Three-Year Outcome Comparison Between Femtosecond Laser-Assisted and Manual Descemet Membrane Endothelial Keratoplasty

Clinical Outcomes of Descemet's Membrane Endothelial Keratoplasty without Routine Prophylactic Peripheral Iridotomy

Objectives: To analyze the outcomes and complications of Descemet's membrane endothelial keratoplasty (DMEK) performed without prophylactic peripheral iridotomy (PI). Methods: Design: Retrospective study.

SETTING

Institutional, tertiary care eye hospital.

STUDY POPULATION

All patients who underwent DMEK or DMEK combined with phacoemulsification (DMEK triple) for Fuchs endothelial dystrophy, using a standardized protocol between August 2016 and July 2021, were included. Previous glaucoma surgery, laser PI, aphakia, or complicated pseudophakia were excluded.

MAIN OUTCOME MEASURES

Primary outcomes: Incidence of pupillary block (PB).

SECONDARY OUTCOMES

Graft detachment (GD), rebubbling rates, uncorrected (UCDVA) and best corrected logMAR distance visual acuity (BCDVA), and endothelial cell loss (ECL) at six months. Data were analyzed using the chi-square test and stepwise backward regression analysis. Results: 104 eyes of 72 patients were included. Four eyes (3.8%) developed PB; in two of these cases, standard protocol was not followed. Overall minor GD occurred in 43.2% (n = 45); significant GD was present only in 7 eyes (6.6%). Overall slit lamp rebubbling rate was 30% (n = 35), though only four patients were rebubbled in theatre (3.8%). PB, GD, and rebubbling rates did not vary with the surgeon, surgery, or tamponade (air or SF6 gas). UCDVA, BCDVA, and ECL at 6 months were 0.29 ± 0.31, 0.20 ± 0.28, and 40.46 ± 20.36%, respectively. Conclusions: Compared to previously reported outcomes of DMEK with PI, our results of PI less DMEK using a standardized protocol have a similar incidence of pupillary block, graft detachment, and rebubbling, with comparable visual acuity and endothelial cell loss.

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.

Fuchs Dystrophy and Cataract: Diagnosis, Evaluation and Treatment

Corneal endothelium plays an important role in maintaining hydration homeostasis and clarity of the cornea. Fuchs endothelial corneal dystrophy (FECD) affects the corneal endothelium resulting in edema and characteristic excrescences on the Descemet's membrane known as corneal guttae. Descemet membrane endothelial keratoplasty (DMEK) has evolved to become the standard of care for patients with FECD with excellent visual acuity outcomes. Patients with FECD may have coexisting cataracts and therefore may require a cataract surgery, which increases the risk of corneal decompensation. The presence of FECD may not only influence the choice of intraocular lens but vision outcomes can also be affected by the corneal condition. The ability to combine the surgeries further raises important considerations regarding the timing and sequence of DMEK and cataract extraction for patients with FECD. This review provides a guide for corneal surgeons in choosing between endothelial keratoplasty and cataract surgery-alone, in combination or sequential-in their management of patients with FECD.

Five-Year Safety and Efficacy of Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty

PURPOSE

The purpose of this study was to evaluate 5-year safety and efficacy outcomes of femtosecond-enabled Descemet membrane endothelial keratoplasty (F-DMEK) in patients with Fuchs' endothelial dystrophy (FED).

METHODS

This was a retrospective study, including patients with FED and cataract who underwent either F-DMEK (16 eyes of 15 patients) or manual DMEK (M-DMEK) (42 eyes of 37 patients) combined with cataract extraction. Outcome measures included visual acuity, graft detachment, graft survival, and endothelial cell loss.

RESULTS

The average follow-up in F-DMEK and M-DMEK was 57.1 ± 12.4 months and 58.5 ± 17.3 months, respectively ( P = 0.757). The rates of primary failure (0% vs. 9.5%, P = 0.567), secondary failure (0% for both), and graft rejection (0% vs. 7.1%, P = 0.533) did not differ significantly between the groups. Improvement in best spectacle-corrected visual acuity was similar in F-DMEK and M-DMEK (0.32 ± 0.27 logarithm of the minimum angle of resolution and 0.35 ± 0.44 logarithm of the minimum angle of resolution, respectively, P = 0.165) and persisted at 2, 3, 4, and 5 years and at the last follow-up. The rates of graft detachment and rebubbling were significantly lower with 6.25% in F-DMEK and 33.3% in M-DMEK ( P = 0.035). Cell-loss rates were lower in F-DMEK compared with M-DMEK throughout the follow-up, significantly so up to 2 years with a difference of 8.6% at 1 year ( P = 0.023), 11.8% at 2 years ( P = 0.021), 7.6% at 3 years ( P = 0.088), 5.8% at 4 years ( P = 0.256), 13.6% at 5 years ( P = 0.169), and 7.1% at the final follow-up ( P = 0.341).

