Risk Factors for Endothelial Decompensation after Penetrating Keratoplasty and Its Novel Therapeutic Strategies

Different Course of Immune Reactions and Endothelial Cell Loss after Penetrating Low-Risk Keratoplasty and Descemet Membrane Endothelial Keratoplasty for Fuchs Endothelial Dystrophy

BACKGROUND

The aim of this study was to compare the incidence of immune reactions and endothelial cell loss after penetrating keratoplasty (PKP) vs. Descemet membrane endothelial keratoplasty (DMEK) in patients with Fuchs endothelial dystrophy (FED).

PATIENTS AND METHODS

In the present retrospective study, a total of 962 surgeries (225 excimer laser PKP and 727 DMEK) of 700 patients performed between 28.06.2007 and 27.08.2020 in the Department of Ophthalmology at Saarland University Medical Center UKS were statistically evaluated. On the one hand, the prevalence and the temporal course of the immune reactions that occurred were analysed using the Kaplan-Meier method, as well as the effect of the immune reactions on the endothelial cells and corneal thickness. Secondly, endothelial cell density, pleomorphism, and polymegethism of the endothelial cells were evaluated for the time points U1 = preoperative, U2 = 6 weeks postoperative, U3 = 6 to 9 months postoperative, U4 = 1 to 2 years postoperative, and U5 = 5 years postoperative. In addition, statistical tests were carried out for differences between the two types of surgery and in the longitudinal course.

RESULTS

A total of 54 immune reactions occurred during the observed period, whereby the probability of such a reaction was significantly greater in the PKP group with 8.9% than in the DMEK group with 4.5% (p = 0.011). The comparison of the two Kaplan-Meier curves also showed a significant difference between the two surgical techniques in the log-rank test (p = 0.012). The endothelial cell loss due to the immune reaction was only significant in PKP (p = 0.003). For all surgical procedures, endothelial cell density decreased significantly with time in both surgical techniques (p < 0.0001 in each case), but more strongly with DMEK than with PKP (p < 0.0001). Furthermore, this cell density was significantly higher with PKP than with DMEK for the whole observation time (p < 0.0001). Polymegethism decreased significantly in the DMEK group (p < 0.0001). Pleomorphism was significantly higher, on average, in DMEK than in PKP (p < 0.0001).

CONCLUSION

The prognosis of DMEK in patients with FED seems to be more favourable after immune reactions than that of PKP, as not only were immune reactions less frequent, but they were also milder. However, endothelial cell density was significantly higher in the PKP group during the entire follow-up.

The impact of donor diabetes on corneal transplant immunity

Corneal transplantation is the most common form of solid tissue grafting, with an approximately 80% to 90% success rate. However, success rates may decline when donor tissues are derived from patients with a history of diabetes mellitus (DM). To evaluate the underlying immunopathologic processes that cause graft rejection, we used streptozotocin-induced type 1 DM (DM1) and transgenic Lepob/ob type 2 DM (DM2) diabetic murine models as donors and nondiabetic BALB/c as recipients. DM resulted in an increased frequency of corneal antigen-presenting cells (APCs) with an acquired immunostimulatory phenotype. Following transplantation, recipients that received either type of diabetic graft showed increased APC migration and T helper type 1 alloreactive cells, impaired functional regulatory T cells, and graft survival. Insulin treatment in streptozotocin-induced diabetic mice led to an increased tolerogenic profile of graft APC, lower T helper type 1 sensitization, and a higher frequency of functional regulatory T cells with high suppressive capacity, reflected in increased graft survival. We conclude that both DM1 and DM2 in donors can impact corneal APC functional phenotype, rendering the tissue more immunogenic and thereby increasing the risk of graft failure.

A Mechanical Evaluation of a Robot-Assisted Cutting Cornea Based on Force Response

The aim of this paper is to propose laws of trephine operation based on a robot-assisted cutting cornea in order to obtain better microsurgical effects for keratoplasty. Using a trephine robot integrated with a microforce sensor and a handheld trephine manipulator, robotic and manual experiments were performed, with porcine corneas as the test subjects. The effect of trephine operational parameters on the results reflected by the biomechanical response is discussed, and the parameters include linear velocity, rotating angle, and angular velocity. Using probability density functions, the distributions of the manual operational parameters show some randomness, and there is a large fluctuation in the trephine force during the experiments. The biomechanical response shows regular trends in the robotic experiments even under different parameters, and compared to manual trephination, the robot may perform the operation of trephine cornea cutting more stably. Under different operational parameters, the cutting force shows different trends, and the optimal initial parameters that result in better trephine effects can be obtained based on the trends. Based on this derived law, the operational parameters can be set in robotic trephination, and surgeons can also be specially trained to achieve a better microsurgical result.

