Prevention and Management of Pupil Block After Descemet Membrane Endothelial Keratoplasty

Anterior Chamber Air Bubble Dynamics With Decreases in Atmospheric Pressure

PURPOSE

To evaluate the effect of decreasing barometric pressure on intracameral bubble size and intraocular pressure (IOP) in eyes with varying air fills in the anterior chamber.

METHODS

A total of 36 human donor eyes received 30%, 50%, or 90% anterior chamber air fill. The eyes were subjected to decreases in atmospheric pressure down to 750 hPa, equal to 2400 m in altitude, and were repeatedly imaged using anterior segment OCT while IOP was measured continuously.

RESULTS

Eyes with 30% air fill initially showed moderate increases in IOP yet rising to an average of 30.83 mm Hg at 850 hPa (mimicking 1400 m altitude) and 42.08 mm Hg at 750 hPa. Eyes with larger air bubbles showed more acute increases in IOP with increases to an average of 47.25 mm Hg in eyes with 50% air fill at 850 hPa and 63.33 mm Hg at 750 hPa. In eyes with 90% air fill in the anterior chamber, IOP readings with an average of 113.42 mm Hg were observed already at 850 hPa, at which point additional pressure reduction was not performed.

CONCLUSIONS

While severe increases in IOP were observed with decreased atmospheric pressure in eyes with large air bubbles in the anterior chamber, small and moderately sized bubbles seem to allow for travel over modest changes in altitude.

Retrospective Study of Preoperative Laser Peripheral Iridotomy Versus Intraoperative Surgical Peripheral Iridectomy in Descemet Membrane Endothelial Keratoplasty

PURPOSE

The aim of this study was to examine the outcomes of laser peripheral iridotomy (LPI) and surgical peripheral iridectomy (SPI) for Descemet membrane endothelial keratoplasty (DMEK) and DMEK with cataract extraction (triple DMEK).

METHODS

This retrospective interventional study included 135 eyes of 135 patients who underwent DMEK alone or triple DMEK. Primary outcomes were graft detachments necessitating rebubbling, repeat grafts, and pupillary block. The secondary outcomes included rejection, cystoid macular edema, uveitis, intraoperative hyphema, visual disturbances, and surgical time.

RESULTS

Thirty-one eyes in the LPI group and 104 eyes in the SPI group were included. Fifty-six eyes had DMEK alone, and 79 had triple DMEK. Visually significant graft detachments occurred in 7 of 31 eyes in the LPI group versus 19 of 104 eyes in the SPI group ( P = 0.61). No statistical significance in DMEK alone versus triple DMEK groups ( P = 0.61 vs. P > 0.99). Two patients in the LPI group and 5 in the SPI group required regraft ( P = 0.66). One (3.2%) experienced pupillary block compared with 5 (4.8%) ( P = 0.99) in the LPI and SPI groups, respectively. Secondary outcomes were similar in both groups ranging from 0% to 3% ( P > 0.99). None had visual disturbances. In DMEK alone, duration of surgery was significantly shorter in the LPI versus SPI group (32.8 vs. 44.1 minutes, P = 0.02).

CONCLUSIONS

This study demonstrated similar outcomes between LPI and SPI, although the LPI group had a shorter duration of surgery when DMEK was performed alone. The remainder of the outcomes demonstrated no statistically significant differences.

Initial results of DMEK combined with cataract surgery and implantation of the light-adjustable lens

PURPOSE

To evaluate the use of light-adjustable intraocular lenses (LALs) to maximize visual acuity (VA) postoperatively in eyes undergoing combined Descemet membrane endothelial keratoplasty (DMEK) and cataract surgery.

SETTING

Private practice, tertiary referral center.

DESIGN

Retrospective review of initial case series.

METHODS

Patients with Fuchs endothelial dystrophy had DMEK combined with phacoemulsification and LAL implantation. Lenses were adjusted based on postoperative manifest refraction and locked-in 3 to 6 months postoperatively. Adjustments to the LAL were started after stabilization of refraction at sequential examinations. Outcomes were uncorrected near and distance VA and manifest refraction 3 to 6 months after locking the lens.

