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      Posterior Lamellar Graft Preparation: A Prospective Review from an Eye Bank on Current and Future Aspects

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          Abstract

          Descemet membrane endothelial keratoplasty (DMEK) is a corneal surgical technique which selectively replaces the damaged posterior part of the cornea with a healthy donor graft retaining the rest of the tissue intact. There is a need to validate and standardize the donor tissue before grafting due to certain issues that can lead to consequences such as graft failure due to poor endothelial cell count, higher mortality, detachment of the graft, or increased surgical expenses, time, and effort. Thus, prospective potential surgeons and eye banks should now aim at developing new improved surgical techniques in order to prepare the best suited, validated, precut, preloaded, and easy to transplant tissue to reduce pre- and postsurgical complications. This could be achieved by defining parameters like graft thickness, accepted mortality threshold of the endothelial cells, and behavior of grafts during preservation and transportation along with using more sophisticated instruments like microkeratome and femtosecond lasers for graft preparation. Thus, a rapport between the eye banks and the surgeons along with the advanced instruments can overcome this challenge to find the best possible solution for endothelial keratoplasty (EK).

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          Most cited references41

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          Comparison of central corneal graft thickness to visual acuity outcomes in endothelial keratoplasty.

          To evaluate visual acuity outcomes after endothelial keratoplasty (EK) and describe the relationship to postoperative central corneal graft thickness as measured by anterior segment optical coherence tomography (AS-OCT). A retrospective case series of 33 eyes in 28 patients undergoing routine EK using precut eye bank tissue was designed. All patients underwent serial central graft thickness measurements with AS-OCT. Based on the median central graft thickness of all patients, the eyes were divided into 2 groups: thin EK and thick EK. Differences between the groups were compared. The median postoperative graft thickness of all eyes was 131 μm. The eyes were divided into 2 groups based on this median: thin EK (graft thickness: ≤ 131 μm; range: 77-131 μm; average: 109 μm) and thick EK (graft thickness: > 131 μm; range: 138-182 μm; average: 162 μm). There was no statistically significant difference in age, sex, or preoperative best spectacle-corrected visual acuity (BSCVA) between the 2 groups. Average postoperative follow-up was 12.8 months. The thin EK group showed better postoperative BSCVA compared with the thick EK group (P < 0.01). All thin EK eyes had BSCVA greater than or equal to 20/25 with 71% of eyes achieving BSCVA of 20/20. In contrast, only 50% of thick EK eyes reached BSCVA greater than or equal to 20/25 with 19% obtaining BSCVA of 20/20. Thin EK versus thick EK, as measured by AS-OCT in the postoperative period, showed a statistically significant improvement in BSCVA.
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            Standardized 'no-touch' donor tissue preparation for DALK and DMEK: harvesting undamaged anterior and posterior transplants from the same donor cornea.

            To describe a standardized 'no-touch' harvesting technique of anterior and Descemet membrane (DM) grafts for use in deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK), which provides undamaged anterior and posterior corneal grafts. A retrospective evaluation was performed of our standard method for harvesting DM grafts and DALK grafts (Technique I; n = 31) versus a newly designed 'no-touch' technique (Technique II; n = 31), in which a peripheral ring of trabecular meshwork tissue is left in-situ, and the DM graft is trephined on an underlying soft contact lens. Endothelial cell density (ECD) before and immediately after DM stripping was used as the main outcome parameter. Endothelial cell density did not differ within Techniques I and II (before versus after DM stripping) (p = 0.75 and p = 0.54, respectively) or among Techniques I and II (p = 0.61). With the latter technique, anterior corneal grafts and posterior DM grafts could be harvested with negligible damage to the endothelial cell layer or the posterior stromal bed. All 93 grafts (62 DM grafts) were eligible for transplantation, and six months post-operatively all transplants used were functional. The new technique offers the following advantages: (i) production of 'undamaged' grafts for DALK and DMEK, (ii) better controlled tissue handling of the thin DM graft during DM stripping and (iii) an increase in availability of corneal grafts obtained from the same donor tissue pool. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.
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              Randomized clinical trial of deep lamellar keratoplasty vs penetrating keratoplasty.

              To prospectively compare the safety and efficacy of deep lamellar keratoplasty (DLKP) and penetrating keratoplasty (PKP). Prospective, randomized clinical trial. Consecutive 26 eyes of 24 patients who had stromal opacity without endothelial abnormalities were randomly assigned to either PKP or DLKP. Best-corrected visual acuity (BCVA), contrast visual acuity, glare test, intraocular pressure, corneal topography, endothelial density, and pachymetry were measured before and after surgery. Two eyes in the DLKP had rupture of the Descemet membrane and one of the eyes developed endothelial decompensation. One eye in the PKP group showed decreases in vision due to secondary glaucoma. None of the eyes developed immunologic rejection. The PKP group showed a tendency of faster recovery in BCVA than the DLKP group, but the difference was not statistically significant. Contrast visual acuity, glare test, and corneal topography did not show significant differences between the two groups. The intraocular pressure was significantly higher at 12 months in the PKP group (P =.004), but not in the DLKP group (P =.41) compared with preoperative values. While the PKP group showed progressive decrease in endothelial density over 24 months, this was not observed in the DLKP group after surgery. Difference in endothelial density at 24 months reached statistical significance (P =.04). We found that DLKP was superior to PKP in its safety such as continuous decreases of endothelium or increases in intraocular pressure. However, endothelial damage can also occur in DLKP, especially in cases of intraoperative Descemet membrane rupture. With the development of easier surgical techniques, DLKP may be a first choice of keratoplasty in most eyes without endothelial abnormalities.
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                Author and article information

                Journal
                J Ophthalmol
                J Ophthalmol
                JOP
                Journal of Ophthalmology
                Hindawi Publishing Corporation
                2090-004X
                2090-0058
                2013
                30 May 2013
                : 2013
                : 769860
                Affiliations
                1The Veneto Eye Bank Foundation, Padiglione Rama, Via Paccagnella 11, Zelarino, 30174 Venice, Italy
                2Department of Ophthalmology, Dell'Angelo Hospital, Zelarino, 30174 Venice, Italy
                Author notes

                Academic Editor: Qing Pan

                Author information
                https://orcid.org/0000-0002-5186-068X
                https://orcid.org/0000-0001-6213-1119
                https://orcid.org/0000-0003-4582-1948
                https://orcid.org/0000-0002-5459-0275
                https://orcid.org/0000-0003-3983-3328
                Article
                10.1155/2013/769860
                3683473
                23819041
                1e81be73-54bd-42b6-b05a-1151d25937a4
                Copyright © 2013 Mohit Parekh et al.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 28 February 2013
                : 30 April 2013
                : 8 May 2013
                Categories
                Review Article

                Ophthalmology & Optometry
                Ophthalmology & Optometry

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