Systematic review and meta-analysis of femtosecond laser-enabled keratoplasty versus conventional 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.

Main issues in penetrating keratoplasty

This review explores contemporary challenges in penetrating keratoplasty (PK), focusing on technical intricacies, technological advancements, and strategies for preventing graft rejection. A systematic literature search from January 2018 to July 2023 was conducted across PubMed, Cochrane, Web of Science, Scopus, and EMBASE. The inclusion criteria comprised studies on PK and its comparison with other corneal pathologies, with emphasis on keratoconus (KC). Two independent reviewers screened studies, extracting relevant data. The review covers PK evolution, highlighting infra-red femtosecond lasers' impact on graft shapes, minimizing astigmatism, and enhancing wound healing. Graft rejection, a primary complication, is examined, detailing risk factors and preventive measures. Preoperative considerations, diagnostic techniques for rejection, and PK in KC are discussed. Postoperative care's significance, including intraocular pressure monitoring and steroid administration, is emphasized. The paper concludes with a comprehensive approach to prevent graft rejection, involving topical and systemic medications. An outlook on evolving monoclonal antibody research is presented. As the field progresses, personalized approaches and ongoing therapeutic exploration are expected to refine strategies, enhancing PK outcomes.

Comparison of Femtosecond Laser Assistance and Manual Trephination in Deep Anterior Lamellar Keratoplasty in the Treatment of Keratoconus: A Meta-Analysis

PURPOSE

To compare the efficacy and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (F-DALK) with those of manual-trephination DALK (M-DALK) in treating keratoconus.

DESIGN

Systematic review and meta-analysis.

METHODS

Through November 2022, we comprehensively searched PubMed, EMBASE, the Cochrane Library, and 4 Chinese databases. Studies that involved comparisons between F-DALK and M-DALK groups and that reported on relevant efficacy and/or safety parameters were included. Primary outcomes were uncorrected- and corrected-distance visual acuity and intraoperative complication rates. Secondary outcomes were spherical equivalent, topographic astigmatism, refractive cylinder, mean keratometry, endothelial cell density, suture removal time, and postoperative complication rates. These data were analyzed using Cochrane Review Manager software version 5.3.

RESULTS

This meta-analysis included 9 nonrandomized controlled studies involving 1713 eyes. In eyes treated with F-DALK, corrected-distance visual acuity at 1 to 6 months (weighted mean difference = -0.07 [95% confidence interval {CI} -0.10 to -0.03]; I2 = 0%; P < .001) after surgery was better and intraoperative Descemet membrane perforation occurred less often (odds ratio = 0.53 [95% CI 0.31-0.92]; I2 = 6%; P = .02) than in eyes treated with M-DALK. No clinically significant differences in other outcomes were found among the groups.

CONCLUSIONS

Both F-DALK and M-DALK are safe and efficacious for patients with keratoconus. Compared with M-DALK, F-DALK can provide better early visual acuity and reduce the intraoperative perforation rate, and its likely improvements to long-term visual quality and endothelial cell preservation warrant further investigation. In addition, the 2 techniques seem to be comparable regarding refractive outcomes and other complications.

Update on Femtosecond Laser-Enabled Keratoplasty

ABSTRACT

The application of femtosecond lasers to corneal transplantation is an intriguing proposition with many potential benefits to patients with various corneal diseases. The customized trephination pattern for donor and host matching offers many advantages regarding wound integrity and high precision of donor and recipient match at the interface, which should lead to faster healing and visual rehabilitation. Femtosecond laser-enabled keratoplasty (FLEK) is an advancement of conventional trephination penetrating keratoplasty, and in large clinical cohorts to date, there are meaningful improvements in visual outcomes and a lower risk of graft rejection. Femtosecond laser-enabled deep anterior lamellar keratoplasty (Femto-DALK) combines the advantage of a customized trephination pattern with the deep anterior lamellar keratoplasty procedure, which eliminates the risk of endothelial rejection. Furthermore, the precision of the femtosecond laser may offer additional novel approaches to lamellar keratoplasties. In time, advancements in femtosecond laser platforms will help cornea surgeons realize the added benefits and better optimize outcomes for patients, such that the cost-benefit calculus shifts toward wider accessibility for patients. Prospective randomized-controlled trials are needed to definitively determine the impact of femtosecond laser-enabled keratoplasties on long-term outcomes.

