 0.99 for Descemet membrane endothelial keratoplasty (DMEK). In BK, the 5-year graft survival ranged from 0.39 to 0.91 for PK, from 0.65 to 0.89 for DSEK, and from 0.84 to 0.95 for DMEK. The 10-year graft survival ranged from 0.20 to 0.90 for PK and from 0.62 to 0.92 for EK. The mean 5-year best spectacle-corrected visual acuity ranged from 0.73 to 0.43 LogMAR for PK, from 0.61 to 0.09 for DSEK, and from 0.31 to 0.05 for DMEK. The 5-year rejection rate ranged from 11.0% to 28.7% for PK, from 5.0% to 7.9% for DSEK, and from 1.7% to 2.6% for DMEK.

CONCLUSIONS

These results suggest a higher 5-year graft survival and better secondary outcomes after EK. Nevertheless, the level of evidence was low.

PROSPERO REGISTRATION

CRD42021260614.

Descemet Stripping Endothelial Keratoplasty: Fifteen-Year Outcomes

PURPOSE

The purpose of this study was to evaluate 15-year outcomes of Descemet stripping endothelial keratoplasty (DSEK).

METHODS

We retrospectively reviewed an initial, consecutive series of 350 DSEK cases in 290 patients (mean age 69 years), performed between December 2003 and December 2005 for Fuchs dystrophy (86%), pseudophakic/aphakic bullous keratopathy (10%), or failed penetrating keratoplasty (4%). Outcomes included best spectacle-corrected visual acuity (BSCVA), endothelial cell density (ECD), and graft failure (defined as regraft for any reason or persistent loss of stromal clarity).

RESULTS

At 15 years, 46 of 350 DSEK grafts (13%) had failed, 155 (44%) were in patients who died, and 84 of the remaining 149 grafts (56%) were examined. After accounting for loss to follow-up, the probability of graft failure was 7% at 5 years, 16% at 10 years, and 23% at 15 years. The main risk factor for late endothelial failure was preoperative glaucoma (hazard ratio: 4.4 for medically managed and 24 for surgically managed glaucoma). The probability of an immunologic rejection episode was 7% by 1 year, 14% by 10 years, and 17% by 15 years. The median donor ECD decreased from 3030 cells/mm 2 before DSEK to 1973 cells/mm 2 at 6 months (36% loss) and 705 cells/mm 2 at 15 years (78% loss). The median BSCVA, including the eyes with ocular comorbidity, was 20/60 preoperatively, 20/40 at 3 through 12 months, and 20/30 from 2 to 15 years.

CONCLUSIONS

DSEK provided excellent long-term visual rehabilitation and graft survival in this early cohort, performed when the technique was still being refined.

Pre-Clinical Evaluation of Efficacy and Safety of Human Limbus-Derived Stromal/Mesenchymal Stem Cells with and without Alginate Encapsulation for Future Clinical Applications

Corneal opacification or scarring is one of the leading causes of blindness worldwide. Human limbus-derived stromal/mesenchymal stem cells (hLMSCs) have the potential of clearing corneal scarring. In the current preclinical studies, we aimed to determine their ability to heal the scarred corneas, in a murine model of corneal scar, and examined their ocular and systemic toxicity after topical administration to rabbit eyes. The hLMSCs were derived from human donor corneas and were cultivated in a clean room facility in compliance with the current good manufacturing practices (cGMP). Before the administration, the hLMSCs were analyzed for their characteristic properties including immunostaining, and were further subjected to sterility and stability analysis. The corneas (right eye) of C57BL/6 mice (n = 56) were stripped of their central epithelium and superficial anterior stroma using a rotary burr (Alger Brush® II). Few mice were left untreated (n = 8), while few (n = 24) were treated immediately with hLMSCs after debridement (prophylaxis group). The rest (n = 24, scar group) were allowed to develop corneal scarring for 2 weeks and then treated with hLMSCs. In both groups, the treatment modalities included encapsulated (En+) and non-encapsulated (En−) hLMSCs and sham (vehicle) treatment. The follow-up (4 weeks) after the treatment or debridement included clinical photography, fluorescein staining, and optical coherence tomography at regular intervals. All the images and scans were analyzed using ImageJ software to assess the changes in corneal haze, scar area, and the reflectivity ratio of the epithelium to the stroma. The scar area and the scar intensity were found to be decreased in the groups that received hLMSCs. The reflectivity of the stroma was found to be normalized to the baseline levels before the debridement in the eyes that were treated with hLMSCs, relative to the untreated. In the safety study, the central corneas of the left eye of 18 New Zealand rabbits were scraped with a needle and then treated with En+ hLMSCs, En− hLMSCs, and the sham (n = 6 each). Rabbits were then followed up for 4 weeks, during which blood and tear samples were collected at regular intervals. These rabbits were then assessed for changes in the quantities of inflammatory markers (TNF-α, IL-6, and IgE) in the sera and tears, changes in the ocular surface observations such as intraocular pressure (IOP), and the hematological and clinical chemistry parameters. Four weeks later, the rabbits were euthanized and examined histopathologically. No significant changes in conjunctival congestion, corneal clarity, or IOP were noticed during the ophthalmic examination. The level of inflammatory molecules (TNF-α and IL-6 TNF-α) and the hematological parameters were similar in all groups without any significant changes. Histological examination of the internal organs and ocular tissues did not reveal any abnormalities. The results of these studies summarize that the En+ and En− hLMSCs are not harmful to the recipient and potentially restore the transparency of debrided or scarred corneas, indicating that hLMSCs can be assessed for clinical use in humans.

Anatomical and functional outcomes of Boston type I keratoprosthesis as primary penetrating corneal procedure in high-risk and non-high-risk cases

PURPOSE

To analyze the anatomical and functional results of Boston type I keratoprosthesis (B1-KPro) as a primary corneal procedure in high-risk (HR) cases and non-high-risk (NHR) cases.