RESULTS

A total of 27 eyes in 17 patients with mean age of 65 years (range 53 to 75 years) were included in this study. 6 eyes (22%) had either a near or intermediate target, and 21 eyes (78%) had a distance target. After lock-in, 57% of eyes with a distance target had uncorrected distance VA (UDVA) of 20/20 or better, 90% were 20/25 or better, and 100% were 20/40 or better. After lens lock-in, 100% of eyes had corrected distance VA (CDVA) of 20/20 or better, 86% had postoperative UDVA the same or better than preoperative CDVA, and 100% of eyes had UDVA within 1 line of the preoperative CDVA. In total, 93% of eyes were within 1 diopter (D) of spherical target, and 93% of eyes had ≤0.5 D of refractive cylinder postoperatively.

CONCLUSIONS

Combining DMEK with LAL implantation provided significantly better UDVA and refractive outcomes than previously reported data on combined implantation of a standard monofocal lens.

Evaluating the forces involved in bubble management in DMEK surgery: mathematical and computational model with clinical implications

PURPOSE

To model postoperative forces involved in Descemet membrane endothelial keratoplasty (DMEK) tissue adherence and bubble management, including the impact of surface tension on graft support, with a view towards clinical applications.

SETTING

Tennent Institute of Ophthalmology, Glasgow, and James Watt School of Engineering, University of Glasgow, Glasgow, United Kingdom.

DESIGN

Mathematical modelling and computer simulation.

METHODS

Theoretical modelling of biphasic flow and interaction of gas, liquid and tissue within the anterior chamber for static horizontal scenario A (adherent DMEK with mobile bubble) and dynamic vertical scenario B (release of bubble due to pupil block following DMEK).

RESULTS

The model assumed incompressibility for both fluids within realistically achievable pressure ranges. Cahn-Hilliard Navier-Stokes equations were discretised through the application of the Finite Element Method. Mathematical modelling and computer simulation showed bubble size, corneal curvature and force intensity influences surface tension support for DMEK tissue in scenario A. Scenario B demonstrated complex, uneven distribution of surface pressure on the DMEK graft during uncontrolled bubble release. Uneven pressure concentration can cause local tissue warping, with air/fluid displacement via capillary waves generated on the fluid-air interface adversely impacting DMEK support.

CONCLUSIONS

We have quantitatively and qualitatively modelled the forces involved in DMEK adherence in normal circumstances. We have shown releasing air/gas can abruptly reduce DMEK tissue support via generation of large pressure gradients at the liquid/bubble/graft interfaces, creating negative local forces. Surgeons should consider these principles to reduce DMEK graft dislocation rates via optimised bubble size to graft size, longer acting bubble support and avoiding rapid decompression where possible.

Safety and clinical outcomes of omitting same and next day review after DMEK performed with an inferior peripheral iridotomy

BACKGROUND/OBJECTIVES

To determine the incidence of day one postoperative complications after Descemet Membrane Endothelial Keratoplasty (DMEK) performed with intraoperative inferior peripheral iridotomy (PI), and whether their early detection influences postoperative intervention.

SUBJECTS/METHODS

70 eyes of 70 consecutive patients that underwent DMEK from August 2019 to August 2021 at a single UK centre were retrospectively analysed. Cases that did not have an inferior PI were excluded. Any action taken at day one and week one postoperative review was noted.

RESULTS

No pupil block or other major adverse events were found at day one review. At one week, 14 eyes (20%) required re-bubbling, all of which had been fully attached at the day one review.

CONCLUSIONS

This series suggests that inferior PI performed alongside DMEK alone or triple DMEK effectively minimizes the risk of pupil block. Since no early complications occurred in this cohort requiring immediate intervention, it may be safe to defer review of these patients to a later time point.

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

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

SETTING

Institutional, tertiary care eye hospital.

STUDY POPULATION

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

MAIN OUTCOME MEASURES

Primary outcomes: Incidence of pupillary block (PB).

