Use of Brilliant Blue G in Descemet's Membrane Endothelial Keratoplasty

Novel Trephine for Descemet Membrane Endothelial Keratoplasty Surgery Improves Surgical Preparation Time and Graft Quality: Pilot Data From the "Number 7" Endothelial Keratoplasty Trephine

PURPOSE

To report the safety and efficacy of a novel asymmetric marking trephine for Descemet membrane endothelial keratoplasty (DMEK) tissue preparation. The trephine design incorporates optimized curves to distribute mechanical forces and minimize the risk of tears without loss of total endothelial cell volume transplanted compared with a standard 8.00 mm circular transplant.

METHODS

A retrospective case series of 40 consecutive DMEK operations comparing 20 cases using the "Number 7" trephine against 20 using a modified shark fin technique as standard. Patient and donor characteristics, tissue preparation time and complications, total surgical time, intraoperative and postoperative complications, and endothelial cell counts at 3 months postsurgery are reported.

RESULTS

DMEK tissue preparation was significantly faster using the "Number 7" trephine (5.4 vs. 7.6 minutes, P = 0.008). Further, fewer complications arose during tissue preparation (0 vs. 2 complications) despite the faster preparation time. Total surgical time was similar between techniques; however, time spent manipulating the graft was reduced (5.1 vs. 6.8 minutes, P = 0.007) primarily because of the lower tissue preparation complications. Fewer postoperative complications were observed (1 vs. 3, of which 1 in the standard technique group requiring a redo-DMEK), again due to the reduced tissue preparation complications. The 3-month endothelial cell count was comparable between techniques (P > 0.05).

CONCLUSIONS

Use of the "Number 7" trephine led to faster and safer DMEK tissue preparation, which in turn reduced graft manipulation times and postoperative complications without compromising total endothelial cell volume transplanted. This novel device is ideal for use by surgeons who prepare their own DMEK tissue and within tissue banks who provide prestripped and preloaded DMEK tissue.

The progress and future of corneal endothelial transplantation

Endothelial transplantation has recently been accepted worldwide, in the long history of corneal transplantation. The introduction of endothelial keratoplasty (Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty) has enabled us to expand the surgical indications owing to the low incidence of rejection and quick recovery of visual function. New technologies have been developed to ensure stable postoperative outcomes with a shorter learning curve, such as transplantation using cultured human endothelial cells and induced pluripotent stem cells (iPS) or new devices such as artificial endothelium. This review discusses the history and characteristics of corneal transplantation alongside new treatment options that may offer hope for patients with endothelial disease in the future.

A Comparison of the Corneal Thickness Following Descemet's Stripping Automated Endothelial Keratoplasty and Descemet's Membrane Endothelial Keratoplasty

PURPOSE

To compare the central corneal thickness before and after Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK), and to evaluate the recipient corneal thickness following DSAEK.

METHODS

The corneal thickness was compared between two groups of eyes following DMEK and DSAEK, performed by a single surgeon between 2015 and 2017. We evaluated the recipient corneal thickness and central corneal thickness pre- and postoperatively at 1, 3, and 6 months using anterior segment optical coherence tomography. Recipient corneal thickness was defined as the corneal thickness without graft thickness.

RESULTS

We included DMEK and DSAEK eyes (n = 26 each), which were similar in terms of their etiologies. Preoperatively, there was no significant difference in the central corneal thickness between the groups (DSAEK, median [interquartile range]: 721 [606.5 to 847.8] µm; and DMEK: 690 [618 to 722.3] µm; p = 0.30). Despite the tendency of the central corneal thickness to be significantly greater (p < .01) at 6 months following DSAEK (619.5 [607.8 to 661.3] µm) compared with that following DMEK (497.5 [475.8 to 525.3] µm), there was no significant difference at 6 months between the recipient corneal thickness following DSAEK (488.5 [443.8 to 515] µm) and central corneal thickness following DMEK (p = 0.54).

CONCLUSIONS

DSAEK eyes display a similar tendency of stromal thinning as DMEK eyes.