METHODS

In this retrospective interventional case series, all patients who underwent B1-KPro at a single center between January 2006 and March 2021 were reviewed and identified. Cases were classified according to the primary diagnosis. Anatomical failure was considered in the case of prosthesis extrusion or phthisis bulbi. Functional failure was a postoperative corrected distance visual acuity (CDVA) ≥ 1.3 LogMAR (≤ 0.05 decimal) at the end of the follow-up period.

RESULTS

Twenty-three eyes were included for analysis. Thirteen eyes were classified as HR and 10 as NHR. The mean age was 46.5 ± 26.5 years (5-84 years) in the HR group and 49.5 ± 26.9 years (2-78 years) in the NHR group. The mean follow-up was 42.0 ± 35.9 months (1.5-118 months) in HR and 44.8 ± 38.8 months (1-107 months) in NHR. Three eyes in the HR and none in the NHR group showed anatomical failure. Functional failure was reported in 5/13 eyes in the HR and 8/10 in the NHR group. Functional cumulative survival probability was 92% and 82% for the HR group at 1 and 2 years, respectively. In the NHR group, it was 27% at both times. No significant differences were found between groups, except for functional survival in the HR group due to better visual potential of the eyes.

CONCLUSIONS

B1-KPro as a primary corneal procedure is a valid option for visual rehabilitation in high-risk cases.

Penetrating Keratoplasty: Indications and Graft Survival by Geographic Region

Corneal transplantation, or penetrating keratoplasty (PK), is the most common form of solid-organ transplantation performed worldwide. Here, we evaluated the indications for PK and rates of transplant survival around the world by geographic region. We conducted a literature search of PubMed, MEDLINE, and Google Scholar databases and identified 155 relevant studies from 41 countries published between 1987 and 2021. The most common indications for PK were keratoconus in Europe, Africa, the Middle East, Australia, New Zealand, and Central and South America, bullous keratopathy in North America, and corneal scarring in Asia. The overall global mean graft survival rates at 1-, 2-, 3-, 5-, and 10-years were 88.6%, 81.2%, 78.9%, 72.8%, and 61.2%, respectively. Through this systematic analysis of PK by region, we hope to bring a new perspective to the corneal transplantation literature and to potentially highlight global differences and unmet needs in patient care.

Outcomes of Penetrating Keratoplasty After Open Globe Injury

PURPOSE

The purpose of this study was to investigate the clinical features, surgical outcomes, and prognostic factors of penetrating keratoplasty (PKP) after open globe injury (OGI).

METHODS

A retrospective review of all patients treated for OGI between January 2000 and July 2017 was conducted. Demographic, preoperative, perioperative, and postoperative data were collected for those who underwent PKP after OGI. The predictive value of each preoperative variable on graft failure was assessed using univariate and multivariable Cox proportional hazards models, and the predictive value of variables on post-PKP visual outcome was assessed using both univariate and multivariable logistic regression models. All eyes that underwent PKP after OGI were included unless they had less than 365 days of follow-up.

RESULTS

Forty-six eyes that underwent PKP met inclusion criteria. The median age was 46 years (interquartile range = 23.00-61.25), median follow-up was 78.5 months (interquartile range = 38.63-122.02), and 37 of 46 subjects (80.4%) were male. The observed 1- and 5-year graft survival estimates were 80.4% and 41.7%, respectively. Factors statistically associated with graft failure in multivariable analyses were rejection episode, hazard ratio (HR) = 3.29; retinal detachment (RD), HR = 3.47; and endophthalmitis, HR = 6.27. Fifteen of 42 eyes (35.7%) regained ambulatory vision (20/200 or better). The strongest predictors of vision worse than 20/200 at the last follow-up were RD, odds ratio (OR) = 43.88; graft rejection, OR = 12.42; and injury outside the workplace, OR = 25.05.

CONCLUSIONS

Despite a high graft survival at 1 year, most of the patients did not regain ambulatory vision. Graft rejection, RD, and endophthalmitis were risk factors for graft failure. These factors should be considered when counseling patients regarding PKP after OGI.

Twenty-Two-Year Clinical Outcome of a Case of Endokeratoplasty

PURPOSE

The purpose of this study was to report the 22-year clinical outcome of a patient who underwent endokeratoplasty.

METHODS

To report the clinical outcomes of 37-year-old male who underwent endokeratoplasty for decompensated Fuchs endothelial dystrophy in 1998.

RESULTS

After subsequent cataract surgery and iridoplasty, at 22 years post endokeratoplasty, the Snellen best spectacle-corrected visual acuity is 20/20 (-5.50 sphere -3.00 cylinder at 135 degrees), endothelial cell count is 645 cells/mm 2 , central corneal thickness is 644 μm, and the cornea remains clear with no evidence of graft rejection or failure.

CONCLUSIONS

To the best of our knowledge, this is the longest reported outcome for selective endothelial replacement. The patient undergoing endokeratoplasty can achieve an excellent visual acuity and long-term graft survival.

Considerations for Corneal Surgery With Patients in the 10th Decade of Life

PURPOSE

The purpose of this study was to report the indications, ocular and systemic comorbidities, and surgical outcomes of corneal transplantation in patients older than 90 years.

METHODS

A retrospective review was conducted to identify individuals 90 years and older who underwent corneal transplantation surgery at the Bascom Palmer Eye Institute between January 2013 and October 2020. Outcomes included best-corrected visual acuity and graft survival over time. Paired t tests were used to compare visual acuity preoperatively versus postoperatively. Graft survival was evaluated with Kaplan-Meier curves.

RESULTS

Fifty-eight eyes of 52 consecutive individuals were included. The mean age of individuals was 92 ± 2 years; 26.9% were male; and 48.1% self-identified as non-Hispanic White and 38.5% as Hispanic. Postoperative follow-up was 14.7 ± 12.1 months. Of the 58 eyes, 44.8% (26/58) underwent penetrating keratoplasty, 46.6% (27/58) Descemet stripping automated endothelial keratoplasty, and 6.9% (4/58) keratoprosthesis. All surgeries were performed under monitored local anesthesia, without major complications. Surgical indications included pseudophakic bullous keratopathy (36.2%), glaucoma-associated corneal decompensation (27.6%), Fuchs endothelial dystrophy (25.9%), and perforated corneal ulceration (19.0%). The best-corrected visual acuity improved by 0.32 (95% confidence interval 0.14-0.50; P < 0.01) as early as 1 month postoperatively, and vision gains were sustained for at least 12 months. Graft survival probability at 12 months was 88%.

