Outcomes of femtosecond laser-assisted mushroom-configuration keratoplasty in advanced keratoconus

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.

EBEI: A new index of eye bank efficiency

PURPOSE

To describe a new proxy of the Eye Bank (EB) activity named "Eye Bank Efficiency Index" (EBEI), calculated as the ratio between the number of corneal tissues distributed by an EB within a certain time period, and the difference between the number of procured and discarded tissues.

METHODS

To demonstrate the effectiveness of the new metric as compared to traditional statistics, an analysis was conducted using data from the largest Italian Eye Bank (Fondazione Banca degli Occhi del Veneto Venice, Italy). Collected data included: the number of corneas retrieved, the number of discarded grafts, and the number of distributed tissues. The analysis focused on three defined timeframes: January to December, March to May (the "Italian Lockdown period"), and June to December (the "Italian post-lockdown period").

RESULTS

In 2020, the annual variation of the EBEI showed a significant increase of up to 3.4% compared to the previous year (0.986 in 2019; 1.020 in 2020), but then gradually decreased to 0.993 in 2022. However, during the months of lockdown in 2020, there was a significant decline of -13.8% in the EBEI compared to the same period in the previous year. The variation in the EBEI during the post-lockdown months was minimal in 2020 and 2021, with the lowest EBEI value of 0.976 being reached in 2022 (-7.8% compared to 2019).

CONCLUSION

The EBEI is a simple and reliable new measure of the EB activity. Its widespread adoption could ensure a more accurate and reliable analysis of EB data for academic, political, and economic purposes.

Penetrating Keratoplasty With Minimal Endothelial Replacement: A Novel Technique for High-Risk Large-Diameter Corneal Grafting

PURPOSE

The purpose of this study was to analyze the outcome of large-diameter penetrating keratoplasty with minimal endothelial replacement (PKMER).

METHODS

Two eyes (2 patients) with advanced keratoconus and central full-thickness pathology, namely, scar and failed graft, were studied. Both eyes had relatively healthy endothelium in the periphery. They were operated using the PKMER technique that involved a large-diameter keratoplasty with retained central island of endothelium in the donor corresponding to the visual axis, whereas the peripheral Descemet membrane was removed. In effect, the peripheral endothelium and deep stroma of the recipient were preserved. Patients were followed up using anterior segment optical coherence tomography and specular microscopy postoperatively for a minimum period of 6 months in one eye and 3 years in the other.

RESULTS

In both eyes, the central cornea maintained clarity throughout follow-up. The astigmatism reduced significantly, and the final uncorrected and best-corrected vision improved from hand motions close to the face to 6/12/n8 in one eye and 6/12/n12 in the other. Anterior segment optical coherence tomography in both eyes showed satisfactory apposition of interfaces at 1 month postkeratoplasty, and the same was maintained throughout follow-up. Both eyes withstood phacoemulsification for preexisting cataracts, which was performed in the second sitting after the PKMER. There were no complications noted except a temporary initial detachment of the peripheral interface in some quadrants in the early postoperative period.

CONCLUSIONS

PKMER may be considered as an alternative technique to large-diameter full-thickness keratoplasty. It is a relatively easier and cost-effective manual technique, which may be used as an alternative to traditional mushroom keratoplasty in selected cases.

[Comparative evaluation of the results of one- and two-piece mushroom keratoplasty]

PURPOSE

To compare and evaluate the outcomes of one- and two-piece mushroom keratoplasty configurations for various corneal pathologies.

MATERIAL AND METHODS

A total of 32 patients (32 eyes) with corneal perforations, descemetocele and deep corneal opacities underwent surgery. Depending on the surgery technique, the patients were divided into 2 groups: group I (17 eyes) underwent manual one-piece mushroom keratoplasty according to our own technique; group II (15 eyes) underwent modified two-piece microkeratome-assisted mushroom keratoplasty according to the technique by M. Busin. All patients underwent clinical and functional studies before surgery and in the course of a 1-year follow-up.