SECONDARY OUTCOMES

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

Influence of Body Position on Intraocular Pressure After Descemet Membrane Endothelial Keratoplasty: A Prospective Randomized Trial

PURPOSE

The purpose of this study was to analyze the influence of patient positioning on intraocular pressure (IOP) after Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic patients treated for Fuchs endothelial corneal dystrophy.

METHODS

Forty patients were included in this prospective, single-blinded, randomized controlled clinical trial. Patients received a YAG iridotomy 1 day before surgery and an 80% anterior chamber tamponade [20% concentration of sulfur hexafluoride (SF6)]. Postoperative positioning was either supine (group 1) or seated (group 2, at least 30 degrees upper-body high position). IOP was measured with iCare.

RESULTS

There was no statistically significant difference in IOP postoperatively [group 1 vs. group 2-after 1h: 13.9 mm Hg (±4.2 mm Hg) versus 13.6 mm Hg (±4.1 mm Hg) ( P = 1.00); after 2h: 13.9 mm Hg (±5.4 mm Hg) versus 15.3 mm Hg (±4.6 mm Hg) ( P = 0.370); after 4h: 13.8 mm Hg (±4.2 mm Hg) versus 15.2 mm Hg (±4.2 mm Hg) ( P = 0.401]. In group 1, 10% of patients showed IOP decompensations well above 30 mm Hg, and in group 2, there were no IOP decompensations. Seated position led to relative risk reduction of 100% and absolute risk reduction of 10% regarding IOP decompensations. The number of patients needed to position seated to prevent 1 additional IOP decompensation was 10. Rebubbling rates, best spectacle-corrected visual acuity, and reduction of corneal thickness were comparable between the 2 groups in the follow-up period up to 1 month.

CONCLUSIONS

After DMEK in pseudophakic eyes with 80% anterior chamber tamponade, positioning patients with at least 30 degrees elevation of the upper body up immediately after surgery until bedtime prevents IOP decompensations.

Optimization of patient positioning for improved healing after corneal transplantation

Corneal transplantation is the only solution which avoids loss of vision, when endothelial cells are dramatically lost. The surgery involves injecting gas into the anterior chamber of the eye, to create a bubble that pushes onto the donor cornea (graft), achieving sutureless adherence to the host cornea. During the postoperative period, patient positioning affects the bubble. To improve healing, we study the shape of the gas-bubble interface throughout the postoperative period, by numerically solving the equations of fluid motion. Patient-specific anterior chambers (ACs) of variable anterior chamber depths (ACD) are considered, for either phakic (with natural lens) and pseudophakic (with artificial lens) eyes. For each AC, gas-graft coverage is computed for different gas fill and patient positioning. The results show that the influence of positioning is negligible, regardless of gas filling, as long as the ACD is small. However, when the ACD value increases, patient positioning becomes important, especially for pseudophakic ACs. The difference between best and worst patient positioning over time, for each AC, is negligible for small ACD but significant for larger ACD, especially for pseudophakic eyes, where guidelines for optimal positioning become essential. Finally, mapping of the bubble position highlights the importance of patient positioning for an even gas-graft coverage.

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.

Descemet's Membrane Endothelial Keratoplasty and Phacoemulsification: Combined versus Sequential Surgery

Purpose:

To compare the outcomes of Descemet's membrane endothelial keratoplasty (DMEK) combined with phacoemulsification versus DMEK following phacoemulsification.

Methods:

In this interventional retrospective comparative nonrandomized case series study, patients with Fuchs endothelial corneal dystrophy (FECD) with either cataract or previous cataract surgery with intraocular lens (IOL) implantation were assigned to one of the two groups according to lens status. Group 1 included patients who had cataract and FECD and would undergo triple procedure (phacoemulsification with IOL implantation and DMEK), whereas Group 2 included patients who had FECD and had phacoemulsification with IOL implantation earlier and would undergo DMEK only as a sequential procedure.

Results:

Postoperative best corrected visual acuity (BCVA) in both groups at 1 week, 1 month, 3 months, and 6 months revealed a statistically nonsignificant difference between the two groups with mean logMAR BCVA at 6 months of 0.07 ± 0.18 and 0.07 ± 0.19 in Group 1 and Group 2, respectively (P > 0.05). The drop in endothelial cell density by the end of the 6^th postoperative month was by 39.44% ±7.92 and 38.73% ±8.10 in the triple-procedure group and DMEK only group, respectively (P = 0.005). Total postoperative complications rate and the rebubbling rate were statistically similar between both groups with 13.5% and 12.5% rebubbling rate in Group 1 and Group 2, respectively (P > 0.05).

