Superior versus temporal approach in descemet membrane endothelial keratoplasty

Descemet membrane endothelial keratoplasty combined with presbyopia-correcting and toric intraocular lenses - a narrative review

Fuchs endothelial corneal dystrophy (FECD) is the leading indication for EK and may coexist with cataract and presbyopia. Notably, the outcomes of phacoemulsification in FECD patients are not as favorable as those in eyes without this condition. Historically, only monofocal intraocular lenses (IOLs) were recommended for these patients. However, recent reports have described the implantation of Premium-IOLs (such as Multifocal IOLs, Enhanced Depth of Focus IOLs, and Toric IOLs) in FECD eyes undergoing cataract surgery and Descemet membrane endothelial keratoplasty (DMEK). While the results are encouraging, they are not as optimal as those from unoperated eyes, especially when comparing simultaneous procedures to sequential ones. It's advised to perform the DMEK first to improve the accuracy of IOL calculations. Still, even successfully operated eyes may experience secondary graft failure or graft rejection after DMEK. The success rate of a secondary DMEK is typically lower than that of the initial procedure. Furthermore, if the postoperative thickness after DMEK is less than anticipated, laser enhancements might not be an option. There's a pressing need for more controlled and randomized clinical trials to ascertain the safety and effectiveness of Premium-IOLs for FECD eyes. This narrative review aims to collate evidence on the use of Premium IOL technologies in eyes receiving EK and to underscore key points for surgeons performing EK combined with cataract surgery.

Refractive outcomes after DMEK: meta-analysis

In this meta-analysis and systematic literature review of refractive outcomes after Descemet membrane endothelial keratoplasty (DMEK), the extent of the refractive shift and an overview of reasons for refractive shift after DMEK are provided. The PubMed library was screened for articles containing the terms "Descemet membrane endothelial keratoplasty," "DMEK," "Descemet membrane endothelial keratoplasty combined with cataract surgery," "triple-DMEK" combined with "refractive outcomes," "refractive shift," and "hyperopic shift." The refractive outcomes after DMEK were analyzed and compared using a fixed and random effects model. The overall mean change of the spherical equivalent outcome when compared with the preoperative value in cases of DMEK or when compared with the preoperative target refraction in cases of DMEK combined with cataract surgery was +0.43 diopters (D) (95% CI, 0.31-0.55). When DMEK is combined with cataract surgery, a target refraction of -0.5 D is recommended to achieve emmetropia. Changes in the posterior corneal curvature are identified as the main cause of the refractive hyperopic shift.

Long-term Results of Intraocular Pressure Elevation and Post-DMEK Glaucoma After Descemet Membrane Endothelial Keratoplasty

PURPOSE

Intraocular pressure (IOP) elevation occurs regularly after Descemet membrane endothelial keratoplasty (DMEK). This study evaluated the long-term incidence of IOP elevation and post-DMEK glaucoma after DMEK.

METHODS

A total of 463 consecutive DMEKs in 352 patients performed between September 2011 and September 2014 at the Universitätsmedizin-Charité Berlin were reviewed. Data of the second treated eye of each patient and of re-DMEKs during the follow-up were excluded. The 12- and 36-month incidence of IOP elevation and post-DMEK glaucoma was analyzed using the Kaplan-Meier survival analysis. IOP elevation was defined as IOP ≥22 mm Hg or ≥10 mm Hg from preoperative baseline. COX regression analysis was used to evaluate the risk factors for IOP elevation and the development of a post-DMEK glaucoma.

RESULTS

The 12-month incidence of IOP elevation was 15.9% [95 confidence interval (CI), 12.0%-19.8%] and that of post-DMEK glaucoma was 3.9% (95 CI, 1.7%-6.1%); the 36-month incidence was 18.8% (95 CI, 14.5%-23.1%) and that of post-DMEK glaucoma was 6.6% (95 CI, 3.7%-9.5%). The most frequent cause was steroid-induced IOP elevation with a 12-month incidence of 11.7% (95 CI, 8.2%-15.2%) and a 36-month incidence of 12.9% (95 CI, 9.2%-16.6%), respectively. The incidence of postoperative pupillary block IOP elevation was 7.5% (95 CI, 4.8%-10.2%). A preexisting glaucoma increased the risk of IOP elevation [P < 0.001, hazard ratio (HR) 3.331; 95% CI, 1.919-5.782] and the development of a post-DMEK glaucoma (P < 0.001, HR 6.633; 95% CI, 2.556-17.215). The preoperative diagnosis also influenced the risk of IOP elevation [Fuchs corneal dystrophy (FED) vs. bullous keratopathy; P = 0.012, HR 2.354; 95% CI, 1.203-4.608] and post-DMEK glaucoma (FED vs. graft failure; P = 0.01, HR 4.412; 95% CI, 1.419-13.723, FED vs. bullous keratopathy; P = 0.09, HR 2.679; 95% CI, 0.858-8.358).