CONCLUSIONS

F-DMEK had an excellent safety and efficacy profile which was maintained over 5 years of follow-up. Lower endothelial cell-loss rates in F-DMEK compared with M-DMEK may help extend the duration of graft survival.

Graft failure rate and complications after Descemet membrane endothelial keratoplasty in eyes with pre-existing glaucoma

PURPOSE

To evaluate the outcome of Descemet Membrane Endothelial Keratoplasty (DMEK) in eyes with pre-existing glaucoma.

DESIGN

In this retrospective, observational case series we included data of 150 consecutive DMEKs in eyes with pre-existing glaucoma of 150 patients after excluding data of the second treated eye of each patient and of re-DMEKs during follow-up. Cumulative incidences of IOP elevation (IOP > 21 mmHg or ≥ 10 mmHg increase in IOP from preoperative value), post-DMEK glaucoma (need of an additional intervention due to worsening of the IOP), graft rejection, and graft failure rate were analyzed using Kaplan-Meier survival analysis. COX regression analysis was used to evaluate independent risk factors.

RESULTS

The 36-month cumulative incidence of IOP elevation was 53.5% [95 CI 43.5-63.5%] and of post-DMEK glaucoma 36.3% [95 CI 26.3-46.3%]. Graft rejection occurred with a 36-month cumulative incidence of 9.2% [CI 95% 2.3-16.1]. None of the analyzed risk factors increased the risk for the development of graft rejection. The 36-month cumulative incidence of graft failure was 16.6% [CI 95% 8.4-24.8]. Independent risk factors for graft failure were the indication for DMEK "status after graft failure" (n = 16) compared to Fuchs' dystrophy (n = 74) (p = 0.045, HR 8.511 [CI 95% 1.054-68.756]) and pre-existing filtrating surgery via glaucoma drainage device (GDD) (n = 10) compared to no surgery/iridectomy (n = 109) (p = 0.014, HR 6.273 [CI 95% 1.456-27.031]).

CONCLUSION

The risks of postoperative complications (IOP elevation, post-DMEK glaucoma, graft rejection, and graft failure) in patients with pre-existing glaucoma are high. In particular, pre-existing filtrating surgery via GDD implantation-but not trabeculectomy-and DMEK after graft failure increase the risk of graft failure.

Femtosecond Laser-Assisted Ophthalmic Surgery: From Laser Fundamentals to Clinical Applications

Femtosecond laser (FSL) technology has created an evolution in ophthalmic surgery in the last few decades. With the advantage of high precision, accuracy, and safety, FSLs have helped surgeons overcome surgical limits in refractive surgery, corneal surgery, and cataract surgery. They also open new avenues in ophthalmic areas that are not yet explored. This review focuses on the fundamentals of FSLs, the advantages in interaction between FSLs and tissues, and typical clinical applications of FSLs in ophthalmology. With the rapid progress that has been made in the state of the art research on FSL technologies, their applications in ophthalmic surgery may soon undergo a booming development.

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.

Long-Term Stability of Femtosecond Astigmatic Keratotomy After Treatment of High Postkeratoplasty Astigmatism

PURPOSE

The purpose of this study was to assess long-term stability and outcomes of femtosecond astigmatic keratotomy (FSAK) after treatment of high postkeratoplasty astigmatism.

METHODS

This retrospective study included patients who underwent FSAK for high astigmatism (≥4 D) after penetrating keratoplasty or deep anterior lamellar keratoplasty. Main outcome measures were corneal astigmatism, uncorrected visual acuity, and best-corrected visual acuity (BCVA) at 1 month and 1, 5, and 10 years.

