Endothelial cell density after descemet membrane endothelial keratoplasty: 1- to 2-year follow-up

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.

Clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) with imported donor corneas in eyes of Asian patients; endothelium-in versus endothelium-out method

Objective

We investigated whether (1) imported pre-cut tissue is feasible for Descemet membrane endothelial keratoplasty (DMEK) in eyes of Asian patients, (2) the clinical outcome is comparable between the endothelium‐in and endothelium‐out methods, and (3) the corneal edema-induced anterior curvature changes may have an effect on the refractive error.

Methods

The medical records of 32 DMEK patients who underwent either the endothelium-out or endothelium-in method using imported pre-cut grafts with a 3-day pre-cut-to-use time were retrospectively analyzed. Fuchs’ endothelial dystrophy (37.5%) and bullous keratopathy (62.5%) cases were included. The main clinical outcome measures were graft survival, best corrected visual acuity (BCVA), endothelial cell density (ECD), corneal thickness (CT), and complications. Correlation of the anterior curvature changes with refractive error was analyzed in the DMEK with cataract surgery group.

Results

The overall survival rate was 71.9%. Final graft failures were caused by rejection, glaucoma, and infection. Visual acuities improved by 89.3%. BCVA better than 20/40 and 20/20 was found in 75% and 28.6% of patients, respectively. The ECDs at 3 months and 1 year were 1400 and 1083 cells/mm², respectively. The mean survival time, ECD, BCVA, CT, and complication rates were not different between the endothelium-in and endothelium-out methods. A hyperopic shift by +0.42 D was not related to the anterior curvature changes.

Conclusion

Imported pre-cut tissues with a ≤ 3-day pre-cut-to-use time are feasible for DMEK in the treatment of corneal endothelial edema in eyes of Asian patients, and both endothelium-in and endothelium-out methods appear to be comparatively effective. Edema-induced anterior curvature change may not affect the refractive shift.

Delivering Endothelial Keratoplasty Grafts: Modern Day Transplant Devices

PURPOSE

To summarize the graft loading, transporting and delivery devices used for endothelial keratoplasty (EK).

METHODS

A literature search of electronic databases was performed.

RESULTS

New techniques and devices have been introduced and implemented to prepare, load, transport and transplant the grafts for EK. The advantages are not only limited to the surgical theatre but also widely spread across the eye banking field. Investigation of advanced materials and designs have been rapidly growing with continuous evolution in the field of eye banking and corneal transplantation. Innovative techniques and modern devices have been evaluated to reduce the endothelial cell loss and increase the precision of the transplant in order to benefit both surgeons and the patients.

CONCLUSIONS

It is extremely important to reduce any potential wastage and optimize the use of every available donor cornea due to the limited availability of healthy cadaveric donor corneas required for transplants. As a result, the use of pre-cut and pre-loaded grafts supplied by the eye banks in calibrated devices have been gaining momentum. Innovation in the field of bioengineering for the development of new devices that facilitate excellent clinical outcomes along with reduction in learning curve has shown promising results.

A simple surgical technique for splitting a single donor cornea for performing deep anterior lamellar keratoplasty and Descemet membrane endothelial keratoplasty without using a microkeratome

Purpose:

To describe a simple manual surgical technique for splitting a single-donor eye for performing both deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK) without using a microkeratome.

Methods:

Twenty-three eyes with anterior stromal pathology and 23 eyes with irreversible endothelial dysfunction were evaluated for keratoplasty at a tertiary eye care referral center. Twenty-three healthy donor corneas were split into two parts. The Descemet’s membrane was stripped and used for DMEK. The stripped stroma was used for DALK. Best-corrected visual acuity (BCVA) of both DALK and DMEK, endothelial cell density, and endothelial cell loss in DMEK were noted at 1-year follow-up, along with any intraoperative or postoperative complications and failures.

Results:

In the DALK group, mean BCVA improved from 1.264 ± 0.25 log Mar preoperatively to 0.355 ± 0.27 log Mar at 12 months follow-up. There were no complications and failures. In the DMEK group, mean BCVA improved from 1.537 ± 0.61 log Mar preoperatively to 0.592 ± 0.67 log Mar and the mean donor ECD was 3071.66 (range, 2783–3487) cells/mm² preoperatively, which was reduced to 1989.33 (range, 1546–2543) cells/mm² at 12 months follow-up indicating a mean endothelial cell loss of 35%. The failure rate was 21.7%.

Conclusion:

This study demonstrates that with a single donor corneal tissue, both DALK and DMEK can be performed successfully without any complications. Our technique will help corneal surgeons in all developing countries to cost effectively perform more lamellar surgeries and help in reducing the magnitude of corneal blindness without the need for expensive microkeratomes.

Changes in Corneal Parameters after DMEK Surgery: A Swept-Source Imaging Analysis at 12-Month Follow-Up Time

Purpose

To assess the time course changes in corneal topographic parameters during the one-year follow-up after Descemet membrane endothelial keratoplasty (DMEK) surgery.

Materials and Methods

Twenty-one patients (24 eyes) who underwent DMEK surgery were evaluated. Best corrected visual acuity (BCVA), endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA), and higher-order aberration (HOA) were assessed at baseline and 1, 3, 6 and 12 months after the surgery using CASIA2 anterior segment swept-source OCT (Tomey, Japan).

Results

In patients who underwent DMEK surgery, BCVA improved gradually at the subsequent visits during the 12-month follow-up. A significant reduction in ECC and CCT at the 1st month was noted, which remained stable until the 6th month postoperatively. Anterior and total MK values remained unchanged, whereas changes in posterior keratometry were noticeable until the 6th month after surgery. A significant reduction in the anterior, posterior, and total astigmatism magnitude as well as astigmatism asymmetry was observed during the first 6 months after surgery. A gradual anterior, posterior, and total HOA decrease was documented until the 12th month after surgery. Negative correlations between baseline values of CCT, MK, MA, AA, and HOA and postoperative variations in those parameters at consecutive follow-up time points were observed. Accordingly, negative correlations between baseline CCT and postoperative changes in corneal topographic parameters after surgery were found.

Conclusion

The stabilization of most corneal topographic parameters takes place within 6 months after the procedure, whereas HOA reduction and BCVA improvement gradually occur during the first year after surgery. Preoperative values of corneal topographic parameters strongly determine their changes detected after DMEK surgery, which may suggest that early therapeutic intervention results in better visual outcomes.

Two-year clinical outcome after Descemet membrane endothelial keratoplasty using a standardized protocol

PURPOSE

The purpose of this study is to evaluate 2-year clinical outcome after Descemet membrane endothelial keratoplasty (DMEK) in a variety of endothelial dysfunctions using a standardized protocol.