Deep anterior lamellar keratoplasty following thermokeratoplasty assisted epikeratophkia: A novel two-stage one-graft method to treat acute corneal hydrops

Purpose

To evaluate the clinical effects of deep anterior lamellar keratoplasty (DALK) using a single graft after thermokeratoplasty assisted epikeratophakia for the treatment of acute corneal hydrops.

Methods

This novel surgical procedure was performed on seven eyes of seven patients between 2019 and 2020. The procedure combines a first-stage surgery of thermokeratoplasty assisted epikeratophkia with intracameral sterile air injection and a second-stage surgery of DALK using the same corneal graft for both procedures. Main outcome measures included pre- and postoperative corrected distance visual acuity (CDVA) and anterior segment optical coherence tomography (AS-OCT) parameters. Corneal transparency, epithelization, and the presence of neovascularization, were evaluated at the 1-year follow-up visit.

Results

Corneal edema resolved rapidly in six of the seven cases. The mean central corneal thickness was significantly reduced from baseline to 1 day, 1 week, 1 month, and 2 months after the first-stage surgery (P < 0.0001). At a mean of 2.1 ± 0.7 months after the first-stage surgery, DALK was successfully performed in all cases. Six months later, the mean central corneal thickness was 611 ± 31 μm and the mean thickness of the recipient's residual stroma bed was 20 ± 6 μm at the central corneal area. Mean LogMAR CDVA improved from 1.74 ± 0.34 at baseline to 0.20 ± 0.11 after DALK (P < 0.0001). No postoperative complications appeared in our case series during the 1-year observation period.

Conclusion

Very good visual results were obtained with a novel technique (thermokeratoplasty assisted epikeratophakia followed by DALK using the same corneal graft) in the treatment of acute corneal hydrops.

The Descemet Membrane Endothelial Keratoplasty (DMEK) "Wave Maneuver"

A novel technique for Descemet membrane endothelial keratoplasty (DMEK) graft handling and centration without the endothelium touching the posterior part of the anterior chamber (AC), is presented here. It is particularly suitable for vitrectomized eyes, deep AC, and AC intraocular lenses (ACIOLs), potentially reducing surgery time and endothelial cell loss during surgery. This retrospective interventional case series includes 27 eyes with complex ocular pathology. All utilized a “Wave maneuver” to center an early elevated graft without completing graft centration on the bottom of the AC. Successful graft attachment and centration were evaluated intra and post-operatively. Best-corrected visual acuity (BCVA), central corneal thickness (CCT), and donor endothelial cell density (ECD) were measured pre-operatively, and three and six months post-operatively. DMEK grafts were successfully attached and centered in all cases. No maneuver-related complications were observed intraoperatively. BCVA improved from a pre-operative 0.2 ± 0.63, to 0.43 ± 0.49 and 0.76 ± 0.51 at the three- and six-month follow-ups, respectively (p < 0.01). CCT decreased from a pre-operative 742 ± 118, to 546 ± 87 and 512 ± 67 at three and six months, respectively (p < 0.01). ECD decreased from 2878 ± 419 cells/mm2 to 1153 ± 466 cells/mm2 at three and six months, respectively (p < 0.01). The “Wave maneuver” may be very beneficial in DMEK cases where the AC is either very deep or the bottom of the AC is compromised. The “Wave maneuver” learning curve was brief.

Clinical Outcomes in Maximum Tolerated Medical Therapy in Penetrating Keratoplasty for Bullous Keratopathy

Purpose

To compare the clinical outcomes of maximum tolerated medical therapy (MTMT) in patients with penetrating keratoplasty (PKP) with those of Ahmed glaucoma valve (AGV) implantation.

Methods

The medical records were retrospectively reviewed in patients who had undergone PKP for bullous keratopathy and were treated with MTMT or AGV implantation for the management of glaucoma. A total of 18 bullous keratopathic patients were investigated between January 2010 and February 2017: 9 patients treated with MTMT and 9 patients treated with AGV implantation. Non-corrected visual acuity (NCVA), intraocular pressure (IOP), endothelial cell density (ECD), hexagonality, coefficient of variation (CV), central corneal thickness (CCT), median survival time of the graft, and the presence of epithelial keratopathy were compared between the groups at each time point or between baseline and after treatment of glaucoma in each group.