An Overview of Corneal Transplantation in the Past Decade

The cornea is a transparent avascular structure located in the front of the eye that refracts light entering the eyes and also serves as a barrier between the outside world and the internal contents of the eye. Like every other body part, the cornea may suffer insult from trauma, infection, and inflammation. In the case of trauma, a prior infection that left a scar, or conditions such as keratoconus that warrant the removal of all or part of the cornea (keratoplasty), it is important to use healthy donor corneal tissues and cells that can replace the damaged cornea. The types of cornea transplant techniques employed currently include: penetrating keratoplasty, endothelial keratoplasty (EK), and artificial cornea transplant. Postoperative failure acutely or after years can result after a cornea transplant and may require a repeat transplant. This minireview briefly examines the various types of corneal transplant methodologies, indications, contraindications, presurgical protocols, sources of cornea transplant material, wound healing after surgery complications, co-morbidities, and the effect of COVID-19 in corneal transplant surgery.

Clinical Evaluation of the Efficacy of Femtosecond Laser-Assisted Anterior Lamellar Keratoplasty

BACKGROUND

To evaluate the clinical outcome, efficacy, and safety of femtosecond laser-assisted anterior lamellar keratoplasty.

MATERIAL AND METHODS

In this prospective study, 21 males and 10 females aged from 15 to 62 years (mean 38.5) with different pathologies of the anterior corneal layers were enrolled for anterior lamellar keratoplasty using femtosecond laser VisuMax (Carl Zeiss, Germany). All patients were examined for uncorrected (UCVA) and best-corrected (BCVA) distance and near visual acuity, astigmatism, endothelial cell density, corneal thickness, and intraocular pressure. These examinations were performed before transplantation, at hospital discharge, and after 3 and 12 months. The mean follow-up time was 65.36 ± 28.54 months.

RESULTS

A statistically significant improvement of both UCVA and BCVA for distance and near vision was registered. BCVA improved from 0.11 preoperatively to 0.168 (p = 0.03), 0.267 (p < 0.01), and 0.472 (p < 0.01) on the hospital discharge day, three months, and 12 months respectively. There were no statistically significant differences in astigmatism, intraocular pressure, endothelial cell density, and corneal pachymetry as compared to preoperative and postoperative values. Six patients (19%) had a graft failure with a rate of 33% at 26 months.

CONCLUSIONS

Femtosecond laser-assisted anterior lamellar keratoplasty is a safe and effective surgical method, providing satisfactory graft survival rates.

Ocular emergencies visits after corneal transplantation at a tertiary eye care hospital in Saudi Arabia

PURPOSE

To evaluate the characteristics of patients with post-keratoplasty complications and their presentation at an emergency center.

DESIGN

Retrospective one-armed cohort study.

METHODS

Data were evaluated on patients who underwent corneal grafts in 2019 and presented to an emergency unit. Data were collected on patient demographics, presenting symptoms, clinical details, diagnosis at emergency visit, final diagnosis, best-corrected visual acuity (BCVA) at presentation and at the last follow-up after management. Severe visual impairment (SVI) and graft rejection were tested for correlations to other factors.

RESULTS

The study sample was comprised of 149 eyes of 124 patients with a mean age of 27.5 years. Keratoconus was the indication for keratoplasty in 94 (75.8%) patients. The main presenting symptoms were pain 57 (38.3%) and red eye in 52 (34.9%) patients. The median interval between emergency visit and keratoplasty was 1.6 years. There were 63 (42.3%) patients who had emergency visits due to suture-related problems. The rates of SVI and graft rejection at the time of discharge after managing emergencies in eyes with previous keratoplasty were 14.1% (95% CI 8.5; 19.7) and 13.4 (95% CI 7.9; 18.9), respectively. Keratoconus (OR = 22.8) and young age (P < 0.001) were negatively associated with SVI after management.

CONCLUSION

Patients with keratoplasty are at high risk for severe vision loss and should be counseled to seek urgent eye care for early detection and management of sight-threatening complications to improve graft survival and vision.