METHODS

: From a group of 230 eyes which underwent DMEK for Fuchs' endothelial corneal dystrophy (FECD), aphakic and pseudophakic bullous keratopathy, failed full thickness corneal transplants, ICE syndrome, failed DSEK, and TASS the clinical outcomes [best spectacle-corrected visual acuity (BSCVA), central endothelial cell density (ECD)] were evaluated before, and at 6, 12, and 24 months and the success rate, failure rate and postoperative complications were also analyzed.

RESULTS

Out of 230 eyes, 144 eyes (70%) had BSCVA 6/9 or better 2 years postoperatively. Mean donor ECD was 2692.23 (range, 2300-3436) cells/mm2 preoperatively, which was reduced to 1433.64 (range, 619.0-2272.0) cells/mm2 2 years after DMEK surgery, indicating a mean reduction of 1258 cells/mm2 (46%) in ECD.

CONCLUSION

DMEK is a highly successful surgical procedure when following a standard protocol for treating diseases of the corneal endothelium providing a near perfect anatomic restoration and a high degree of visual rehabilitation.

Surgery for glaucoma in modern corneal graft procedures

Glaucoma is a common cause of vision loss after corneal transplantion and is considered a major risk factor for graft failure. Glaucoma may be present before corneal transplant surgery, or increased intraocular pressure may develop after keratoplasty in up to one-third of patients. Pre-existing glaucoma should be controlled before keratoplasty, either medically or surgically. For postkeratoplasty increase in intraocular pressure; identifying the risk factors allows appropiate follow-up and management. Patients undergoing anterior lamellar keratoplasty may take advantage of reduced rates of postkeratoplasty glaucoma. Glaucoma also complicates eyes with endothelial keratoplasties, mostly related to management of intraocular pressure spikes derived from anterior chamber air bubbles. Nevertheless, the severity is less, and the intraocular pressure is more easily controlled when compared with penetrating keratoplasty. Adequate management of glaucoma that develops before or after keratoplasty may save eyes from irreversible damage to the optic nerve and increase graft survival.

Regeneration of the Corneal Endothelium

Penetrating keratoplasty was the only therapeutic choice for the treatment of corneal endothelial decompensation until the introduction of evolutional endothelial keratoplasties, namely Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK). Although now in widespread use, DSAEK and DMEK still have associated problems, such as difficulty of the surgical technique, acute and chronic cell loss, and shortage of donor corneas. Therefore, regeneration of the corneal endothelium by tissue engineering techniques is being researched to overcome these problems. The concept of transplantation of cultured corneal endothelial cells (CECs) was proposed in the 1970s. However, cultivation of human CECs (HCECs) in sufficient quantity and with acceptable quality for clinical use has proven surprisingly difficult, and the development of methods for transplanting cultured HCECs has been necessary. Numerous research groups have developed culture protocols and techniques that are now bringing corneal endothelial regeneration closer to real-world therapy. For instance, we started a clinical trial in 2013 involving the injection of cultured HCECs into the anterior chamber of patients with corneal endothelial decompensation. This review outlines the rapid progression of this research field, including clinical trial results, and is also intended to identify topics that still require further research or discussion.

Significant differences between specular microscopy and corneal bank endothelial cell counts - a pilot study

BACKGROUND

It was shown recently that endothelial cell count performed by cornea banks overestimates the real number of endothelial cells. The aim of this study was to investigate the internal quality of preclinical ECD in human donor corneas using two widely used methods for endothelial cell counting, transmitted light microscopy used in organ culture tissue bank and clinically used specular microscopy.

METHODS

Twenty human donor corneas that could not be transplanted were included in this analysis. Differences in evaluating endothelial cell density (ECD) and hexagonal endothelial cell ratio (HEX) between clinical specular microscopy (CSM) and corneal bank transmitted light microscope (CBLM) were evaluated as well as differences between automated and manual cell counts.

RESULTS

Automated CBLM showed a higher ECD of 31.85% compared to automated CSM, while manual CBLM counting is 10.51% higher compared to manual CSM (p < 0.01). Further, higher average ECD values result in a higher difference between CSM and CBLM measurements. The manual CBLM ECDs were significantly higher compared to automated derived ECD from CSM (p < 0.01). However, no systematic bias can be detected when comparing the differences of the measurements with the average ECD measurements of both methods.

CONCLUSION

This preclinical pilot study confirmed a significant higher ECD using transmitted light microscopy in organ culture compared to clinical specular microscopy. This indicates that the early rapid decrease of EC universally observed after surgery might be partly artefactual.

Clinical Outcomes Of Descemet Membrane Endothelial Keratoplasty Using The Bonfadini-Todd Injector For Graft Insertion

Purpose

To evaluate the clinical outcomes of using an Alcon intraocular lens (IOL) B cartridge for graft insertion during Descemet membrane endothelial keratoplasty (DMEK).

Patients and methods

We retrospectively reviewed medical charts of patients who underwent DMEK using the Bonfadini-Todd injector, composed of an Alcon IOL B cartridge connected to plastic tubing and a syringe, for graft insertion between May 2016 and August 2018. Patient demographics, diagnoses, donor information, visual acuity, intraocular pressure (IOP), graft position and attachment status, pachymetry, and postoperative complications were recorded.

Results

Twenty-four eyes of 23 patients with an average age of 72.8 ± 10.0 years (range, 48–87 years) were included. Mean follow-up duration was 13.3 ± 6.6 months (range, 3–26 months). Twenty-one (87.5%) patients had a primary diagnosis of Fuchs endothelial dystrophy, two (8.3%) patients had bullous keratopathy and one (4.2%) had Peter’s anomaly. Sixteen (66.7%) cases combined phacoemulsification and IOL implantation. Best-corrected visual acuity improved from a median of 0.398 logMAR preoperatively to 0.097 logMAR (P <0.001) at last follow-up examination, and central corneal thickness decreased from a median of 651 μm to 533.5 μm (P <0.001). Nine of 24 patients (37.5%) required re-bubbling due to partial graft detachment with a mean time of 12.1 ± 9.2 days (range, 5–35 days). One patient (4.2%) developed graft failure after re-bubbling and underwent Descemet stripping endothelial keratoplasty.

Conclusion

The Alcon IOL B cartridge for DMEK graft insertion is safe and simple.

Favourable outcome after late reorientation of an upside-down Descemet Membrane Endothelial Keratoplasty (DMEK) graft: a case report

Background

Clinical outcome after successful reorientation of an upside-down implanted DMEK (Descemet Membrane Endothelial Keratoplasty) graft 4 weeks after initial transplantation.

Case presentation

A 71-year-old woman presented with Fuchs’ endothelial corneal dystrophy for DMEK. After initial DMEK the donor graft was fully attached and well centred during intracameral gas filling. When the gas bubble was fully resorbed the graft started to detach. Therefore, two intracameral gas injections were consecutively performed. During the second re-bubbling, an upside-down orientation was observed and so the graft was flipped, centred, re-attached and finally stabilized by an intracameral gas bubble. Three weeks after reorientation slit lamp examinations showed a well centred and attached graft, endothelial cells that started functioning and a patient’s visual acuity of 20/40. Visual acuity increased to a 20/32 vision in the observed eye three months later and further improved to 20/20 6 months after reorientation and stayed stable between 20/32 and 20/20 during the remaining 15 months of follow-up, with a clear and well-attached graft.