Conclusion:

Visual outcomes, endothelial cell loss, and rebubbling rate are comparable when DMEK is combined with phacoemulsification or when it is performed as staged procedure, without statistically significant difference in the outcomes.

Impact of Early Intraocular Pressure Elevation on Postoperative Outcome After Descemet Membrane Endothelial Keratoplasty in Non-glaucoma Patients

PURPOSE

The purpose of this study was to investigate the impact of transient elevations in postoperative intraocular pressure (IOP) on the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) surgery in non-glaucoma patients.

METHODS

Retrospective analysis from a prospective database of eyes without preexisting glaucoma that underwent DMEK with 90% anterior chamber and 20% sulfur hexafluoride endotamponade. Group A included eyes without postoperative IOP increase (IOP <30 mm Hg and a relative increase from preoperative value <10 mm Hg). Group B included eyes with IOP elevation (postoperative IOP ≥30 mm Hg or a relative increase from preoperative value ≥10 mm Hg) handled according to a standardized protocol. The impact of elevated IOP within 3 days after DMEK surgery was evaluated regarding best-corrected visual acuity (BCVA), central corneal thickness (CCT), and endothelial cell count (ECC) at 1, 3, and 6 months.

RESULTS

One hundred seventy-six eyes from 164 patients were included. An IOP increase after DMEK occurred in 20 eyes (11.3%; 19 patients, group B), and the mean peak IOP was 48 ± 12 mm Hg (range 32-69 mm Hg). There were no significant postoperative differences in BCVA, CCT, and ECC on comparing both groups. The BCVA increased significantly (P < 0.001, respectively), whereas CCT (P < 0.001, respectively) and ECC (P < 0.001, respectively) decreased significantly from preoperative values. The rebubbling rate tended to be higher in group B without statistical significance (6.4% vs. 10%, P = 0.648).

CONCLUSIONS

Temporary IOP elevation after DMEK may not affect functional and morphological outcomes in non-glaucoma patients. However, careful postoperative IOP monitoring and appropriate management are crucial to avoid irreversible ocular damage.

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.

Rebubbling of detached descemet membrane endothelial grafts at the slit lamp with 50% air fill after PI-less DMEK during COVID-19 era

PURPOSE

To describe the effective use of only 50% air fill of the anterior chamber for rebubbling partially detached Descemet Membrane Endothelial Keratoplasty (DMEK) grafts at the slit lamp at a time of restricted operating theatre access during the COVID-19 pandemic.

METHODS

We present two cases of patients who underwent rebubbling of a partially detached DMEK grafts at the slit lamp following DMEK surgery without peripheral iridotomy. The rebubbling was performed with a 27-gauge needle attached to a 1ml syringe and the patients seated at the slit lamp. Air was injected into the anterior chamber until a 50% air fill was achieved. The patients were instructed to lie supine for 30 min in clinic and the remainder of the day at home.

RESULTS

We performed two rebubbling procedures at the slit lamp using the standard needle and syringe. Both cases achieved 50% air fills without any complications. At 3 days post-procedure the air bubble had resolved and the graft appeared attached centrally and at day 14 post-procedure the two patients had a clear and attached corneal graft with corrected visual acuity of 6/7.5 and 6/9, respectively.

CONCLUSION

Rebubbling of detached DMEK grafts at the slit lamp with 50% air fill in the anterior chamber is a relatively simple and effective procedure. This provides an alternative approach for managing the complication of partially detached DMEK grafts in the era of COVID-19 with limited operating theatre access and avoids the risk of complications such as pupillary block in 'PI-less' DMEK.