RESULTS

Transparent engraftment of the cornea was achieved in 82 and 80% of cases; best corrected visual acuity (BCVA) averaged 0.57±0.19 and 0.53±0.17; spherical component of refraction varied from 1.25 to +5.5 and from 1.25 to 6.0 diopters; mean corneal astigmatism was 3.15±1.73 and 3.21±1.89 diopters in groups I and II, respectively. At 6 months after surgery, the mean endothelial cell density (ECD) was 2336±198 and 2291±175 cells/mm², at 1 year - 2041±189 and 1955±161 cells/mm² in groups I and II, respectively.

CONCLUSION

One- and two-piece mushroom keratoplasty is effective in surgical treatment of various corneal pathologies ensuring a high rate of transparent corneal engraftment. The revealed risk of false chambers formation between separate parts of the graft after the two-piece method could in most cases be eliminated by re-injecting air into the anterior eye chamber.

Tuck In Femtosecond Laser Assisted Anterior Lamellar Keratoplasty (T-FALK) for the Management of Superficial Anterior Corneal Scars-A Modified Technique

PURPOSE

To report a modified sutureless and glue-less technique, termed tuck in femtosecond laser assisted anterior lamellar keratoplasty (T-FALK), and to achieve a good graft-host junction apposition.

METHODS

This is a prospective interventional case series of 15 eyes of 15 patients who underwent T-FALK. Depth of the anterior corneal scar was assessed using anterior segment optical coherence tomography (ASOCT). The donor and recipient lenticules were prepared using femtosecond laser. After removing the recipient anterior scarred lenticule, the transparent donor lenticule was positioned on the recipient bed and margins tucked in under the recipient cornea. A bandage contact lens was applied for 3 weeks. Postoperatively, topical antibiotic and steroid combination eye drops were given, and the assessment of healing of the graft-host junction was done using ASOCT.

RESULTS

A total of 15 patients (8 men and 7 women) underwent T-FALK. Six patients had superficial corneal opacities after healed microbial keratitis, 5 patients had spheroidal corneal degeneration, 3 patients had Salzman nodular degeneration, and 1 patient had vortex keratopathy. No intraoperative or postoperative complications were noted during T-FALK. All patients had good graft-host junction apposition postoperatively, as demonstrated by ASOCT.

CONCLUSIONS

Sutureless and glue-less T-FALK can be the best way ahead for management of superficial anterior corneal scars with good visual outcome.

Femtosecond Laser-Assisted Big-Bubble Deep Anterior Lamellar Keratoplasty

Purpose

To determine whether type 1 big-bubble (BB) formation is influenced by the sequence of incisions created with the Victus femtosecond laser (FSL) enabled with software version 3.4 (SV 3.4) during deep anterior lamellar keratoplasty (DALK).

Materials and Methods

Consecutive FSL-assisted DALK BB procedures were performed on 20 human donor corneas: 10 shaped by tunnel incision followed by lamellar incision (tunnel-lamellar group, TL) and 10 in the reverse order (lamellar-tunnel group, LT). The BB type was assessed by evaluating dynamic air movement during air inflation; bubble diameter and floor thickness were measured by anterior segment optical coherence tomography.

Results

Overall, a type 1 BB formed in 85% of eyes: 100% in the TL group and 70% in the LT group. In the LT group, a type 2 BB formed in 2 corneas and one cornea was perforated during cannula insertion. Type 1 BB was achieved after one attempt in 90% of eyes in the TL group and in 57% in the LT group.

Conclusion

Shaping the tunnel before rather than after lamellar incision may be more effective for obtaining a type 1 BB by air injection.

Laser-assisted corneal transplantation surgery

Corneal transplant surgeries have a broad range of indications with outcomes largely dependent on surgeon experience. Traditional manual techniques have certain limitations pertaining to the preparation of donor tissue and the recipient bed that might affect the predictability of visual outcomes. Use of lasers for keratoplasty procedures not only improves the repeatability and consistency of the technique, but also enables the surgeon to control the thickness and shape of the transplant tissue tailored to the specific condition. Despite the advantages, cost-effectiveness and technical know-how remain the major challenges. We discuss the various techniques of laser-assisted keratoplasties with respect to their methods, precision, and efficacy in various corneal indications.

Comparison of the effects of femtosecond laser energy on corneal endothelium at two different dissection levels in femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus

PURPOSE

The objective of this study is to compare the endothelial safety of femtosecond laser (FSL) energy at two different dissection depths in FSL-assisted deep anterior lamellar keratoplasty (FSDALK) for keratoconus.