Risk factors for intraocular pressure elevation following Descemet membrane endothelial keratoplasty in Asian patients

PURPOSE

To investigate risk factors for increased intraocular pressure (IOP) after Descemet membrane endothelial keratoplasty (DMEK) in Asian patients.

METHODS

Data from January 2015 to February 2021 were obtained from our prospective database. IOP elevation after DMEK was defined as IOP ≥ 22 mmHg or an increase in IOP of ≥ 10 mmHg from baseline. In addition, we examined maximum IOP. Using iCare, we measured IOP 1, 2, 3, and 6 months after DMEK, and every 6 months thereafter. Logistic regression and linear regression were performed to find factors predictive of IOP elevation and maximum IOP, respectively, based on the results of univariate analysis.

RESULTS

We enrolled 90 eyes (mean patient age, 74.9 ± 7.5 years; mean follow-up duration, 25.6 ± 9.9 months) that underwent DMEK. IOP elevation was present in 19 eyes (21%). IOP increased from 12.6 ± 3.9 mmHg preoperatively to a postoperative maximum of 17.0 ± 5.5 mmHg up to 36 months after DMEK (p < 0.0001). In univariate logistic regression analysis for IOP elevation, only one variable, pseudoexfoliation syndrome (PEX) and preexisting glaucoma, was significant (p < 0.05). Preexisting glaucoma without PEX (OR, 19.33; 95% CI, 4.75-93.46), PEX without glaucoma (OR, 7.25; 95% CI, 1.20-41.63), and PEX glaucoma (OR, 58.00; 95% CI, 6.78-1298.29) were associated with higher risk of IOP elevation.

CONCLUSIONS

In this cohort, the eyes of patients with PEX and preexisting glaucoma were found to be prone to IOP elevation after DMEK.

Scaffold-Free Strategy Using a PEG-Dextran Aqueous Two-Phase-System for Corneal Tissue Repair

Forming thin tissue constructs with minimal extracellular matrix surrounding them is important for tissue engineering applications. Here, we explore and optimize a strategy that enables rapid fabrication of scaffold-free corneal tissue constructs using the liquid-liquid interface of an aqueous two-phase system (ATPS) that is based on biocompatible polymers, dextran and polyethylene glycol. Intact tissue-like constructs, made of corneal epithelial or endothelial cells, can be formed on the interface between the two liquid phases of ATPS within hours and subsequently collected simply by removing the liquid phases. The formed corneal cell constructs express essential physiological markers and have preserved viability and proliferative ability in vitro. The corneal epithelial cell constructs are also able to re-epithelialize the corneal epithelial wound in vitro. The results suggest the promise of our reported strategy in corneal repair.

Dye-based identification of the orientation of tissue for Descemet stripping automated endothelial keratoplasty: A laboratory-based study

Purpose:

To describe the features enabling the identification of the orientation of Descemet stripping automated endothelial keratoplasty (DSAEK) lenticule with the assistance of vital dyes.

Methods:

This is a blinded experimental lab-based study, including 30 microkeratome prepared precut DSAEK lenticules. The lenticules were divided into control and study arms which included 10 unstained and 20 stained lenticules, respectively. In the study arm, vital dyes like trypan blue (TB), brilliant blue (BB), indocyanine green (ICG) and fluorescein stain (FS) were used to stain 5 lenticules each. They were examined by experienced (group 1) and novice surgeons (group 2) to identify the correct orientation of the lenticule. The results were tabulated and analyzed.

Results:

Of the 30 lenticules examined, the average of total scores obtained by each observer was higher (78%) in group 1 as compared to group 2 (65.3%) which was statistically significant (P < 0.005). In group 1, the accuracy of identifying the correct orientation of unstained lenticules was 70% which improved to 82% on staining. The accuracy in group 2 was 58% with unstained lenticules which improved to 69% on staining. Within the study arm, irrespective of surgical experience, the accuracy was highest with BB (86%), followed by TB (82%), ICG (72%) and FS (62%).