Corneal endothelial dysfunction: Evolving understanding and treatment options

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

Temporary Filtering Bleb Failure Induced by Anterior Chamber Sulfur Hexafluoride Gas: A Complication after Descemet Membrane Endothelial Keratoplasty

Herein, we report two clinical cases with acute temporary filtering bleb obstruction by gas tamponade after Descemet membrane endothelial keratoplasty (DMEK) surgery and postoperative intraocular pressure (IOP) peaks. Both patients underwent uncomplicated DMEK surgery with 20% sulfur hexafluoride (SF₆) anterior chamber tamponade and had previous trabeculectomy for glaucoma. Prior to surgery, both patients showed patent bleb function with low to normal IOP without antiglaucomatous medication. After uneventful DMEK surgery, both patients showed postoperative IOP peaks of up to 50 mm Hg despite patent inferior iridotomy and no sign of a pupillary block. In both cases, SF₆ gas bubbles could be visualized obstructing the bleb. Both patients were treated with IOP-lowering agents topically as well as systemically. In addition, anterior chamber paracenteses were performed to reduce the SF₆ volume within the anterior chamber. Under this treatment, IOP normalized within the first 18 h after surgery. We hypothesize that the SF₆ gas tamponade from the anterior chamber migrates into the ostium and below the bleb, leading to an acute temporary insufficiency of bleb function and to a consecutive IOP peak after surgery. In contrast to a pupillary block, this mechanism cannot be antagonized by preoperative iridotomy and needs to be taken into account for every glaucoma patient with functional bleb undergoing DMEK surgery.

Safety of air tamponade versus corneal hydration for sealing clear corneal incisions in cataract surgery

PURPOSE

To compare safety of wound hydration to anterior chamber air tamponade for securing watertight closure of clear corneal incisions, during uneventful cataract surgery.

METHODS

Prospective, comparative case-control series. Patients undergoing phacoemulsification were assigned to receive either anterior chamber air bubble (Group A) or intrastromal wound hydration with balanced salt solution (Group B) at the end of the procedure. Two high-volume surgeons operated equal number of cases in each group employing identical surgical technique, except for corneal side incision management. Patients were assessed pre- and postoperatively at day 1, day 4, day 9, and day 30 after surgery.

RESULTS

One hundred eyes of 100 patients were enrolled, of which 2 were lost to follow-up. The two groups were comparable in terms of preoperative risk factor assessment, baseline central corneal thickness (CCT), preoperative endothelial cell density, as well as cumulative dissipated energy and duration of phacoemulsification (p > 0.05). Mean CCT and best-corrected visual acuity were better in Group B on the first postoperative day, but did not differ between the two groups at all other timepoints. Surgically induced astigmatism was comparable in the two groups (p > 0.05). Endothelial cell density loss at 1 month postoperatively was greater in Group A (34.06%) compared to Group B (16.45%).

CONCLUSIONS

Wound sealing with intrastromal hydration proved to be safer than air tamponade in terms of preserving endothelial cell density and function.

Gas-Graft Coverage After DMEK: A Clinically Validated Numeric Study

Purpose

We investigate the influence of positioning, gas fill, and anterior chamber size on bubble configuration and graft coverage after Descemet's membrane endothelial keratoplasty (DMEK).

Methods

We use a mathematical model to study the bubble shape and graft coverage in eyes of varying anterior chamber depths (ACD). The governing equations are solved numericly using the open source software OpenFOAM. Numeric results are validated clinically so that clinical gas fill measures can be correlated with numeric results providing gas-graft coverage information otherwise clinically inaccessible.

Results

In a phakic eye (ACD = 2.65 mm) with a gas fill of 35%, graft contact ranged from 35% to 38% depending on positioning and increased to 85% to 92% with a 70% fill. In contrast, positioning of a pseudophakic eye (ACD = 4.35) with a gas fill of 35% results in graft contact ranging from 8% to 52%, increasing to 63% to 94% with a 70% fill. The mathematical model demonstrates negligible differences between air and SF6 results and interestingly, a very thin central patch of aqueous humor within the gas bubble is found in some cases.

Conclusions

Graft coverage in phakic eyes (ACD ≤ 3 mm) is dominated by the gas fill and less sensitive to patient positioning. In pseudophakic eyes with larger values of ACD, the graft coverage depends on gas fill and patient positioning with positioning even more important as ACD increases.