METHODS

This prospective double-armed interventional study included 25 eyes from 21 patients with advanced keratoconus who underwent FSDALK (big bubble technique) at a trephination depth of 110 µm in group I (11 eyes) and 80 µm in group II (14 eyes)-all of which were anterior to the Descemet's membrane (DM). Visual acuity measurement, anterior and posterior segment examination, corneal tomography, and specular microscopy were performed preoperatively and at 3, 6, and 12 months, postoperatively. Endothelial cell density, coefficient of variation, percentage of cell hexagonality, and pachymetry were used to evaluate endothelial safety.

RESULTS

No statistically significant difference in any of the endothelial safety parameters was found between the two groups. The mean 12-month postoperative endothelial cell loss rate was 17.46% and 12.91% in group I and II, respectively (P = 0.345). Most of the endothelial cell loss occurred during the first 3 months after surgery. Group II showed statistically greater improvement in the mean keratometry values at all follow-up visits.

CONCLUSION

The endothelial safety profiles of lamellar FSL cuts at 110 µm and 80 µm anterior to the DM are comparable. Cuts as deep as 80 µm anterior to the DM can be safely applied without causing significant injury to the endothelium. Further studies are needed to compare the endothelial safety profiles of different FSL platforms available in the market. Trial registration PACTR201901615323963. Registered 24 November 2018-retrospectively registered.

Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty for Keratoconus: Multi-surgeon Results

PURPOSE

To compare the clinical outcomes in femtosecond laser-assisted deep anterior lamellar keratoplasty (F-DALK) to manual non-laser deep anterior lamellar keratoplasty (M-DALK) for keratoconus in a multi-surgeon public healthcare setting.

DESIGN

Single-center, comparative, retrospective interventional case series.

METHODS

Population: Consecutive cases of keratoconus treated with big-bubble F-DALK from August 1, 2015, to September 1, 2018 and big-bubble M-DALK from September 1, 2012, to September 30, 2016.

SETTING

Moorfields Eye Hospital, London.

OBSERVATIONS

Data on preoperative status, operative details, intraoperative and postoperative complications, secondary interventions, and visual outcomes were archived on a customized spreadsheet for analysis. MainOutcomeMeasures: Rate of intraoperative perforation and conversion to penetrating keratoplasty (PK) and the percentage of patients, post removal of sutures (ROS), with corrected distance visual acuity (CDVA) ≥20/40.

RESULTS

We analyzed 58 eyes of 55 patients who underwent F-DALK and 326 eyes of 309 patients who underwent M-DALK. Intraoperative perforation of Descemet membrane occurred in 15 of 58 (25.9%) F-DALK cases compared to 148 of 326 (45.4%) M-DALK cases (P = .006). Intraoperative conversion to PK was carried out in 2 of 58 (3.4%) F-DALK cases compared to 80 of 326 (24.5%) M-DALK cases (P = .001). Post ROS, 86.5% of F-DALK eyes had a CDVA of ≥20/40 (15 ± 7.3 months after surgery) compared to 83.7% of M-DALK eyes (24.9 ± 10.6 months) (P = .825).

CONCLUSION

Laser automation of some steps in DALK for keratoconus may reduce the rate of intraoperative Descemet perforation and the conversion to PK in a multi-surgeon setting.

[One-piece mushroom keratoplasty outcomes]

PURPOSE

To clinically evaluate the results of one-piece mushroom-shaped keratoplasty.

MATERIAL AND METHODS

A total of 10 patients (10 eyes) were enrolled, all having corneal perforations and deep stromal opacities with involvement of Descemet's membrane. For transplantation, hypothermic preserved donor corneas with mean endothelial cell density of 2896±327 cells per 1 mm² were used. Surgical technique. Recipient tissues as well as the graft were cut with the Moria trephine. For that, the 8.5-mm blade was replaced by a 6.5-mm one and vice versa, respectively, with attention paid not to violate the vacuum while making the cuts.

RESULTS

Transparent cornea engraftment was achieved in all patients. Best corrected visual acuity averaged 0.55±0.22. Spherical component of refraction varied from -4.25 to +2.75 diopters. Mean corneal astigmatism was 3.35±1.73 diopters. At 6 months after surgery, the mean endothelial cell density was 2355±336 cells/mm², at 1 year - 2141±304 cells/mm2.