RESULTS

Overall, 61 eyes of 61 patients (mean age 56 ± 19 years, 54.1% male) were included in this study. Preoperative corneal astigmatism ranged from 4 to 25 D. One month after FSAK, mean corneal astigmatism was significantly reduced from 9.02 ± 3.97 D to 4.86 ± 3.10 D (P < 0.001). Thereafter, corneal astigmatism remained stable at all visits up to 10 years (P < 0.05 for all compared with baseline). After FSAK, there was a significant improvement in logMAR uncorrected visual acuity from 1.21 ± 0.48 to 0.87 ±0.54 (P < 0.001) and logMAR BCVA from 1.03 ± 0.55 to 0.49 ± 0.45 (P < 0.001) which remained stable up to 10 years. A mild reduction in BCVA improvement was seen between 1 month and 1 year.

CONCLUSIONS

Femtosecond astigmatic keratotomy was effective and stable at reducing very high magnitudes of postkeratoplasty astigmatism over the long term. The procedure also had a stable effect on visual acuity, albeit some reduction in the degree of BCVA improvement was seen over the early postoperative period.

Posterior lamellar keratoplasty: techniques, outcomes, and recent advances

Over the past 2 decades, posterior lamellar keratoplasty (PLK) has emerged as an alternative to penetrating keratoplasty in the treatment of corneal endothelial disorders. The reasons for this trend include the search for a safer procedure to replace diseased endothelium that provides faster and better visual rehabilitation and reduces the need for postoperative care. Different surgical techniques, surgical instruments, devices, and lasers have been introduced to overcome technical difficulties, thus improving clinical outcomes. Yet, surgeons and eye banks must address the complications and limitations that arise during the transition to these new techniques. This review discusses the most significant aspects of the evolution of PLK, including a detailed description of current techniques and the direction of future treatment for corneal endothelial disease with the use of laser-assisted surgery, bioengineered corneas, cell therapy, and new pharmacologic therapy.

Femtosecond laser-assisted descemetorhexis for Descemet membrane endothelial keratoplasty: a cell- and tissue-based ex-vivo analysis in terms of precision and safety

PURPOSE

To analyze precision and safety of femtosecond laser-assisted descemetorhexis as well as postoperative corneal wound healing in human ex vivo specimens.

SETTING

Department of Ophthalmology, University Hospital, LMU Munich, Munich, Germany.

DESIGN

Experimental ex vivo study.

METHODS

Four donor corneas underwent femtosecond laser-assisted descemetorhexis. The descemetorhexis was performed using the LDV Z8 femtosecond laser followed by live/dead staining, phase contrast microscopy and scanning electron microscopy. The descemetorhexis parameters were set using a modified optical coherence tomography image capturing of 8 segments within a focus of 100 μm at the posterior corneal stroma (reversed capsulotomy program).

RESULTS

Live/dead sample staining analysis demonstrated that the femtosecond laser had minimal impact on the vitality of surrounding endothelial cells. Phase contrast microscopy and scanning electron microscopy evaluation showed that the laser produced precise, clear-cut edges leaving no stromal tissue bridges.

CONCLUSIONS

Femtosecond laser-assisted descemetorhexis could serve as a safe and precise technique with only minimal endothelial cell damage. To minimize stromal damage, further laser energy profile adjustments are necessary to optimize corneal treatment within different stages of corneal tissue swelling.

Endothelial Keratoplasty Update 2020

ABSTRACT

Endothelial keratoplasty has revolutionized the treatment of corneal endothelial dysfunction and lowered the threshold for treatment by providing rapid visual rehabilitation and setting a high standard for safety and efficacy. Over time, endothelial keratoplasty techniques have evolved toward the use of thinner tissue to optimize visual outcomes; refinements have facilitated donor tissue preparation, handling, and attachment; and adaptations have expanded utilization in eyes with challenging ocular anatomy. Despite early concerns about graft longevity, emerging 10-year endothelial cell loss and graft survival data have been encouraging. A shortage of human donor corneas restricts utilization in many areas of the world and is driving a search for keratoplasty alternatives. Further work is needed to expand the donor supply, minimize impediments to adoption, optimize graft survival, and improve refractive predictability.

Femtosecond Lasers in Cornea & Refractive Surgery

Since the introduction of femtosecond laser (FS) systems for corneal flap creation in laser-assisted in-situ keratomileusis there have been numerous applications for FS laser in corneal surgery. This manuscript details the utility of FS lasers in corneal surgical procedures including refractive laser surgeries, intracorneal ring segment tunnels, presbyopic treatments, and FS-assisted keratoplasty. We also review the role of FS lasers in diagnostic procedures such as two photon excitation fluorescence and second harmonic generation.