Conclusion

Reorientation of an upside down DMEK graft was successful even 4 weeks after initial DMEK. Visual recovery and endothelial cell count increase were stepwise noticed during the first 6 months and 15 months after reorientation, respectively. Finally a favourable outcome with 20/32 to 20/20 vision at least 6 months after graft reorientation was achieved. Therefore, restoring full graft function could last several weeks or even months following (late) reorientation of an upside-down DMEK graft.

Corneal endothelial cell dysfunction: etiologies and management

A transparent cornea is essential for the formation of a clear image on the retina. The human cornea is arranged into well-organized layers, and each layer plays a significant role in maintaining the transparency and viability of the tissue. The endothelium has both barrier and pump functions, which are important for the maintenance of corneal clarity. Many etiologies, including Fuchs’ endothelial corneal dystrophy, surgical trauma, and congenital hereditary endothelial dystrophy, lead to endothelial cell dysfunction. The main treatment for corneal decompensation is replacement of the abnormal corneal layers with normal donor tissue. Nowadays, the trend is to perform selective endothelial keratoplasty, including Descemet stripping automated endothelial keratoplasty and Descemet’s membrane endothelial keratoplasty, to manage corneal endothelial dysfunction. This selective approach has several advantages over penetrating keratoplasty, including rapid recovery of visual acuity, less likelihood of graft rejection, and better patient satisfaction. However, the global limitation in the supply of donor corneas is becoming an increasing challenge, necessitating alternatives to reduce this demand. Consequently, in vitro expansion of human corneal endothelial cells is evolving as a sustainable choice. This method is intended to prepare corneal endothelial cells in vitro that can be transferred to the eye. Herein, we describe the etiologies and manifestations of human corneal endothelial cell dysfunction. We also summarize the available options for as well as recent developments in the management of corneal endothelial dysfunction.

Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty Grafts With Endothelium Tri-Folded Inwards

PURPOSE

To evaluate the initial outcomes and complications of Descemet membrane endothelial keratoplasty (DMEK) using donor tissues tri-folded with the endothelium inwards, preloaded at the Eye Bank, and delivered with bimanual pull-through technique.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

Setting: Eye bank and tertiary care eye department.

PATIENT POPULATION

Forty-six consecutive eyes of 41 patients with Fuchs endothelial dystrophy with or without cataract operated between November 2016 and March 2017.

INTERVENTION

DMEK tissues prepared with SCUBA technique and punched to a diameter of 8.25 mm were preloaded with the endothelium tri-folded inwards in an intraocular lens (IOL) cartridge with a 2.2-mm opening filled with the same tissue culture medium contained in the vial used for shipment to the surgeon. Standardized DMEK was performed as a single procedure (n = 15) or in combination with phacoemulsification and IOL implantation (n = 31) within 48 hours from preparation using a bimanual pull-through technique.

MAIN OUTCOME MEASURES

Preparation and surgical times, intraoperative and postoperative complications, best spectacle-corrected visual acuity (BSCVA), endothelial cell density (ECD), and graft detachment rate.

RESULTS

Preparation time averaged 26.2 ± 4.1 minutes (range 17-36 minutes), while the surgical time from opening of the stoppers to air fill of the anterior chamber never exceeded 9 minutes (range 3-9 minutes). Surgery was uneventful in all cases. Postoperative complications included graft detachment in 9 of 46 cases (19.6%), successfully managed in all cases by single rebubbling within 6 days from surgery, and glaucoma irresponsive to conservative treatment in 1 of 46 cases (2.1%). In all eyes without comorbidities (35 of 40 eyes) BSCVA was 20/25 (0.097 logMAR) or better as early as 3 months after surgery. Six months postoperatively, ECD was available in 24 of 25 eyes with an endothelial cell loss calculated as a percentage of the preoperative value determined at the eye bank (ranging from 2500 to 2800 cells/mm²) of 29.5% ± 14.8% (range 8.3%-52.1%).

CONCLUSIONS

Delivering a preloaded DMEK tissue, tri-folded with the endothelium inwards, minimizes surgical time and costs without negatively affecting the outcomes of the procedure.

Donor Tissue Preparation for Descemet Membrane Endothelial Keratoplasty: An Updated Review

PURPOSE

To provide an overview of the current literature on donor tissue preparation for Descemet membrane endothelial keratoplasty (DMEK).

METHODS

A comprehensive database search without date restrictions was performed in PubMed and in The Cochrane Library in May, 2017. Keywords included Descemet membrane endothelial keratoplasty, corneal transplantation, graft, harvest, dissection, preparation, endothelial cell, and endothelial cell density. Articles aiming to describe or evaluate a technique for DMEK graft preparation were considered eligible and were included in this review.

RESULTS

A graft dissection technique that provides consistent tissue qualities and a low risk of preparation failure is essential for surgeons and eye banks preparing DMEK tissue. Various techniques have been described aiming to facilitate DMEK graft dissection, including manual dissection, pneumatic dissection, and hydrodissection. All show a trend toward a no-touch technique, for example, without direct physical tissue manipulation during tissue harvesting, as a potential ideal approach to minimize graft damage.

CONCLUSIONS

An overview of the current harvesting techniques available for DMEK may benefit corneal surgeons and eye banks in choosing the best approach for each specific user.

Quantitative Analysis of Endothelial Cell Loss in Preloaded Descemet Membrane Endothelial Keratoplasty Grafts

PURPOSE

Availability of preloaded Descemet membrane endothelial keratoplasty (pDMEK) tissue may increase acceptance of DMEK in surgical management of endothelial disease. The goal of this study was to determine the safety of pDMEK grafts for 24 hours before surgery by analyzing endothelial cell loss (ECL) using 2 image analysis software programs.

METHODS

A total of 18 cadaveric corneas were prepared for DMEK using a standardized technique and loaded in a modified Jones tube injector. Nine of the corneas were injected into Calcein AM vital dye after 1 minute (controls), and the remaining 9 corneas were left preloaded for 24 hours before injection into vital dye for staining. The stained corneas were imaged using an inverted confocal microscope. ECL was then analyzed and quantified by 2 different graders using 2 image analysis software programs.

RESULTS

The control DMEK tissue resulted in 22.0% ± 4.0% ECL compared with pDMEK tissue, which resulted in 19.2% ± 7.2% ECL (P = 0.31). Interobserver agreement was 0.93 for MetaMorph and 0.92 for Fiji. The average time required to process images with MetaMorph was 2 ± 1 minutes and with Fiji was 20 ± 10 minutes. Intraobserver agreement was 0.97 for MetaMorph and 0.93 for Fiji.