CONCLUSION

One-piece mushroom keratoplasty is an effective surgical treatment of corneal perforations and deep stromal opacities with involvement of Descemet's membrane that ensures a high rate of transparent corneal engraftment. The use of the Moria vacuum trephine in combination with blades of different diameters and secure fixation of the vacuum part of the trephine eliminate the risk of the 'mushroom stem' decentration relative to its 'head'.

Comparison of long-term results after manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty for keratoconus

AIM

To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty (FS-DALK) for keratoconus.

METHODS

In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity (UCVA), corrected distance visual acuity (CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent (MRSE), flat and steep corneal keratometry (K1 and K2), endothelial cell density (ECD), and time of epithelium healing and suture removal.

RESULTS

Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23mo (range, 12-36mo). At 12mo, the mean UCVA was better in the manual-DALK group (P=0.039), and the refractive sphere was lower in the FS-DALK group (P=0.040). MRSE between groups differed at 1, 6, and 12mo postoperatively (P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2, corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group (P=0.042) while complete suture removal time was similar (P=0.122).

CONCLUSION

Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FS-DALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.

Shaped corneal transplantation surgery

Since its inception in 1905, keratoplasty techniques have continuously evolved. Shaped keratoplasty procedures have allowed corneal surgeons to use complex graft-host junctions and non-circular graft designs to optimise wound strength and healing, facilitate early suture removal and expedite visual rehabilitation. While this was initially limited to penetrating procedures, shaped lamellar keratoplasty techniques have since emerged. Furthermore, the arrival of femtosecond laser has dramatically increased the range of graft designs available to surgeons, due to the technology's ability to precisely cut complex wound edges. This review describes the broad range of shaped keratoplasty grafts currently available and elaborates on their respective advantages and disadvantages in relation to conventional keratoplasty.

[Modern modifications of penetrating keratoplasty with complex operative incision]

The basic principle of modern keratoplasty is selectivity, i.e. the choice of whether to replace only the affected corneal layer. However, when layer-by-layer and interlayer transplantation is not indicated, the method of choice is conventional penetrating keratoplasty. An alternative can be its modifications with complex profiles of the transplant edges and the bed, which are better justified in terms of pathogenesis. The most popular among them are mushroom, zig-zag and top-hat. These surgeries combine optical benefits of penetrating keratoplasty as they do not involve dissection of the corneal optical zone and can negate - to a certain degree - its main downsides such as low trauma tolerance of the postoperative scar, significant level of postoperative astigmatism, and increased visual rehabilitation time. Mushroom-shaped incisions can be performed manually with a femtosecond laser or a microkeratome, zig-zag incision - only with a femtosecond laser. Considering the diversity of keratoplasty modifications with complex operative incisions, further research is required for evaluation of their clinical effectiveness and analysis of postoperative complications.

Femtosecond laser-assisted deep anterior lamellar keratoplasty

PURPOSE OF REVIEW

A survey of the recent literature of deep anterior lamellar keratoplasty using femtosecond laser technology.

RECENT FINDINGS

There are several recent reports in the literature assessing technique and outcomes of deep anterior lamellar keratoplasty done with a femtosecond laser trephination. Most of these reports are laboratory studies and small case series with short-term outcomes. The laser technology is expensive and may not produce better results than conventional manual techniques. However, there are several theoretical advantages to femtosecond laser incisions in deep anterior lamellar keratoplasty that should be explored, including possible increased success of Descemet's membrane separation from stroma during surgery as well as postsurgical astigmatism benefits, earlier suture removal, and increased wound strength and healing.

SUMMARY

Femtosecond laser trephination in the setting of DALK may improve the technique by decreasing the number of descemet's membrane ruptures and improving short-term and long-term outcomes as compared with manual techniques. However, there is no consensus on a standardized approach for wound design or postoperative management. The literature would benefit from a prospective randomized controlled trial.

Toric IOL implantation in a patient with keratoconus and previous penetrating keratoplasty: a case report and review of literature

BACKGROUND

Cataract surgery in patients with keratoconus with or without previous penetrating keratoplasty (PKP) can be demanding due to difficulties in selecting the intraocular lens (IOL) and predicting the refractive outcome. We report a case of cataract surgery in a patient with keratoconus and previous PKP in one eye.

