[Influence of 20 % sulfur hexafluoride (SF6) on human corneal endothelial cells : An in vitro study]

Graft survival of Descemet membrane endothelial keratoplasty (DMEK) in corneal endothelial decompensation after glaucoma surgery

Purpose

This study aims to assess the results, rebubbling rate, and graft survival after Descemet membrane endothelial keratoplasty (DMEK) with regard to the number and type of previous glaucoma surgeries.

Methods

This is a clinical retrospective review of 1845 consecutive DMEK surgeries between 07/2011 and 08/2017 at the Department of Ophthalmology, University of Cologne. Sixty-six eyes were included: group 1 (eyes with previous glaucoma drainage devices (GDD); n = 27) and group 2 (eyes with previous trabeculectomy (TE); n = 39). Endothelial cell loss (ECL), central corneal thickness, graft failure, rebubbling rate, and best spectacle-corrected visual acuity (BSCVA) up to 3 years after DMEK were compared between subgroups of patients with different numbers of and the two most common types of glaucoma surgeries either GDD or TE or both.

Results

Re-DMEK rate due to secondary graft failure was 55.6% (15/27) in group 1 and 35.9% in group 2. The mean graft survival time in group 1 was 25 ± 11 months and 31.3 ± 8.6 months in group 2 (p = 0.009).

ECL in surviving grafts in group 1 was 35% (n = 13) at 6 months, 36% at 12 months (n = 8), and 27% (n = 4) at 2 years postoperatively. In group 2, ECL in surviving grafts was 41% (n = 10) at 6 months, 36% (n = 9) at 12 months, and 38% (n = 8) at 2 years postoperatively. Rebubbling rate in group 1 was 18.5% (5/27) and 35.9% (14/39) in group 2 (p = 0.079).

Conclusion

Eyes with previous GDD had no higher risk for an increased rebubbling rate but a higher risk for a re-DMEK due to secondary graft failure with a mean transplant survival time of about 2 years. Compared to eyes with preexisting glaucoma drainage device, eyes after trabeculectomy had less secondary graft failures and a longer mean graft survival rate.

Descemet Membrane Endothelial Keratoplasty (DMEK) in Previously Vitrectomized Eyes: Complications and Clinical Outcomes

PURPOSE

To evaluate the results and complications of Descemet membrane endothelial keratoplasty (DMEK) in previously vitrectomized eyes.

DESIGN

Retrospective study of 35 eyes that had undergone DMEK, due to Fuchs endothelial corneal dystrophy (FECD), at our department with a follow-up after 6 months postoperatively. We compared the intraoperative procedure, complications, and results of DMEK between 14 previously vitrectomized pseudophakic eyes (group 1) and a control group of 21 pseudophakic non-vitrectomized eyes (group 2).

RESULTS

The unfolding time (in minutes) was significantly longer in group 1 than in group 2 (10.5 ± 6.4 vs. 3.2 ± 1.5, p < 0.01). A single re-bubbling was needed in 8 patients in group 1 (57.1%) and in 3 patients in group 2 (14.2%) (p < 0.01). Repeated re-bubbling (≥ 1 time) was performed in only 5 patients of group 1 (35.7%). There was significant postoperative improvement in best-corrected visual acuity (BCVA, in LogMAR) in both groups (p = 0.04 in group 1 and p < 0.01 in group 2). The central corneal thickness (CCT, in µm) did not differ significantly between the two groups preoperatively (p = 0.4) or postoperatively (p = 0.1). However, the CCT decreased significantly postoperatively in both groups (p < 0.01 in both groups). The postoperative endothelial cell density (ECD in cell/mm²) was significantly lower in group 1 than in group 2 (p = 0.03).

CONCLUSION

DMEK in previously vitrectomized eyes presents a surgical challenge, which requires special, and sometimes unpredictable, intraoperative maneuvers, but good functional and morphological results can be achieved. The use of the endothelial Descemet membrane lamellae (EDML) of older donors might be recommended to facilitate the intraoperative unfolding process.