CONCLUSIONS

Preloading DMEK tissue is safe and may provide an alternative technique for tissue distribution and surgery for DMEK. The use of MetaMorph software for quantifying ECL is a novel and accurate imaging method with increased efficiency and reproducibility compared with the previously validated Fiji.

Lutein and Brilliant Blue-Based Dye for Donor Preparation and Transplantation in Descemet Membrane Endothelial Keratoplasty

PURPOSE

Trypan blue (TB) is used for visualization of the endothelium-Descemet membrane graft during Descemet membrane endothelial keratoplasty (DMEK). However, TB is assumed to have a dose-dependent toxic effect on the corneal endothelium. We retrospectively compared a lutein/zeaxanthin and Brilliant Blue (LZ/BB)-based dye for preparation and transplantation of the graft in DMEK to TB.

METHODS

In 20 patients, a dye composed of 1% LZ /0.025% BB was used, and in 22 patients, 0.06% TB was used for graft visualization in DMEK. We evaluated the rebubbling rate, best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) before and 3 and 6 months after transplantation.

RESULTS

Staining of endothelium-Descemet membrane with LZ/BB was faint but sufficient. There was no significant difference between both groups, except in CCT after 3 months, which was lower in the LZ/BB group (P = 0.02). In the LZ/BB group, BSCVA improved from 0.48 ± 0.39 before DMEK to 0.19 ± 0.09 after 6 months (P < 0.05) (20% rebubbling rate). Donor ECD decreased from 2735 ± 259 cells/m preoperatively to 1876 ± 316 cells/mm (P < 0.0001) at 6 months (31.4%). CCT decreased from 642 ± 130 μm preoperatively to 519.8 ± 38 μm (P < 0.0001) at 6 months. In the TB group, BSCVA improved from 0.43 ± 0.27 to 0.17 ± 0.14 (P = 0.0003) at 6 months (30% rebubbling rate). ECD decreased from 2825 ± 263 to 1777 ± 302 cells/mm (P < 0.0001) after 6 months (36.3%), CCT from 638 ± 48 μm preoperatively to 531 ± 48 μm (P < 0.0001) at 6 months.

CONCLUSIONS

LZ/BB-based dyes are suitable for DMEK with outcomes comparable to TB. However, available formulas result in faint staining, discouraging their routine use in donors with assumed difficult preparation.

Comparison of Femtosecond Laser-Enabled Descemetorhexis and Manual Descemetorhexis in Descemet Membrane Endothelial Keratoplasty

PURPOSE

To introduce a novel method to perform descemetorhexis in Descemet membrane endothelial keratoplasty (DMEK) using the femtosecond laser and to compare it with Descemet membrane endothelial keratoplasty performed with manual descemetorhexis (M-DMEK).

METHODS

A retrospective medical chart review of 2 groups of patients who underwent DMEK surgery combined with cataract surgery secondary to Fuchs corneal endothelial dystrophy and cataract: 17 patients underwent femtosecond laser-enabled descemetorhexis Descemet membrane endothelial keratoplasty (FE-DMEK) and 89 patients underwent DMEK surgery with M-DMEK. Best spectacle-corrected visual acuity, endothelial cell density (ECD), graft detachment rate, and complications were compared.

RESULTS

Average age of the 106 patients (64 women and 42 men) was 68 ± 11 years. Postoperative best spectacle-corrected visual acuity was 0.19 ± 0.13 logarithm of the minimum angle of resolution in the FE-DMEK group and 0.35 ± 0.48 logarithm of the minimum angle of resolution in the M-DMEK group (P = 0.218). One day after surgery, there were no significant graft detachments in the FE-DMEK group, compared with 20% graft detachment rate in the M-DMEK group (P = 0.041). Rebubbling was performed in 17% of eyes in the M-DMEK group compared with none in the FE-DMEK group (P = 0.066). The mean endothelial cell count in the FE-DMEK and M-DMEK groups at 6 months after surgery were 2105 ± 285 cells per square millimeter (24% cells loss) and 1990 ± 600 cells per square millimeter (29% cells loss), respectively (P = 0.579).

CONCLUSIONS

FE-DMEK shows efficacy similar to that of M-DMEK with apparently less graft detachment and reduced need for rebubbling.

Vent Incisions to Facilitate Peripheral Unfolding of the DMEK Graft

PURPOSE

To present the results of 15 cases in which a modified technique of Descemet membrane endothelial keratoplasty (DMEK) with vent incisions was used to assist unfolding of tight peripheral inward folds.

METHODS

This is a retrospective case series of 15 consecutive eyes that underwent a modified vent incision technique for DMEK. Six oblique, small-size (1 mm) vent incisions parallel to the limbus and 3.5 mm from the center were performed after descemetorhexis. The graft was opened with standard no-touch techniques and was partially attached to the stroma with air injection. Then, in cases with remaining tight inward folds despite gentle corneal tapping, jets of balanced salt solution were pulsed through the vent incisions directed at the peripheral folds to achieve complete unfolding.

RESULTS

Descemet membrane endothelial keratoplasty was performed in 2 phakic eyes (14%) and 13 pseudophakic eyes (86%). Six cases (40%) required fluid injection through the vent incisions: 3 corresponded to grafts from younger donors (54, 41, and 29 years old), and 3 had a 9.0-mm-sized graft. Complete graft unfolding was successfully achieved in 14 cases (93%), and in 1 case (7%), peripheral folds remained because of spontaneous bleeding in the anterior chamber. A clear cornea was achieved in all cases, and there were no postoperative complications associated with the vent incisions.

CONCLUSIONS

This technique provides a different DMEK no-touch approach that could be used in challenging cases of graft unfolding such as young donors and/or large-sized grafts. It may also avoid excessive unfolding times and direct manipulation that are related to higher endothelial cell loss.

Results of Femtosecond Laser-Assisted Descemet Stripping Automated Endothelial Keratoplasty

Purpose

To evaluate femtosecond laser in DSAEK surgery as an improvement to manual DSAEK.

Settings

Department of Ophthalmology, Cairo University.

Design

A retrospective observational clinical study.

Methods

20 eyes with SBK and Fuchs' dystrophy underwent a Femto-assisted DSAEK by laser cutting of two matching posterior stromal discs in the recipient and donor corneas and then fitting the donor disc in the posterior corneal defect of the recipient using Busin's glide or Terry forceps.

Results

Corneal thickness decreased significantly from a mean of 900-micron preoperative values (900.7 m) to 562 m postoperatively. Evidence of side healing was documented by OCT. One patient had a double AC, one patient had an air interface entrapment “Double Bubble,” one patient had a fungal infection and was treated by a therapeutic penetrating keratoplasty, and one patient had a CMO.