Conclusion:

This study found that the accuracy of identifying the orientation of DSAEK lenticules increased with experience and with the assistance of staining using vital dyes. This accuracy improved with blue dyes like brilliant blue and trypan blue, irrespective of the level of experience.

Iris Posterior Synechiae After Descemet Membrane Endothelial Keratoplasty in Asian Eyes: Prevention and Management of Posterior Synechiae

OBJECTIVES

To evaluate the efficacy of a mydriatic agent for posterior synechiae after phacoemulsification and intraocular lens (IOL) implantation followed by Descemet membrane endothelial keratoplasty (staged DMEK).

METHODS

In this prospective study, the outcomes of DMEK with or without mydriasis (0.5% tropicamide and 0.5% phenylephrine hydrochloride [Mydrin-P; Santen, Osaka, Japan]) after the DMEK procedure were analyzed. Patients underwent IOL implantation approximately 4 weeks before DMEK. Six months after DMEK, the iris posterior synechiae severity score was evaluated based on the extent of posterior synechiae affecting the eight areas (45° each) of the pupillary rim (posterior synechiae score; grades 0-8). Best spectacle-corrected visual acuity, central corneal thickness, endothelial cell density, axial length, and the amount of air at the end of the surgery were also evaluated.

RESULTS

Fifteen eyes of 15 patients (mydriatic: n=8, control: n=7) were eligible for inclusion. Iris posterior synechiae were detected in all seven eyes (100.0%) in the control group, whereas they were noted in two eyes in the mydriatic group (25%). The mean iris posterior synechiae score was 0.69±1.20 in the mydriatic group and was significantly lower than that in the control group (4.57±0.90; P<0.001). There was no significant difference in other clinical factors. Although the incidence and scores of posterior synechiae in the control group were higher, the incidence was significantly reduced with the use of a mydriatic agent (in the mydriatic group).

CONCLUSIONS

Use of a mydriatic agent is an effective measure to prevent postoperative synechiae after DMEK.

Optical characteristics after Descemet membrane endothelial keratoplasty: 1-year results

PURPOSE

To evaluate the corneal characteristics after Descemet membrane endothelial keratoplasty (DMEK) compared with normal corneas.

METHODS

Patients who underwent DMEK at Yokohama Minami Kyosai Hospital were included and prospectively evaluated pre-operatively and at postoperative months 1, 3, 6, and 12, and compared to healthy controls. Corneal characteristics evaluated included corneal curvature (keratometric value [KV]; D), central corneal thickness (CCT), peripheral corneal thickness (PCT), and corneal higher-order aberrations [HOAs] at 6.0 mm diameter, calculated by anterior segment optical coherence tomography and logarithm of the minimal angle of resolution [logMAR].

RESULTS

A total of 30 eyes of 30 patients (6 men, 24 women, mean age 73.4 ± 7.4 years) were included and compared with 31 age-matched healthy control eyes (13 men, 18 women; mean age 73.0 ± 6.7 years). LogMAR after DMEK improved from 0.87 ± 0.07 preoperatively to 0.04 ± 0.07 at 12 months postoperatively (p<0.001). Although anterior KVs of DMEK eyes were similar to those of control eyes, posterior KVs were significantly larger (-6.4 ± 0.3 D vs. -6.3 ± 0.2 D; p = 0.02). Total HOAs after DMEK improved from 1.94 ± 1.05 μm preoperatively to 1.05 ± 0.16 μm at 12 months postoperatively (p<0.001), which was significantly higher than that in control eyes (0.63 ± 0.06) (p<0.001). Despite the similar CCTs in the two groups, the PCT was significantly larger in DMEK eyes (704 ± 41 μm vs 669 ± 38 μm, p = 0.002) at 12 months.

CONCLUSION

Despite achieving good visual function and excellent corneal clarity, eyes that underwent DMEK showed a steeper posterior KV and higher corneal HOAs than normal eyes even at 12 months after surgery.

Descemet's membrane endothelial keratoplasty for pseudoexfoliation syndrome: a case series

Background

To evaluate the clinical outcomes and features of Descemet’s membrane endothelial keratoplasty (DMEK) for eyes with pseudoexfoliation syndrome (PEX).