CONCLUSIONS

Incidence of IOP elevation is high in the first 12 months after DMEK, especially steroid-induced IOP elevation. Steroid-induced IOP elevation could be treated effectively by tapering down the steroid medication or changing the steroid drug. A preexisting glaucoma and the preoperative diagnosis increase the risk for an IOP elevation and a post-DMEK glaucoma.

Component corneal surgery: An update

Several decades ago, penetrating keratoplasty was a challenge to corneal surgeons. Constant effort by the corneal surgeon to improve the outcomes as well as utilization of the available resources has led to a revolutionary change in the field of keratoplasty. All these efforts have led to the evolution of techniques that allow a corneal surgeon to disease-specific transplant of individual layers of corneal “so-called component corneal surgery” depending on the layer of cornea affected. This has led to an improvement in corneal graft survival as well as a better utilization of corneal tissues. This article reviews the currently available literature on component corneal surgeries and provides an update on the available techniques.

Descemet Membrane Endothelial Keratoplasty: Safety and Outcomes: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature on the safety and outcomes of Descemet membrane endothelial keratoplasty (DMEK) for the surgical treatment of corneal endothelial dysfunction.

METHODS

Literature searches were last conducted in the PubMed and the Cochrane Library databases most recently in May 2017. The searches, which were limited to English-language abstracts, yielded 1085 articles. The panel reviewed the abstracts, and 47 were determined to be relevant to this assessment.

RESULTS

After DMEK surgery, the mean best-corrected visual acuity (BCVA) ranged from 20/21 to 20/31, with follow-up ranging from 5.7 to 68 months. At 6 months, 37.6% to 85% of eyes achieved BCVA of 20/25 or better and 17% to 67% achieved BCVA of 20/20 or better. Mean endothelial cell (EC) loss was 33% (range, 25%-47%) at 6 months. Overall change in spherical equivalent was +0.43 diopters (D; range, -1.17 to +1.2 D), with minimal induced astigmatism of +0.03 D (range, -0.03 to +1.11 D). The most common complication was partial graft detachment requiring air injection (mean, 28.8%; range, 0.2%-76%). Intraocular pressure elevation was the second most common complication (range, 0%-22%) after DMEK, followed by primary graft failure (mean, 1.7%; range, 0%-12.5%), secondary graft failure (mean, 2.2%; range, 0%-6.3%), and immune rejection (mean, 1.9%; range, 0%-5.9%). Overall graft survival rates after DMEK ranged from 92% to 100% at last follow-up. Best-corrected visual acuity after Descemet's stripping endothelial keratoplasty (DSEK) ranged from 20/34 to 20/66 at 9 months. The most common complications after DSEK were graft detachment (mean, 14%; range, 0%-82%), endothelial rejection (mean, 10%; range, 0%-45%), and primary graft failure (mean, 5%; range, 0%-29%). Mean EC loss after DSEK was 37% at 6 months.

CONCLUSIONS

The evidence reviewed supports DMEK as a safe and effective treatment for endothelial failure. With respect to visual recovery time, visual outcomes, and rejection rates, DMEK seems to be superior to DSEK and to induce less refractive error with similar surgical risks and EC loss compared with DSEK. The rate of air injection and repeat keratoplasty were similar in DMEK and DSEK after the learning curve for DMEK.

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

PURPOSE

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

DESIGN

A prospective, interventional, nonrandomized study.

METHODS

setting: Department of Ophthalmology, Charité - Universitätsmedizin Berlin.

STUDY POPULATION

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

OBSERVATION

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

Corneal Astigmatism Stability in Descemet Membrane Endothelial Keratoplasty for Fuchs Corneal Dystrophy

PURPOSE

To calculate the magnitude and angle of the shift in corneal astigmatism associated with Descemet membrane endothelial keratoplasty (DMEK) surgery to determine the feasibility of concurrent astigmatism correction at the time of DMEK triple procedures.

DESIGN

Retrospective study.