CONCLUSIONS

Corneal transplantation is a safe and successful procedure in restoring the visual acuity for patients older than 90 years after careful preoperative evaluation. Further research is needed to evaluate the impact of corneal transplantation on quality of life in patients in the 10th decade of life.

Management and Treatment Outcomes of High-Risk Corneal Transplantations

Corneal transplantation is the most effective treatment for corneal blindness. Standard planned keratoplasties have a high success rate. Conditions such as active inflammation at the time of surgery, the presence of ocular surface disease, previous graft disease, or neovascularization make them more susceptible to rejection. These are so-called high-risk corneal transplantations. In our study, we selected 52 patients with a higher risk of graft rejection. A total of 78 procedures were performed. The main indications for the first keratoplasty were infections (59.6%) and traumas (21.2%). Visual acuity (VA) significantly improved from 2.05 logMAR on the day of keratoplasty to 1.66 logMAR in the latest examination (p = 0.003). An analysis of the graft survival showed a 1-year survival of 54% and a 5-year survival of 19.8% of grafts. The mean observation time without complications after the first, second, and third surgery was 23, 13, and 14 months, respectively. The best results were noted among patients with infectious indications for keratoplasty (p = 0.001). Among them, those with bacterial infection had the best visual outcomes (p = 0.047).

Long-Term Outcomes of Bowman Layer Inlay Transplantation for the Treatment of Progressive Keratoconus

PURPOSE

To report long-term clinical outcomes and estimated success rates after Bowman layer (BL) inlay transplantation in eyes treated for progressive keratoconus (KC).

METHODS

Thirty-five eyes (29 patients) with progressive KC underwent BL inlay transplantation. Best-corrected spectacle and contact lens visual acuity, Scheimpflug-based corneal tomography [simulated and maximum keratometry (Kmax)], central corneal thickness, thinnest point thickness, complications, and success rate were evaluated up to 8 years postoperatively for the total group and 2 subgroups [group 1: preoperative Kmax > 69 diopter (D) (n = 26); group 2: preoperative Kmax < 69D (n = 9)].

RESULTS

Mean logarithm of the minimum angle of resolution best contact lens-corrected visual acuity for the total group and the 2 subgroups did not change from preoperative up to the last available follow-up (all P > 0.05), whereas best spectacle-corrected visual acuity improved for group 1 ( P = 0.03). Group 1 showed an average Kmax reduction of 7D in the first month ( P < 0.001) with no further changes up to 8 years postoperatively ( P > 0.05), whereas no significant changes were observed in group 2 (all P > 0.05). Postoperative KC progression occurred in 4 eyes (n = 3 group 1, n = 1 group 2) and 1 eye (group 2) underwent retransplantation for unsatisfactory visual performance. Kaplan-Meier analysis showed an estimated success rate of 85% at the 5 to 8 years follow-up in group 1 and of 75% at the 5 to 7 years follow-up for group 2.

CONCLUSIONS

BL inlay transplantation stabilized KC in most eyes along with preservation of contact lens tolerance up to 8 years postoperatively and may be a successful treatment option, in particular for eyes with progressive advanced KC (Kmax > 69D).

Descemet membrane endothelial keratoplasty: Update on preoperative considerations, surgical techniques, and outcomes

Descemet membrane endothelial keratoplasty (DMEK) is the closest to the physiological replacement of endothelial cells. In the initial years, the technique was surgically challenging. Over the years, with better understanding and modifications in the surgical steps, the technique has evolved as an alternative to more popular procedure Descemet stripping endothelial keratoplasty. The article highlights the various preoperative, intraoperative, and postoperative nuances of DMEK. Additionally, it summarizes the various comparative and noncomparative studies on DMEK outcomes.

Bevacizumab in High-Risk Corneal Transplantation: A Pilot Multicenter Prospective Randomized Control Trial

PURPOSE

To determine the efficacy of local (subconjunctival and topical) bevacizumab (Avastin) treatment in patients undergoing vascularized high-risk corneal transplantation.

DESIGN

Pilot, prospective, randomized, double-blind, placebo-controlled clinical trial conducted at 5 clinical centers in the United States, India, and Brazil.

PARTICIPANTS

Patients aged > 18 years undergoing high-risk penetrating keratoplasty, defined as corneal neovascularization (NV) in 1 or more quadrants ≥2 mm from the limbus or extension of corneal NV to the graft-host junction in a previously failed graft.

METHODS

Patients were randomized to receive subconjunctival bevacizumab (2.5 mg/0.1 ml) or placebo at the time of surgery, followed by topical bevacizumab (10 mg/ml) or topical placebo, administered 4 times per day for 4 weeks.

MAIN OUTCOME MEASURE

The 52-week endothelial immune rejection rate.

RESULTS

Ninety-two patients were randomized to receive bevacizumab (n = 48) or control (n = 44). The 52-week endothelial rejection rate was 10% in the bevacizumab group and 19% in the control group (P = 0.20). Post hoc, extended follow-up at the lead study site showed an endothelial rejection rate of 3% in the bevacizumab group and 38% in the control group (P = 0.003). Treatment with bevacizumab was found to have a hazard ratio of 0.15 (95% confidence interval, 0.03-0.65, P = 0.01) in a post hoc Cox regression analysis.

CONCLUSIONS

In patients undergoing vascularized high-risk corneal transplantation, there was no statistically significant difference in the rate of endothelial rejection at 1 year in the bevacizumab treatment group compared with the control group. This study may have been underpowered to detect a difference between treatment groups, and taken together, our data suggest that, in the current trial design, bevacizumab has a positive but not (yet) significant effect on endothelial rejection.