Results

There were no significant differences in the visual acuity and corneal thickness between the two groups or within each group over time. Both groups showed a significant reduction in IOP compared with the baseline IOP, and IOP reductions were greater in the AGV group than in the MTMT group (p = 0.040). Significant ECD reductions were found in each group between the baseline and 6 months (p = 0.008 in the MTMT group, p = 0.015 in the AGV group); however, no differences were found between the two groups until 12 months. The significant hexagonality reduction was found in the AGV group between the baseline and 12 months (p = 0.018). The median survival time showed no significant difference in the survival analysis.

Conclusions

Maximum tolerated medical therapy in penetrating keratoplasty for bullous keratopathy seems to similarly affect the endothelial cell density or graft survival when compared with at least 12 month-followed Ahmed glaucoma valve implantation.

[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.

Effects of femtosecond laser-assisted trephination on donor tissue in liquid interface as compared to applanated interface

Purpose

To evaluate the effects of femtosecond laser‐assisted keratoplasty using a liquid patient interface (L‐PI) as opposed to an applanated interface (A‐PI) on graft quality and functionality markers.

Methods

Pressure measurements during femtosecond laser‐assisted trephination were performed using two groups of 10 porcine eyes. Trephination was performed either in an L‐PI or in an A‐PI setting. Pressure sensor needles placed intravitreally continuously recorded intraocular pressure during trephination. Twenty paired human donor eyes were used to test the morphological quality of donor tissue after trephination in L‐PI and A‐PI settings. Optical coherence tomography (OCT) scans were performed before and after trephination. Images were processed using ImageJ and pixel².

Results

During trephination, pressure measurements with an L‐PI were significantly lower than with an A‐PI (p = 0.0121). Mean pressure during trephination was 78.1 mmHg ± 37.6 mmHg with L‐PI and 188.6 mmHg ± 17.7 mmHg with A‐PI. Trephination in A‐PI produced a significantly larger increase (p < 0.00001) in donor pachymetry than trephination in L‐PI. Significantly lower areas of Descemet folds were achieved in L‐PI trephination than in A‐PI trephination (p < 0.01). There was no significant difference in circularity between A‐PI and L‐PI (p = 0.27). Total time required for trephination was comparable between L‐PI and A‐PI (p = 0.45). Time taken to reach working vacuum was achieved significantly more quickly in L‐PI (p < 0.05).

Conclusion

Femtosecond laser‐assisted L‐PI keratoplasty appears to be a promising method to decrease stress to donor and recipient tissue during femtosecond laser‐assisted trephination. Results showed favourable donor tissue morphology markers after L‐PI trephination.

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.

Incidence of Ultrathin Descemet Stripping Endothelial Keratoplasty Corneal Graft Rejection following Steroid Discontinuation

Purpose/Aims: To determine the incidence of corneal graft rejection in patients with approximately 1 year of steroid therapy following uDSEK. A shortened course of corticosteroids may be beneficial and a viable option in Ultrathin Descemet's Stripping Endothelial Keratoplasty (uDSEK).Materials and Methods: This retrospective cohort study evaluated corneal graft rejection rate in 170 cases of uDSEK that met inclusion criteria with approximately 1 year of steroid therapy. Corneal graft rejection was defined by anterior chamber cell/flare, keratic precipitates with/without corneal edema, and/or a rejection line. The following were collected retrospectively from January 1, 2005 through January 1, 2013: gender, age, race, indication for uDSEK, length of follow-up, length of steroid therapy. Continuous data were compared using Wilcoxon Rank Sum Test and categorical data were compared using Fisher's Exact Test.Results: The included eyes had an average length of steroid therapy of 431 days (range 85-720 days) with an average follow-up of 1274 days (range 395-3186 days). During the follow-up period without steroid, 5 of the 170 eyes were diagnosed with rejection (2.94%). Of the five eyes that experienced rejection, four eyes resolved after topical prednisone was reinstituted alone and did not require repeat uDSEK. The other eye was lost to follow-up. The cumulative probability of rejection after steroid cessation was calculated at 0.67% after 12 months, 2.20% after 18 months, 3.08% after 24 months, and 4.55% after 36 months.Conclusion: Discontinuation of topical steroid at approximately 1 year after uDSEK results in a low rate of corneal graft rejection and may prove extended use unnecessary.

Acute corneal edema decades after penetrating keratoplasty for keratoconus in eyes wearing scleral contact lenses

PURPOSE

To report three cases of acute corneal edema occurring decades after penetrating keratoplasty (PK) for keratoconus in eyes wearing scleral contact lenses (ScCLs) with previously clear corneal grafts.