METHODS

Forty-seven eyes that previously underwent the DMEK procedure for Fuchs endothelial corneal dystrophy and that had more than 1.0 diopter (D) of front corneal astigmatism preoperatively were identified. All DMEK surgeries used a clear corneal temporal incision of 3.2 mm. Surgically induced astigmatism (SIA) was evaluated 6 months postsurgery with vector analysis using Scheimpflug image reading.

RESULTS

We did not find a difference between pre- and postoperative magnitude of front astigmatism (P = 0.88; paired t test). The magnitude of the SIA front surface was 0.77 ± 0.63 D (range, 0.10-3.14 D). The centroid vector of the SIA front surface was 0.14 at 89.3°. A hyperopic corneal power shift was noted in both the front surface by 0.26 ± 0.74 D (range, 0.45-3.05 D) (P = 0.018; paired t test) and back surface by 0.56 ± 0.55 D (range, 0.25-2.40 D) (P < 0.01; paired t test).

CONCLUSIONS

DMEK surgery induces minimal amounts of corneal astigmatism that is a with-the-rule shift associated with a temporal clear corneal incision. The stability of these data from preop to postop supports the plausibility of incorporating astigmatism correction with the cautious use of toric intraocular lenses for patients with Fuchs corneal dystrophy and cataract.

The location of incision in cataract surgery and its impact on induced astigmatism

PURPOSE OF REVIEW

The purpose of the present study is a systematic review of previous studies on choosing the best incision site for the correction of astigmatism in cataract surgery and assessing the amount of surgically induced astigmatism (SIA) with each approach.

RECENT FINDINGS

Regardless of astigmatism axis, studies show that using an on-axis incision is associated with favorable results for 0.5-1.0 diopter (D) of astigmatism. In cases with more than 1.0 D astigmatism, paired on-axis incisions can be appreciably efficient in astigmatism correction and cause at least 1.5 D SIA. Considering the amount of SIA, a temporal incision is the best approach when the patient has minimal amounts of corneal astigmatism preoperatively. At higher levels of astigmatism, if no other astigmatism correction method is used simultaneously, the temporal incision is used less frequently; however, since it is associated with the least SIA, it is still the choice site when another correction method is used.

SUMMARY

The temporal incisions in cataract surgery are associated with little SIA and are appropriate choices for mild preoperative astigmatism. At higher levels of preoperative astigmatism, superior incisions are associated with better results when combined methods are not applied.

[Triple Descemet membrane endothelial keratoplasty. Indications, variations and results]

When Descemet membrane endothelial keratoplasty (DMEK) is indicated in patients with phakic eyes, a combination with phacoemulsification and intraocular lens implantation in one sitting should be considered as a triple DMEK. The best possible preoperative deswelling of the cornea should be strived for in order to allow sufficient viewing conditions for the individual stages of cataract surgery. Furthermore, technical details, e.g. regulation of pupillary width also must be considered. The power of the intraocular lens has to be adjusted in order to compensate for the shift of refraction towards hyperopic values induced by DMEK surgery. A rapid and clear improvement in visual acuity can normally be achieved after a triple DMEK. There seem to be no disadvantages compared with a two-stage procedure for DMEK and cataract surgery.

[Refractive changes in triple Descemet membrane endothelial keratoplasty]

BACKGROUND

A hyperopic shift, i.e. a shift of refraction in the direction of plus values, in Descemet membrane endothelial keratoplasty (DMEK) is a well-known phenomenon. Because of the need to select an appropriate intraocular lens power this becomes particularly relevant in triple DMEK, which is a combination of DMEK and cataract surgery.

OBJECTIVES

In this study the refractive changes induced by triple DMEK were evaluated. The underlying mechanisms were classified based on corneal topographical data.

MATERIAL AND METHODS

The study involved a retrospective evaluation of 29 eyes from 26 patients who underwent triple DMEK. The preoperative and postoperative refractions were compared with the initially desired target refraction. Calculations concerning refractive power were performed using corneal topographical data and the Gullstrand formula.

RESULTS

On average a hyperopic shift was observed. The operation led to steepening of the posterior corneal surface and flattening of the anterior corneal surface. Both resulted in a reduction of corneal refractive power but changes of the posterior corneal surface were identified as the most important factor. Those patients in whom both eyes had been operated on, showed very similar postoperative topography for both eyes, irrespective of the preoperative values.

CONCLUSION

The observed hyperopic shift was a mean value. A prediction of refraction in the individual cases by means of the available parameters was not possible. In general, the selection of an intraocular lens with a stronger myopic target refraction than that for standard cataract surgery is recommended.