Young donor-graft assisted endothelial keratoplasty (PDEK/DMEK) with epithelial debridement for chronic pseudophakic bullous keratopathy

The pre-Descemet's layer (Dua's layer, also known as the Dua-Fine layer and the pre-posterior limiting lamina layer): Discovery, characterisation, clinical and surgical applications, and the controversy

The pre-Descemet's layer/Dua's layer, also termed the Dua-Fine layer and the pre-posterior limiting lamina layer, lies anterior to the Descemet's membrane in the cornea, is 10 μm (range 6-16) thick, made predominantly of type I and some type VI collagen with abundant elastin, more than any other layer of the cornea. It has high tensile strength (bursting pressure up to 700 mm of Hg), is impervious to air and almost acellular. At the periphery it demonstrates fenestrations and ramifies to become the core of the trabecular meshwork, with implications for intraocular pressure and glaucoma. It has been demonstrated in some species of animals. The layer has assumed considerable importance in anterior and posterior lamellar corneal transplant surgery by improving our understanding of the behaviour of corneal tissue during these procedures, improved techniques and made the surgery safer with better outcomes. It has led to the innovation of new surgical procedures namely, pre-Descemet's endothelial keratoplasty, suture management of acute hydrops, DALK-triple and Fogla's mini DALK. The discovery and knowledge of the layer has introduced paradigm shifts in our age old concepts of Descemet's membrane detachment, acute corneal hydrops in keratoconus and Descemetoceles, with impact on management approaches. It has been shown to contribute to the pathology and clinical signs observed in corneal infections and some corneal dystrophies. Early evidence suggests that it may have a role in the pathogenesis of keratoconus in relation to its elastin content. Its contribution to corneal biomechanics and glaucoma are subjects of current investigations.

Challenges of DMEK Technique with Young Corneal Donors' Grafts: Surgical Keys for Success-A Pilot Study

PURPOSE

To report on the surgical maneuvers recommended for a successful unfolding of very young donors in order to accomplish an uneventful Descemet Membrane Endothelial Keratoplasty (DMEK) surgery.

METHODS

Five patients (three females and two males, mean age 71.2 ± 6.7 years) with Fuchs endothelial cell dystrophy who underwent DMEK with very young donors (between 20 and 30 years old) were included. The following demographic data were assessed: donor's age, donor's endothelial cell density (ECD), preservation time, recipient's age and sex and unfolding surgical time. Best-corrected visual acuity (BCVA; decimal system), ECD and corneal central thickness (CCT) were assessed preoperatively and at 6-month follow-up.

RESULTS

Donors' mean age was 23.6 ± 3.6 years (range 21 to 30) and the mean ECD was 2748.6 ± 162.6 cells/mm2. All of them underwent an uneventful DMEK as a single procedure performed by one experienced surgeon (MAG) with a mean unfolding time of 7.2 ± 4.9 min (range 4 to 15). The essential steps, including patient preparation as well as DMEK graft implantation, orientation, unrolling and centering are detailed. At 6 months, BCVA was 0.6 ± 0.2, ECD was 1945.0 ± 455.5 cells/mm2 and CCT was 497.0 ± 19.7 microns.

CONCLUSIONS

We hereby present the keys to overcome tightly scrolled grafts of very young donors, which prove perfectly suitable for DMEK surgery. The graft shape tends towards a double-roll and specific maneuvers are strongly recommended.

Concomitant sutureless scleral fixation of intraocular lens with keratoplasty: Review of surgical techniques

Sutureless scleral fixation of intraocular lens (sSFIOL) is a commonly employed method of optical rehabilitation of aphakic patients with deficient capsular support, and corneal transplant surgeries can be simultaneously combined with sSFIOL to handle aphakic corneal opacities. A single-stage procedure circumvents the need for repeat intraocular procedures and carries lower risk of graft endothelial damage, endophthalmitis, and macular edema associated with sequential surgeries. However, it mandates surgical expertise and increases the chances of postoperative inflammation. A basket of options is available with the corneal surgeons regarding the manner of host and donor preparation as well as the approaches to scleral fixation and certain intraoperative modifications along with postoperative vigilance may enhance the surgical outcomes. Most of the studies pertaining to keratoplasty with sSFIOL categorize to case reports/series, surgical techniques, and retrospective studies with very limited prospective data available currently. The purpose of the present review is to consolidate all available literature on concomitant sSFIOLs and keratoplasty procedures.

Comparison of Pre-Descemet Endothelial Keratoplasty and Descemet Membrane Endothelial Keratoplasty in Endothelial Decompensation

PURPOSE

The purpose of this study was to compare the outcomes of pre-Descemet endothelial keratoplasty (PDEK) and Descemet membrane endothelial keratoplasty (DMEK) in cases of endothelial decompensation.

METHODS

This was a prospective, randomized, interventional study conducted at a tertiary eye hospital in North India. Thirty eyes of 28 patients with corneal decompensation were randomly subjected to PDEK (n = 15 eyes) and DMEK (n = 15 eyes). Preoperative demographic details, surgical indications, uncorrected distance visual acuity, corrected distance visual acuity, contrast sensitivity, anterior and posterior segment details, intraocular pressure, central corneal thickness, endothelial cell count, and corneal aberrometry tracing on wavefront analysis were recorded. Patients were followed up for 6 months postsurgery. Visual and graft survival outcomes were assessed.