Repeated Femtosecond Laser-Assisted Astigmatic Keratotomies in Post-Keratoplasty Eyes

Visual rehabilitation after a keratoplasty is often compromised due to high amounts of residual astigmatism. Femtosecond laser-assisted astigmatic keratotomy (FLAK) is gaining popularity in decreasing this astigmatism. Though one set of two incisions suffices in most cases, sometimes the treatment proves insufficient and additional treatment is required. This case series evaluates the outcomes in patients who underwent two consecutive FLAK sets to correct post-keratoplasty residual astigmatism. All repeated FLAK cases performed on post-keratoplasty eyes were reviewed in a high-volume clinic as a non-comparative retrospective case series. The data extracted include the procedure parameters, time between procedures, refraction including sphere, astigmatism, spherical equivalent (SE), and uncorrected and best-spectacle-corrected distance visual acuity (UDVA, BSDVA, respectively). Eleven eyes of eleven patients aged 25.5 ± 10 treated with more than one FLAK procedure were identified. The average follow-up time was 6 months after the first FLAK and 24 ± 10 months after the second. The second FLAK was performed six months after the first. The preoperative mean astigmatism was −9.59 ± 2.36 D. At the final follow-up, the mean astigmatism decreased to −5.38 ± 1.79 D (p = 0.001). Repeated FLAK procedures achieved a significant and stable reduction of astigmatism in post-keratoplasty eyes. This procedure shows safety and effectivity in these complex eyes and may prevent the need for a further keratoplasty.

3D biomaterial P scaffolds carrying umbilical cord mesenchymal stem cells improve biointegration of keratoprosthesis

Biointegration of a keratoprosthesis (KPro) is critical for the device stability and long-term retention. Biointegration of the KPro device and host tissue takes place between the surrounding corneal graft and the central optic [made by poly (methyl methacrylate) (PMMA)]. Our previous clinical results showed that auricular cartilage reinforcement is able to enhance the KPro biointegration. However, the auricular cartilage is non-renewable and difficult to acquire. In this study, we developed a novel type of biomaterial using a three-dimensional porous polyethylene glycol acrylate scaffold (3D biological P-scaffold) carrier with chondrocytes differentiated from induced human umbilical cord mesenchymal stem cells (hUC-MSCs) and tested in rabbit corneas. The results showed hUC-MSCs bear stem cell properties and coule be induced into chondrocytes, P-scaffold is beneficial to the growth and differentiation of hUC-MSCs both in vivo and in vitro. Besides, after implanting the P-scaffold into the corneal stroma, no serious immune rejection response, such as corneal ulcer or perforation were seen, suggested a good biocompatibility of P-scaffold with the corneal tissue. Moreover, after implanting P-scaffold in together with the differentiated chondrocytes into the rabbit corneal stroma, they significantly increased corneal thickness and strengthened the host cornea, and chondrocytes could stably persist inside the cornea. In summary, the 3D biological P-scaffold carrying differentiated hUC-MSCs could be the preferable material for KPro reinforcement.

Impact of vaccination on keratoplasty

PURPOSE OF REVIEW

Corneal graft rejection has been reported after coronavirus disease 2019 (COVID-19) vaccination. The purpose of this review is to evaluate the literature regarding corneal graft rejection after vaccination, including rejection rates and risk factors. We aim to create a framework to identify patients who are at higher risk for graft rejection and may warrant consideration of prophylactic interventions.

RECENT FINDINGS

Graft rejection has been reported following administration of mRNA, viral vector, and inactivated whole-virion COVID-19 vaccines. Most cases had additional risk factors associated with rejection. Vaccination increases circulation of proinflammatory cytokines, CD4+ and CD8+ T-cell responses, and antispike neutralizing antibody, all of which may contribute to graft rejection. Two prospective studies have found no relationship between recent vaccination and rejection but 20% of cornea specialists report to have seen a vaccine-associated rejection and 22% recommend delaying vaccination in certain circumstances. Many specialists recommend prophylactic topical corticosteroids before and after vaccination to mitigate rejection risk but there is no evidence to support this practice on a wider scale.

SUMMARY

Our framework identified 96.8% of penetrating keratoplasty patients with vaccine-associated rejection as higher risk. Further research is needed in order to develop evidence-based guidelines.

Risk factors of rejection after penetrating keratoplasty: a retrospective monocentric study

PURPOSE

To assess risk factors of rejection after penetrating keratoplasty (PKP).

METHODS

This retrospective monocentric study assessed risk factors for rejection in patients who underwent PKP at Montpellier University Hospital between June 2005 and September 2018. Graft and donor data were obtained from our tissue bank in Montpellier. Clinical data of recipients were recorded from medical files. Survival was estimated by the Kaplan-Meir method. Potential risk factors of rejection were assessed by multivariate Cox proportional hazards analysis, estimating hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Among the 316 consecutive patients (59% male, mean SD] age 52 [17]), 360 eyes underwent PKP. Indications for PKP were bullous keratopathy (27%), infectious keratitis (20%), and keratoconus (15%). The median follow-up was 44 months (IQR 22-73). The overall graft survival and irreversible rejection rate at 5 years were 70% and 29%, respectively. Factors associated with risk of rejection were prior indication for graft rejection (SHR [CI 95%] = 7.8 [2.6-23.1]), trauma (SHR [CI 95%] = 3.6 [1.1-11.7]), and infectious keratitis (SHR [CI 95%] = 2.7 [1.2-11.1]), history of corneal neovascularization (SHR [CI 95%] = 2.1 [1.2-3.8]), hypertonia (SHR [CI 95%] = 2.8 [1.8-4.3]), and mixed sex matching (SHR [CI 95%] = 2.0 [1.01-4.0]).

CONCLUSION

The significant risk factors of graft rejection after PKP found in this study agree with those from major international cohorts: prior indication for graft rejection, history of neovascularization and high intraocular pressure. Sex matching donor-recipient is a most recent parameter in the literature confirmed by the present analysis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04791696.

Evaluation of the Clinical Findings of Patients with Penetrating Keratoplasty Followed by Telephone Due to the COVID-19 Pandemic

Objectives:

To evaluate changes in the clinical findings of keratoplasty patients who could not be examined face-to-face and were followed up by telephone during the coronavirus disease 2019 (COVID-19) pandemic.