Translational Relevance

Anterior chamber depth markedly influences the role of patient positioning in gas-filled eyes after DMEK due to the interplay between anterior chamber anatomy and gas bubble morphology.

"PI-less DMEK": results of Descemet's membrane endothelial keratoplasty (DMEK) without a peripheral iridotomy

PURPOSE

To assess Descemet's membrane endothelial keratoplasty (DMEK) without performing a peripheral iridotomy (PI) prior to or during surgery ("PI-less DMEK").

MATERIALS AND METHODS

This retrospective study included consecutive patients that underwent PI-less DMEK by a single surgeon (E.L) between February 2016 and February 2017 at the Rabin Medical Center, a Tertiary Hospital. Intraoperative and postoperative complications were assessed.

RESULTS

Thirty-one patients, mean age 75.9 ± 7.9 years with 58.1% female were included. Leading indications for surgery were pseudophakic bullous keratopathy (18/31) and Fuchs' endothelial dystrophy (9/31). Preoperative best-corrected distance visual acuity was 1.13 ± 0.59 logMAR (~6/80 Snellen). For 12/31 that had postoperative endothelial cell count measurements, cell loss was 49 ± 20%. Intraoperative complications included anterior chamber (AC) hyphema during graft insertion requiring reinsertion (n = 1), and minor hyphema from the main corneal incision (n = 1). Partial slit lamp gas evacuation was performed in all patients 1.5 h postoperatively. Postoperative complications included partial graft detachment requiring rebubbling (n = 5), self-resolving minimal peripheral graft detachment (n = 5), uncontrolled intraocular hypertension requiring trabeculectomy in a patient with a history of medically controlled glaucoma (n = 1), postoperative cystoid macular edema that resolved medically (n = 1) and graft failure 5 months postoperatively (n = 1). No patients developed pupillary block. Excluding graft failure (n = 1), preoperative amblyopia (n = 2) and premature loss to follow-up (n = 1), final corrected distance visual acuity was 0.18 ± 0.14 logMAR (~20/30 Snellen) with 44.4% reaching 6/7.5 (Snellen) or more.

CONCLUSIONS

PI-Less DMEK is a safe, technically easy, and effective modification that avoids the time and complications associated with performing a PI before or during surgery.

Five-Year Graft Survival of Descemet Membrane Endothelial Keratoplasty (EK) versus Descemet Stripping EK and the Effect of Donor Sex Matching

PURPOSE

To determine whether the reduced risk of immunologic rejection with Descemet membrane endothelial keratoplasty (DMEK) results in a 5-year survival advantage relative to Descemet stripping endothelial keratoplasty (DSEK) and to determine whether matching the donor and recipient sex affects the rejection episode and graft survival rates.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients with Fuchs' endothelial corneal dystrophy treated with DSEK or DMEK.

METHODS

This study reviewed 2017 consecutive cases (1312 DSEK and 705 DMEK) performed by 13 surgeons between 2003 and 2012 and included the surgeons' first cases. Survival rates were calculated by Kaplan-Meier analysis.

MAIN OUTCOME MEASURES

Immunologic rejection episodes, graft failure or replacement for any reason, and endothelial cell loss.

RESULTS

The 5-year rejection episode rate was lower with DMEK (2.6% vs. 7.9% with DSEK, relative risk, 0.29; 95% confidence interval, 0.16-0.53) despite early reduction of topical corticosteroids in 25% of the DMEK cases. African Americans (n = 46) had a higher risk of rejection episodes than other races (relative risk, 4.4; 95% confidence interval, 2.0-9.6). The cumulative 5-year survival rate was 93% with DSEK and DMEK (P = 0.86). Forty-four DMEK and 69 DSEK grafts failed or were replaced within 5 years, but only 1 DMEK and 4 DSEK failures followed a rejection episode. Rejection episodes increased endothelial cell loss (P = 0.004) but were not a significant risk factor for graft failure within 5 years (P = 0.90). The mean 5-year endothelial cell loss was similar between DMEK (48%±19%) and DSEK (47%±19%) (P = 0.22). Graft rejection episode and survival rates were not significantly influenced by whether the sex of the donor matched that of the recipient (rejection episodes: P = 0.07 for female recipients and P = 0.33 for male recipients; graft survival: P = 0.67 for female recipients and P = 0.17 for male recipients).