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.

Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

Graft detachments in endothelial keratoplasty

Graft detachment is the most common complication of endothelial keratoplasty. With the ongoing advancements in the field of endothelial keratoplasty, our understanding of risk factors of graft detachments and its management has been evolving. Various prevention measures have been described in literature including presoaking the donor graft, anterior chamber tamponade, venting incisions, sutures to prevent dislocation of graft. Management of a detached graft involves secondary interventions such as rebubbling, suturing and regrafts. In this review, we discuss graft detachment in different types of endothelial keratoplasty techniques including Descemet stripping endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty and Descemet's membrane endothelial keratoplasty; with emphasis on incidence, risk factors, preventive measures and their management.

Four-Year Survival of Descemet Membrane Endothelial Keratoplasty in Patients With Previous Glaucoma Surgery

PURPOSE

To evaluate 4-year outcomes of Descemet membrane endothelial keratoplasty (DMEK) in eyes with previous glaucoma surgery.

DESIGN

Retrospective, comparative case series.

METHODS

Patients with previous trabeculectomy or glaucoma drainage device (GDD) implantation who later underwent DMEK (study group) were matched for follow-up duration with Fuchs dystrophy DMEK patients (control group). The minimum follow-up was 18 months. Primary outcomes included graft survival and rejection rates, and secondary outcomes included rates of detachment/rebubble, endothelial cell loss, best spectacle-corrected visual acuity, intraocular pressure, and glaucoma medications/surgeries. Subgroup analysis compared eyes with and without a GDD.

RESULTS

Ninety-four eyes of 91 patients were included. There were 51 eyes of 49 patients in the study group (GDD = 32 eyes, no GDD = 19 eyes) and 43 eyes of 42 patients in the control group. The mean follow-up was 37.9 ± 15.2 and 33.8 ± 13.5 months, respectively (P = .322). Graft survival probability of the study group at 12, 24, 36, and 48 months was 75%, 60%, 43%, and 27%, respectively, compared with a consistent 88% in the control group (P < .001). Survival curves of study subgroups (GDD and no GDD) were significantly lower than the control group (P < .001). Rejection rates in the study and control groups were 19.6% and 2.3%, respectively (P = .010). Endothelial cell loss in the study group was 12%-22% higher than the control group at 12, 24, 36, and 48 months (P = .049, P = .027, P = .200, and P = .004).

CONCLUSIONS

In eyes with previous glaucoma surgery, DMEK has good early outcomes, but longer-term rejection and failure rates are high. Physicians and patients should be cognizant of the high likelihood of graft failure in this setting.

Corneal endothelial dysfunction: Evolving understanding and treatment options

The cornea is exquisitely designed to protect the eye while transmitting and focusing incoming light. Precise control of corneal hydration by the endothelial cell layer that lines the inner surface of the cornea is required for optimal transparency, and endothelial dysfunction or damage can result in corneal edema and visual impairment. Advances in corneal transplantation now allow selective replacement of dysfunctional corneal endothelium, providing rapid visual rehabilitation. A series of technique improvements have minimized complications and various adaptations allow use even in eyes with complicated anatomy. While selective endothelial keratoplasty sets a very high standard for safety and efficacy, a shortage of donor corneas in many parts of the world restricts access, prompting a search for alternatives. Clinical trials are underway to evaluate the potential for self-recovery after removal of dysfunctional central endothelium in patients with healthy peripheral endothelium. Various approaches to using cultured human corneal endothelial cells are also in clinical trials; these aim to multiply cells from a single donor cornea for use in potentially hundreds of patients. Pre-clinical studies are underway with induced pluripotent stem cells, endothelial stem cell regeneration, gene therapy, anti-sense oligonucleotides, and various biologic/pharmacologic approaches designed to treat, prevent, or retard corneal endothelial dysfunction. The availability of more therapeutic options will hopefully expand access around the world while also allowing treatment to be more precisely tailored to each individual patient.

Descemet membrane endothelial keratoplasty in patients with prior glaucoma surgery

OBJECTIVE

To present outcomes of Descemet membrane endothelial keratoplasty (DMEK) in eyes with prior trabeculectomy or a glaucoma drainage device (GDD).