METHODS

Retrospective chart review of three ScCL wearers presenting for sudden onset pain and blurred vision. Data extracted included clinical presentation, year and reason for PK, ocular medications and comorbidities, contact lens wearing history, results of any ancillary testing available including corneal topography, anterior segment optical coherence tomography (OCT), and specular microscopy surrounding the event, treatment and outcomes of intervention. The number of PK eyes fit with ScCLs in the author's practice was determined to estimate the prevalence of this event.

RESULTS

The three patients each had a longstanding PK for keratoconus performed between 33-35 years prior to presentation and recurrent ectasia. Each patient presented with an acute, painful eye and reduced vision either 3 days, 4 months or 9 years after refitting into ScCLs. Each eye had well demarcated focal microcystic epithelial and stromal edema within the graft and crossing the wound margin onto the host cornea. Although a definitive break or detachment of Descemet's membrane was not visualized, the presentations suggest these were episodes of acute hydrops.

CONCLUSIONS

Longstanding PKs with recurrent ectasia and acute focal edema suggestive of corneal hydrops is demonstrated in this case series of ScCL wearers. Although similar events have occurred as part of the natural history of post-PK corneas for keratoconus, the proximity of ScCL refitting to two of the events suggests some association.

The Cologne rebubbling study: a reappraisal of 624 rebubblings after Descemet membrane endothelial keratoplasty

Background/Aims

To analyse graft detachments prior to rebubbling, the influence of rebubbling on the postoperative outcome after Descemet membrane endothelial keratoplasty (DMEK) and the need for rebubbling on the contralateral eye.

Methods

In this retrospective cohort study, out of 1541 DMEKs, optical coherence tomography scans and clinical records of 499 eyes undergoing rebubbling after DMEK at the University Hospital of Cologne, Cologne, Germany, were examined. Main Outcome measures were (a) number, localisation and size of graft detachments; (b) influence of rebubbling/s on postoperative outcome after 12 months; and (c) rebubbling risk of the contralateral eye after DMEK.

Results

Mean number of detachment areas was 2.02±0.9. Mean lateral diameter of all detachments was 4534.76±1920.83 μm. Mean axial diameter was 382.53±282.02 μm. Detachments were equally distributed over all regions of the cornea. Best spectacle corrected visual acuity ( BSCVA) after 12 months was 0.197±0.23 logarithm of the minimum angle of resolution, endothelial cell density (ECD) was 1575.21±397.71 cells/mm2and mean central corneal thickness (CCT) was 566.37±68.11 μm. BSCVA, CCT, ECD or endothelial cell loss of all rebubbled patients were not influenced by the number of rebubblings or the time between DMEK and rebubbling. Of the rebubbled patients, which received a DMEK subsequently on the other eye, 193 (58.8%) also received a rebubbling, which was significantly higher, when compared to the overall rebubbling rate of 32.3% (p=0.000).

Conclusions

The overall number of rebubblings has no influence on the postoperative outcome after DMEK, if a rebubbling becomes necessary. Patients who received a rebubbling on one eye have an elevated risk for a rebubbling on the fellow eye.

Corneae from body donors in anatomy department: valuable use for clinical transplantation and experimental research

Background

Explanted corneae are highly needed for the surgical management of patients with severe corneal diseases. The aim of this study was to determine whether the body donors from the Institute of Anatomy are a suitable source of donor corneae.

Methods

At the Institute of Anatomy at Saarland University Medical Center in Homburg, corneae are prelevated from body donors who had consented to the removal of tissues for transplantation purposes during their lifetime. Following the report of death, the LIONS Eye Bank is informed and the contraindications of corneal explantation are clarified. Obtaining a blood sample within 24 h postmortem is mandatory.

Results

The Institute of Anatomy had 150 body donors in the time period from January 2018 to June 2019. Out of these, 68 (45.3%) were reported to the Eye Bank. The age of the donors (median 82 years (range: 57–96)) is not critical since the quality of the corneae depends on the number of endothelial cells (mean: 2109 ± 67 cells/mm² (range: 511–2944 cells/mm²)). Contraindications were present in 19 (12.6%) cases. The corneae were extracted from 49 (32.7%) body donors. Out of these 98 corneae, 46 (46.9%) were successfully transplanted. Of all non-transplanted corneae, 6 (6.1%) were microbiologically contaminated, 10 (10.2%) had a positive serology, 22 (22.5%) had an endothelial cell count < 2000 cells/mm² and 6 (6.1%) are at time of this analysis still in culture medium. The non-transplanted tissues were used for research.

Conclusions

Explanted corneae from the Institute of Anatomy are a valuable option in obtaining grafts for corneal transplantation, which is why we are working toward on expanding cooperation with this department.