Materials and Methods:

Patients with penetrating keratoplasty who presented to the cornea department between March 2020 and February 2021 were grouped according to whether they showed clinical deterioration (Group 1: no deterioration, Group 2: deterioration). The patients’ last visit prior to the COVID-19 pandemic and their first visit after the pandemic-related lockdown ended were evaluated. The demographic data, follow-up period, and ophthalmological examination findings of all patients were recorded and the data were compared between the groups.

Results:

Thirty-five eyes of 35 patients were included in the study. Signs of deterioration were detected in 8 (22.8%) of the patients (Group 1), while no deterioration was detected in 27 (77.2%) of the patients (Group 2). In the last follow-up visit prior to the COVID-19 pandemic, mean best corrected visual acuity (BCVA) was 1.26±0.43 LogMAR (range: 0.52-1.80) in Group 1 and 1.41±1.02 LogMAR (range: 0-3.1) in Group 2 (p=0.692). Mean BCVA in the first control during the pandemic was 2.07±0.86 LogMAR (range: 1.3-3.1) in Group 1 and 1.49±1.08 LogMAR (range: 0-3.1) in Group 2 (p=0.08). At the first visit during the COVID-19 pandemic, the mean intraocular pressure of Group 1 was 16.38±8.58 mmHg (range: 0-31), and Group 2 was 17.11±3.7 mmHg (range: 11-26) (p=0.984).

Conclusion:

The continuation of treatment initiated prior to the pandemic was probably the most important reason why deterioration was not observed in keratoplasty patients. In situations such as pandemics where face-to-face visits with patients may be disrupted, it may be possible to follow the patients safely with telemedicine visits until the difficult circumstances resolve.

Presence of Panel-reactive Antibodies after Penetrating Keratoplasty

PURPOSE

To evaluate the relationship between penetrating keratoplasty (PK) and postoperative PRA level and number of unacceptable antigens.

METHODS

A cross-sectionalstudy was performed on patients with history of PK. Patients with prior solid organ transplantation, pregnancy, or blood transfusion were excluded. These findings were combined with a retrospective review. Patients were grouped by single or multiple PKs. The primary outcome was postoperative PRA level.

RESULTS

Incidence of postoperative PRA elevation and mean peak PRA was higher in the multiple PK group (p = .08 and p = .010, respectively). Mean number of unacceptable antigens was elevated in the multiple PK group (p = .024). There was a moderately positive correlation between number of PK grafts and PRA level (r = 0.629, p = .0002).

CONCLUSIONS

PRA level may be influenced by PKs, with higher PRA associated with increased prior PKs. Further studies are necessary to determine the potential prognostic value.Abbreviations: PK: penetrating keratoplasty; PRA: panel reactive antibodies; OSST: ocular surface stem cell transplantation; LSCD: limbal stem cell deficiency.

[Penetrating keratoplasty]

Penetrating keratoplasty is a tissue transplant commonly performed around the world. For over a century, penetrating keratoplasty has been the standard method of treatment for many corneal diseases causing visual impairment. Recently, lamellar anterior keratoplasty (LAK) or lamellar endothelial (LEK) have become preferable options, resulting in fewer complications and faster functional rehabilitation. While penetrating keratoplasty is less frequently indicated, in favor of these lamellar grafts, it has not necessarily become obsolete, and its use remains appropriate for its chosen indications. Functional results are good if the indication for surgery is properly assessed, therapeutic precautions are taken in view of complications, and follow-up aims to improve initial refractive results as needed.

Current Perspectives on Corneal Transplantation

Disease of the cornea is the third leading cause of blindness worldwide. Corneal graft surgery is one of the most successful forms of solid organ transplantations in humans, with ever-increasing developments in surgical technique. To date, approximately 4504 corneal transplants are performed in the United Kingdom each year. While full thickness transplantation was the most commonly performed keratoplasty over the last few decades, selective lamellar transplantation of the diseased layers of the cornea has been universally adopted. This comprehensive review aims to provide an updated synthesis on different types of corneal transplantations, their treatment outcomes, and the associated complications of each procedure in both adult and paediatric population. In addition, we also present an up-to-date summary of the emerging therapeutic approaches that have the potential to reduce the demand for donor-dependent keratoplasty.

A Liquid Hydrogel to Restore Long Term Corneal Integrity After Perforating and Non-Perforating Trauma in Feline Eyes

Purpose: To evaluate long-term in vivo functionality of corneas regenerated using a cell-free, liquid hydrogel filler (LiQD Cornea) after deep corneal trauma in the feline model.

Methods: Two healthy cats underwent 4 mm diameter stepwise 250/450 µm deep surgical corneal ablation with and without needle perforation. The filler comprising 10% (w/w) collagen-like peptide conjugated to polyethylene glycol (CLP-PEG) and 1% fibrinogen and crosslinked with 2% (w/w) 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM), was applied to the wound bed previously coated with thrombin (250 U/ml). In situ gelation occurred within 5 min, and a temporary tarsorrhaphy was performed. Eyes were examined weekly for 1 month, then monthly over 12 months. Outcome parameters included slit-lamp, Scheimpflug tomography, optical coherence tomography, confocal and specular microscopy, and immunohistochemistry studies.

Results: The gelled filler was seamlessly incorporated, supporting smooth corneal re-epithelialization. Progressive in-growth of keratocytes and nerves into the filler corresponding to the mild haze observed faded with time. The regenerated neo-cornea remained stably integrated throughout the 12 months, without swelling, inflammation, infection, neovascularization, or rejection. The surrounding host stroma and endothelium remained normal at all times. Tomography confirmed restoration of a smooth surface curvature.

Conclusion: Biointegration of this hydrogel filler allowed stable restoration of corneal shape and transparency in the feline model, with less inflammation and no neovascularization compared to previous reports in the minipig and rabbit models. It offers a promising alternative to cyanoacrylate glue and corneal transplantation for ulcerated and traumatized corneas in human patients.