Impact of Re-bubbling after Descemet Membrane Endothelial Keratoplasty on Long-term Results

Purpose/Aim of the study: Graft detachment after DMEK can be treated easily with an additional air injection - re-bubbling. The aim of our study was to investigate the effect of a re-bubbling on the postoperative outcome.Materials and Methods: In this retrospective, comparative, cohort study we included eyes from patients that underwent DMEK surgery. A graft detachment was diagnosed by slit-lamp examination and OCT scan. All eyes were divided into three groups: no re-bubbling, one re-bubbling, more than one re-bubbling. We analyzed the visual acuity, endothelial cell density and rate of graft failure.Results: In 163 of 463 eyes (35.2%) a re-bubbling was performed (119 eyes 1 re-bubbling, 44 eyes more than one re-bubbling). Visual acuity improved significantly in all groups. After controlling for donor age, reason for surgery, time of cultivation of the graft and preoperative visual acuity, no difference in the visual acuity was seen at any point of follow-up. All patients showed a significant reduction in endothelial cell density 1 month after DMEK. Controlling for donor age, reason for surgery, type of surgery (DMEK-only or DMEK combined with cataract surgery) and the time of cultivation of the graft, the difference in endothelial cell density at 1 month post-surgery between no re-bubbling and one re-bubbling was 157 cells/mm² (95% CI 2-310, p = .047) and between no re-bubbling and more than one re-bubbling 504 cells/mm² (95% CI 267 - 741, p < .001). The difference in endothelial cell density remained over the course of follow-up. Twenty patients (4.3%) developed a graft failure during postoperative follow-up. Controlling for donor age, reason for surgery and the time of cultivation of the graft, we did not find any difference in the risk of graft failure between re-bubbling categories.Conclusions: Re-bubbling increased the risk for an endothelial cell loss, but did not influence the postoperative visual acuity and the rate of graft failure.

Descemet's Membrane Endothelial Keratoplasty with Split Corneal Grafts: The Influence of Tamponade Material and Endothelial Storage Time

Purpose: The aim of this study was to describe the clinical outcome of Descemet's membrane endothelial keratoplasty (DMEK) performed with split corneal grafts and to evaluate the influence of tamponade material and endothelial storage time on DMEK success. Material and Method: The records of 43 patients who underwent DMEK surgery with a split corneal graft were reviewed. Diagnosis of the patients, preoperative and postoperative best-corrected visual acuity (BCVA), corneal and endothelial storage time, tamponade material, complications, and success rates were specifically tabulated. Results: The most common indication for DMEK was pseudophakic bullous keratopathy (n = 25, 58.2%). Re-bubbling was needed in 10 cases (23.2%), and a re-DMEK was scheduled in 2 cases and penetrating keratoplasty in 4 cases (9.3%). BCVA improved significantly postoperatively (p < .001). There was an insignificant trend towards a lower re-bubbling rate and better long-term anatomic outcome in favor of 20% SF6 group compared to air tamponade (p = .18 and p = .25). There was no significant difference between the early endothelial transplant (<24 h) and delayed endothelial transplant (3 to 14 days) groups for anatomic success, corneal thickness or BCVA (p = .94, p = .13 and p = .35). Conclusion: The success rate of DMEK was satisfactory with split corneal grafts. There was no adverse influence of delayed endothelial transplantation on clinical outcome. The success rate of 20% SF6 tamponade was slightly better than room air.

[10 years of Descemet membrane endothelial keratoplasty in Fuchs endothelial corneal dystrophy : What have we learned?]

BACKGROUND AND OBJECTIVE

Descemet membrane endothelial keratoplasty (DMEK) has increased in popularity since its introduction over 10 years ago. This article presents a summary of the experiences of the past years collected at the Department of Ophthalmology at the University of Cologne.

METHODS

A literature review of DMEK studies primarily from the Department of Ophthalmology at the University of Cologne, Germany was carried out. Own experiences in the fields of donor selection and graft preparation, DMEK surgery, complication management and postoperative treatment are summarized.