CONCLUSIONS

Five-year graft survival was similar between DMEK and DSEK. Although DMEK had a significantly lower risk of immunologic rejection, rejection episodes rarely resulted in graft failure within 5 years with either procedure. Sex matching the donor and recipient provided no survival advantage with DSEK or DMEK.

Viscoelastic Tamponade Applied to the Ocular Surface for Enhanced Control of Gaseous Egress From the Anterior Chamber During Final Bubble Titration in DMEK Surgery: The "Polite" Burp

PURPOSE

To present a novel technique for enhancing the surgeon's control over the volume of air or gas that is "burped" from the anterior chamber during final bubble and intraocular pressure (IOP) titration in Descemet membrane endothelial keratoplasty.

METHODS

After ascertaining that the intracameral bubble is either too large and/or has rendered IOP too high, a bead of ophthalmic viscoelastic is applied to the ocular surface over a paracentesis incision, which is then depressed in the usual fashion to burp gas from the anterior chamber.

RESULTS

The weight and viscosity of the viscoelastic create a tamponade that slows the egress of gas from the anterior chamber, thereby making it more controllable.

CONCLUSIONS

If the bubble size or IOP needs to be reduced at the conclusion of the Descemet membrane endothelial keratoplasty procedure, application of ophthalmic viscoelastic over the paracentesis can enhance the surgeon's control over the volume of gas burped from the anterior chamber, thereby reducing the tendency to swing between a bubble that is too large or too small.

Descemet stripping automated endothelial keratoplasty in phakic eyes: incision modification reducing cataract formation

AIM

To evaluate the efficacy of a technical modification to reduce the incidence of traumatic cataract induced by Descemet stripping automated endothelial keratoplasty (DSAEK) performed in phakic eyes.

METHODS

A retrospective cohort study. The records of all patients with a clear crystalline lens and endothelial failure that underwent modified DSAEK at our insitution were reviewed. In this modification, in order to avoid inadvertent touch of the insertion forceps against the exposed crystalline lens while passing across the anterior chamber, the incision sites were shifted from the standard 9 and 3 o'clock positions, superiorly to the 10 and 2 o'clock position respectively. Formation of typically traumatic, anterior subcapsular cataract in these patients was compared to that observed in a cohort including all the patients with a clear crystalline lens and endothelial failure that underwent conventional DSAEK at our institution.

RESULTS

The study group included 49 eyes following modified DSAEK and the control group included 35 eyes following DSAEK with conventional incision sites. Anterior subcapsular cataract occurring 4mo or less postoperatively was identified in 2 of 49 (4%) eyes in the study group and 7 of 35 (20%) eyes in the control group. The rates of traumatic cataract were significantly higher in the control group in comparison to the study group (P=0.03, RR=4.9, 95%CI 1.08-22.1).

CONCLUSION

Traumatic cataract formation following phakic DSAEK may be avoided with a simple modification to the position of the incision sites.

Combined Cataract/DSEK/DMEK: Changing Expectations

Endothelial keratoplasty (EK) has revolutionized corneal transplant surgery by providing rapid visual recovery and improved visual outcomes. In parts of the world with Fuchs endothelial dystrophy, many patients may present with both cataracts and corneal degeneration requiring surgery. Other forms of endothelial decompensation may also present with cataracts. The staging or combination of transplant surgery and cataract surgery depend on both the abilities of the surgeon and the surgical techniques being considered. We currently use phacoemulsification to remove cataracts and routinely perform both cataract surgery and EK with topical anesthesia. The decision to perform either combined or staged cataract and transplant surgery depends upon the examination of the eye including assessment of the anterior chamber depth and the status of the anterior surface of the cornea, which affects the ability to reliably assess keratometry. Additional considerations include the type of lens implant to use, the desired refractive outcome, and the patient's preference about whether to undergo 1 or 2 surgical procedures per eye.