Artificial Cornea: Past, Current, and Future Directions

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Immunology and Donor-Specific Antibodies in Corneal Transplantation

The first human corneal transplantation was performed in 1905 by Eduard Zirm in the Olomouc Eye Clinic, now Czech Republic. However, despite great advancements in microsurgical eye procedures, penetrating keratoplasty in high-risk patients (e.g., vascularized or inflamed corneal tissue, consecutive transplants) remains a challenge. The difficulty is mainly due to the risk of irreversible allograft rejection, as an ocular immune privilege in these patients is abolished and graft rejection is the main cause of corneal graft failure. Therefore, tailored immunosuppressive treatment based on immunological monitoring [e.g., donor-specific antibodies (DSA)] is considered one of the best strategies to prevent rejection in transplant recipients. Although there is indirect evidence on the mechanisms underlying antibody-mediated rejection, the impact of DSA on cornea transplantation remains unknown. Determining the role of pre-existing and/or de novo DSA could advance our understanding of corneal graft rejection mechanisms. This may help stratify the immunological risk of rejection, ultimately leading to personalized treatment for this group of transplant recipients.

Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets

"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.

Survival Outcome and Prognostic Factors of Corneal Transplantation: A 15-Year Retrospective Cohort Study at King Chulalongkorn Memorial Hospital

Purpose

To evaluate long-term survival outcomes and determine the prognostic factors of corneal transplantation performed at a tertiary referral hospital in Thailand.

Design

A 15-year retrospective cohort study.

Materials and Methods

One corneal graft per patient was selected; graft failure was defined as graft opacity due to recurrent disease or endothelial cell dysfunction. Kaplan–Meier survival analysis was performed. Median time to failure was compared using the Log rank test. Prognostic factors were identified using the Cox proportional hazards model.

Results

We enrolled 704 transplanted grafts. Surgical indications were optical (88.5%), therapeutic (10.2%), and tectonic (1.3%). The most common diagnoses were corneal opacity (25.3%), bullous keratopathy (15.8%), and regraft (14.8%). The overall survival rates at 1, 3, 5, and 10 years were 87.5%, 72.0%, 59.2%, and 41.7%, respectively. Univariate analysis identified age, primary diagnosis, graft size, pre-existing glaucoma, prior lens status, prior intraocular surgery, indication for surgery, donor endothelial cell density, and previous graft rejection as prognostic factors for graft failure. Multivariate analysis revealed three prognostic factors: primary diagnosis of perforation/peripheral ulceration/Mooren’s ulcer (hazard ratio [HR]=28.57; 95% confidence interval [CI], 6.32–129.16; P<0.001), active keratitis (HR=24.30; 95% CI, 5.88–100.43; P<0.001), regraft (HR=9.37; 95% CI, 2.27–38.66; P=0.002), and pseudophakic/aphakic bullous keratopathy (HR=7.97; 95% CI, 1.93–32.87; P=0.004); pre-existing glaucoma (HR=1.52; 95% CI, 1.13–2.04; P=0.006); and previous graft rejection (HR=1.95; 95% CI, 1.54–2.48; P<0.001).

Conclusion

Overall corneal graft survival rate was high in the first postoperative year and decreased after that. Primary diagnosis, pre-existing glaucoma, and previous graft rejection negatively influenced graft survival.

Topical 0.03% tacrolimus versus systemic mycophenolate mofetil as adjuncts to systemic corticosteroids for preventing graft rejection after repeat keratoplasty: one-year results of a randomized clinical trial

PURPOSE

To compare the efficacy of topical 0.03% tacrolimus in combination with systemic corticosteroids versus systemic mycophenolate mofetil (MMF) and corticosteroids in preventing corneal allograft rejection after repeat keratoplasty.

METHODS

This prospective, randomized clinical trial enrolled 63 consecutive eyes of 63 patients who underwent repeat keratoplasty after a failed penetrating keratoplasty. Group 1 (32 eyes) received MMF orally 1 g twice daily for the first 6 months and then 1 g daily for the next 6 months, and group 2 (31 eyes) received topical 0.03% tacrolimus four times a day for 12 months. All patients were treated with topical and oral corticosteroids postoperatively. The participants were observed closely for signs of graft rejection, and the rates of rejection-free graft survival were calculated and compared between the two groups at postoperative month 12.

RESULTS

The groups were balanced in patient's age and risk factors for graft rejection (e.g., original diagnosis, number of previous grafts, and quadrants of corneal vascularization). Endothelial graft rejection occurred in 5 eyes (15.6%) of group 1 and 6 eyes (19.4%) of group 2 (P = 0.75). Irreversible endothelial graft rejection resulting in graft failure occurred in 3 eyes of each group (P = 0.99). The rate of rejection-free graft survival was 84.4% in group 1 and 80.6% in group 2 at postoperative month 12 (P = 0.74).

CONCLUSION

Topical 0.03% tacrolimus was as effective as systemic MMF as adjuncts to topical and systemic corticosteroids in reducing endothelial graft rejection with 12 months follow up after repeat keratoplasty.

Time-Dependent Serial Changes of Antigen-Presenting Cell Subsets in the Ocular Surface Are Distinct between Corneal Sterile Inflammation and Allosensitization in a Murine Model

The kinetics of antigen-presenting cells (APCs) vary depending on their resident tissues and the manner of immunization. We investigated the long-term changes in mature APC and T-cell subsets over 4 weeks in the ocular surface in murine models of corneal quiescent or potent sterile inflammation, and allosensitization using partial (PT), syngeneic (Syn), and allogeneic (Allo) corneal transplantation. In PT, CD11b^intCD11c^hiMHCII^hiCD86^hi cells increased until 4 weeks with an increase in IFNγ^hi T cells. In Syn, both CD11b^intCD11c^hiMHCII^hiCD86^hi and CD11b^hiCD11c^hiMHCII^hiCD86^hi APC subsets increased until 4 weeks with a brief increase in CD69^hi T cells at 2 weeks. In Allo, CD11b^intCD11c^hiMHCII^hiCD86^hi and CD11b^hiCD11c^hiMHCII^hiCD86^hi APC subsets increased until 4 weeks, and an early increase in CD69^hi T cells was observed at 2 weeks followed by a late increase in IFNγ^hi T cells at 4 weeks. The frequency of the IFNγ^hi T cell subset was positively correlated with the frequency of the CD11b^intCD11c^hiMHCII^hiCD86^hi subset, indicating the existence of APC–T cell interaction in the ocular surface. Together, the results indicate that allosensitization in mature APCs leads to T-cell activation in the ocular surface, whereas sterile inflammation merely induces a brief and non-specific T-cell activation in the ocular surface.