RESULTS

Since the introduction of DMEK experience has been gained and ongoing improvements have occurred ranging from donor-recipient allocation to postoperative follow-up. These led to a better reproducibility of the intervention for the surgeon, to a better postoperative result and to a reduction of the complication rate.

DISCUSSION

The DMEK represents a safe and individualized procedure for endothelial transplantation for corneal endothelial dysfunction. Continuing development of the method leads to optimization and safer results.

Isoexpansile sulfur hexafluoride gas to repair near-total iris disinsertion

Iridodialysis is commonly encountered after blunt trauma to the eye. Most iris detachments are small, superior, and asymptomatic and require no surgical intervention. However, large areas of iridodialysis require early surgical repair to prevent the onset of iris necrosis, pigment dispersion, and secondary glaucoma. Suture fixation of iris to the sclera is the most commonly used method for iris repair; however, this technique becomes difficult in cases of near-total iris disinsertion, even in expert hands. We describe a case of posttraumatic near-total iris disinsertion with subluxated cataract managed with phacoemulsification and iris preservation with the help of intracameral injection of isoexpansile sulfur hexafluoride.

Evolution of Consecutive Descemet Membrane Endothelial Keratoplasty Outcomes Throughout a 5-Year Period Performed by Two Experienced Surgeons

PURPOSE

To assess the evolution of clinical outcomes of more than 1300 Descemet membrane endothelial keratoplasties (DMEKs) alone or in combination with cataract surgery (triple DMEK) throughout a 5-year period at a single center, performed by 2 already experienced DMEK surgeons.

DESIGN

Retrospective trend study.

METHODS

Review of charts between July 2011 and July 2016 at the Department of Ophthalmology, University of Cologne, Germany.

RESULTS

A total of 1340 out of 1340 eyes with sufficient information were included. Six-month and 12-month best spectacle-corrected visual acuity (logMAR) had already reached high levels for the surgeries performed in 2011 (0.10 ± 0.06 and 0.09 ± 0.07, respectively) and did not further improve in later years (P = .272). Likewise, endothelial cell loss (ECL) and central corneal thickness (CCT) reached comparable levels independently of the year of surgery (average 12-month ECL was 38% ± 15% and average 6-month CCT decrease was 19% ± 11%). However, there was a decrease in the rebubbling rate, from 68% in 2011, 67% in 2012, and 70% in 2013 to 53% in 2014, 29% in 2015, and 16% in 2016, which was associated with the introduction of 20% sulfur hexafluoride (SF₆) instead of room air for anterior chamber tamponade in 2015 (n = 986; P < .001). The percentage of severe complications after DMEK surgery also decreased significantly with surgeons' growing experience (P < .001; 95% confidence interval [0.09; 0.12]) over the years.

CONCLUSIONS

After an initial learning curve in DMEK surgery, results of visual acuity and ECL do not seem to further improve. However, the complication rate continuously declines, at least over the subsequent 5-year period analyzed herein.

[Critical endothelial procedures during posterior lamellar graft preparation and transplantation]

BACKGROUND

In view of the very low proliferation rate and functional importance of the corneal endothelium in maintaining corneal transparency, safeguarding the integrity of this monolayer plays a central role in posterior lamellar corneal transplantation. Several critical endothelial procedural stages are necessary to carry out such a transplantation.

OBJECTIVE

This article presents various preparatory and operative approaches for carrying out the necessary and critical stages within the framework of posterior lamellar corneal transplantation and concentrates on the question of optimization.

METHODS

A review of our own studies and studies of other groups is presented.

RESULTS

For the performance of critical endothelial procedural steps, a variety of approaches are available. These range from preparation and insertion of the transplant, through the manipulation during centralization up to the effects of postoperative air or gas bubble tamponade.

CONCLUSION

Because endothelial damage can permanently impair the integrity of lamellar transplants, a minimal handling and no touch policy should be strived for in all critical procedures. Long-term data on the follow-up course will show which of the procedures favored by various authors lead to the best postoperative results.