Conclusion

Femtolaser-assisted DSAEK may be superior to manual techniques as it offers better centration, thinner graft/host complex, earlier corneal detergecense, and stronger healing. This study was registered at Researchregistry.com with a UID: researchregistry2274.

Incidence and Clinical Course of Immune Reactions after Descemet Membrane Endothelial Keratoplasty: Retrospective Analysis of 1000 Consecutive Eyes

PURPOSE

To analyze the incidence and clinical course of graft rejection episodes after Descemet membrane endothelial keratoplasty (DMEK).

DESIGN

Retrospective analysis of a consecutive, interventional case series.

PARTICIPANTS

One thousand eyes that underwent DMEK from July 2011 through August 2015 at the Department of Ophthalmology, University of Cologne.

METHODS

All cases with follow-up of at least 1 month were included (mean follow-up, 18.5 months). Patients with a graft rejection episode were followed up for 1 additional year.

MAIN OUTCOME MEASURES

Incidence of graft rejection, best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD), and need for regraft.

RESULTS

Nine hundred five cases met the inclusion criteria. A graft rejection episode developed in 12 patients (estimated probability of rejection at 1 year, 0.9%; at 2 years, 2.3%; at 4 years, 2.3%). At time of rejection, 9 of 12 patients had stopped corticosteroids. Five patients were symptomatic and 7 did not note the rejection episode. Intensified topical corticosteroid therapy was started immediately after diagnosis of rejection. Two eyes decompensated and required a regraft, whereas the remaining 10 eyes required no regraft (BSCVA, 0.27±0.28 logarithm of the minimum angle of resolution [logMAR]; CCT, 554.1±39.1 μm at last visit before rejection vs. BSCVA, 0.21±0.15 logMAR; CCT, 540.0±15.0 μm 3 months after rejection). One year after the rejection episodes, BSCVA and CCT in these eyes remained unchanged when compared with the last visit before rejection (BSCVA, 0.15±0.11 logMAR; CCT, 533.8±26.0 μm). Significant changes were observed for ECD values (1741±274.5 cells/mm² at last visit before rejection vs. 1356±380.3 cells/mm² after 3 months [P = 0.04] and 1290±359.0 cells/mm² after 1 year [P = 0.01]).

CONCLUSIONS

The risk for graft rejection after DMEK is low, and an even smaller minority requires a regraft. After intensified local corticosteroid therapy, most patients show stable visual acuity and CCT, although ECD decreases. The occurrence of immune reactions up to 2 years after surgery predominantly in patients not receiving corticosteroids supports the prolonged use of corticosteroids after DMEK.

Fuchs endothelial corneal dystrophy: current perspectives

Fuchs endothelial corneal dystrophy (FECD) is the most common corneal dystrophy and frequently results in vision loss. Hallmarks of the disease include loss of corneal endothelial cells and formation of excrescences of Descemet's membrane. Later stages involve all layers of the cornea. Impairment of endothelial barrier and pump function and cell death from oxidative and unfolded protein stress contribute to disease progression. The genetic basis of FECD includes numerous genes and chromosomal loci, although alterations in the transcription factor 4 gene are associated with the majority of cases. Definitive treatment of FECD is corneal transplantation. In this paper, we highlight advances that have been made in understanding FECD's clinical features, pathophysiology, and genetics. We also discuss recent advances in endothelial keratoplasty and potential future treatments.

Optimization of Cultured Human Corneal Endothelial Cell Sheet Transplantation and Post-Operative Sheet Evaluation in a Rabbit Model

PURPOSE

To optimize cultured human corneal endothelial cell (cHCEC) sheet transplantation technique for maintenance of cHCEC viability.

MATERIALS AND METHODS

cHCEC sheets cultured on a collagen scaffold were covered with or without Viscoat® and exposed to humidified air in the incubator. cHCEC sheets with or without Viscoat® were transplanted into cadaveric porcine eyes by the DSAEK technique with full air tamponade and incubated for various time periods. Then cell viability was determined by using the live/dead assay kit. cHCEC sheets with Viscoat® were transplanted into rabbit eyes and the sheets were histologically evaluated before and 14 days after transplantation.

RESULTS

A collagen scaffold and Viscoat® were effective for protecting cHCEC from damage due to air exposure in vitro. All cells died after 18 hours of air exposure in porcine eyes in Viscoat® untreated control. In contrast, Viscoat® treatment sustained full cell viability following 2 hours and could maintain approximately 80% viability after 18 hours. In a rabbit model, transplanted cHCEC sheet with Viscoat® maintained cell density at 2803 ± 229 mm(2) (18% cell loss) and expression of N-cadherin, zonula occludens-1, and actin-filament localized to cell boundary as similar as donor HCEC.

CONCLUSION

Viscoat® can contribute to cHCEC protection from damage caused by exposure to air.

Fellow Eye Comparison of Descemet Membrane Endothelial Keratoplasty and Penetrating Keratoplasty

PURPOSE

To compare the visual outcomes and postoperative complications in patients undergoing penetrating keratoplasty (PKP) in 1 eye followed by Descemet membrane endothelial keratoplasty (DMEK) in their fellow eye.

METHODS

A retrospective analysis of 11 patients, who underwent a PKP procedure first in 1 eye and then a DMEK surgery in their fellow eye, was performed. Intraoperative and postoperative complications were recorded. Visual and refractive outcomes were also evaluated, including higher-order aberrations (HOAs) and contrast thresholds. A subjective questionnaire was used to evaluate patient satisfaction.

RESULTS

Both uncorrected and best-corrected visual acuities were significantly better in the case of DMEK when compared with that in the case of PKP (0.82 vs. 0.37 logMAR, P = 0.005; 0.61 vs. 0.21 logMAR, P = 0.011, respectively). Postkeratoplasty astigmatism, mean spherical equivalent, and HOAs were also significantly lower in eyes after undergoing DMEK than after undergoing PKP (3.90 vs. 0.89 diopters, P = 0.005; -3.90 vs. -0.68 diopters, P = 0.005; 6.81 vs. 1.71 µm, P = 0.043, respectively). Visual outcome and patient satisfaction were significantly better in those who underwent DMEK (2.91 vs. 4.45, P = 0.011; 3.27 vs. 5.64, P = 0.016, respectively). The estimated time for recovery and rehabilitation was significantly shorter after DMEK (64.0 vs. 9.3 days, P = 0.012). Contrast threshold was better after the DMEK. Ten of 11 patients preferred DMEK procedure.

CONCLUSIONS

The Patients preferred DMEK to PKP. The reasons for better patient satisfaction after DMEK included better uncorrected visual acuity, better best-corrected visual acuity, avoidance of surgery-induced astigmatism, and lower HOA.