CASE PRESENTATION

A 71-year-old man with bilateral cataract and advanced bilateral keratoconus and previous PKP in the left eye. Preoperatively, best corrected visual acuity (BCVA) was 20/150, with - 5.75 sph - 9.75 cyl 72°, in the right eye and 20/40, with - 0.25 sph - 5.0 cyl 50°, in the left eye. The patient was subjected to phacoemulsification with implantation of a spherical IOL in the right eye and a toric IOL in the left eye. BCVA postoperatively was 20/80 with + 1.25 sph - 3 cyl 65° in the right eye and 20/25 with - 0.5 sph - 3.25 cyl 80° in the left eye.

CONCLUSIONS

Correction of post-PKP astigmatism and cataract with phacoemulsification and implantation of a toric IOL can be an effective and safe choice. Predicting the refractive outcome in cataract surgery is difficult in patients with advanced keratoconus even when using non-toric IOLs, and the surgeon should be aware of different sources of biometric errors and the possible consequences.

Analysis of the VSX1 gene in sporadic keratoconus patients from China

Background

Keratoconus normally presents as a sporadic disease. Although different studies have found sequence variants of the visual system homeobox 1 (VSX1) gene associated with keratoconus in humans, no research has detected such variants in sporadic keratoconus patients from China. To investigate the possibility of VSX1 being a candidate susceptibility gene for Chinese patients with sporadic keratoconus, we performed sequence screening of this gene in such patients.

Methods

Whole DNA was obtained from the leukocytes in the peripheral venous blood of 50 patients with sporadic keratoconus and 50 control subjects without this ocular disorder. Polymerase chain reaction single-strand conformation polymorphism analysis and direct DNA sequencing technology were used to detect sequence variation in the five exons and splicing regions of the introns of the VSX1 gene. The sequencing results were analyzed using DNAstar software.

Results

One novel missense heterozygous sequence variant (p.Arg131Pro) was found in the first exon of the VSX1 gene in one keratoconus patient. Another heterozygous sequence variant (p.Gly160Val) in the second exon was found in two keratoconus patients. These variants were not detected in the control subjects. In the third intron of the VSX1 gene, c.8326G > A nucleotide substitution (including heterozygous and homozygous change) was also discovered. The frequency of this variation did not differ significantly between patients and controls, it should belong to single-nucleotide polymorphism of the VSX1 gene. Bioinformatic analysis also predicted that one missense sequence variation (p.Arg131Pro) may not cause a pathogenic change.

Conclusions

In this study, we added one novel missense sequence variation (p.Arg131Pro) in the coding region of the VSX1 gene to the range of VSX1 coding region variations observed in patients with sporadic keratoconus from China. Our work suggests that VSX1 sequence variants might be involved in the pathogenesis of sporadic keratoconus, but their precise role in disease causation requires further investigation.

Cataract Surgery in Patients with Keratoconus: Pearls and Pitfalls

Background:

Keratoconus (KC) is a common ectatic disorder resulting in progressive corneal thinning and irregular astigmatism. It has been observed that patients affected by KC are more likely to develop lens opacities earlier compared to non-keratoconic patients.

Objective:

Intraocular lens (IOL) selection and refractive outcome prediction are among a number of factors that can make cataract surgery in keratoconic patients challenging. Accurate biometry is often difficult to obtain due to unreliable K measurements and lack of dedicated biometric formulae. The use of toric IOLs has also been investigated.

Conclusions:

Determining the stage of KC, pre-operative patient counselling and the preferred method of refractive correction are all crucial to obtain successful postoperative outcomes and good patient satisfaction. The use of toric IOLs can achieve good results only in selected low-grade keratoconic eyes.

Keratoconus Treatment Algorithm

Keratoconus management has significantly changed over the last two decades. The advent of new interventions such as cornea cross-linking, intrastromal corneal ring segments, and combined treatments provide corneal clinicians a variety of treatment options for the visual rehabilitation of keratoconus patients. This review summarizes current evidence for these treatments and highlights their place in keratoconus management while new promising emerging therapies are being investigated.