RESULTS

Intraoperatively, a surgeon reported better ease of preparation and intracameral handling with PDEK grafts. Both groups showed comparable improvement in visual acuity, contrast, and high-order aberrations. A decrease in central corneal thickness was significantly higher in DMEK (196 ± 26 vs. 140 ± 14 μm) patients. DMEK grafts were significantly thinner than PDEK grafts at the 6-month follow-up (16 ± 2.17 vs. 27.2 ± 1.93 μm). Endothelial cell loss (35% in DMEK vs. 33.4% in PDEK, P = 0.48) and rise of intraocular pressure (from 15.33 ± 2.85 mm Hg to 15.53 ± 2.2 mm Hg in the DMEK group vs. from 14.6 ± 1.99 mm Hg to 16.2 ± 1.43 mm Hg in the PDEK group) were comparable. Rebubbling rates were higher in the DMEK group (3/15, 20%) compared with the PDEK group (1/15, 6.66%; P = 0.165).

CONCLUSIONS

DMEK and PDEK were comparable for both quantitative and qualitative visual outcomes and anatomically for graft survival at the 6-month follow-up.

Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty With Endothelium Inward: A 24-Month Comparative Analysis Between Fuchs Endothelial Corneal Dystrophy and Bullous Keratopathy

PURPOSE

The aim of this study was to compare long-term clinical outcomes of preloaded Descemet membrane endothelial keratoplasty (DMEK) between Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).

METHODS

In this single-center retrospective clinical case series, 71 eyes of 64 patients indicated with FECD (62%) or BK (38%) (with or without cataract) were treated with preloaded DMEK grafts between March 2018 and February 2020. Standard DMEK peeling, followed by manual folding of the tissue with endothelium-inward orientation and storing in a preloaded fashion inside a 2.2-mm intraocular lens cartridge. All tissues were delivered using a bimanual pull-through technique, followed by air tamponade. Graft unfolding time, endothelial cell loss, corrected distance visual acuity, central corneal thickness, rebubbling rate, and intraoperative and postoperative complications at 1, 3, 6, 12, and 24 months were recorded.

RESULTS

The mean intraoperative graft unfolding time in FECD did not differ from the BK group ( P = 0.6061). Cystoid macular edema did not differ in either group ( P = 0.6866). The rebubbling rate was found to be significantly higher in FECD compared with the BK group ( P = 0.0423). Corrected distance visual acuity significantly improved at the first month after surgery ( P = 0.0012), with no differences between FECD and BK at 24 months ( P = 0.2578). Central corneal thickness was stable postoperatively and showed no differences between the groups ( P = 0.3693). Significantly higher endothelial cell counts were observed in the FECD group at 24 months ( P = 0.0002).

CONCLUSIONS

Preloaded DMEK with "endothelium-in" offers acceptable intraoperative time, rebubbling rate, and clinical outcomes in both FECD and BK groups. Patients with FECD show better postoperative clinical outcomes even if the rebubbling rate is relatively high.

Posterior lamellar keratoplasty: techniques, outcomes, and recent advances

Over the past 2 decades, posterior lamellar keratoplasty (PLK) has emerged as an alternative to penetrating keratoplasty in the treatment of corneal endothelial disorders. The reasons for this trend include the search for a safer procedure to replace diseased endothelium that provides faster and better visual rehabilitation and reduces the need for postoperative care. Different surgical techniques, surgical instruments, devices, and lasers have been introduced to overcome technical difficulties, thus improving clinical outcomes. Yet, surgeons and eye banks must address the complications and limitations that arise during the transition to these new techniques. This review discusses the most significant aspects of the evolution of PLK, including a detailed description of current techniques and the direction of future treatment for corneal endothelial disease with the use of laser-assisted surgery, bioengineered corneas, cell therapy, and new pharmacologic therapy.

Optimizing pre-Descemet endothelial keratoplasty technique

Pre-Descemet endothelial keratoplasty (PDEK) is an alternative technique to Descemet membrane endothelial keratoplasty (DMEK). The preparation of PDEK tissue by pneumatic dissection is simple and reproducible. The PDEK clamp helps to consistently obtain a type 1 big bubble. The mean size of type 1 big bubble is 7.255 ± 0.535 × 6.745 ± 0.668 mm. The volume of air required to obtain type 1 big bubble is 0.14 to 0.37 mL. Dissection of PDEK tissue can be achieved by trephination or manual excision. Insertion of tissue into the recipient eye can be by injection or pulling. Unfolding techniques used for PDEK are similar to those used in DMEK. Unlike DMEK, PDEK tissue is easier to handle and unscroll and allows use of younger donors. It could help surgeons converting to endothelial keratoplasty, with significant advantages in preparation, handling, and unscrolling in the eye.

Phacoemulsification with single-pass four-throw pupilloplasty and pre-Descemet's endothelial keratoplasty for management of cosmetic iris implant complication

Placement of an anterior chamber iris implant for cosmetic reasons has been associated with development of various complications. Even after the implant has been explanted from the eye, it leaves a trail of after effects that necessitate surgical management. We describe a technique that comprises of performing phacoemulsification with single-pass four-throw pupilloplasty and a pre-Descemet's endothelial keratoplasty procedure for this eye with cosmetic iris implant complication.

Pre-Descemet's endothelial keratoplasty

Endothelial keratoplasty (EK) has supplanted the penetrating keratoplasty procedure for corneal endothelial disorders. A review of literature on pre-descemet's EK, that is, a latest iterant in EK is described along with our experiences.