Determinants of visual quality after endothelial keratoplasty

Endothelial keratoplasty is now favored over full-thickness penetrating keratoplasty for corneal decompensation secondary to endothelial dysfunction. Although endothelial keratoplasty has evolved as surgeons strive to improve outcomes, fewer patients than expected achieve best corrected visual acuity of 20/20 despite healthy grafts and no ocular comorbidities. Reasons for this remain unclear, with theories including anterior stromal changes, differences in graft thickness and regularity, induced high-order aberrations, and the nature of the graft-host interface. Newer iterations of endothelial keratoplasty such as thin manual Descemet stripping endothelial keratoplasty, ultrathin automated Descemet stripping endothelial keratoplasty, and Descemet membrane endothelial keratoplasty have achieved rates of 20/20 acuity of approximately 50%, comparable to modern cataract surgery, and it may be that a ceiling exists, particularly in the older age group of patients. Establishing the relative contribution of the factors that determine visual quality following endothelial keratoplasty will help drive further innovation, optimizing visual and patient-reported outcomes while improving surgical efficacy and safety.

Descemet's Stripping Automated Endothelial Keratoplasty versus Descemet's Membrane Endothelial Keratoplasty in the Fellow Eye for Fuchs Endothelial Dystrophy: A Retrospective Study

Aim. To evaluate visual outcome and endothelial cell density (ECD) after Descemet's Membrane Endothelial Keratoplasty (DMEK) in comparison with Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) in the fellow eye for Fuchs endothelial dystrophy (FED). Design. Single-centre, retrospective case series. Methods. 30 eyes of 30 patients undergoing DMEK, who completed a 1-year follow-up, were compared with 30 fellow eyes which underwent DSAEK for bilateral FED. Main outcome measures studied included Best Corrected Visual Acuity (BCVA) and ECD during a 1-year follow-up period. Results. BCVA improved from 0.78 ± 0.35 logMAR, and 0.73 ± 0.31 logMAR before surgery to 0.22 ± 0.1 logMAR and 0.35 ± 0.12 logMAR 6 months after DMEK and DSEK, respectively (P < 0.001). At one year after surgery, the BCVA was maintained at 0.21 ± 0.12 logMAR and 0.34 ± 0.1 logMAR, respectively, after DMEK and DSAEK. A statistically better visual outcome was observed after DMEK compared to DSAEK (P < 0.05) in fellow eyes. Conclusions. DMEK provided better visual rehabilitation when compared to DSAEK. Nevertheless, there were no significant differences with regard to the ECD within a 1-year follow-up.

The First 100 Eyes of Standardized Descemet Stripping Automated Endothelial Keratoplasty versus Standardized Descemet Membrane Endothelial Keratoplasty

PURPOSE

To compare results of the first 100 eyes of Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) that were performed with a standardized technique at a single institution.

DESIGN

Single-center, retrospective case series.

PARTICIPANTS

The first 100 eyes of standardized DSAEK and DMEK that underwent surgery for Fuchs corneal dystrophy at our center. We excluded patients with prior ocular surgery other than cataract surgery to limit confounding variables.

METHODS

Best spectacle-corrected visual acuity (BSCVA; in logarithm of the minimal angle of resolution [logMAR] units) was obtained and specular microscopy of donor corneal tissue was performed before surgery. Postoperative complications, BSCVA, and the percent of endothelial cell loss (ECL) recorded at 6 months were compared with the Student t test. Patients with pre-existing ocular comorbidity that impacted visual potential such as macular degeneration, amblyopia, advanced glaucoma, and other optic neuropathies were excluded from the analysis of visual acuity, but were included for the outcomes of complications and ECL.

MAIN OUTCOME MEASURES

Visual acuity improvement, ECL 6 months after surgery, postoperative complications, iatrogenic primary graft failure (IPGF), and rebubbling.

RESULTS

Of the 200 eyes, 62 DSAEK eyes and 70 DMEK eyes had 6-month BSCVA available and no vision-limiting comorbidities. Mean BSCVA increased from 0.41±0.19 logMAR and 0.27±0.11 logMAR before surgery to 0.20±0.13 logMAR and 0.11±0.13 logMAR 6 months after DSAEK and DMEK, respectively (P<0.001). Seventy-one DSAEK eyes and 70 DMEK eyes had 6-month ECL data available: ECL was 25.9±14.0% after DSAEK and 27.9±16.0% after DMEK (P=0.38). There were no IPGFs in the DSAEK cohort and there were 4 of 100 IPGFs after DMEK (P=0.12). Rebubbling was performed in 2 of 100 eyes after DSAEK and in 6 of 100 eyes after DMEK (P=0.28).

CONCLUSIONS

Compared with DSAEK, DMEK provided better visual recovery and comparable 6-month ECL. The DMEK group had a higher, although not statistically significant, percentage of rebubbling procedures and IPGFs.

Repeat Descemet Membrane Endothelial Keratoplasty: Secondary Grafts with Early Intervention Are Comparable with Fellow-Eye Primary Grafts

PURPOSE

To evaluate the outcomes of secondary Descemet membrane endothelial keratoplasty (DMEK) after failed primary DMEK.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Fifty-five DMEK recipients 42 to 89 years of age.

METHODS

An initial consecutive series of 1655 DMEK surgeries was reviewed to identify cases of secondary DMEK after failed primary DMEK (n = 55). A paired fellow-eye analysis was performed with a subgroup of 29 patients who underwent secondary DMEK in 1 eye and successful primary DMEK in the fellow eye.

MAIN OUTCOME MEASURES

Corrected distance visual acuity (CDVA), central corneal thickness, and 1-year endothelial cell loss.

RESULTS

The median follow-up after DMEK regraft was 18 months (range, 3-61 months). All 55 regrafts cleared, 8 (15%) had air reinjected to promote attachment, 1 eye (2%) with trabeculectomy and progressive synechiae demonstrated late endothelial failure, and no rejection episodes occurred (0%). In the paired analysis, the median duration of endothelial decompensation before the regraft was 21 days (range, 2-133 days). At 1, 3, 6, or 12 months, CDVA did not differ between the primary and secondary grafts in fellow eyes (mean difference, ≤2 Snellen letters; P > 0.05 at all examinations). At 1 year, the visual acuity was ≥20/20 in 61%, ≥20/25 in 81%, and ≥20/40 in 100% of the secondary grafts in the paired analysis, excluding 1 eye with retinal problems. Vision differed by ≤1 line between fellow eyes in all but the 1 patient with the longest time to regraft (133 days), who demonstrated central haze and irregular astigmatism from anterior stromal scarring during that period. At 1 year, CDVA associated with the scarring was 20/40 versus 20/20 for the fellow-eye primary graft. The central corneal thickness was comparable between fellow-eye primary and secondary grafts at 3, 6, and 12 months (mean difference at 1 year, 2 μm; P = 0.57). The 1-year endothelial cell loss was comparable in primary and secondary grafts (27% vs. 31%, respectively; P = 0.58).

CONCLUSIONS

In patients who received prompt intervention to minimize the duration of central corneal decompensation, the visual outcomes with secondary DMEK matched the fellow-eye visual outcomes with primary DMEK.