Methods

In this retrospective study, 37 DMEK cases were reviewed from available medical records. Patients who exhibited endothelial dysfunction derived from PEX or Fuchs endothelial corneal dystrophy (FECD) and successfully underwent cataract surgery about four weeks before DMEK were enrolled. The best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD), and incidence of intra-operative/post-operative complications of DMEK were analyzed.

Results

This study included 14 eyes of 14 patients (PEX: n = 6, FECD: n = 8). There was no primary graft failure. In the PEX group, BSCVA improved from 0.67 ± 0.28 at the preoperative point to 0.43 ± 0.14 at 1 month, 0.27 ± 0.10 at 3 months, and 0.19 ± 0.08 at 6 months after DMEK. The donor corneal ECD was 2704 ± 225 cells/mm² at the preoperative point and decreased to 1691 ± 498 cells/mm² at 1 month, 1425 ± 366 cells/mm² at 3 months, and 1281 ± 340 cells/mm² (52.7 ± 11.7% less than ECD of the donor graft) at 6 months after DMEK. None of the patients required rebubbling. When compared with the FECD group, no statistical difference was observed in CCT (p = 0.821); BSCVA (p = 0.001) and the reduction rate of ECD (p = 0.010) were relatively worse.

Conclusions

DMEK is effective for the treatment of endothelial dysfunction due to PEX.

Electronic supplementary material

The online version of this article (10.1186/s12886-019-1130-1) contains supplementary material, which is available to authorized users.

Evaluation of Patent Blue as the Vital Dye in an Animal Model of Descemet Membrane Endothelial Keratoplasty

PURPOSE

To evaluate the safety and feasibility of patent blue (PB) as the vital dye in Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Bovine corneal endothelial cells were incubated with different concentrations (0.02%-2.5%) of PB. The cell viability, which was assessed by Cell Counting Kit-8 assay, was compared with that of untreated control and 0.06% to 0.4% trypan blue. The dyes were also used for graft preparation and implantation in the porcine eye model to evaluate stain quality, dye retention, and the feasibility of using PB in DMEK surgery.

RESULTS

No obvious increase in cytotoxicity was detected for 0.06% to 0.4% trypan blue and PB at concentrations up to 1.0%, but the cell viability after incubating with 1.5% to 2.5% PB was significantly reduced. PB at 0.5% to 1.0% generated good staining quality that can be used to facilitate graft implantation. Although the staining quality of 0.5% to 1.0% PB faded to an intermediate level after a 30-minute wash in phosphate-buffered saline, dye retention persisted for up to 24 hours.

CONCLUSIONS

PB at 0.5% to 1.0% is biocompatible and can stain the graft sufficiently, making it an alternative for DMEK surgery.

Outcomes of Descemet Membrane Endothelial Keratoplasty for Vitrectomized Eyes with Sutured Posterior Chamber Intraocular Lens

Purpose

To evaluate the clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) for vitrectomized eyes that underwent pars plana vitrectomy (PPV) and transscleral-sutured intraocular lens (IOL) implantation.

Methods

In this retrospective study, DMEK cases were reviewed from medical records and divided into two groups: the eyes after PPV and transscleral-sutured IOL implantation (vitrectomized group) and the eyes with in-the-bag IOL implantation (control group) prior to DMEK. The main outcome measures included time of graft unfolding during surgery and best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) at 1, 3, and 6 months after the DMEK.

Results

Twenty-three eyes (vitrectomized group, n = 8; control group, n = 15) in 23 patients were included in this study. The unfolding time was significantly longer in the vitrectomized group than in the control group (P < 0.001). Postoperative BSCVA was worse in the vitrectomized group (0.16 ± 0.15) than in the control group (−0.06 ± 0.06; P = 0.017). The improvement in BSCVA was negatively correlated with the patients' age and frequency of previous surgeries.

Conclusions

Despite the longer graft unfolding time and limited visual recovery, DMEK should be applicable to vitrectomized eyes with transscleral-sutured IOL implantation.