Long-Term Maintenance of Corneal Endothelial Cell Density After Corneal Transplantation

PURPOSE

To investigate the key factors associated with eyes with an endothelial cell density (ECD) of ≥2000 cells/mm at 5 years after corneal transplantation.

METHODS

This retrospective cohort study included 174 eyes that underwent penetrating keratoplasty by 1 corneal specialist surgeon at the Baptist Eye Institute, Kyoto, Japan, from 1998 through 2011 and that were carefully followed for over 5 years postoperative. In all operated eyes, corneal ECD was measured at 1, 2, 3, 4, and 5 years postoperative. Multivariate analysis with adjustment for preoperative donor ECD was performed between eyes with an ECD of ≥2000 cells/mm and those with an ECD of <2000 cells/mm at 5 years postoperative.

RESULTS

Of the 174 eligible eyes, 16 eyes (9.2%) had an ECD of ≥2000 cells/mm at 5 years postoperative, and the annual rate of endothelial cell loss (mean ± SD) was 2.3% ± 3.7%. Multivariate analysis findings revealed that the donor-associated and surgery-related factors were not significant factors. Only the recipient diagnosis of bullous keratopathy was significantly associated with an ECD of <2000 cells/mm at 5 years postoperative. Of those 16 eyes, 6 (37.5%) had a recipient diagnosis of bullous keratopathy.

CONCLUSIONS

None of the donor- and surgery-related factors, previously recognized as associated with a lower endothelial cell loss after penetrating keratoplasty, were found to be significant in this study, thus suggesting that there are still unknown factors associated with maintaining a higher ECD over the long-term postoperative period.

Spontaneous Descemet Membrane Detachment After Penetrating Keratoplasty-Clinical Presentation and Outcome of Air/Gas Descemetopexy

PURPOSE

To describe the clinical characteristics and treatment of spontaneous Descemet membrane (DM) detachment occurring decades after penetrating keratoplasty (PK).

METHODS

A multicenter interventional case series design was used. We reviewed the medical records of 4 patients with a history of PK presenting with spontaneous DM detachment at 3 university hospitals in Israel and an ocular surgery institute in The Netherlands in 2016 to 2019. Patient demographic and clinical data, postoperative best corrected visual acuity, findings on preoperative and postoperative anterior segment optical coherence tomography (AS-OCT), and graft survival were recorded.

RESULTS

Patients were aged 46 to 50 years. All had undergone PK for keratoconus 20 to 26 years previously. Patients presented within 18 to 180 days of onset of visual disturbance. Symptoms included sudden painless visual loss (2 patients), gradual visual loss and foreign body sensation (1 patients), and visual loss not otherwise specified (1 patient). Slit-lamp examination showed corneal edema, and AS-OCT showed DM detachment of variable extent. In 2 patients, the initial diagnosis was graft rejection and failure. Treatment consisted of anterior chamber injection of air (n = 3) or 20% SF6 (n = 1). In 3 patients, the DM reattached and the cornea regained its clarity. The fourth patient had persistent DM detachment that required repeated PK.

CONCLUSIONS

Spontaneous DM detachment can mimic late graft failure in patients after PK. If diagnosed early, DM reattachment may be performed by air/gas injection, avoiding repeated keratoplasty. Eyes with presumed late penetrating graft rejection or failure should be examined by AS-OCT to exclude DM detachment.

Topical corticosteroids with topical cyclosporine A versus topical corticosteroids alone for immunological corneal graft rejection

PURPOSE

To assess the efficacy and safety of supplementing topical cyclosporine A (CsA) to topical corticosteroids (CS), in the prophylaxis and treatment of corneal graft rejection following penetrating keratoplasty (PK).

METHODS

Meta-analysis. Search was performed in PubMed, CENTRAL, ClinicalTrials.gov, reference lists of articles and conference proceedings. Primary outcomes: 1-year rejection-free survival rate (prophylaxis); resolution rate of rejection episodes (treatment). Secondary outcomes: 6- and 24-month rejection-free graft survival rate, number of rejection episodes during follow-up, time-to-resolution of rejection episode, 12- and 24-months graft survival rate, adverse events. Subgroup analyses were planned for high-risk grafts; primary vs. secondary prophylaxis of graft rejection episodes; and CsA concentrations of 0.05%, 1%, and 2%.

RESULTS

Five studies of moderate methodological quality were included (one retrospective, four RCT), assessing 459 eyes (CS + CsA 226, CS 233). In the prophylaxis setting, supplemental CsA was associated with a higher rejection-free survival rate at 12-months (RR 1.25, 95% CI: 1.00-1.56, p = 0.05) and 24-months post-PK (RR 1.56, 95% CI: 1.15-2.11, p < 0.01), though no differences were found at the 6-months timepoint (p = 0.93). This effect was mostly verified using CsA 2% in the high-risk subset of patients. In the treatment setting, no differences were found in the resolution rate of rejection episodes (p = 0.23). No differences existed on drug-related adverse events.

CONCLUSION

In the prophylaxis of rejection episodes post-PK, the combined regimen of CS + CsA was associated with a higher 1- and 2-year rejection-free graft survival rate. Subgroup analysis mostly supported the use of CsA 2% for high-risk grafts. Further studies are needed to validate these results.