Descemet membrane endothelial keratoplasty

Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged endothelial cells, using only donor Descemet's membrane with endothelium. However, early adoption by corneal surgeons has been limited (illustrated by graft registry reports: 0.7% all corneal transplants in the USA; 0.4% in Australia for 2011) due to challenges in donor preparation and surgical technique. Recently, innovative donor preparation techniques may improve availability of pre-stripped DMEK donors from eye banks. The refinement of donor insertion and manipulation techniques has also improved outcomes and reduced graft detachment rates-still, the most common postoperative complication following DMEK. Randomised studies are needed to compare clinical practices and surgeon preferences, such as intraoperative use of long-acting gas, early versus late intervention of graft detachments and postoperative steroid management. A review of current literature reveals that most publications to date are reports from similar study cohorts by surgeons who pioneered and advocate this technique. Thus, more long-term clinical studies in other tertiary centres are required in order to confirm if the purported advantages of DMEK such as improved visual outcomes and reduced graft rejection are replicable among most corneal surgeons.

Corneal transplantation: Beyond the horizon

Evolving techniques in keratoplasty have undoubtedly led to thinner corneal grafts. These newer iterations of keratoplasty aim to reduce graft rejections, improve visual acuity and visual rehabilitation. Each technique poses its own advantages and disadvantages; the surgeon should select patients suitable for a particular technique while accounting for their surgical competency given the learning curve associated with these newer techniques. Alternatives to corneal transplant may have a role in addressing the shortages of corneal graft, these bioengineered material and medical treatment still need further studies to demonstrate its clinical applicability.

Contralateral eye comparison of descemet membrane endothelial keratoplasty and descemet stripping automated endothelial keratoplasty

PURPOSE

To compare objective and subjective outcomes after Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in the fellow eye of the same patients.

STUDY DESIGN

Single-center, retrospective case series.

METHODS

Seventeen patients with bilateral Fuchs endothelial dystrophy who underwent DSAEK earlier in 1 eye, and later underwent DMEK in the contralateral eye, composed study population. A chart review was completed to obtain follow-up data for at least 6 months after each surgery. Outcome measures included best spectacle-corrected visual acuity (BSCVA) and endothelial cell density (ECD). Subjective questionnaires were used to assess patients' satisfaction.

RESULTS

Preoperative BSCVA (logMAR) was similar in both groups, 0.66 ± 0.4 in DMEK and 0.59 ± 0.4 in DSAEK (P = .6). The DMEK group showed better BSCVA than the DSAEK group at the 6-month time point (0.25 ± 0.1 and 0.39 ± 0.1, for DMEK and DSAEK, respectively, P = .02). Preoperative ECD (cells/mm(2)) was similar in both groups (2647 ± 249 and 2768 ± 404, P = .3) in DMEK and DSAEK, respectively. There was statistically significant difference found in ECD at 6 months (2227 ± 565 for DMEK and 1780 ± 433 for DSAEK, P = .049). Subjective level of average satisfaction after DMEK was 6 and after DSAEK was 4.87 ± 1.19 (P = .002).

CONCLUSIONS

DMEK provided better visual outcome and lower endothelial cell loss than DSAEK and a higher level of patient satisfaction when assessed at 6 months after surgery. Our results comparing the 2 procedures in the same patients support the benefits of DMEK, and suggest the need for long-term studies observing this new surgical procedure.

Visual acuity and endothelial cell density with respect to the graft thickness in Descemet's stripping automated endothelial keratoplasty: one year results

AIM

To evaluate the visual acuity and endothelial cell density according to the thickness in Descemet's stripping automated endothelial keratoplasty (DSAEK) one year after surgery.

METHODS

DSAEK patients' data were reviewed. Thirty-seven eyes of 37 patients who underwent DSAEK for pseudophakic bullous keratopathy (PBK) were included in this study. Graft thickness was measured with optical coherence tomography (OCT) 12mo after DSAEK. Eyes were divided into 3 groups based on the graft thickness: thick (>200 µm), medium-thick (150-200 µm) and thin (<150 µm). Best corrected visual acuity (BCVA), endothelial cells density (ECD) and complications were assessed and comparisons were done between groups.

RESULTS

There was no significant difference in age, sex, preoperative BCVA, or follow-up period between DSAEK groups. At postoperative 12mo, mean BCVA was 0.28±0.10 in thick graft group, 0.52±0.08 in medium-thick graft group, and 0.72±0.06 in thin graft group. Thin grafts showed better postoperative BCVA as compared with the medium-thick and thick grafts (P=0.001). Thick graft group had 1637.44±88.19-mm(2), medium thick graft had 1764.50±34.28-mm(2) and thin graft group had 1845.30±65.62-mm(2) ECD at 12mo after the surgery. Thin graft group had better ECD at 12mo after surgery (P=0.001).

CONCLUSION

Thin grafts after DSAEK ensure better visual rehabilitation. Eyes with thin grafts had significantly lesser loss of ECD compared to eyes with medium-thick and thick grafts one year after surgery.

Historical Review and Update of Surgical Treatment for Corneal Endothelial Diseases

The cornea remains in a state of deturgescence, maintained by endothelial cell Na+/K+ ATPase and by tight junctions between endothelial cells that limit entrance of fluid into the stroma. Fuchs' endothelial corneal dystrophy (FECD) was initially described by Fuchs in 1910 as a combination of epithelial and stromal edema in older patients. It manifests as bilateral, albeit asymmetric, central corneal guttae, corneal edema, and reduced vision. When edema is severe, the corneal epithelium can detach from its basement membrane, creating painful bullae on the anterior surface of the cornea. The course of this dystrophy can be further accelerated after intraocular surgery, specifically cataract extraction. Pseudophakic bullous keratopathy (PBK) is endothelial cell loss caused by surgery in the anterior chamber. If the corneal endothelium is damaged during surgery, the same spectrum of symptoms as found in FECD can develop. In the nineteenth century, penetrating keratoplasty was the only surgical procedure available for isolated endothelial disease. In the 1960s, Dr. José Barraquer described a method of endothelial keratoplasty using an anterior approach via laser-assisted in situ keratomileusis (LASIK) flap. In 1999, Melles and colleague described their technique of posterior lamellar keratoplasty. Later, Melles et al. started to change host dissection using simple "descemetorhexis" in a procedure known as Descemet's stripping endothelial keratoplasty. Following the widespread adoption of Descemet's stripping automated endothelial keratoplasty, the Melles group revisited selective Descemet's membrane transplantation and reported the results of a new procedure, Descemet's membrane endothelial keratoplasty (DMEK). Recently, some eye banks have experimented with the preparation of DMEK/Descemet's membrane automated endothelial keratoplasty donor tissue that may help the surgeon avoid the risk of tissue loss during the stromal separation step. Recently, the authors described a new bimanual technique for insertion and positioning of endothelium-Descemet membrane grafts in DMEK.