Rebubbling in Descemet Membrane Endothelial Keratoplasty: Influence of Pressure and Duration of the Intracameral Air Tamponade

PURPOSE

To explore the impact of intracameral air tamponade pressure and duration on graft attachment and rebubbling rates.

DESIGN

A prospective, interventional, nonrandomized study.

METHODS

setting: Department of Ophthalmology, Charité - Universitätsmedizin Berlin.

STUDY POPULATION

One hundred seventeen patients who underwent Descemet membrane endothelial keratoplasty (DMEK).

OBSERVATION

Intraocular pressure (IOP) at the end of the surgery, immediately after filling the anterior chamber with air, categorized into low (<10 mm Hg), normal (10-20 mm Hg), and high (>20 mm Hg), and the time until partial removal of the air.

MAIN OUTCOME MEASURES

Rebubbling rates and endothelial cell density over a 3-month follow-up period analyzed by a multivariable Cox regression model and an analysis of covariance model.

RESULTS

Thirty-two patients required a rebubbling (27% [95% CI 19%-35%]). Nine patients required more than 1 rebubbling (7% [95% CI 3%-12%]). Compared with normal IOP, lower (HR 8.98 [95% CI 1.07-75.41]) and higher IOP (HR 10.63 [95% CI 1.44-78.27]) increased the risk of requiring a rebubbling (P = .006). Independent of the IOP, an air tamponade duration beyond 2 hours reduced the risk of rebubbling (HR 0.36 [95% CI 0.18-0.71, P = .003]). One month after surgery, the mean endothelial cell loss was 13% (95% CI 2%-25%) and 23% (95% CI 17%-29%) in the group with air tamponade duration of below and above 2 hours, respectively (P = .126). At 3 months after surgery, it was 31% (95% CI 17%-42%) and 42% (95% CI 32%-52%) in the respective groups (P = .229).

CONCLUSIONS

A postsurgical air tamponade of at least 2 hours with an IOP within the physiological range could help to reduce rebubbling rates.

The effect of air, SF6 and C3F8 on immortalized human corneal endothelial cells

PURPOSE

While anterior chamber air bubbles aid attachment during posterior lamellar surgery only for few days, these periods can be prolonged with gases in non-expanding concentrations. To test the effects of different gas compositions on immortalized human corneal endothelial cells (HCEC-12), we utilized Transwell inserts with semipermeable membranes as an artificial anterior chamber model.

METHODS

Human corneal endothelial cells (HCEC-12) were cultured on Transwell inserts for 24 hr, then flipped, burdened and sunk with titanium rings in medium (M1), as well as filled with 2 ml of air (A), 20% sulphur hexafluoride (SF6) (S), or 12% C3F8 (C). After gas exposition for 24, 48 and 120 hr, cells were evaluated by live/dead staining, cell viability assay and Ki67 immunohistochemistry.

RESULTS

Proliferation was significantly reduced (Ki67-positive fraction; M1, 14.8 ± 2.0%; A, 7.9 ± 1.4%; S, 8.1 ± 1.3%; C, 9.9 ± 2.3%; p-values; A, S, C versus M1 < 0.01), the total cell number decreased and the percentage of dead cells increased under gas exposition, independently of the type of gas (120 hr cell count/2.25 cm² : M1 = 660.8 ± 57.0 cells; A = 125.5 ± 17.4 cells, S = 123.5 ± 17.0 cells, C = 118.8 ± 16.6 cells; p-value: M versus A/S/C < 0.001; 120 hr dead cells: M = 2.6 ± 1.0%, A = 8.4 ± 2.7%, S = 9.5 ± 3.2%, C = 11.3 ± 3.1%; p-value: M1 versus A/S/C < 0.01). Medium (M1)-control also proved significantly higher cell viability values in comparison with the gases, which did not differ significantly among them (120 hr luminescence: M1 = 1752.2 ± 91.4, A = 433.0 ± 30.3, S = 507.8 ± 23.3, C = 523.8 ± 20.3; p-value: M1 versus A/S/C < 0.01).

CONCLUSIONS

Gas exposition led to a reduction in proliferation and an increase in cell death in HCEC-12, independently of the gas composition.