METHODS

A retrospective case series, including patients that had previously undergone trabeculectomy and/or GDD implantation, who later underwent DMEK between 2013 and 2016 at Toronto Western Hospital and the Kensington Eye Institute. Outcome measures: best spectacle-corrected visual acuity (BSCVA), endothelial cell (EC) density, intraoperative and postoperative complications.

RESULTS

Twenty-seven eyes of 27 patients were included. All DMEK procedures were uneventful. Mean follow-up time was 14.6 ± 6.1 months. In eyes with no visually limiting comorbidities (n = 16), BSCVA improved from 1.34 ± 0.65 logMAR (Snellen equivalent ~20/440) preoperatively to 0.51 ± 0.24 logMAR (Snellen equivalent ~20/65) and 0.50 ± 0.33 logMAR (Snellen equivalent ~20/65) at 6 and 12 months, respectively (p < 0.001 for both). In eyes with visually limiting comorbidities (n = 11), BSCVA improved from 1.92 ± 0.72 logMAR (Snellen equivalent ~20/1665) preoperatively to 1.43 ± 0.83 logMAR (Snellen equivalent ~20/540) and 1.37 ± 0.99 logMAR (Snellen equivalent ~20/470) at 6 and 12 months, respectively (p = 0.008 and p = 0.037).Graft detachment rate was 24.1% and rebubble rate was 17.2%. Primary and secondary graft failure rates were 3.7% and 10.3%, respectively. Rejection rate was 17.2%. EC-loss rate at 6 months and 12 months was 36.7% and 50.5%, respectively.

CONCLUSIONS

DMEK performed in eyes with previous trabeculectomy or a GDD is more challenging than conventional DMEK, but has good outcomes. Higher rates of graft rejection and secondary graft failure in this setting should be further evaluated in long-term studies.

Comparison of Manual and Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty for Failed Penetrating Keratoplasty

PURPOSE

To compare outcomes of manual Descemet membrane endothelial keratoplasty (M-DMEK) and femtosecond laser-assisted Descemet membrane endothelial keratoplasty (F-DMEK) in treatment of penetrating keratoplasty (PK) graft failure.

METHODS

Setting: Retrospective, interventional comparative case series. PatientPopulation: Included were all patients with a failed PK graft who underwent either F-DMEK (10 eyes of 10 patients) or M-DMEK (29 eyes of 29 patients) at Toronto Western Hospital and the Kensington Eye Institute between 2014 and 2019, and had 6 months of postoperative follow-up. OutcomeMeasures: Rates of graft detachment, rebubbling, rejection and failure, best spectacle-corrected visual acuity (BSCVA), and endothelial cell (EC) density.

RESULTS

Rate of significant graft detachment (detachment requiring either rebubble or repeat keratoplasty) was 10.0% in F-DMEK and 65.5% in M-DMEK (P = .003). Rebubble rate was 10.0% in F-DMEK and 58.6% in M-DMEK (P = .011). Primary failure rate was 0% in F-DMEK and 27.6% in M-DMEK (P = .086). Rates of rejection and secondary failure did not differ between the groups (P = 1.000 for both). In a multivariable analysis, F-DMEK was found to be the only independent factor significantly associated with reduced postoperative detachment. Postoperative BSCVA at 6 months returned to prefailure levels in both groups, with no significant difference between the groups at any time point. EC loss rates were 43.8% in F-DMEK and 38.0% in M-DMEK at 6 months (P = .453).

CONCLUSIONS

F-DMEK is a safe and effective procedure in failed PK patients, with outcomes comparable to M-DMEK, and with reduced detachment and rebubble rates. A trend towards reduced primary failure should be further studied.

Application of Femtosecond Laser in Anterior Segment Surgery

Femtosecond laser (FSL) is a near-infrared laser that can create reliable and reproducible tissue cutting with minimal damage to adjacent tissue. As the laser can also create incisions with various orientations, depths, and shapes, it is expected to be a useful tool for anterior segment surgery, such as cornea, refractive, and cataract surgery. In this review, the authors will introduce the application of FSL in various anterior segment surgeries and discuss the results of studies regarding the efficacy and safety of FSL in cornea, refractive, and cataract surgery. Experimental studies regarding the potential use of FSL will also be introduced. The studies discussed in this review suggest that FSL may be a useful tool for improving the prognosis and safety of surgeries of the anterior segment.