Approaches for corneal endothelium regenerative medicine

The state of the art therapy for treating corneal endothelial disease is transplantation. Advances in the reproducibility and accessibility of surgical techniques are increasing the number of corneal transplants, thereby causing a global deficit of donor corneas and leaving 12.7 million patients with addressable visual impairment. Approaches to regenerate the corneal endothelium offer a solution to the current tissue scarcity and a treatment to those in need. Methods for generating corneal endothelial cells into numbers that could address the current tissue shortage and the possible strategies used to deliver them have now become a therapeutic reality with clinical trials taking place in Japan, Singapore and Mexico. Nevertheless, there is still a long way before such therapies are approved by regulatory bodies and become clinical practice. Moreover, acellular corneal endothelial graft equivalents and certain drugs could provide a treatment option for specific disease conditions without the need of donor tissue or cells. Finally, with the emergence of gene modulation therapies to treat corneal endothelial disease, it would be possible to treat presymptomatic patients or those presenting early symptoms, drastically reducing the need for donor tissue. It is necessary to understand the most recent developments in this rapidly evolving field to know which conditions could be treated with which approach. This article provides an overview of the current and developing regenerative medicine therapies to treat corneal endothelial disease and provides the necessary guidance and understanding towards the treatment of corneal endothelial disease.

Development of a Nomogram to Predict Graft Survival After Penetrating Keratoplasty

PURPOSE

To develop a nomogram to predict the 3- and 5-year likelihood of graft survival after penetrating keratoplasty (PK) based on preoperative assessment and intraoperative plan.

DESIGN

Retrospective clinical case-control study.

METHODS

Data from 1,029 consecutive PKs in 903 eyes of 835 patients performed at a single tertiary center from May 2007 to September 2018 were extracted from electronic medical records and evaluated for corneal graft failure, defined as irreversible and visually significant graft edema, haze, or scarring. Thirty-seven variables were assessed by multivariable Cox models. A nomogram to predict the probability of graft survival was created.

RESULTS

Mean recipient age was 57.1 ± 22.0 years and mean follow-up was 4.22 ± 3.05 years. Overall, 37.4% of grafts failed during follow-up. Eleven variables were significantly associated with graft failure, including active microbial infection at the time of PK (hazard ratio [HR] = 5.10, 95% confidence interval [CI] 3.53-7.37), intraocular silicone oil at the conclusion of the PK (HR = 4.28, 95% CI 2.38-7.71), history of systemic autoimmune disease (HR = 2.83, 95% CI 1.63-4.90), 4 quadrants of corneal neovascularization (HR = 2.76, 95% CI 1.56-4.86), any prior anterior segment surgery (HR = 2.41, 95% CI 1.55-3.75), and lens status as anterior chamber intraocular lens at the conclusion of surgery (HR = 2.35, 95% CI 1.30-4.26). The nomogram exhibited a concordance index of 0.76 (95% CI 0.74-0.78); internal calibration plots depicted strong correlation between prediction and observation of graft survival.

CONCLUSIONS

PK graft prognosis may be predicted relatively accurately based on 11 variables. Although established from retrospective data, this nomogram would be valuable for data-driven patient counseling prior to corneal transplantation.

Two-step keratoplasty for deep vascularized corneal opacity with severe peripheral thinning following Acanthamoeba keratitis

PURPOSE

In cases of corneal opacity with vascularization and peripheral thinning, traditional keratoplasty techniques have several risks and drawbacks. We report the results of a two-step surgical strategy consisting in performing a large diameter tectonic lamellar keratoplasty (TLK) to restore appropriate corneal thickness and an avascular recipient bed, followed by central optical PK within the lamellar graft at a later date.

METHODS

This single-institution study analyzes the results of 7 eyes of 7 patients who received PK after large diameter TLK. All patients were affected by deep post-infectious corneal opacity with persistent stromal vascularization and peripheral thinning. The main outcomes measured were graft survival, visual acuity, refraction, and endothelial cell density.

RESULTS

TLK was performed in all cases with 10/10.1-mm diameters. After a mean interval of 14 months, central PK was performed with a median host-graft diameter of 7.75/8.25 mm. Mean follow-up after PK was 52 months. At last follow-up, 6/7 (86%) grafts were clear. Endothelial rejection occurred in 5/7 (71%) eyes, with one patient having multiple episodes and subsequent graft failure. At 2 years, all patients had a visual acuity ≥ 20/40, with an average refractive astigmatism of 3.75 diopters.

CONCLUSION

Optical PK within a previous TLK is a safe and efficient technique for treating deep corneal opacity associated with extensive vascularization and peripheral thinning. Extended follow-up period is necessary to assess endothelial cell loss and long-term efficacy of the procedure.

Comparative Study of Long-term Graft Survival Between Penetrating Keratoplasty and Deep Anterior Lamellar Keratoplasty

PURPOSE

Endothelial failure and immunological graft rejection remain long-term complications leading to late graft failure in penetrating keratoplasty (PK). Deep anterior lamellar keratoplasty (DALK) has emerged as a viable alternative that enables preservation of the host's endothelial cells to eliminate risks of endothelial rejection and failure. The aim of this study was to compare long-term graft survival between PK and DALK.

DESIGN

Retrospective clinical cohort study.

METHODS

All consecutive primary grafts of DALKs (n = 362) and PKs (n = 307) performed for optical indications in a tertiary eye center from the ongoing, prospective Singapore Corneal Transplant Study. Ten-year graft survival outcomes were compared. Cases in which endothelial pathologies were diagnosed were excluded, as DALK was not performed for such cases. Main outcome measurements were mean graft survival rate.

RESULTS

The survival rate for PK was 94.4%, 80.4%, and 72.0% at 1, 5, and 10 years, respectively; and 95.8%, 93.9%, and 93.9% at 1, 5, and 10 years, respectively, for DALK (P = .001). Patients who underwent PK developed more complications of glaucoma (29.3% vs. 11.6%, respectively; P < .001), allograft rejection (16.6% vs. 1.7%, respectively; P < .001), epithelial problems (10.4% vs. 5.5%, respectively; P = .018), and nonimmunological failure (7.8% vs. 1.9%, respectively; P < .001), compared to DALK. Rates of graft failure attributable to rejection (36.7% vs. 5.9%, respectively; P = .015) and endothelial failure (36.7% vs. 5.9%, respectively; P = .015) were lower in DALK.

CONCLUSIONS

The 10-year graft survival for primary DALK was superior to that for PK for corneal pathologies with functional endothelium. Primary DALK resulted in fewer post-operative complications and lower rates of graft rejection and failure. This study strengthens the case in favor of performing DALK over PK when possible.