Retrospective contralateral study comparing Descemet membrane endothelial keratoplasty with Descemet stripping automated endothelial keratoplasty

PURPOSE

In this retrospective study, the visual outcomes and postoperative complications after Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) in the fellow eye were compared. The patient's satisfaction was evaluated.

METHODS

A retrospective analysis of 10 patients, who underwent DSAEK in one eye and DMEK surgery in their fellow eye, was performed. Intraoperative and postoperative complications were recorded. Visual and refractive outcomes were evaluated, including higher-order aberrations (HOA) and contrast thresholds. A subjective questionnaire was used to evaluate patient satisfaction.

RESULTS

Best-corrected visual acuity (BCVA) was significantly better in DMEK when compared with DSAEK (0.16±0.10 vs 0.45±0.58 logMAR, P=0.043). Contrast threshold was significantly higher after DMEK than after DSAEK (0.49±0.23 vs 0.25±0.18, P=0.043). Post-keratoplasty astigmatism, mean spherical equivalent, and HOA did not differ. Nine out of ten patients preferred the DMEK procedure. Visual outcome (4.80±1.14 vs 4.50±1.58, P=0.257), surgery associated pain and burden (DMEK: 1.30±0.48 vs DSAEK: 1.30±0.48, P=1.0), estimated time for recovery and rehabilitation (27.6±54.0 vs 24.9±54.8 days, P=0.173), and mean patient satisfaction (5.40±0.84 vs 5.00±1.05, P=0.257) were evaluated equally.

CONCLUSION

Patient satisfaction reached high, equal values after DMEK and after DSAEK. Nevertheless, patients preferred DMEK, if given a choice. Reasons for the preference may include better uncorrected and BCVA, and especially a better contrast sensitivity.

Trends in corneal transplantation: indications and techniques

PURPOSE OF REVIEW

To describe trends in corneal transplantation surgery, including indications for surgery, evolution of lamellar keratoplasty, current surgical techniques, and future directions.

RECENT FINDINGS

Over the past decade, anterior and posterior lamellar keratoplasty have begun to supplant penetrating keratoplasty. Surgical techniques continue to change and improve outcomes. In recent years, Descemet membrane endothelial keratoplasty (DMEK) has gained interest as it eliminates the corneal stromal interface, which may limit visual acuity after Descemet stripping automated endothelial keratoplasty. Despite the promising results with improved visual acuity and decreased rejection, the technical challenges associated with DMEK have limited widespread acceptance. With technical refinements and more eye banks providing precut tissue for both Descemet stripping automated endothelial keratoplasty and DMEK, it is likely both procedures will continue to increase over time.

SUMMARY

Corneal transplantation has evolved rapidly over the past decade, from full-thickness penetrating keratoplasty towards lamellar keratoplasty to only remove and replace damaged layers of the cornea. Achieving minimal induced astigmatism with excellent visual acuity remains a challenge in corneal transplantation. Further refinements in surgical technique may help improve technical challenges and visual outcomes. In this article, we review changing trends in corneal transplantation and highlight developing medical treatments that may be available in the future.

Does thickness matter: ultrathin Descemet stripping automated endothelial keratoplasty

PURPOSE OF REVIEW

Descemet stripping automated endothelial keratoplasty (DSAEK) has become worldwide the procedure of choice for the replacement of diseased corneal endothelium. More recently, ultrathin DSAEK (UT-DSAEK) has been introduced to guarantee better visual outcomes preserving good donor graft manipulation.

RECENT FINDINGS

As DSAEK may still have major challenges such as suboptimal visual acuity and relatively slow visual rehabilitation, fairly new techniques such as UT-DSAEK and Descemet membrane endothelial keratoplasty (DMEK) have been introduced to allow much quicker and optimal visual rehabilitation. This article goes through the most recent findings and results of these techniques.

SUMMARY

UT-DSAEK is a procedure that shares the improved visual outcome and lower immunologic rejection rate of DMEK over DSAEK, while minimizing all types of postoperative complications. In addition, similar to DSAEK and unlike DMEK, UT-DSAEK can be performed in all types of eyes, even in those with complicated anatomy or poor anterior chamber visualization.

New perspectives on lamellar keratoplasty

Lamellar (anterior and posterior) keratoplasty entails the surgical replacement of diseased-only corneal tissue, while healthy host corneal tissue is preserved. Selective keratoplasty offers several advantages in comparison to penetrating keratoplasty such as a lower rate of graft rejection, less endothelial cell loss, faster/superior visual rehabilitation and enhanced resistance to closed injury. The surgical approach of "partial corneal transplantation" may be divided into anterior and posterior: techniques including superficial and deep anterior lamellar keratoplasty (SALK and DALK, respectively) and endothelial keratoplasty as well as Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). These novel surgical procedures are rapidly becoming the preferred therapy option for specific corneal dysfunctions involving the corneal stroma (SALK, DALK), or corneal endothelium (DSAEK, DMEK). During the past decade, the continuing advancement of surgical techniques and the development of innovative surgical instruments have significantly enhanced corneal transplantation. Lamellar keratoplasty techniques facilitate corneal surgery, provide patients with superior outcomes and can successfully restore vision in corneal-related blindness. Nevertheless, more long-term evidence is needed to better evaluate these promising new techniques.

Double port injector device to reduce endothelial damage in DMEK

OBJECTIVE

To study endothelial injury from a newly designed asymmetric double port Descemet Membrane Endothelial Keratoplasty (DMEK) injector, both ex-vivo and in clinical practice.

DESIGN

Laboratory investigation with an interventional case series study.

METHOD

Sixteen rabbit endothelial rolls were tested for injection using a no-touch technique. For each pair of rolls, one endothelial graft underwent injection with a single port Pasteur pipette twice, wheras the other was injected with a novel asymmetric double port injector with a larger diameter entry port than the exit port also twice. Each graft was stained with 4-6-diamidino-2-phenylinidole dihydrochloride and was counted under a fluorescence-inverted microscope before and after injection. The proportion of graft injury was calculated and the differences were analyzed. Subsequently, six patients requiring DMEK underwent surgery using this novel insertion device and endothelial cell loss was calculated 3 months after the surgery.

RESULTS

After injection, the mean proportion of endothelial cell survival with the single port pipette was 78.8% (n=8; SD: ±20.9%), whereas the double port injector yielded a survival rate of 96.8% (n=8; SD: ±8.4%). This difference was statistically significant (P=0.008), representing less endothelial injury with the double port device. Early endothelial cell loss after 3 months in the DMEK patients was 26.1% (SD: ±6.1%).

CONCLUSION

In our injection model, using a double port injector created significantly less endothelial cell damage than with the single port pipette. Clinically, this device yielded early endothelial cell loss comparable to that of the series performed by experienced DMEK surgeons.